path: root/rts/linker/PEi386.c

/* --------------------------------------------------------------------------
 * PEi386(+) specifics (Win32 targets)
 * ------------------------------------------------------------------------*/

/* The information for this linker comes from
      Microsoft Portable Executable
      and Common Object File Format Specification
      revision 8.3 February 2013

   It can be found online at:

      https://msdn.microsoft.com/en-us/windows/hardware/gg463119.aspx

   Things move, so if that fails, try searching for it via

      http://www.google.com/search?q=PE+COFF+specification

   The ultimate reference for the PE format is the Winnt.h
   header file that comes with the Platform SDKs; as always,
   implementations will drift wrt their documentation.

   A good background article on the PE format is Matt Pietrek's
   March 1994 article in Microsoft System Journal (MSJ)
   (Vol.9, No. 3): "Peering Inside the PE: A Tour of the
   Win32 Portable Executable File Format." The info in there
   has recently been updated in a two part article in
   MSDN magazine, issues Feb and March 2002,
   "Inside Windows: An In-Depth Look into the Win32 Portable
   Executable File Format"

   John Levine's book "Linkers and Loaders" contains useful
   info on PE too.

   The PE specification doesn't specify how to do the actual
   relocations. For this reason, and because both PE and ELF are
   based on COFF, the relocations for the PEi386+ code is based on
   the ELF relocations for the equivalent relocation type.

   The ELF ABI can be found at

   http://www.x86-64.org/documentation/abi.pdf

   The current code is based on version 0.99.6 - October 2013

   The current GHCi linker supports the following four object file formats:

   * PE/PE+ obj - The normal COFF_ANON_OBJ format which is generated by default
     from Windows compilers

   * PE/PE+ big-obj - The big object format COFF_ANON_BIG_OBJ which extends the
     number of sections to 2^31 and the number of symbols in each section. This
     requires a flag but all Windows compilers can produce it.

   * PE Import format - The import library format defined in the PE standard
     COFF_IMPORT_LIB and commonly has the file extension .lib

   * GNU BFD import format - The import library format defined and used by GNU
     tools and commonly has the file extension .dll.a . See note below.

   Note [The need for import libraries]
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   In its original incarnation, PE had no native support for dynamic linking.
   Let's examine how dynamic linking is now implemented. Consider a simple
   program with a reference to function and data symbols provided by a DLL:

       // myprogram.c
       #include <libfoo.h>
       int do_something() {
           libfoo_function();
           return libfoo_data;
       }

   The header file shipped with libfoo will look like the following:

       // libfoo.h
       __declspec(dllimport) int libfoo_function();
       __declspec(dllimport) int libfoo_data;

   When the C compiler is compiling myprogram.c, it will see these dllimport
   declarations and use them to produce a module definition (.def) file which
   summarizes the symbols that we expect the DLL to export. This will look like:

      EXPORTS
        libfoo_function
        libfoo_data DATA

   The C compiler will pass this file to the `dlltool` utility, which will
   generate an *import library*. The import library will contain
   placeholder symbols (with names starting with `__imp_`), along with
   instructions for the dynamic linker to fix-up these references to point to
   the "real" symbol definition.

   For historical reasons involving lack of documentation, NDAs, and (probably)
   Steve Balmer, there are two flavours of import flavours:

    * Native Windows-style import libraries. These typically bear the .lib file
      extension and encode their relocation information in the `.idata` section.
      Documentation for this format is not available
      [here](https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-library-format).
      These are handled in `checkAndLoadImportLibrary()`

    * GNU BFD-style import libraries. These typically have the .dll.a
      extension and encode the relocation information in a set of sections
      named `.idata$<N>` where `<N>` is an integer which encodes the section's
      meaning. Somewhat ironically, despite being devised in response to the
      native Windows format having no public documentation, there is no official
      documentation for this format but Note [BFD import library] attempts to
      summarize what we know.  These are handled in `ocGetNames_PEi386()`.


   Note [BFD import library]
   ~~~~~~~~~~~~~~~~~~~~~~~~~
   On Windows, compilers don't link directly to dynamic libraries.
   The reason for this is that the exports are not always by symbol, the
   Import Address Table (IAT) also allows exports by ordinal number
   or raw addresses.

   So to solve the linking issue, import libraries were added. Import libraries
   can be seen as a specification of how to link implicitly against a dynamic
   library. As a side note, import libraries are also the mechanism which
   can be used to break mutual dependencies between shared libraries and to
   implement delay loading or override the location of a shared library at
   startup.

   Linkers use these import libraries to populate the IAT of the resulting
   binary. At startup the system dynamic loader processes the IAT entries
   and populates the symbols with the correct addresses.

   Anyway, the Windows PE format specifies a simple and efficient format for
   this: It's essentially a list, saying these X symbols can be found in DLL y.
   Commonly, y is a versioned name. e.g. `liby_43.dll`. This is an artifact of
   the days when Windows did not support side-by-side assemblies. So the
   solution was to version the DLLs by renaming them to include explicit
   version numbers, and to then use the import libraries to point to the right
   version, having the linker do the leg work.

   The format in the PE specification is commonly named using the suffix .lib.
   Unfortunately, GCC/binutils decided not to implement this format, and instead
   have created their own format. This format is either named using the suffix
   .dll.a or .a depending on the tool that makes them. This format is
   undocumented. However the source of dlltool.c in binutils is pretty handy to
   understand it (see binutils/dlltool.c; grep for ".idata section description").

   To understand the implementation in GHC, this is what is important:

   The import library is generally an archive containing one object file for
   each imported symbol. In addition, there is a "head" object, which contains
   the name of the DLL which the symbols are imported from, among other things.

   The `.idata$` section group is used to hold this information. An import library
   object file will always have these section groups, but the specific
   configuration depends on what the purpose of the file is. They will also
   never have a CODE or DATA section, though depending on the tool that creates
   them they may have the section headers, which will mostly be empty.

   The import data sections consist of the following:

     * `.idata$2` contains the Import Directory Table (IDT), which contains an entry
       for each imported DLL. Each entry contains: a reference to the DLL's name
       (in `.idata$7`) and references to its entries in the ILT and IAT sections.
       This is contained in the head object.

     * `.idata$6` contains the Hint Name Table (HNT). This is a table of
       of (symbol ordinal, symbol name) pairs, which are referred to be the ILT
       and IAT as described below.

     * `.idata$5` contains the Import Address Table (IAT). This consists of an
       array of pointers (one array for each imported DLL) which the loader will
       update to point to the target symbol identified by the hint referenced by
       the corresponding ILT entry. Moreover, the IAT pointers' initial values
       also point to the corresponding HNT entry.

     * `.idata$4` contains the Import Lookup Table (ILT). This contains an array
       of references to HNT entries for each imported DLL.

     * `.idata$7` contains the names of the imported DLLs. This is contained
       in the head object.

   You have two different possible configurations:

   1) Those that define a redirection. In this case the `.idata$7` section will
      contain the name of the actual dll to load. This will be the only content
      of the section. In the symbol table, the last symbol will be the name
      used to refer to the dll in the relocation tables. This name will always
      be in the format `symbol_name_iname`, however when referred to, the format
      `_head_symbol_name` is used.

      We record this symbol early on during `ocGetNames` and load the dll and use
      the module handle as the symbol address.

   2) Symbol definitions. In this case the HNT (`.idata$6`) will contain the
      symbol to load.  This is stored in the fixed format of 2-byte ordinals
      followed by (null-terminated) symbol name. The ordinal is
      to be used when the DLL does not export symbols by name. (note: We don't
      currently support this in the runtime linker, but it's easy to add should
      it be needed). The last symbol in the symbol table of the section will
      contain the name symbol which contains the dll name to use to resolve the
      reference.

   As a technicality, this also means that the GCC format will allow us to use
   one library to store references to multiple dlls. This can't be produced by
   dlltool, but it can be combined using ar. This is an important feature
   required for dynamic linking support for GHC. So the runtime linker now
   supports this too.


   Example: Dynamic code references
   --------------------------------
   To see what such an import library looks like, let's first start with the case
   of a function (e.g. `libfoo_function` above) with bind-now semantics (lazy-loading
   will look much different). The import library will contain the following:

        .section .text
        # This stub (which Windows calls a thunk) is what calls to
        # libfoo_function will hit if the symbol isn't declared with
        # __declspec(dllimport)
        libfoo_function:
            jmp   *0x0(%rip)
            .quad __imp_libfoo_function

        .section .idata$5                               # IAT
        # This is the location which the loader will
        # update to point to the definition
        #  of libfoo_function
        __imp_libfoo_function:
            .quad hint1 - __image_base__

        .section .idata$4                               # ILT
        # This (and hint1 below) is what tells the
        # loader where __imp_libfoo_function should point
        ilt1:
            .quad hint1 - __image_base__

        .section .idata$6                               # HNT
        hint1:
            .short ORDINAL_OF_libfoo_function
            .asciiz "libfoo_function"

   To handle a reference to an IAT entry like `__imp_libfoo_function`, the GHC
   linker will (in `lookupSymbolInDLLs`) first strip off the `__imp_` prefix to
   find the name of the referenced dynamic symbol. It then resolves the
   symbol's address and allocates an `IndirectAddr` where it can place the
   address, which it will return as the resolution of the `___libfoo_function`.

   Example: Dynamic data references
   --------------------------------
   Let's now consider the import library for a data symbol. This is essentially
   equivalent to the code case, but without the need to emit a thunk:

        .section .idata$5                               # IAT
        __imp_libfoo_data:
            .quad hint2 - __image_base__

        .section .idata$4                               # ILT
        ilt2:
            .quad hint2 - __image_base__

        .section .idata$6                               # ILT
        hint2:
            .short ORDINAL_OF_libfoo_data
            .asciiz "libfoo_data"


   Note [Memory allocation]
   ~~~~~~~~~~~~~~~~~~~~~~~~
   The loading of an object begins in `preloadObjectFile`, which allocates a buffer,
   `oc->image`, into which the object file is read. It then calls `ocVerifyImage`,
   where we traverse the object file's header and populate `ObjectCode.sections`.
   Specifically, we create a Section for each of the object's sections such
   that:

     * the `.start` field points to its data in the mapped image
     * the `.size` field reflects its intended size
     * the .`info` field contains a `SectionFormatField` with other information
       from its section header entry (namely `VirtualSize`, `VirtualAddress`, and
       `Characteristics`)

   We then proceed to `ocGetNames`, where we again walk the section table header
   and determine which sections need to be mapped and how (e.g. as readable-writable or
   readable-executable). We then allocate memory for each section using the
   appropriate m32 allocator and, where necessary, copy the data from
   `section.start` (which points to the section in `oc->image`)
   into the new allocation.  Finally, `addSection()` updates the `section.start` field
   to reflect the section's new home. In addition, we also allocate space for
   the global BSS section.

   At this point we have no further need for the preloaded image buffer,
   `oc->image` and therefore free it.

   Having populated the sections, we can proceed to add the object's symbols to
   the symbol table. This is a matter of walking the object file's symbol table,
   computing the symbol's address, and calling `ghciInsertSymbolTable`.

   Finally, we enter `ocResolve`, where we resolve relocations and and allocate
   jump islands (using the m32 allocator for backing storage) as necessary.

*/

#include "Rts.h"

#if defined(x86_64_HOST_ARCH)
#define USED_IF_x86_64_HOST_ARCH    /* Nothing */
#else
#define USED_IF_x86_64_HOST_ARCH    STG_UNUSED
#endif

#if defined(mingw32_HOST_OS)

#include "RtsUtils.h"
#include "RtsSymbolInfo.h"
#include "CheckUnload.h"
#include "LinkerInternals.h"
#include "linker/PEi386.h"
#include "linker/PEi386Types.h"
#include "linker/SymbolExtras.h"

#include <windows.h>
#include <shfolder.h> /* SHGetFolderPathW */
#include <math.h>
#include <wchar.h>
#include <stdbool.h>
#include <stdint.h>

#include <inttypes.h>
#include <dbghelp.h>
#include <stdlib.h>
#include <psapi.h>

#if defined(x86_64_HOST_ARCH)
static size_t makeSymbolExtra_PEi386(
    ObjectCode* oc,
    uint64_t index,
    size_t s,
    SymbolName* symbol,
    SymType sym_type);
#endif

static void addDLLHandle(
    pathchar* dll_name,
    HINSTANCE instance);

static bool verifyCOFFHeader(
    uint16_t machine,
    IMAGE_FILE_HEADER *hdr,
    pathchar *fileName);

static bool checkIfDllLoaded(
    HINSTANCE instance);

static uint32_t getSectionAlignment(
    Section section);

static size_t getAlignedValue(
    size_t value,
    Section section);

static void releaseOcInfo(
    ObjectCode* oc);

static SymbolAddr *lookupSymbolInDLLs ( const SymbolName* lbl, ObjectCode *dependent );

const Alignments pe_alignments[] = {
  { IMAGE_SCN_ALIGN_1BYTES   , 1   },
  { IMAGE_SCN_ALIGN_2BYTES   , 2   },
  { IMAGE_SCN_ALIGN_4BYTES   , 4   },
  { IMAGE_SCN_ALIGN_8BYTES   , 8   },
  { IMAGE_SCN_ALIGN_16BYTES  , 16  },
  { IMAGE_SCN_ALIGN_32BYTES  , 32  },
  { IMAGE_SCN_ALIGN_64BYTES  , 64  },
  { IMAGE_SCN_ALIGN_128BYTES , 128 },
  { IMAGE_SCN_ALIGN_256BYTES , 256 },
  { IMAGE_SCN_ALIGN_512BYTES , 512 },
  { IMAGE_SCN_ALIGN_1024BYTES, 1024},
  { IMAGE_SCN_ALIGN_2048BYTES, 2048},
  { IMAGE_SCN_ALIGN_4096BYTES, 4096},
  { IMAGE_SCN_ALIGN_8192BYTES, 8192},
 };

const int pe_alignments_cnt = sizeof (pe_alignments) / sizeof (Alignments);
const int default_alignment = 8;

/* See Note [_iob_func symbol]
   In order to emulate __iob_func the memory location needs to point the
   location of the I/O structures in memory.  As such we need RODATA to contain
   the pointer as a redirect.  Essentially it's a DATA DLL reference.  */
const void* __rts_iob_func = (void*)&__acrt_iob_func;

void initLinker_PEi386()
{
    if (!ghciInsertSymbolTable(WSTR("(GHCi/Ld special symbols)"),
                               symhash, "__image_base__",
                               GetModuleHandleW (NULL), HS_BOOL_TRUE,
                               SYM_TYPE_CODE, NULL)) {
        barf("ghciInsertSymbolTable failed");
    }

#if defined(mingw32_HOST_OS)
    addDLLHandle(WSTR("*.exe"), GetModuleHandle(NULL));
#endif

  /* Register the cleanup routine as an exit handler,  this gives other exit handlers
     a chance to run which may need linker information.  Exit handlers are ran in
     reverse registration order so this needs to be before the linker loads anything.  */
  atexit (exitLinker_PEi386);
}

void exitLinker_PEi386()
{
}

/* A list thereof. */
static OpenedDLL* opened_dlls = NULL;

/* Adds a DLL instance to the list of DLLs in which to search for symbols. */
static void addDLLHandle(pathchar* dll_name, HINSTANCE instance) {

    /* At this point, we actually know what was loaded.
       So bail out if it's already been loaded.  */
    if (checkIfDllLoaded(instance))
    {
        return;
    }

    OpenedDLL* o_dll;
    o_dll           = stgMallocBytes( sizeof(OpenedDLL), "addDLLHandle" );
    o_dll->name     = dll_name ? pathdup(dll_name) : NULL;
    o_dll->instance = instance;
    o_dll->next     = opened_dlls;
    opened_dlls     = o_dll;

    /* Now discover the dependencies of dll_name that were
       just loaded in our process space. The reason is we have access to them
       without the user having to explicitly specify them.  */
    PIMAGE_NT_HEADERS header =
        (PIMAGE_NT_HEADERS)((BYTE *)instance +
         ((PIMAGE_DOS_HEADER)instance)->e_lfanew);
    PIMAGE_IMPORT_DESCRIPTOR imports =
        (PIMAGE_IMPORT_DESCRIPTOR)((BYTE *)instance + header->
        OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress);

    bool importTableMissing =
        header->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].Size == 0;

    if (importTableMissing) {
        return;
    }

    /* Ignore these compatibility shims.  */
    const pathchar* ms_dll = WSTR("api-ms-win-");
    const int len = wcslen(ms_dll);

    do {
        pathchar* module = mkPath((char*)(BYTE *)instance + imports->Name);
        HINSTANCE module_instance = GetModuleHandleW(module);
        if (0 != wcsncmp(module, ms_dll, len)
            && module_instance
            && !checkIfDllLoaded(module_instance))
        {
            IF_DEBUG(linker, debugBelch("Loading dependency %" PATH_FMT " -> %" PATH_FMT ".\n", dll_name, module));
            /* Now recursively load dependencies too.  */
            addDLLHandle(module, module_instance);
        }
        stgFree(module);
        imports++;
    } while (imports->Name);
}

static OpenedDLL* findLoadedDll(HINSTANCE instance)
{
    for (OpenedDLL* o_dll = opened_dlls; o_dll != NULL; o_dll = o_dll->next) {
        if (o_dll->instance == instance)
        {
            return o_dll;
        }
    }

    return NULL;
}

static bool checkIfDllLoaded(HINSTANCE instance)
{
    return findLoadedDll (instance) != NULL;
}

void freePreloadObjectFile_PEi386(ObjectCode *oc)
{
    if (oc->image) {
        stgFree (oc->image);
        oc->image = NULL;
    }

    if (oc->info) {
        /* Release the unwinder information.
           See Note [Exception Unwinding].  */
        if (oc->info->pdata) {
            if (!RtlDeleteFunctionTable (oc->info->pdata->start))
              debugBelch ("Unable to remove Exception handlers for %" PATH_FMT "\n",
                          oc->fileName);
            oc->info->xdata = NULL;
            oc->info->pdata = NULL;
        }

        if (oc->info->ch_info) {
           stgFree (oc->info->ch_info);
        }
        stgFree (oc->info);
        oc->info = NULL;
    }
}

// Free oc->info and oc->sections[i]->info.
static void releaseOcInfo(ObjectCode* oc) {
    if (!oc) return;

    if (oc->info) {
        freeInitFiniList(oc->info->init);
        freeInitFiniList(oc->info->fini);
        stgFree (oc->info->ch_info);
        stgFree (oc->info->symbols);
        stgFree (oc->info->str_tab);
        stgFree (oc->info);
        oc->info = NULL;
    }
    for (int i = 0; i < oc->n_sections; i++){
        Section *section = &oc->sections[i];
        if (section->info) {
            stgFree (section->info->name);
            if (section->info->relocs) {
                stgFree (section->info->relocs);
                section->info->relocs = NULL;
            }
            stgFree (section->info);
            section->info = NULL;
        }
    }
}

/*************
 * This function determines what kind of COFF image we are dealing with.
 * This is needed in order to correctly load and verify objects and their
 * sections.
 *************/
COFF_OBJ_TYPE getObjectType ( char* image, pathchar* fileName )
{
    /* {D1BAA1C7-BAEE-4ba9-AF20-FAF66AA4DCB8} */
    static const char header_bigobj_classid[16] =
    {
      0xC7, 0xA1, 0xBA, 0xD1,
      0xEE, 0xBA,
      0xa9, 0x4b,
      0xAF, 0x20,
      0xFA, 0xF6, 0x6A, 0xA4, 0xDC, 0xB8
    };

    WORD machine;
    COFF_OBJ_TYPE ret = COFF_UNKNOWN;
    /* First check if we have an ANON_OBJECT_HEADER signature.  */
    ANON_OBJECT_HEADER* anon = (ANON_OBJECT_HEADER*)image;
    if (   anon->Sig1 == IMAGE_FILE_MACHINE_UNKNOWN
        && anon->Sig2 == IMPORT_OBJECT_HDR_SIG2)
    {
        machine = anon->Machine;
        if (verifyCOFFHeader (machine, NULL, fileName))
        {
            switch (anon->Version)
            {
                case 0:
                    ret = COFF_IMPORT_LIB;
                    break;
                case 1:
                    ret = COFF_ANON_OBJ;
                    break;
                case 2:
                    if (memcmp (&anon->ClassID, header_bigobj_classid, 16) == 0)
                        ret = COFF_ANON_BIG_OBJ;
                    break;
                default:
                    break;
            }
        }
    } else {
        /* If it's not an ANON_OBJECT then try an image file.  */
        IMAGE_FILE_HEADER* img = (IMAGE_FILE_HEADER*)image;
        machine = img->Machine;
        if (verifyCOFFHeader (machine, img, fileName))
            ret = COFF_IMAGE;
    }
    return ret;
}

/*************
 * Retrieve common header information
 *************/
COFF_HEADER_INFO* getHeaderInfo ( ObjectCode* oc )
{
   COFF_OBJ_TYPE coff_type = getObjectType (oc->image, OC_INFORMATIVE_FILENAME(oc));

   COFF_HEADER_INFO* info
     = stgMallocBytes (sizeof(COFF_HEADER_INFO), "getHeaderInfo");
   memset (info, 0, sizeof(COFF_HEADER_INFO));
   info->type = coff_type;
   switch (coff_type)
   {
       case COFF_IMAGE:
        {
         IMAGE_FILE_HEADER* hdr = (IMAGE_FILE_HEADER*)oc->image;
         info->sizeOfHeader         = sizeof(IMAGE_FILE_HEADER);
         info->sizeOfOptionalHeader = hdr->SizeOfOptionalHeader;
         info->pointerToSymbolTable = hdr->PointerToSymbolTable;
         info->numberOfSymbols      = hdr->NumberOfSymbols;
         info->numberOfSections     = hdr->NumberOfSections;
        }
        break;
       case COFF_ANON_BIG_OBJ:
        {
         ANON_OBJECT_HEADER_BIGOBJ* hdr = (ANON_OBJECT_HEADER_BIGOBJ*)oc->image;
         info->sizeOfHeader         = sizeof(ANON_OBJECT_HEADER_BIGOBJ);
         info->sizeOfOptionalHeader = 0;
         info->pointerToSymbolTable = hdr->PointerToSymbolTable;
         info->numberOfSymbols      = hdr->NumberOfSymbols;
         info->numberOfSections     = hdr->NumberOfSections;
        }
        break;
       default:
        {
         stgFree (info);
         info = NULL;
         errorBelch ("Unknown COFF %d type in getHeaderInfo.", coff_type);
        }
        break;
   }

   return info;
}

/*************
 * Symbol utility functions
 *************/
__attribute__ ((always_inline)) inline
size_t getSymbolSize ( COFF_HEADER_INFO *info )
{
    ASSERT(info);
    switch (info->type)
    {
        case COFF_ANON_BIG_OBJ:
            return sizeof_COFF_symbol_ex;
        default:
            return sizeof_COFF_symbol_og;
    }
}

__attribute__ ((always_inline)) inline
int32_t getSymSectionNumber ( COFF_HEADER_INFO *info, COFF_symbol* sym )
{
    ASSERT(info);
    ASSERT(sym);
    switch (info->type)
    {
        case COFF_ANON_BIG_OBJ:
            return sym->ex.SectionNumber;
        default:
            return sym->og.SectionNumber;
    }
}

__attribute__ ((always_inline)) inline
uint32_t getSymValue ( COFF_HEADER_INFO *info, COFF_symbol* sym )
{
    ASSERT(info);
    ASSERT(sym);
    switch (info->type)
    {
        case COFF_ANON_BIG_OBJ:
            return sym->ex.Value;
        default:
            return sym->og.Value;
    }
}

__attribute__ ((always_inline)) inline
uint8_t getSymStorageClass ( COFF_HEADER_INFO *info, COFF_symbol* sym )
{
    ASSERT(info);
    ASSERT(sym);
    switch (info->type)
    {
        case COFF_ANON_BIG_OBJ:
            return sym->ex.StorageClass;
        default:
            return sym->og.StorageClass;
    }
}

__attribute__ ((always_inline)) inline
uint8_t getSymNumberOfAuxSymbols ( COFF_HEADER_INFO *info, COFF_symbol* sym )
{
    ASSERT(info);
    ASSERT(sym);
    switch (info->type)
    {
        case COFF_ANON_BIG_OBJ:
            return sym->ex.NumberOfAuxSymbols;
        default:
            return sym->og.NumberOfAuxSymbols;
    }
}

__attribute__ ((always_inline)) inline
uint16_t getSymType ( COFF_HEADER_INFO *info, COFF_symbol* sym )
{
    ASSERT(info);
    ASSERT(sym);
    switch (info->type)
    {
        case COFF_ANON_BIG_OBJ:
            return sym->ex.Type;
        default:
            return sym->og.Type;
    }
}

__attribute__ ((always_inline)) inline
uint8_t* getSymShortName ( COFF_HEADER_INFO *info, COFF_symbol* sym )
{
    ASSERT(info);
    ASSERT(sym);
    switch (info->type)
    {
        case COFF_ANON_BIG_OBJ:
            return sym->ex.N.ShortName;
        default:
            return sym->og.N.ShortName;
    }
}

const char *
addDLL_PEi386( pathchar *dll_name, HINSTANCE *loaded )
{
   /* ------------------- Win32 DLL loader ------------------- */

   pathchar*  buf;
   HINSTANCE  instance;

   IF_DEBUG(linker, debugBelch("addDLL; dll_name = `%" PATH_FMT "'\n", dll_name));

    /* The file name has no suffix (yet) so that we can try
       both foo.dll and foo.drv

      The documentation for LoadLibrary says:
        If no file name extension is specified in the lpFileName
        parameter, the default library extension .dll is
        appended. However, the file name string can include a trailing
        point character (.) to indicate that the module name has no
        extension. */

    size_t bufsize = pathlen(dll_name) + 10;
    buf = stgMallocBytes(bufsize * sizeof(wchar_t), "addDLL");

    /* These are ordered by probability of success and order we'd like them.  */
    const wchar_t *formats[] = { L"%ls.DLL", L"%ls.DRV", L"lib%ls.DLL", L"%ls" };
    const DWORD flags[] = { LOAD_LIBRARY_SEARCH_USER_DIRS | LOAD_LIBRARY_SEARCH_DEFAULT_DIRS, 0 };

    int cFormat, cFlag;
    int flags_start = 1; /* Assume we don't support the new API.  */

    /* Detect if newer API are available, if not, skip the first flags entry.  */
    if (GetProcAddress((HMODULE)LoadLibraryW(L"Kernel32.DLL"), "AddDllDirectory")) {
        flags_start = 0;
    }

    /* Iterate through the possible flags and formats.  */
    for (cFlag = flags_start; cFlag < 2; cFlag++)
    {
        for (cFormat = 0; cFormat < 4; cFormat++)
        {
            snwprintf(buf, bufsize, formats[cFormat], dll_name);
            instance = LoadLibraryExW(buf, NULL, flags[cFlag]);
            if (instance == NULL) {
                if (GetLastError() != ERROR_MOD_NOT_FOUND)
                {
                    goto error;
                }
            }
            else
            {
                break; /* We're done. DLL has been loaded.  */
            }
        }
    }

    /* Check if we managed to load the DLL.  */
    if (instance == NULL) {
        goto error;
    }

    addDLLHandle(buf, instance);
    if (loaded) {
        *loaded = instance;
    }
    stgFree(buf);

    return NULL;

error:
    stgFree(buf);

    char* errormsg = stgMallocBytes(sizeof(char) * 80, "addDLL_PEi386");
    snprintf(errormsg, 80, "addDLL: %" PATH_FMT " or dependencies not loaded. (Win32 error %lu)", dll_name, GetLastError());
    /* LoadLibrary failed; return a ptr to the error msg. */
    return errormsg;
}

pathchar* findSystemLibrary_PEi386( pathchar* dll_name )
{
    const unsigned int init_buf_size = 1024;
    unsigned int bufsize             = init_buf_size;
    wchar_t* result = stgMallocBytes(sizeof(wchar_t) * bufsize, "findSystemLibrary_PEi386");
    DWORD wResult   = SearchPathW(NULL, dll_name, NULL, bufsize, result, NULL);

    if (wResult > bufsize) {
        result  = realloc(result, sizeof(wchar_t) * wResult);
        wResult = SearchPathW(NULL, dll_name, NULL, wResult, result, NULL);
    }


    if (!wResult) {
        stgFree(result);
        return NULL;
    }

    return result;
}

HsPtr addLibrarySearchPath_PEi386(pathchar* dll_path)
{
    // Make sure the path is an absolute path in UNC-style to ensure that we
    // aren't subject to the MAX_PATH restriction. See #21059.
    wchar_t *abs_path = __rts_create_device_name(dll_path);

    HsPtr result = AddDllDirectory(abs_path);
    if (!result) {
        sysErrorBelch("addLibrarySearchPath: %" PATH_FMT " (Win32 error %lu)", abs_path, GetLastError());
        stgFree(abs_path);
        return NULL;
    }

    stgFree(abs_path);
    return result;
}

bool removeLibrarySearchPath_PEi386(HsPtr dll_path_index)
{
    bool result = false;

    if (dll_path_index != NULL) {
        result = RemoveDllDirectory(dll_path_index);
        // dll_path_index is now invalid, do not use it after this point.

        if (!result) {
            sysErrorBelch("removeLibrarySearchPath: (Win32 error %lu)", GetLastError());
            return false;
        }
    }

    return !result;
}


/* We assume file pointer is right at the
   beginning of COFF object.
 */
static uint32_t getSectionAlignment(
        Section section) {
   uint32_t c = section.info->props;
   for(int i = 0; i < pe_alignments_cnt; i++)
   {
       if ((c & 0xF00000) == pe_alignments[i].mask)
          return pe_alignments[i].value;
   }

   /* No alignment flag found, assume 8-byte aligned.  */
   return default_alignment;
}

/* ----------------------
 * return a value aligned to the section requirements
 */
static size_t getAlignedValue(
        size_t value, Section section) {
   uint32_t alignment = getSectionAlignment(section);
   uint32_t mask = (uint32_t)alignment - 1;
   return (size_t)((value + mask) & ~mask);
}

/* -----------------------
 * This loads import libraries following Microsoft's official standard in the PE
 * documentation. This is a smaller more efficient format which is just a list
 * of symbol name => dll.
 *
 * This function must fail gracefully and if it does, the filestream needs to
 * be reset to what it was when the function was called.
 */
bool checkAndLoadImportLibrary( pathchar* arch_name, char* member_name, FILE* f )
{
    char* image;
    static bool load_dll_warn = false;

    if (load_dll_warn) { return 0; }

    /* Based on Import Library specification. PE Spec section 7.1 */

    COFF_import_header hdr;
    size_t n;

    n = fread(&hdr, 1, sizeof_COFF_import_Header, f);
    if (n != sizeof_COFF_import_Header)  {
        errorBelch("loadImportLibrary: error whilst reading `%s' header "
                   "in `%" PATH_FMT "'\n",
                   member_name, arch_name);
        fseek(f, -(long int)sizeof_COFF_import_Header, SEEK_CUR);
        return false;
    }

    if (   hdr.Sig1 != IMAGE_FILE_MACHINE_UNKNOWN
        || hdr.Sig2 != IMPORT_OBJECT_HDR_SIG2
        || getObjectType ((char*)&hdr, arch_name) != COFF_IMPORT_LIB) {
        fseek(f, -(long int)sizeof_COFF_import_Header, SEEK_CUR);
        IF_DEBUG(linker, debugBelch("loadArchive: Object `%s` is not an import lib. Skipping...\n", member_name));
        return false;
    }

    IF_DEBUG(linker, debugBelch("loadArchive: reading %lu bytes at %ld\n", hdr.SizeOfData, ftell(f)));

    image = stgMallocBytes(hdr.SizeOfData, "checkAndLoadImportLibrary(image)");
    n = fread(image, 1, hdr.SizeOfData, f);
    if (n != hdr.SizeOfData) {
        errorBelch("loadArchive: error whilst reading `%s' header in `%" PATH_FMT "'. Did not read enough bytes.\n",
            member_name, arch_name);
        fseek(f, -(n + sizeof_COFF_import_Header), SEEK_CUR);
        return false;
    }

    char* symbol  = strtok(image, "\0");
    int symLen    = strlen(symbol) + 1;
    int nameLen   = n - symLen;
    char* dllName = stgMallocBytes(sizeof(char) * nameLen,
                                   "checkAndLoadImportLibrary(dllname)");
    dllName       = strncpy(dllName, image + symLen, nameLen);
    pathchar* dll = stgMallocBytes(sizeof(wchar_t) * nameLen,
                                   "checkAndLoadImportLibrary(dll)");
    mbstowcs(dll, dllName, nameLen);
    stgFree(dllName);

    IF_DEBUG(linker, debugBelch("loadArchive: read symbol %s from lib `%" PATH_FMT "'\n", symbol, dll));
    const char* result = addDLL(dll);

    stgFree(image);

    if (result != NULL) {
        errorBelch("Could not load `%" PATH_FMT "'. Reason: %s\n", dll, result);
        load_dll_warn = true;

        stgFree(dll);
        fseek(f, -(n + sizeof_COFF_import_Header), SEEK_CUR);
        return false;
    }

    stgFree(dll);
    return true;
}

static void
printName ( uint8_t* name, ObjectCode* oc )
{
   if (name[0]==0 && name[1]==0 && name[2]==0 && name[3]==0) {
      uint32_t strtab_offset = * (uint32_t*)(name + 4);
      debugBelch("%s",
                 oc->info->str_tab + strtab_offset - PEi386_STRTAB_OFFSET);
   } else {
      int i;
      for (i = 0; i < 8; i++) {
         if (name[i] == 0) break;
         debugBelch("%c", name[i] );
      }
   }
}


static void
copyName ( uint8_t* name, ObjectCode* oc, uint8_t* dst, int dstSize )
{
   if (name[0]==0 && name[1]==0 && name[2]==0 && name[3]==0) {
      uint32_t strtab_offset = * (uint32_t*)(name + 4);
      strncpy ((char*)dst,
               oc->info->str_tab + strtab_offset - PEi386_STRTAB_OFFSET,
               dstSize);
      dst[dstSize-1] = 0;
   } else {
      int i = 0;
      while (1) {
         if (i >= 8) break;
         if (name[i] == 0) break;
         dst[i] = name[i];
         i++;
      }
      dst[i] = 0;
   }
}


char*
get_sym_name ( uint8_t* name, ObjectCode* oc )
{
   char* newstr;
   /* If the string is longer than 8 bytes, look in the
      string table for it -- this will be correctly zero terminated.
   */
   if (name[0]==0 && name[1]==0 && name[2]==0 && name[3]==0) {
      uint32_t strtab_offset = * (uint32_t*)(name + 4);
      return oc->info->str_tab + strtab_offset - PEi386_STRTAB_OFFSET;
   }
   /* Otherwise, if shorter than 8 bytes, return the original,
      which by defn is correctly terminated.
   */
   if (name[7]==0) return (char*)name;
   /* The annoying case: 8 bytes.  Copy into a temporary
      (XXX which is never freed ...)
   */
   newstr = stgMallocBytes(9, "get_sym_name");
   ASSERT(newstr);
   strncpy (newstr, (char*)name,8);
   newstr[8] = 0;
   return newstr;
}

/* Getting the name of a section is mildly tricky, so we make a
   function for it.  Sadly, in one case we have to copy the string
   (when it is exactly 8 bytes long there's no trailing '\0'), so for
   consistency we *always* copy the string; the caller must free it
*/
char *
get_name_string (uint8_t* name, ObjectCode* oc)
{
    char *newstr;

    if (name[0]=='/') {
        int strtab_offset = strtol((char*)name+1,NULL,10)-PEi386_STRTAB_OFFSET;
        char* str = oc->info->str_tab + strtab_offset;
        int len   = strlen(str);

        newstr = stgMallocBytes(len + 1, "cstring_from_section_symbol_name");
        strncpy(newstr, str, len + 1);
        return newstr;
    }
    else
    {
        newstr = stgMallocBytes(9, "cstring_from_section_symbol_name");
        ASSERT(newstr);
        strncpy(newstr,(char*)name,8);
        newstr[8] = 0;
        return newstr;
    }
}

/* See Note [mingw-w64 name decoration scheme] */
#if !defined(x86_64_HOST_ARCH)
static void
zapTrailingAtSign ( SymbolName* sym )
{
  char* lst = strrchr (sym, '@');
  if (lst) lst[0]='\0';
}
#endif

SymbolAddr*
lookupSymbolInDLLs ( const SymbolName* lbl, ObjectCode *dependent )
{
    OpenedDLL* o_dll;
    SymbolAddr* sym;

    for (o_dll = opened_dlls; o_dll != NULL; o_dll = o_dll->next) {
        /* debugBelch("look in %ls for %s\n", o_dll->name, lbl); */

        sym = GetProcAddress(o_dll->instance, lbl+STRIP_LEADING_UNDERSCORE);
        if (sym != NULL) {
            /*debugBelch("found %s in %s\n", lbl+1,o_dll->name);*/
            return sym;
        }

        // TODO: Drop this
        /* Ticket #2283.
           Long description: http://support.microsoft.com/kb/132044
           tl;dr:
             If C/C++ compiler sees __declspec(dllimport) ... foo ...
             it generates call *__imp_foo, and __imp_foo here has exactly
             the same semantics as in __imp_foo = GetProcAddress(..., "foo")
         */
        if (sym == NULL && strncmp (lbl, "__imp_", 6) == 0) {
            sym = GetProcAddress(o_dll->instance,
                                 lbl + 6 + STRIP_LEADING_UNDERSCORE);
            if (sym != NULL) {
                SymbolAddr** indirect = m32_alloc(dependent->rw_m32, sizeof(SymbolAddr*), 8);
                if (indirect == NULL) {
                    barf("lookupSymbolInDLLs: Failed to allocation indirection");
                }
                *indirect = sym;
                IF_DEBUG(linker,
                  debugBelch("warning: %s from %S is linked instead of %s\n",
                             lbl+6+STRIP_LEADING_UNDERSCORE, o_dll->name, lbl));
                return (void*) indirect;
               }
        }

        sym = GetProcAddress(o_dll->instance, lbl);
        if (sym != NULL) {
            /*debugBelch("found %s in %s\n", lbl,o_dll->name);*/
            return sym;
           }
    }
    return NULL;
}

static bool
verifyCOFFHeader ( uint16_t machine, IMAGE_FILE_HEADER *hdr,
                   pathchar *fileName )
{
#if defined(i386_HOST_ARCH)
   if (machine != IMAGE_FILE_MACHINE_I386) {
      errorBelch("%" PATH_FMT ": Not a x86 PE file.", fileName);
      return false;
   }
#elif defined(x86_64_HOST_ARCH)
   if (machine != IMAGE_FILE_MACHINE_AMD64) {
      errorBelch("%" PATH_FMT ": Not a x86_64 PE+ file.", fileName);
      return false;
   }
#else
   errorBelch("PE/PE+ not supported on this arch.");
#endif

   if (!hdr)
     return true;

   if (hdr->SizeOfOptionalHeader != 0) {
      errorBelch("%" PATH_FMT ": PE/PE+ with nonempty optional header",
                 fileName);
      return 0;
   }
   if ( (hdr->Characteristics & IMAGE_FILE_EXECUTABLE_IMAGE) ||
        (hdr->Characteristics & IMAGE_FILE_DLL             ) ||
        (hdr->Characteristics & IMAGE_FILE_SYSTEM          ) ) {
      errorBelch("%" PATH_FMT ": Not a PE/PE+ object file", fileName);
      return false;
   }
   if ( (hdr->Characteristics & IMAGE_FILE_BYTES_REVERSED_HI)) {
      errorBelch("%" PATH_FMT ": Invalid PE/PE+ word size or endianness: %d",
                 fileName,
                 (int)(hdr->Characteristics));
      return false;
   }
   return true;
}

bool
ocVerifyImage_PEi386 ( ObjectCode* oc )
{
   COFF_HEADER_INFO *info = getHeaderInfo (oc);

   /* If the header could not be read, then don't process the ObjectCode.
      This the case when the ObjectCode has been partially freed.  */
   if (!info)
     return false;

   uint32_t i, noRelocs;
   COFF_section* sectab;
   COFF_symbol*  symtab;
   uint8_t*      strtab;

   sectab = (COFF_section*) (
               ((uint8_t*)(oc->image))
               + info->sizeOfHeader + info->sizeOfOptionalHeader
            );
   symtab = (COFF_symbol*) (
               ((uint8_t*)(oc->image))
               + info->pointerToSymbolTable
            );
   strtab = ((uint8_t*)symtab)
            + info->numberOfSymbols * getSymbolSize (info);

   /* .BSS Section is initialized in ocGetNames_PEi386
      but we need the Sections array initialized here already. */
   Section *sections;
   sections = (Section*)stgCallocBytes(
       sizeof(Section),
       info->numberOfSections + 1, /* +1 for the global BSS section see ocGetNames_PEi386 */
       "ocVerifyImage_PEi386(sections)");
   oc->sections = sections;
   oc->n_sections = info->numberOfSections + 1;
   oc->info       = stgCallocBytes (sizeof(struct ObjectCodeFormatInfo), 1,
                                    "ocVerifyImage_PEi386(info)");
   oc->info->init          = NULL;
   oc->info->fini          = NULL;
   oc->info->ch_info       = info;

   /* Copy the tables over from object-file. Copying these allows us to
      simplify the indexing and to release the object file immediately after
      this step as all information we need would be in available.  After
      loading we can also release everything in the info structure as it won't
      be needed again further freeing up memory.
      COFF_symbol is a union type, so we have to "adjust" the array to be able
      to access it using normal subscript notation. This eliminates the complex
      indexing later on.  */
   uint32_t s_symbols = info->numberOfSymbols * sizeof(COFF_symbol);
   uint32_t sym_size  = getSymbolSize (info);
   oc->info->symbols
     = stgMallocBytes (s_symbols, "ocVerifyImage_PEi386(oc->info->symbols)");
   for (i = 0; i < info->numberOfSymbols; i++)
     memcpy (oc->info->symbols+i, (char*)symtab + sym_size * i, sym_size);

   uint32_t n_strtab = (*(uint32_t*)strtab) - PEi386_STRTAB_OFFSET;
   oc->info->str_tab
     = stgMallocBytes (n_strtab, "ocVerifyImage_PEi386(oc->info->str_tab)");
   memcpy (oc->info->str_tab, strtab + PEi386_STRTAB_OFFSET, n_strtab);

   /* Initialize the Sections */
   for (i = 0; i < info->numberOfSections; i++) {
       uint32_t relocs_offset;
       COFF_section* sectab_i
           = (COFF_section*)
           myindex(sizeof_COFF_section, sectab, i);

      Section *section = &sections[i];
      /* Calculate the start of the section data.  */
      section->start = oc->image + sectab_i->PointerToRawData;
      section->size  = sectab_i->SizeOfRawData;
      section->info  = stgCallocBytes (sizeof(struct SectionFormatInfo), 1,
                                       "ocVerifyImage_PEi386(section.info)");
      section->info->name        = get_name_string (sectab_i->Name, oc);
      section->info->alignment   = getSectionAlignment (*section);
      section->info->props       = sectab_i->Characteristics;
      section->info->virtualSize = sectab_i->Misc.VirtualSize;
      section->info->virtualAddr = sectab_i->VirtualAddress;

      COFF_reloc* reltab
        = (COFF_reloc*) (oc->image + sectab_i->PointerToRelocations);

      if (section->info->props & IMAGE_SCN_LNK_NRELOC_OVFL ) {
        /* If the relocation field (a short) has overflowed, the
         * real count can be found in the first reloc entry.
         *
         * See Section 4.1 (last para) of the PE spec (rev6.0).
         */
        COFF_reloc* rel = (COFF_reloc*)
                           myindex ( sizeof_COFF_reloc, reltab, 0 );
        noRelocs = rel->VirtualAddress - 1;
        relocs_offset = 1;
      } else {
        noRelocs = sectab_i->NumberOfRelocations;
        relocs_offset = 0;
      }

      section->info->noRelocs = noRelocs;
      section->info->relocs   = NULL;
      if (noRelocs > 0) {
        section->info->relocs
            = stgMallocBytes (noRelocs * sizeof (COFF_reloc),
                            "ocVerifyImage_PEi386(section->info->relocs)");
        memcpy (section->info->relocs, reltab + relocs_offset,
                noRelocs * sizeof (COFF_reloc));
      }
   }

   /* Initialize the last section's info field which contains the .bss
      section, the .info of which will be initialized by ocGetNames. Discard the
      .info that we computed above. */
  stgFree(sections[info->numberOfSections].info);
  sections[info->numberOfSections].info = NULL;

   /* No further verification after this point; only debug printing.  */
   i = 0;
   IF_DEBUG(linker, i=1);
   if (i == 0) return true;

   debugBelch("sectab offset = %" FMT_SizeT "\n",
              ((uint8_t*)sectab) - ((uint8_t*)oc->image) );
   debugBelch("symtab offset = %" FMT_SizeT "\n",
              ((uint8_t*)symtab) - ((uint8_t*)oc->image) );
   debugBelch("strtab offset = %" FMT_SizeT "\n",
              ((uint8_t*)strtab) - ((uint8_t*)oc->image) );

   debugBelch("\n" );
   if (info->type == COFF_IMAGE)
    {
      IMAGE_FILE_HEADER* hdr = (IMAGE_FILE_HEADER*)oc->image;
      debugBelch( "COFF Type:         IMAGE_FILE_HEADER\n");
      debugBelch( "Machine:           0x%x\n",
                  (uint32_t)(hdr->Machine) );
      debugBelch( "# sections:        %d\n",
                  (uint32_t)(hdr->NumberOfSections) );
      debugBelch( "time/date:         0x%x\n",
                  (uint32_t)(hdr->TimeDateStamp) );
      debugBelch( "symtab offset:     %d\n",
                  (uint32_t)(hdr->PointerToSymbolTable) );
      debugBelch( "# symbols:         %d\n",
                  (uint32_t)(hdr->NumberOfSymbols) );
      debugBelch( "sz of opt hdr:     %d\n",
                  (uint32_t)(hdr->SizeOfOptionalHeader) );
      debugBelch( "characteristics:   0x%x\n",
                  (uint32_t)(hdr->Characteristics) );
    }
   else if (info->type == COFF_ANON_BIG_OBJ)
    {
      ANON_OBJECT_HEADER_BIGOBJ* hdr = (ANON_OBJECT_HEADER_BIGOBJ*)oc->image;
      debugBelch( "COFF Type:         ANON_OBJECT_HEADER_BIGOBJ\n");
      debugBelch( "Machine:           0x%x\n",
                  (uint32_t)(hdr->Machine) );
      debugBelch( "# sections:        %d\n",
                  (uint32_t)(hdr->NumberOfSections) );
      debugBelch( "time/date:         0x%x\n",
                  (uint32_t)(hdr->TimeDateStamp) );
      debugBelch( "symtab offset:     %d\n",
                  (uint32_t)(hdr->PointerToSymbolTable) );
      debugBelch( "# symbols:         %d\n",
                  (uint32_t)(hdr->NumberOfSymbols) );
    }
   else
    {
      debugBelch( "COFF Type:         UNKNOWN\n");
      return false;
    }

   i = 0;
   IF_DEBUG(linker_verbose, i=1);
   if (i == 0) return true;

   /* Print the section table. */
   debugBelch("\n" );
   for (i = 0; i < info->numberOfSections; i++) {
      COFF_section* sectab_i
         = (COFF_section*)
           myindex ( sizeof_COFF_section, sectab, i );
      Section section = sections[i];
      debugBelch(
                "\n"
                "section %d\n"
                "     name `",
                i
              );
      printName (sectab_i->Name, oc);
      debugBelch(
                "'\n"
                "    vsize %lu\n"
                "    vaddr %lu\n"
                "  data sz %lu\n"
                " data off 0x%p\n"
                "  num rel %hu\n"
                "  off rel %lu\n"
                "  ptr raw 0x%lx\n"
                "    align %u\n"
                " data adj %zu\n",
                sectab_i->Misc.VirtualSize,
                sectab_i->VirtualAddress,
                sectab_i->SizeOfRawData,
                section.start,
                sectab_i->NumberOfRelocations,
                sectab_i->PointerToRelocations,
                sectab_i->PointerToRawData,
                getSectionAlignment (section),
                getAlignedValue (section.size, section)
              );

      noRelocs = section.info->noRelocs;
      for (uint32_t j = 0; j < noRelocs; j++) {
         COFF_reloc rel = section.info->relocs[j];
         debugBelch(
                   "        type 0x%-4x   vaddr 0x%-8lx   name `",
                   rel.Type,
                   rel.VirtualAddress );
         COFF_symbol sym = oc->info->symbols[rel.SymbolTableIndex];
         printName (getSymShortName (info, &sym), oc);
         debugBelch("'\n" );
      }

      debugBelch("\n" );
   }
   debugBelch("\n" );
   debugBelch("string table has size 0x%x\n", n_strtab + PEi386_STRTAB_OFFSET);
   debugBelch("---START of string table---\n");
   for (i = 4; i < n_strtab; i++) {
      if (strtab[i] == 0)
         debugBelch("\n"); else
         debugBelch("%c", strtab[i] );
   }
   debugBelch("--- END  of string table---\n");

   debugBelch("\n" );

   for (i = 0; i < info->numberOfSymbols; i++) {
      COFF_symbol* symtab_i = &oc->info->symbols[i];
      debugBelch(
                "symbol %d\n"
                "     name `",
                i
              );
      printName (getSymShortName (info, symtab_i), oc);
      debugBelch(
                "'\n"
                "    value 0x%x\n"
                "   1+sec# %d\n"
                "     type 0x%x\n"
                "   sclass 0x%x\n"
                "     nAux %d\n",
                getSymValue (info, symtab_i),
                getSymSectionNumber (info, symtab_i),
                getSymType (info, symtab_i),
                getSymStorageClass (info, symtab_i),
                getSymNumberOfAuxSymbols (info, symtab_i)
              );
      i += getSymNumberOfAuxSymbols (info, symtab_i);
   }

   debugBelch("\n" );
   return true;
}

bool
ocGetNames_PEi386 ( ObjectCode* oc )
{
   bool has_code_section = false;
   COFF_HEADER_INFO *info = oc->info->ch_info;

   /* Copy section information into the ObjectCode. */

   for (unsigned int i = 0; i < info->numberOfSections; i++) {
      /* By default consider all section as CODE or DATA,
         which means we want to load them. */
      SectionKind kind = SECTIONKIND_CODE_OR_RODATA;
      Section *section  = &oc->sections[i];
      uint32_t alignment = getSectionAlignment(*section);

      // These will be computed below and determine how we will handle the
      // section
      size_t sz = section->size;
      bool do_copy = true;
      bool do_zero = false;

      IF_DEBUG(linker, debugBelch("section name = %s (%x)\n", section->info->name, section->info->props ));

      /* The PE file section flag indicates whether the section
         contains code or data. */
      if (section->info->props & IMAGE_SCN_CNT_CODE) {
          has_code_section = has_code_section || section->size > 0;
          kind = SECTIONKIND_CODE_OR_RODATA;
       }

      if (section->info->props & IMAGE_SCN_MEM_WRITE) {
          kind = SECTIONKIND_RWDATA;
      }

      /* Check next if it contains any uninitialized data */
      if (section->info->props & IMAGE_SCN_CNT_UNINITIALIZED_DATA) {
          kind = SECTIONKIND_RWDATA;
          do_copy = false;
      }

      /* Finally check if it can be discarded.
         This will also ignore .debug sections */
      if (   section->info->props & IMAGE_SCN_MEM_DISCARDABLE
          || section->info->props & IMAGE_SCN_LNK_REMOVE) {
          kind = SECTIONKIND_OTHER;
      }

      if (0==strncmp(".ctors", section->info->name, 6)) {
          /* N.B. a compilation unit may have more than one .ctor section; we
           * must run them all. See #21618 for a case where this happened */
          uint32_t prio;
          if (sscanf(section->info->name, ".ctors.%d", &prio) != 1) {
              // Sections without an explicit priority are run last
              prio = 0;
          }
          // .ctors/.dtors are executed in reverse order: higher numbers are
          // executed first
          prio = 0xffff - prio;
          addInitFini(&oc->info->init, &oc->sections[i], INITFINI_CTORS, prio);
          kind = SECTIONKIND_INIT_ARRAY;
      }

      if (0==strncmp(".dtors", section->info->name, 6)) {
          uint32_t prio;
          if (sscanf(section->info->name, ".dtors.%d", &prio) != 1) {
              // Sections without an explicit priority are run last
              prio = 0;
          }
          // .ctors/.dtors are executed in reverse order: higher numbers are
          // executed first
          prio = 0xffff - prio;
          addInitFini(&oc->info->fini, &oc->sections[i], INITFINI_DTORS, prio);
          kind = SECTIONKIND_FINI_ARRAY;
      }

      if (   0 == strncmp(".stab"     , section->info->name, 5 )
          || 0 == strncmp(".stabstr"  , section->info->name, 8 )
          || 0 == strncmp(".debug"    , section->info->name, 6 )
          || 0 == strncmp(".rdata$zzz", section->info->name, 10))
          kind = SECTIONKIND_DEBUG;

      /* Exception Unwind information. See Note [Exception Unwinding].  */
      if (0 == strncmp(".xdata"    , section->info->name, 6 )) {
          kind = SECTIONKIND_EXCEPTION_UNWIND;
      }

      /* Exception handler tables, See Note [Exception Unwinding].  */
      if (0 == strncmp(".pdata"    , section->info->name, 6 )) {
          kind = SECTIONKIND_EXCEPTION_TABLE;
      }

      if (0==strncmp(".idata", section->info->name, 6)) {
          kind = SECTIONKIND_IMPORT;
      }


      /* See Note [BFD import library].  */
      if (0==strncmp(".idata$7", section->info->name, 8)) {
          kind = SECTIONKIND_BFD_IMPORT_LIBRARY_HEAD;
      }

      if (0==strncmp(".idata$6", section->info->name, 8)) {
          kind = SECTIONKIND_BFD_IMPORT_LIBRARY;
      }

      /* Allocate space for any (local, anonymous) .bss sections. */
      if (0==strncmp(".bss", section->info->name, 4)) {
        /* sof 10/05: the PE spec text isn't too clear regarding what
         * the SizeOfRawData field is supposed to hold for object
         * file sections containing just uninitialized data -- for executables,
         * it is supposed to be zero; unclear what it's supposed to be
         * for object files. However, VirtualSize is guaranteed to be
         * zero for object files, which definitely suggests that SizeOfRawData
         * will be non-zero (where else would the size of this .bss section be
         * stored?) Looking at the COFF_section info for incoming object files,
         * this certainly appears to be the case.
         *
         * => I suspect we've been incorrectly handling .bss sections in
         * (relocatable) object files up until now. This turned out to bite us
         * with ghc-6.4.1's use of gcc-3.4.x, which has started to emit
         * initially-zeroed-out local 'static' variable decls into the .bss
         * section. (The specific function in Q which triggered this is
         * libraries/base/cbits/dirUtils.c:__hscore_getFolderPath())
         *
         * TODO: check if this comment is still relevant.
         */
        if (section->info->virtualSize == 0 && section->size == 0) {
          IF_DEBUG(linker_verbose, debugBelch("skipping empty .bss section\n"));
          continue;
        }

        /* This is a non-empty .bss section.
            Allocate zeroed space for it */
        kind = SECTIONKIND_RWDATA;
        do_zero = true;
        do_copy = false;
        IF_DEBUG(linker_verbose, debugBelch("BSS anon section\n"));
      }

      CHECK(section->size == 0 || section->info->virtualSize == 0);
      if (sz < section->info->virtualSize) {
          sz = section->info->virtualSize;
      }

      // Ignore these section types
      if (kind == SECTIONKIND_OTHER || sz == 0) {
        continue;
      }

      // Allocate memory for the section.
      uint8_t *start;
      if (section->info->props & IMAGE_SCN_MEM_WRITE) {
          start = m32_alloc(oc->rw_m32, sz, alignment);
      } else {
          start = m32_alloc(oc->rx_m32, sz, alignment);
      }
      if (!start) {
        barf("Could not allocate any heap memory from private heap (requested %" FMT_SizeT " bytes).",
             sz);
      }

      if (do_copy) {
        memcpy(start, section->start, sz);
      } else if (do_zero) {
        memset(start, 0, sz);
      }

      addSection(section, kind, SECTION_NOMEM, start, sz, 0, 0, 0);
      addProddableBlock(oc, oc->sections[i].start, sz);
   }

   /* Copy exported symbols into the ObjectCode. */

   oc->n_symbols = info->numberOfSymbols;
   oc->symbols   = stgCallocBytes(sizeof(Symbol_t), oc->n_symbols,
                                  "ocGetNames_PEi386(oc->symbols)");

   /* Work out the size of the global BSS section */
   StgWord globalBssSize = 0;
   for (unsigned int i=0; i < info->numberOfSymbols; i++) {
      COFF_symbol* sym = &oc->info->symbols[i];
      if (getSymSectionNumber (info, sym) == IMAGE_SYM_UNDEFINED
           && getSymValue (info, sym) > 0
           && getSymStorageClass (info, sym) != IMAGE_SYM_CLASS_SECTION) {
           globalBssSize += getSymValue (info, sym);
      }
      i += getSymNumberOfAuxSymbols (info, sym);
   }

   /* Allocate BSS space */
   SymbolAddr* bss = NULL;
   if (globalBssSize > 0) {
       bss = m32_alloc(oc->rw_m32, globalBssSize, 16);
       if (bss == NULL) {
           barf("ocGetNames_PEi386: Failed to allocate global bss section");
       }
       addSection(&oc->sections[oc->n_sections-1],
                  SECTIONKIND_RWDATA, SECTION_MALLOC,
                  bss, globalBssSize, 0, 0, 0);
       IF_DEBUG(linker_verbose, debugBelch("bss @ %p %" FMT_Word "\n", bss, globalBssSize));
       addProddableBlock(oc, bss, globalBssSize);
   } else {
       addSection(&oc->sections[oc->n_sections-1],
                  SECTIONKIND_OTHER, SECTION_NOMEM, NULL, 0, 0, 0, 0);
   }

   /* At this point we're done with oc->image and all relevant memory have
      been copied. Release it to free up the memory.  */
   stgFree (oc->image);
   oc->image = NULL;

   for (unsigned int i = 0; i < (uint32_t)oc->n_symbols; i++) {
      COFF_symbol* sym = &oc->info->symbols[i];

      int32_t secNumber = getSymSectionNumber (info, sym);
      uint32_t symValue = getSymValue (info, sym);
      uint8_t symStorageClass = getSymStorageClass (info, sym);

      SymbolAddr *addr = NULL;
      bool isWeak = false;
      SymbolName *sname = get_sym_name (getSymShortName (info, sym), oc);
      Section *section = secNumber > 0 ? &oc->sections[secNumber-1] : NULL;

      SymType type;
      switch (getSymType(oc->info->ch_info, sym)) {
      case 0x00: type = SYM_TYPE_DATA; break;
      case 0x20: type = SYM_TYPE_CODE; break;
      default:
          debugBelch("Invalid symbol type: 0x%x\n", getSymType(oc->info->ch_info, sym));
          return 1;
      }

      if (   secNumber != IMAGE_SYM_UNDEFINED
          && secNumber > 0
          && section
          && section->kind != SECTIONKIND_BFD_IMPORT_LIBRARY) {
         /* This symbol is global and defined, viz, exported */
         /* for IMAGE_SYMCLASS_EXTERNAL
                && !IMAGE_SYM_UNDEFINED,
            the address of the symbol is:
                address of relevant section + offset in section
         */
         if (symStorageClass == IMAGE_SYM_CLASS_EXTERNAL
            || (   symStorageClass == IMAGE_SYM_CLASS_STATIC
                && section->info->props & IMAGE_SCN_LNK_COMDAT)
            ) {
                addr   = (SymbolAddr*)((size_t)section->start + symValue);
                isWeak = section->info->props & IMAGE_SCN_LNK_COMDAT;
         }
      }
      else if (symStorageClass == IMAGE_SYM_CLASS_WEAK_EXTERNAL) {
          isWeak = true;
          CHECK(getSymNumberOfAuxSymbols (info, sym) == 1);
          CHECK(symValue == 0);
          COFF_symbol_aux_weak_external *aux = (COFF_symbol_aux_weak_external *) (sym+1);
          COFF_symbol* targetSym = &oc->info->symbols[aux->TagIndex];
          int32_t targetSecNumber = getSymSectionNumber (info, targetSym);
          Section *targetSection = targetSecNumber > 0 ? &oc->sections[targetSecNumber-1] : NULL;
          addr = (SymbolAddr*) ((size_t) targetSection->start + getSymValue(info, targetSym));
      }
      else if (  secNumber == IMAGE_SYM_UNDEFINED && symValue > 0) {
         /* This symbol isn't in any section at all, ie, global bss.
            Allocate zeroed space for it from the BSS section */
          addr = bss;
          bss = (SymbolAddr*)((StgWord)bss + (StgWord)symValue);
          IF_DEBUG(linker_verbose, debugBelch("bss symbol @ %p %u\n", addr, symValue));
      }
      else if (section && section->kind == SECTIONKIND_BFD_IMPORT_LIBRARY) {
          setImportSymbol(oc, sname);
          // There is nothing that we need to resolve in this object since we
          // will never call the import stubs in its text section
          oc->status = OBJECT_DONT_RESOLVE;

          IF_DEBUG(linker_verbose, debugBelch("import symbol %s\n", sname));
      }
      else if (secNumber > 0
               && section
               && section->kind == SECTIONKIND_BFD_IMPORT_LIBRARY_HEAD) {
          /* This is an Gnu BFD import section. We should load the dll and lookup
             the symbols.
             See Note [BFD import library].  */
          char* dllName = section->start;
          if (strlen(dllName) == 0 || dllName[0] == 0 || has_code_section)
              continue;

          pathchar* dirName = pathdir(oc->fileName);
          HsPtr token       = addLibrarySearchPath(dirName);
          stgFree(dirName);

          sym   = &oc->info->symbols[oc->n_symbols-1];
          sname = get_sym_name (getSymShortName (info, sym), oc);

          IF_DEBUG(linker_verbose,
                   debugBelch("loading symbol `%s' from dll: '%ls' => `%s'\n",
                              sname, oc->fileName, dllName));

          pathchar* dll = mkPath(dllName);
          HINSTANCE dllInstance = 0;
          const char* result = addDLL_PEi386(dll, &dllInstance);
          removeLibrarySearchPath(token);
          stgFree(dll);

          if (result != NULL || dllInstance == 0) {
              errorBelch("Could not load `%s'. Reason: %s\n",
                         (char*)dllName, result);
              return false;
          }

          /* Set the _dll_iname symbol to the dll's handle.  */
          addr = (SymbolAddr*)dllInstance;

          /* the symbols are named <name>_iname when defined, but are named
             _head_<name> when looked up. (Ugh. thanks GCC.) So correct it when
             stored so we don't have to correct it each time when retrieved.  */
          int size  = strlen(sname)+1;
          char *tmp = stgMallocBytes(size * sizeof(char),
                                     "ocGetNames_PEi386");
          strncpy (tmp, sname, size);
          char *pos = strstr(tmp, "_iname");
          /* drop anything after the name. There are some inconsistencies with
             whitespaces trailing the name.  */
          if (pos) pos[0] = '\0';
          int start = 0;

          /* msys2 project's import lib builder has some inconsistent name
             mangling. Their names start with _ or __ yet they drop this when
             making the _head_ symbol. So do the same.  */
          while (tmp[start]=='_')
            start++;

          snprintf (sname, size, "_head_%s", tmp+start);
          sname[size-start]='\0';
          stgFree(tmp);
          sname = strdup (sname);
          if (!ghciInsertSymbolTable(oc->fileName, symhash, sname,
                                     addr, false, type, oc))
               return false;

          break;
      }

      if ((addr != NULL || isWeak)
         && (!section || (section && section->kind != SECTIONKIND_IMPORT))) {
         /* debugBelch("addSymbol %p `%s' Weak:%lld \n", addr, sname, isWeak); */
         sname = strdup (sname);
         IF_DEBUG(linker_verbose, debugBelch("addSymbol %p `%s'\n", addr, sname));
         ASSERT(i < (uint32_t)oc->n_symbols);
         oc->symbols[i].name = sname;
         oc->symbols[i].addr = addr;
         oc->symbols[i].type = type;
         if (isWeak) {
             setWeakSymbol(oc, sname);
         }

         if (! ghciInsertSymbolTable(oc->fileName, symhash, sname, addr,
                                     isWeak, type, oc))
             return false;
      } else {
          /* We're skipping the symbol, but if we ever load this
          object file we'll want to skip it then too. */
          oc->symbols[i].name = NULL;
          oc->symbols[i].addr = NULL;
      }

      i += getSymNumberOfAuxSymbols (info, sym);
   }

   return true;
}

#if defined(x86_64_HOST_ARCH)

static size_t
makeSymbolExtra_PEi386( ObjectCode* oc, uint64_t index STG_UNUSED, size_t s, char* symbol STG_UNUSED, SymType type )
{
    SymbolExtra *extra;

    if (type == SYM_TYPE_CODE) {
        // jmp *-14(%rip)
        extra = m32_alloc(oc->rx_m32, sizeof(SymbolExtra), 8);
        CHECK(extra);
        extra->addr = (uint64_t)s;
        static uint8_t jmp[] = { 0xFF, 0x25, 0xF2, 0xFF, 0xFF, 0xFF };
        memcpy(extra->jumpIsland, jmp, 6);
        IF_DEBUG(linker_verbose, debugBelch("makeSymbolExtra(code): %s -> %p\n", symbol, &extra->jumpIsland));
        return (size_t)&extra->jumpIsland;
    } else if (type == SYM_TYPE_INDIRECT_DATA) {
        extra = m32_alloc(oc->rw_m32, sizeof(SymbolExtra), 8);
        CHECK(extra);
        void *v = *(void**) s;
        extra->addr = (uint64_t)v;
        IF_DEBUG(linker_verbose, debugBelch("makeSymbolExtra(data): %s -> %p\n", symbol, &extra->addr));
        return (size_t)&extra->addr;
    } else {
        extra = m32_alloc(oc->rw_m32, sizeof(SymbolExtra), 8);
        CHECK(extra);
        extra->addr = (uint64_t)s;
        IF_DEBUG(linker_verbose, debugBelch("makeSymbolExtra(indirect-data): %s -> %p\n", symbol, &extra->addr));
        return (size_t)&extra->addr;
    }
}

void ocProtectExtras(ObjectCode* oc STG_UNUSED) { }

#endif /* x86_64_HOST_ARCH */

bool
ocResolve_PEi386 ( ObjectCode* oc )
{
   uint64_t    A;
   size_t      S;
   SymbolAddr* pP;

   unsigned int i;
   uint32_t j, noRelocs;

   /* ToDo: should be variable-sized?  But is at least safe in the
      sense of buffer-overrun-proof. */
   uint8_t symbol[1000];
    /* debugBelch("resolving for %"PATH_FMT "\n", oc->fileName); */

   /* Such libraries have been partially freed and can't be resolved.  */
   if (oc->status == OBJECT_DONT_RESOLVE)
     return 1;

   COFF_HEADER_INFO *info = oc->info->ch_info;
   uint32_t numberOfSections = info->numberOfSections;

   for (i = 0; i < numberOfSections; i++) {
      Section section = oc->sections[i];

      /* Ignore sections called which contain stabs debugging information. */
      if (section.kind == SECTIONKIND_DEBUG)
         continue;

      noRelocs = section.info->noRelocs;
      for (j = 0; j < noRelocs; j++) {
         COFF_symbol* sym;
         COFF_reloc* reloc = &section.info->relocs[j];

         /* the location to patch */
         pP = (SymbolAddr*)(
                   (uintptr_t)section.start
                 + (uintptr_t)reloc->VirtualAddress
                 - (uintptr_t)section.info->virtualAddr
              );
         /* the existing contents of pP */
         A = *(uint32_t*)pP;
         /* the symbol to connect to */
         uint64_t symIndex = reloc->SymbolTableIndex;
         sym = &oc->info->symbols[symIndex];

         SymType sym_type;

         IF_DEBUG(linker_verbose,
                  debugBelch(
                            "reloc sec %2d num %3d:  P=%p, type 0x%-4x   "
                            "vaddr 0x%-8lx   name `",
                            i, j, pP,
                            reloc->Type,
                            reloc->VirtualAddress );
                            printName (getSymShortName (info, sym), oc);
                  debugBelch("'\n" ));

         if (getSymStorageClass (info, sym) == IMAGE_SYM_CLASS_STATIC) {
            Section section = oc->sections[getSymSectionNumber (info, sym)-1];
            S = ((size_t)(section.start))
              + ((size_t)(getSymValue (info, sym)));
         } else {
            copyName ( getSymShortName (info, sym), oc, symbol,
                       sizeof(symbol)-1 );
            S = (size_t) lookupDependentSymbol( (char*)symbol, oc, &sym_type );
            if ((void*)S == NULL) {
                errorBelch(" | %" PATH_FMT ": unknown symbol `%s'", oc->fileName, symbol);
                releaseOcInfo (oc);
                return false;
            }
         }
         IF_DEBUG(linker_verbose, debugBelch("S=%zx\n", S));

         /* All supported relocations write at least 4 bytes */
         checkProddableBlock(oc, pP, 4);
         switch (reloc->Type) {
#if defined(i386_HOST_ARCH)
            case IMAGE_REL_I386_DIR32:
            case IMAGE_REL_I386_DIR32NB:
               *(uint32_t *)pP = S + A;
               break;
            case IMAGE_REL_I386_REL32:
               /* Tricky.  We have to insert a displacement at
                  pP which, when added to the PC for the _next_
                  insn, gives the address of the target (S).
                  Problem is to know the address of the next insn
                  when we only know pP.  We assume that this
                  literal field is always the last in the insn,
                  so that the address of the next insn is pP+4
                  -- hence the constant 4.
                  Also I don't know if A should be added, but so
                  far it has always been zero.

                  SOF 05/2005: 'A' (old contents of *pP) have been observed
                  to contain values other than zero (the 'wx' object file
                  that came with wxhaskell-0.9.4; dunno how it was compiled..).
                  So, add displacement to old value instead of asserting
                  A to be zero. Fixes wxhaskell-related crashes, and no other
                  ill effects have been observed.

                  Update: the reason why we're seeing these more elaborate
                  relocations is due to a switch in how the NCG compiles SRTs
                  and offsets to them from info tables. SRTs live in .(ro)data,
                  while info tables live in .text, causing GAS to emit REL32/DISP32
                  relocations with non-zero values. Adding the displacement is
                  the right thing to do.
               */
               *(uint32_t *)pP = ((uint32_t)S) + A - ((uint32_t)(size_t)pP) - 4;
               break;
#elif defined(x86_64_HOST_ARCH)
            case 1: /* R_X86_64_64 (ELF constant 1) - IMAGE_REL_AMD64_ADDR64 (PE constant 1) */
               {
                   uint64_t A;
                   checkProddableBlock(oc, pP, 8);
                   A = *(uint64_t*)pP;
                   *(uint64_t *)pP = S + A;
                   break;
               }
            case 2: /* R_X86_64_32 (ELF constant 10) - IMAGE_REL_AMD64_ADDR32 (PE constant 2) */
            case 3: /* IMAGE_REL_AMD64_ADDR32NB (PE constant 3) */
            case 17: /* R_X86_64_32S ELF constant, no PE mapping. See note [ELF constant in PE file] */
               {
                   uint64_t v;
                   v = S + A;

                   /* If IMAGE_REL_AMD64_ADDR32NB then subtract the image base.  */
                   if (reloc->Type == 3)
                     v -= (uint64_t) GetModuleHandleW(NULL);

                   // N.B. in the case of the sign-extended relocations we must ensure that v
                   // fits in a signed 32-bit value. See #15808.
                   if (((int64_t) v > (int64_t) INT32_MAX) || ((int64_t) v < (int64_t) INT32_MIN)) {
                       copyName (getSymShortName (info, sym), oc,
                                 symbol, sizeof(symbol)-1);
                       S = makeSymbolExtra_PEi386(oc, symIndex, S, (char *)symbol, sym_type);
                       /* And retry */
                       v = S + A;

                       /* If IMAGE_REL_AMD64_ADDR32NB then subtract the image base.  */
                       if (reloc->Type == 3)
                         v -= (uint64_t) GetModuleHandleW(NULL);

                       if (((int64_t) v > (int64_t) INT32_MAX) || ((int64_t) v < (int64_t) INT32_MIN)) {
                           barf("IMAGE_REL_AMD64_ADDR32[NB]: High bits are set in 0x%zx for %s",
                                v, (char *)symbol);
                       }
                   }
                   *(uint32_t *)pP = (uint32_t)v;
                   break;
               }
            case 4: /* R_X86_64_PC32 (ELF constant 2) - IMAGE_REL_AMD64_REL32 (PE constant 4) */
               {
                   intptr_t v;
                   v = S + (int32_t)A - ((intptr_t)pP) - 4;
                   if ((v > (int64_t) INT32_MAX) || (v < (int64_t) INT32_MIN)) {
                       /* Make the trampoline then */
                       copyName (getSymShortName (info, sym),
                                 oc, symbol, sizeof(symbol)-1);
                       S = makeSymbolExtra_PEi386(oc, symIndex, S, (char *)symbol, sym_type);
                       /* And retry */
                       v = S + (int32_t)A - ((intptr_t)pP) - 4;
                       if ((v > (int64_t) INT32_MAX) || (v < (int64_t) INT32_MIN)) {
                           barf("IMAGE_REL_AMD64_REL32: High bits are set in 0x%zx for %s",
                                v, (char *)symbol);
                       }
                   }
                   *(uint32_t *)pP = (uint32_t)v;
                   break;
               }
#endif
            default:
               debugBelch("%" PATH_FMT ": unhandled PEi386 relocation type %d\n",
                     oc->fileName, reloc->Type);
               releaseOcInfo (oc);
               return false;
         }

      }

      /* Register the exceptions inside this OC.
         See Note [Exception Unwinding].  */
      if (section.kind == SECTIONKIND_EXCEPTION_TABLE) {
          oc->info->pdata = &oc->sections[i];
#if defined(x86_64_HOST_ARCH)
          unsigned numEntries = section.size / sizeof(RUNTIME_FUNCTION);
          if (numEntries == 0)
            continue;

          /* Now register the exception handler for the range and point it
             to the unwind data.  */
          if (!RtlAddFunctionTable (section.start, numEntries, (uintptr_t) GetModuleHandleW(NULL))) {
            sysErrorBelch("Unable to register Exception handler for %p for "
                          "section %s in %" PATH_FMT " (Win32 error %lu)",
                          section.start, section.info->name, oc->fileName,
                          GetLastError());
            releaseOcInfo (oc);
            return false;
          }
#endif /* x86_64_HOST_ARCH.  */
      } else if (section.kind == SECTIONKIND_EXCEPTION_UNWIND) {
          oc->info->xdata = &oc->sections[i];
      }
   }

   // We now have no more need of info->ch_info and info->symbols.
   stgFree(oc->info->ch_info);
   oc->info->ch_info = NULL;
   stgFree(oc->info->symbols);
   oc->info->symbols = NULL;

   IF_DEBUG(linker, debugBelch("completed %" PATH_FMT "\n", oc->fileName));
   return true;
}

/*
  Note [ELF constant in PE file]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  For some reason, the PE files produced by GHC contain a linux
  relocation constant 17 (0x11) in the object files. As far as I (Phyx-) can tell
  this constant doesn't seem like it's coming from GHC, or at least I could not find
  anything in the .s output that GHC produces which specifies the relocation type.

  This leads me to believe that this is a bug in GAS. However because this constant is
  there we must deal with it. This is done by mapping it to the equivalent in behaviour PE
  relocation constant 0x03.

  See #9907
*/

/*
  Note [Exception Unwinding]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~

  Exception Unwinding on Windows is handled using two named sections.

  .pdata: Exception registration tables.

  The .pdata section contains an array of function table entries (of type
  RUNTIME_FUNCTION) that are used for exception handling.  The entries must be
  sorted according to the function addresses (the first field in each
  structure) before being emitted into the final image.  It is pointed to by
  the exception table entry in the image data directory. For x64 each entry
  contains:

  Offset    Size    Field              Description
  0         4       Begin Address      The RVA of the corresponding function.
  4         4       End Address        The RVA of the end of the function.
  8         4       Unwind Information The RVA of the unwind information.

  Note that these are RVAs even after being resolved by the linker, they are
  however ImageBase relative rather than PC relative.  These are typically
  filled in by an ADDR32NB relocation.  On disk the section looks like:

    Function Table #6 (4)

            Begin     End       Info

    00000000 00000000  000001A1  00000000
    0000000C 000001A1  000001BF  00000034
    00000018 000001BF  00000201  00000040
    00000024 00000201  0000021F  0000004C

    RELOCATIONS #6
                                                    Symbol    Symbol
    Offset    Type              Applied To         Index     Name
    --------  ----------------  -----------------  --------  ------
    00000000  ADDR32NB                   00000000         E  .text
    00000004  ADDR32NB                   000001A1         E  .text
    00000008  ADDR32NB                   00000000        16  .xdata
    0000000C  ADDR32NB                   000001A1         E  .text
    00000010  ADDR32NB                   000001BF         E  .text
    00000014  ADDR32NB                   00000034        16  .xdata
    00000018  ADDR32NB                   000001BF         E  .text
    0000001C  ADDR32NB                   00000201         E  .text
    00000020  ADDR32NB                   00000040        16  .xdata
    00000024  ADDR32NB                   00000201         E  .text
    00000028  ADDR32NB                   0000021F         E  .text
    0000002C  ADDR32NB                   0000004C        16  .xdata

  This means that if we leave it up to the relocation processing to
  do the work we don't need to do anything special here. Note that
  every single function will have an entry in this table regardless
  whether they have an unwind code or not.  The reason for this is
  that unwind handlers can be chained, and such another function
  may have registered an overlapping region.

  .xdata: Exception unwind codes.

  This section contains an array of entries telling the unwinder how
  to do unwinding.  They are pointed to by the .pdata table enteries
  from the Info field.  Each entry is very complicated but for now
  what is important is that the addresses are resolved by the relocs
  for us.

  Once we have resolved .pdata and .xdata we can simply pass the
  content of .pdata on to RtlAddFunctionTable and the OS will do
  the rest.  When we're unloading the object we have to unregister
  them using RtlDeleteFunctionTable.
*/

bool
ocRunInit_PEi386 ( ObjectCode *oc )
{
    if (oc && oc->info && oc->info->init) {
        return runInit(&oc->info->init);
    }
    return true;
}

bool ocRunFini_PEi386( ObjectCode *oc )
{
    if (oc && oc->info && oc->info->fini) {
        return runFini(&oc->info->fini);
    }
    return true;
}

SymbolAddr *lookupSymbol_PEi386(SymbolName *lbl, ObjectCode *dependent, SymType *type)
{
    RtsSymbolInfo *pinfo;

    if (!ghciLookupSymbolInfo(symhash, lbl, &pinfo)) {
        IF_DEBUG(linker, debugBelch("lookupSymbol: symbol '%s' not found\n", lbl));

        SymbolAddr* sym;

/* See Note [mingw-w64 name decoration scheme] */
#if !defined(x86_64_HOST_ARCH)
        zapTrailingAtSign ( lbl );
#endif
        if (type) {
            // Unfortunately we can only assume that this is the case. Ideally
            // the user would have given us an import library, which would allow
            // us to determine the symbol type precisely.
            *type = SYM_TYPE_CODE;
        }
        sym = lookupSymbolInDLLs(lbl, dependent);
        return sym; // might be NULL if not found
    } else {
        if (type) *type = pinfo->type;

        if (pinfo && pinfo->owner && isSymbolImport (pinfo->owner, lbl))
        {
            /* See Note [BFD import library].  */
            HINSTANCE dllInstance = (HINSTANCE)lookupDependentSymbol(pinfo->value, dependent, type);
            if (!dllInstance && pinfo->value)
               return pinfo->value;

            if (!dllInstance)
            {
               errorBelch("Unable to load import dll symbol `%s'. "
                          "No _iname symbol.", lbl);
               return NULL;
            }
            IF_DEBUG(linker,
               debugBelch("indexing import %s => %s using dll instance %p\n",
                   lbl, (char*)pinfo->value, dllInstance));
            pinfo->value = GetProcAddress((HMODULE)dllInstance, lbl);
            clearImportSymbol (pinfo->owner, lbl);
            return pinfo->value;
        } else {
            if (dependent) {
                // Add dependent as symbol's owner's dependency
                ObjectCode *owner = pinfo->owner;
                if (owner) {
                    // TODO: what does it mean for a symbol to not have an owner?
                    insertHashSet(dependent->dependencies, (W_)owner);
                }
            }
            return loadSymbol(lbl, pinfo);
        }
    }
}

/* -----------------------------------------------------------------------------
 * Debugging operations.
 */

typedef struct _SymX { SymbolName* name; uintptr_t loc; } SymX;

static int comp (const void * elem1, const void * elem2)
{
    SymX f = *((SymX*)elem1);
    SymX s = *((SymX*)elem2);
    if (f.loc > s.loc) return  1;
    if (f.loc < s.loc) return -1;
    return 0;
}

pathchar*
resolveSymbolAddr_PEi386 (pathchar* buffer, int size,
                          SymbolAddr* symbol, uintptr_t* top ){
    SYMBOL_INFO sym;
    ZeroMemory (&sym, sizeof(SYMBOL_INFO));
    sym.MaxNameLen = sizeof(char) * 1024;

    DWORD64 uDisplacement = 0;
    HANDLE hProcess = GetCurrentProcess();
    ObjectCode* obj = NULL;
    uintptr_t start, end;
    *top = 0;

    pathprintf (buffer, size, WSTR("0x%" PRIxPTR), symbol);

    if (SymFromAddr (hProcess, (uintptr_t)symbol, &uDisplacement, &sym))
    {
      /* Try using Windows symbols.  */
      wcscat (buffer, WSTR(" "));
      pathchar* name = mkPath (sym.Name);
      wcscat (buffer, name);
      stgFree (name);
      if (uDisplacement != 0)
      {
        int64_t displacement = (int64_t)uDisplacement;
        pathchar s_disp[50];
        if (displacement < 0)
          pathprintf ((pathchar*)s_disp, 50, WSTR("-%ld"), -displacement);
        else
          pathprintf ((pathchar*)s_disp, 50, WSTR("+%ld"), displacement);

        wcscat (buffer, s_disp);
      }
    }
    else
    {
      /* Try to calculate from information inside the rts.  */
      uintptr_t loc = (uintptr_t)symbol;
      for (ObjectCode* oc = objects; oc; oc = oc->next) {
          for (int i = 0; i < oc->n_sections; i++) {
              Section section = oc->sections[i];
              start = (uintptr_t)section.start;
              end   = start + section.size;
              if (loc > start && loc <= end)
              {
                  wcscat (buffer, WSTR(" "));
                  if (oc->archiveMemberName)
                  {
                      wcscat (buffer, oc->archiveMemberName);
                  }
                  else
                  {
                      wcscat (buffer, oc->fileName);
                  }
                  pathchar s_disp[50];
                  pathprintf (s_disp, 50, WSTR("+0x%" PRIxPTR), loc - start);
                  wcscat (buffer, s_disp);
                  obj = oc;
                  goto exit_loop;
              }
          }
      }

      /* If we managed to make it here, we must not have any symbols nor be
         dealing with code we've linked. The only thing left is an internal
         segfault or one in a dynamic library. So let's enumerate the module
         address space.  */
      HMODULE *hMods = NULL;
      DWORD cbNeeded;
      EnumProcessModules (hProcess, hMods, 0, &cbNeeded);
      hMods = stgMallocBytes (cbNeeded, "resolveSymbolAddr_PEi386");
      if (EnumProcessModules (hProcess, hMods, cbNeeded, &cbNeeded))
      {
        uintptr_t loc = (uintptr_t)symbol;
        MODULEINFO info;
        for (uint32_t i = 0; i < cbNeeded / sizeof(HMODULE); i++) {
           ZeroMemory (&info, sizeof (MODULEINFO));
           if (GetModuleInformation (hProcess, hMods[i], &info,
                                     sizeof(MODULEINFO)))
           {
             uintptr_t start = (uintptr_t)info.lpBaseOfDll;
             uintptr_t end   = start + info.SizeOfImage;
             if (loc >= start && loc < end)
             {
                /* Hoera, finally found some information.  */
                pathchar tmp[MAX_PATH];
                if (GetModuleFileNameExW (hProcess, hMods[i], tmp, MAX_PATH))
                {
                  wcscat (buffer, WSTR(" "));
                  wcscat (buffer, tmp);
                  pathprintf (tmp, MAX_PATH, WSTR("+0x%" PRIxPTR), loc - start);
                  wcscat (buffer, tmp);
                }
                break;
             }
           }
        }
      }

      stgFree(hMods);
    }

    /* Finally any file/line number.  */
    IMAGEHLP_LINE64 lineInfo = {0};
    DWORD dwDisplacement = 0;
  exit_loop:
    if (SymGetLineFromAddr64(hProcess, (uintptr_t)symbol, &dwDisplacement,
                             &lineInfo))
    {
      /* Try using Windows symbols.  */
      pathchar s_line[512];
      pathprintf ((pathchar*) s_line, 512, WSTR("   %ls (%lu)"),
                  lineInfo.FileName, lineInfo.LineNumber);
      wcscat (buffer, s_line);
      if (dwDisplacement != 0)
      {
        pathprintf ((pathchar*) s_line, 512, WSTR(" +%lu byte%s"),
                    dwDisplacement,
                    (dwDisplacement == 1 ? WSTR("") : WSTR("s")));
      }
      wcscat (buffer, s_line);
    }
    else if (obj)
    {
      /* Try to calculate from information inside the rts.  */
      SymX* locs = stgCallocBytes (sizeof(SymX), obj->n_symbols,
                                   "resolveSymbolAddr");
      int blanks = 0;
      for (int i = 0; i < obj->n_symbols; i++) {
          SymbolName* sym = obj->symbols[i].name;
          if (sym == NULL)
            {
               blanks++;
               continue;
            }
          RtsSymbolInfo* a = NULL;
          ghciLookupSymbolInfo(symhash, sym, &a);
          if (a) {
              SymX sx = {0};
              sx.name = sym;
              sx.loc  = (uintptr_t)a->value;
              locs[i] = sx;
          }
      }
      qsort (locs, obj->n_symbols, sizeof (SymX), comp);
      uintptr_t key  = (uintptr_t)symbol;
      SymX* res = NULL;

      for (int x = blanks; x < obj->n_symbols; x++) {
          if (x < (obj->n_symbols -1)) {
              if (locs[x].loc >= key && key < locs[x+1].loc) {
                res = &locs[x];
                break;
              }
          }
          else
          {
              if (locs[x].loc >= key) {
                  res = &locs[x];
                  break;
                }
          }
      }

      if (res) {
          pathchar s_disp[512];
          *top = (uintptr_t)res->loc;
          pathprintf ((pathchar*)s_disp, 512,
                      WSTR("\n\t\t (%s+0x%" PRIxPTR ")"),
                      res->name, res->loc - key);
          wcscat (buffer, s_disp);
      }
      stgFree (locs);
    }

    return buffer;
}
#endif /* mingw32_HOST_OS */