diff options
Diffstat (limited to 'winsup/cygwin/fork.cc')
| -rw-r--r-- | winsup/cygwin/fork.cc | 751 |
1 files changed, 751 insertions, 0 deletions
diff --git a/winsup/cygwin/fork.cc b/winsup/cygwin/fork.cc new file mode 100644 index 00000000000..7639a621d47 --- /dev/null +++ b/winsup/cygwin/fork.cc @@ -0,0 +1,751 @@ +/* fork.cc + + Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002 Red Hat, Inc. + +This file is part of Cygwin. + +This software is a copyrighted work licensed under the terms of the +Cygwin license. Please consult the file "CYGWIN_LICENSE" for +details. */ + +#include "winsup.h" +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <stdarg.h> +#include <errno.h> +#include "security.h" +#include "path.h" +#include "fhandler.h" +#include "dtable.h" +#include "cygerrno.h" +#include "sigproc.h" +#include "pinfo.h" +#include "cygheap.h" +#include "child_info.h" +#define NEED_VFORK +#include "perthread.h" +#include "perprocess.h" +#include "dll_init.h" +#include "sync.h" +#include "shared_info.h" +#include "cygmalloc.h" +#include "cygthread.h" + +#ifdef DEBUGGING +static int npid; +static int npid_max; +static pid_t fork_pids[100]; +#endif + +/* Timeout to wait for child to start, parent to init child, etc. */ +/* FIXME: Once things stabilize, bump up to a few minutes. */ +#define FORK_WAIT_TIMEOUT (300 * 1000) /* 300 seconds */ + +#define dll_data_start &_data_start__ +#define dll_data_end &_data_end__ +#define dll_bss_start &_bss_start__ +#define dll_bss_end &_bss_end__ + +void +per_thread::set (void *s) +{ + if (s == PER_THREAD_FORK_CLEAR) + { + tls = TlsAlloc (); + s = NULL; + } + TlsSetValue (get_tls (), s); +} + +static void +stack_base (child_info_fork &ch) +{ + MEMORY_BASIC_INFORMATION m; + memset (&m, 0, sizeof m); + if (!VirtualQuery ((LPCVOID) &m, &m, sizeof m)) + system_printf ("couldn't get memory info, %E"); + + ch.stacktop = m.AllocationBase; + ch.stackbottom = (LPBYTE) m.BaseAddress + m.RegionSize; + ch.stacksize = (DWORD) ch.stackbottom - (DWORD) &m; + debug_printf ("bottom %p, top %p, stack %p, size %d, reserve %d", + ch.stackbottom, ch.stacktop, &m, ch.stacksize, + (DWORD) ch.stackbottom - (DWORD) ch.stacktop); +} + +/* Copy memory from parent to child. + The result is a boolean indicating success. */ + +static int +fork_copy (PROCESS_INFORMATION &pi, const char *what, ...) +{ + va_list args; + char *low; + int pass = 0; + + va_start (args, what); + + while ((low = va_arg (args, char *))) + { + char *high = va_arg (args, char *); + DWORD todo = wincap.chunksize () ?: high - low; + char *here; + + for (here = low; here < high; here += todo) + { + DWORD done = 0; + if (here + todo > high) + todo = high - here; + int res = WriteProcessMemory (pi.hProcess, here, here, todo, &done); + debug_printf ("child handle %p, low %p, high %p, res %d", pi.hProcess, + low, high, res); + if (!res || todo != done) + { + if (!res) + __seterrno (); + /* If this happens then there is a bug in our fork + implementation somewhere. */ + system_printf ("%s pass %d failed, %p..%p, done %d, windows pid %u, %E", + what, pass, low, high, done, pi.dwProcessId); + goto err; + } + } + + pass++; + } + + debug_printf ("done"); + return 1; + + err: + TerminateProcess (pi.hProcess, 1); + set_errno (EAGAIN); + return 0; +} + +/* Wait for child to finish what it's doing and signal us. + We don't want to wait forever here.If there's a problem somewhere + it'll hang the entire system (since all forks are mutex'd). If we + time out, set errno = EAGAIN and hope the app tries again. */ +static int +sync_with_child (PROCESS_INFORMATION &pi, HANDLE subproc_ready, + BOOL hang_child, const char *s) +{ + /* We also add the child process handle to the wait. If the child fails + to initialize (eg. because of a missing dll). Then this + handle will become signalled. This stops a *looong* timeout wait. + */ + HANDLE w4[2]; + + debug_printf ("waiting for child. reason: %s, hang_child %d", s, + hang_child); + w4[1] = pi.hProcess; + w4[0] = subproc_ready; + DWORD rc = WaitForMultipleObjects (2, w4, FALSE, FORK_WAIT_TIMEOUT); + + if (rc == WAIT_OBJECT_0 || + WaitForSingleObject (subproc_ready, 0) == WAIT_OBJECT_0) + /* That's ok */; + else if (rc == WAIT_FAILED || rc == WAIT_TIMEOUT) + { + if (rc != WAIT_FAILED) + system_printf ("WaitForMultipleObjects timed out"); + else + system_printf ("WaitForMultipleObjects failed, %E"); + set_errno (EAGAIN); + syscall_printf ("-1 = fork(), WaitForMultipleObjects failed"); + TerminateProcess (pi.hProcess, 1); + return 0; + } + else + { + /* Child died. Clean up and exit. */ + DWORD errcode; + GetExitCodeProcess (pi.hProcess, &errcode); + /* Fix me. This is not enough. The fork should not be considered + * to have failed if the process was essentially killed by a signal. + */ + if (errcode != STATUS_CONTROL_C_EXIT) + { + system_printf ("child %d(%p) died before initialization with status code %p", + pi.dwProcessId, pi.hProcess, errcode); + system_printf ("*** child state %s", s); +#ifdef DEBUGGING + abort (); +#endif + } + set_errno (EAGAIN); + syscall_printf ("Child died before subproc_ready signalled"); + return 0; + } + + debug_printf ("child signalled me"); + return 1; +} + +static int +resume_child (PROCESS_INFORMATION &pi, HANDLE forker_finished) +{ + SetEvent (forker_finished); + debug_printf ("signalled child"); + return 1; +} + +/* Notify parent that it is time for the next step. + Note that this has to be a macro since the parent may be messing with + our stack. */ +static void __stdcall +sync_with_parent (const char *s, bool hang_self) +{ + debug_printf ("signalling parent: %s", s); + /* Tell our parent we're waiting. */ + if (!SetEvent (fork_info->subproc_ready)) + api_fatal ("fork child - SetEvent for %s failed, %E", s); + if (hang_self) + { + HANDLE h = fork_info->forker_finished; + /* Wait for the parent to fill in our stack and heap. + Don't wait forever here. If our parent dies we don't want to clog + the system. If the wait fails, we really can't continue so exit. */ + DWORD psync_rc = WaitForSingleObject (h, FORK_WAIT_TIMEOUT); + debug_printf ("awake"); + switch (psync_rc) + { + case WAIT_TIMEOUT: + api_fatal ("WFSO timed out for %s", s); + break; + case WAIT_FAILED: + if (GetLastError () == ERROR_INVALID_HANDLE && + WaitForSingleObject (fork_info->forker_finished, 1) != WAIT_FAILED) + break; + api_fatal ("WFSO failed for %s, fork_finished %p, %E", s, + fork_info->forker_finished); + break; + default: + debug_printf ("no problems"); + break; + } + } +} + +static int __stdcall +fork_child (HANDLE& hParent, dll *&first_dll, bool& load_dlls) +{ + debug_printf ("child is running. pid %d, ppid %d, stack here %p", + myself->pid, myself->ppid, __builtin_frame_address (0)); + + /* Restore the inheritance state as in parent + Don't call setuid here! The flags are already set. */ + if (cygheap->user.impersonated) + { + debug_printf ("Impersonation of child, token: %d", cygheap->user.token); + if (cygheap->user.token == INVALID_HANDLE_VALUE) + RevertToSelf (); // probably not needed + else if (!ImpersonateLoggedOnUser (cygheap->user.token)) + system_printf ("Impersonate for forked child failed: %E"); + } + + sync_with_parent ("after longjmp.", TRUE); + sigproc_printf ("hParent %p, child 1 first_dll %p, load_dlls %d", hParent, + first_dll, load_dlls); + +#ifdef DEBUGGING + char c; + if (GetEnvironmentVariable ("FORKDEBUG", &c, 1)) + try_to_debug (); + char buf[80]; + /* This is useful for debugging fork problems. Use gdb to attach to + the pid reported here. */ + if (GetEnvironmentVariable ("CYGWIN_FORK_SLEEP", buf, sizeof (buf))) + { + small_printf ("Sleeping %d after fork, pid %u\n", atoi (buf), GetCurrentProcessId ()); + Sleep (atoi (buf)); + } +#endif + + /* If we've played with the stack, stacksize != 0. That means that + fork() was invoked from other than the main thread. Make sure that + when the "main" thread exits it calls do_exit, like a normal process. + Exit with a status code of 0. */ + if (fork_info->stacksize) + { + ((DWORD *)fork_info->stackbottom)[-17] = (DWORD)do_exit; + ((DWORD *)fork_info->stackbottom)[-15] = (DWORD)0; + } + + set_file_api_mode (current_codepage); + + MALLOC_CHECK; + + if (fixup_mmaps_after_fork (hParent)) + api_fatal ("recreate_mmaps_after_fork_failed"); + + + MALLOC_CHECK; + + /* If we haven't dynamically loaded any dlls, just signal + the parent. Otherwise, load all the dlls, tell the parent + that we're done, and wait for the parent to fill in the. + loaded dlls' data/bss. */ + if (!load_dlls) + { + cygheap->fdtab.fixup_after_fork (hParent); + ProtectHandleINH (hParent); + sync_with_parent ("performed fork fixup.", FALSE); + } + else + { + dlls.load_after_fork (hParent, first_dll); + cygheap->fdtab.fixup_after_fork (hParent); + ProtectHandleINH (hParent); + sync_with_parent ("loaded dlls", TRUE); + } + + ForceCloseHandle (hParent); + (void) ForceCloseHandle1 (fork_info->subproc_ready, subproc_ready); + (void) ForceCloseHandle1 (fork_info->forker_finished, forker_finished); + + if (fixup_shms_after_fork ()) + api_fatal ("recreate_shm areas after fork failed"); + + pinfo_fixup_after_fork (); + signal_fixup_after_fork (); + + /* Set thread local stuff to zero. Under Windows 95/98 this is sometimes + non-zero, for some reason. + FIXME: There is a memory leak here after a fork. */ + for (per_thread **t = threadstuff; *t; t++) + if ((*t)->clear_on_fork ()) + (*t)->set (); + + pthread::atforkchild (); + wait_for_sigthread (); + cygbench ("fork-child"); + return 0; +} + +static void +slow_pid_reuse (HANDLE h) +{ + static NO_COPY HANDLE last_fork_procs[8] = {0}; + static NO_COPY unsigned nfork_procs = 0; + + if (nfork_procs >= (sizeof (last_fork_procs) / sizeof (last_fork_procs [0]))) + nfork_procs = 0; + /* Keep a list of handles to forked processes sitting around to prevent + Windows from reusing the same pid n times in a row. Having the same pids + close in succesion confuses bash. Keeping a handle open will stop + windows from reusing the same pid. */ + if (last_fork_procs[nfork_procs]) + ForceCloseHandle1 (last_fork_procs[nfork_procs], fork_stupidity); + if (DuplicateHandle (hMainProc, h, hMainProc, &last_fork_procs[nfork_procs], + 0, FALSE, DUPLICATE_SAME_ACCESS)) + ProtectHandle1 (last_fork_procs[nfork_procs], fork_stupidity); + else + { + last_fork_procs[nfork_procs] = NULL; + system_printf ("couldn't create last_fork_proc, %E"); + } + nfork_procs++; +} + +static int __stdcall +fork_parent (HANDLE& hParent, dll *&first_dll, + bool& load_dlls, void *stack_here, child_info_fork &ch) +{ + HANDLE subproc_ready, forker_finished; + DWORD rc; + PROCESS_INFORMATION pi = {0, NULL, 0, 0}; + + pthread::atforkprepare (); + + subproc_init (); + + int c_flags = GetPriorityClass (hMainProc) /*| + CREATE_NEW_PROCESS_GROUP*/; + STARTUPINFO si = {0, NULL, NULL, NULL, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, NULL, NULL, NULL, NULL}; + + /* If we don't have a console, then don't create a console for the + child either. */ + HANDLE console_handle = CreateFile ("CONOUT$", GENERIC_WRITE, + FILE_SHARE_WRITE, &sec_none_nih, + OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, + NULL); + + if (console_handle != INVALID_HANDLE_VALUE) + CloseHandle (console_handle); + else + c_flags |= DETACHED_PROCESS; + + /* Some file types (currently only sockets) need extra effort in the + parent after CreateProcess and before copying the datastructures + to the child. So we have to start the child in suspend state, + unfortunately, to avoid a race condition. */ + if (cygheap->fdtab.need_fixup_before ()) + c_flags |= CREATE_SUSPENDED; + + /* Create an inheritable handle to pass to the child process. This will + allow the child to duplicate handles from the parent to itself. */ + hParent = NULL; + if (!DuplicateHandle (hMainProc, hMainProc, hMainProc, &hParent, 0, 1, + DUPLICATE_SAME_ACCESS)) + { + system_printf ("couldn't create handle to myself for child, %E"); + return -1; + } + + /* Remember the address of the first loaded dll and decide + if we need to load dlls. We do this here so that this + information will be available in the parent and, when + the stack is copied, in the child. */ + first_dll = dlls.start.next; + load_dlls = dlls.reload_on_fork && dlls.loaded_dlls; + + /* This will help some of the confusion. */ + fflush (stdout); + + subproc_ready = CreateEvent (&sec_all, FALSE, FALSE, NULL); + if (subproc_ready == NULL) + { + CloseHandle (hParent); + system_printf ("unable to allocate subproc_ready event, %E"); + return -1; + } + forker_finished = CreateEvent (&sec_all, FALSE, FALSE, NULL); + if (forker_finished == NULL) + { + CloseHandle (hParent); + CloseHandle (subproc_ready); + system_printf ("unable to allocate forker_finished event, %E"); + return -1; + } + + ProtectHandleINH (subproc_ready); + ProtectHandleINH (forker_finished); + + init_child_info (PROC_FORK, &ch, 1, subproc_ready); + + ch.forker_finished = forker_finished; + + stack_base (ch); + + si.cb = sizeof (STARTUPINFO); + si.lpReserved2 = (LPBYTE)&ch; + si.cbReserved2 = sizeof (ch); + + /* Remove impersonation */ + if (cygheap->user.issetuid ()) + RevertToSelf (); + + ch.parent = hParent; +#ifdef DEBUGGING + if (npid_max) + { + for (int pass = 0; pass < 2; pass++) + { + pid_t pid; + while ((pid = fork_pids[npid++])) + if (!pinfo (pid)) + { + ch.cygpid = pid; + goto out; + } + npid = 0; + } + } + out: +#endif + + char sa_buf[1024]; + PSECURITY_ATTRIBUTES sec_attribs = sec_user_nih (sa_buf); + syscall_printf ("CreateProcess (%s, %s, 0, 0, 1, %x, 0, 0, %p, %p)", + myself->progname, myself->progname, c_flags, &si, &pi); + __malloc_lock (); + void *newheap; + newheap = cygheap_setup_for_child (&ch, cygheap->fdtab.need_fixup_before ()); + rc = CreateProcess (myself->progname, /* image to run */ + myself->progname, /* what we send in arg0 */ + sec_attribs, + sec_attribs, + TRUE, /* inherit handles from parent */ + c_flags, + NULL, /* environment filled in later */ + 0, /* use current drive/directory */ + &si, + &pi); + + CloseHandle (hParent); + + if (!rc) + { + __seterrno (); + syscall_printf ("CreateProcessA failed, %E"); + ForceCloseHandle (subproc_ready); + ForceCloseHandle (forker_finished); + /* Restore impersonation */ + if (cygheap->user.issetuid ()) + ImpersonateLoggedOnUser (cygheap->user.token); + cygheap_setup_for_child_cleanup (newheap, &ch, 0); + return -1; + } + + /* Fixup the parent datastructure if needed and resume the child's + main thread. */ + if (!cygheap->fdtab.need_fixup_before ()) + cygheap_setup_for_child_cleanup (newheap, &ch, 0); + else + { + cygheap->fdtab.fixup_before_fork (pi.dwProcessId); + cygheap_setup_for_child_cleanup (newheap, &ch, 1); + ResumeThread (pi.hThread); + } + +#ifdef DEBUGGING + pinfo forked ((ch.cygpid != 1 ? ch.cygpid : cygwin_pid (pi.dwProcessId)), 1); +#else + pinfo forked (cygwin_pid (pi.dwProcessId), 1); +#endif + + /* Initialize things that are done later in dll_crt0_1 that aren't done + for the forkee. */ + strcpy (forked->progname, myself->progname); + + /* Restore impersonation */ + if (cygheap->user.issetuid ()) + ImpersonateLoggedOnUser (cygheap->user.token); + + ProtectHandle (pi.hThread); + /* Protect the handle but name it similarly to the way it will + be called in subproc handling. */ + ProtectHandle1 (pi.hProcess, childhProc); + + /* Fill in fields in the child's process table entry. */ + forked->hProcess = pi.hProcess; + forked->dwProcessId = pi.dwProcessId; + forked->copysigs (myself); + + /* Hopefully, this will succeed. The alternative to doing things this + way is to reserve space prior to calling CreateProcess and then fill + it in afterwards. This requires more bookkeeping than I like, though, + so we'll just do it the easy way. So, terminate any child process if + we can't actually record the pid in the internal table. */ + if (!forked.remember ()) + { + TerminateProcess (pi.hProcess, 1); + set_errno (EAGAIN); + goto cleanup; + } + + slow_pid_reuse (pi.hProcess); + + /* Wait for subproc to initialize itself. */ + if (!sync_with_child (pi, subproc_ready, TRUE, "waiting for longjmp")) + goto cleanup; + + /* CHILD IS STOPPED */ + debug_printf ("child is alive (but stopped)"); + + /* Initialize, in order: data, bss, heap, stack, dll data, dll bss + Note: variables marked as NO_COPY will not be copied + since they are placed in a protected segment. */ + + + MALLOC_CHECK; + rc = fork_copy (pi, "user/cygwin data", + user_data->data_start, user_data->data_end, + user_data->bss_start, user_data->bss_end, + cygheap->user_heap.base, cygheap->user_heap.ptr, + stack_here, ch.stackbottom, + dll_data_start, dll_data_end, + dll_bss_start, dll_bss_end, NULL); + + __malloc_unlock (); + MALLOC_CHECK; + if (!rc) + goto cleanup; + + /* Now fill data/bss of any DLLs that were linked into the program. */ + for (dll *d = dlls.istart (DLL_LINK); d; d = dlls.inext ()) + { + debug_printf ("copying data/bss of a linked dll"); + if (!fork_copy (pi, "linked dll data/bss", d->p.data_start, d->p.data_end, + d->p.bss_start, d->p.bss_end, + NULL)) + goto cleanup; + } + + /* Start thread, and wait for it to reload dlls. */ + if (!resume_child (pi, forker_finished) || + !sync_with_child (pi, subproc_ready, load_dlls, "child loading dlls")) + goto cleanup; + + /* If DLLs were loaded in the parent, then the child has reloaded all + of them and is now waiting to have all of the individual data and + bss sections filled in. */ + if (load_dlls) + { + /* CHILD IS STOPPED */ + /* write memory of reloaded dlls */ + for (dll *d = dlls.istart (DLL_LOAD); d; d = dlls.inext ()) + { + debug_printf ("copying data/bss for a loaded dll"); + if (!fork_copy (pi, "loaded dll data/bss", d->p.data_start, d->p.data_end, + d->p.bss_start, d->p.bss_end, + NULL)) + goto cleanup; + } + /* Start the child up again. */ + (void) resume_child (pi, forker_finished); + } + + ForceCloseHandle (subproc_ready); + ForceCloseHandle (pi.hThread); + ForceCloseHandle (forker_finished); + forker_finished = NULL; + pi.hThread = NULL; + pthread::atforkparent (); + + return forked->pid; + +/* Common cleanup code for failure cases */ + cleanup: + /* Remember to de-allocate the fd table. */ + if (pi.hProcess) + ForceCloseHandle1 (pi.hProcess, childhProc); + if (pi.hThread) + ForceCloseHandle (pi.hThread); + if (subproc_ready) + ForceCloseHandle (subproc_ready); + if (forker_finished) + ForceCloseHandle (forker_finished); + return -1; +} + +extern "C" int +fork () +{ + struct + { + HANDLE hParent; + dll *first_dll; + bool load_dlls; + } grouped; + + MALLOC_CHECK; + sigframe thisframe (mainthread); + + debug_printf ("entering"); + grouped.hParent = grouped.first_dll = NULL; + grouped.load_dlls = 0; + + if (ISSTATE(myself, PID_SPLIT_HEAP)) + { + system_printf ("The heap has been split, CYGWIN can't fork this process."); + system_printf ("Increase the heap_chunk_size in the registry and try again."); + set_errno (ENOMEM); + syscall_printf ("-1 = fork (), split heap"); + return -1; + } + + void *esp; + __asm__ volatile ("movl %%esp,%0": "=r" (esp)); + + myself->set_has_pgid_children (); + + child_info_fork ch; + + int res = setjmp (ch.jmp); + + if (res) + res = fork_child (grouped.hParent, grouped.first_dll, grouped.load_dlls); + else + res = fork_parent (grouped.hParent, grouped.first_dll, grouped.load_dlls, esp, ch); + + MALLOC_CHECK; + syscall_printf ("%d = fork()", res); + return res; +} +#ifdef DEBUGGING +void +fork_init () +{ + char buf[1024]; + if (!GetEnvironmentVariable ("CYGWIN_FORK_PIDS", buf, 1024)) + return; + pid_t pid; + char *p, *pe; + for (p = buf; (pid = strtol (p, &pe, 10)); p = pe) + fork_pids[npid_max++] = pid; +} +#endif /*DEBUGGING*/ + +#ifdef NEWVFORK +/* Dummy function to force second assignment below to actually be + carried out */ +static vfork_save * +get_vfork_val () +{ + return vfork_storage.val (); +} +#endif + +extern "C" int +vfork () +{ +#ifndef NEWVFORK + return fork (); +#else + sigframe thisframe; + vfork_save *vf = get_vfork_val (); + char **esp, **pp; + + if (vf == NULL) + vf = vfork_storage.create (); + else if (vf->pid) + return fork (); + + if (!setjmp (vf->j)) + { + vf->pid = -1; + __asm__ volatile ("movl %%esp,%0": "=r" (vf->vfork_esp):); + __asm__ volatile ("movl %%ebp,%0": "=r" (vf->vfork_ebp):); + for (pp = (char **)vf->frame, esp = vf->vfork_esp; + esp <= vf->vfork_ebp + 2; pp++, esp++) + *pp = *esp; + vf->ctty = myself->ctty; + vf->sid = myself->sid; + vf->pgid = myself->pgid; + int res = cygheap->fdtab.vfork_child_dup () ? 0 : -1; + debug_printf ("%d = vfork()", res); + return res; + } + + vf = get_vfork_val (); + + for (pp = (char **)vf->frame, esp = vf->vfork_esp; + esp <= vf->vfork_ebp + 2; pp++, esp++) + *esp = *pp; + + thisframe.init (mainthread); + cygheap->fdtab.vfork_parent_restore (); + + myself->ctty = vf->ctty; + myself->sid = vf->sid; + myself->pgid = vf->pgid; + + if (vf->pid < 0) + { + int exitval = vf->exitval; + vf->pid = 0; + if ((vf->pid = fork ()) == 0) + exit (exitval); + } + + int pid = vf->pid; + vf->pid = 0; + debug_printf ("exiting vfork, pid %d", pid); + sig_dispatch_pending (); + return pid; +#endif +} |