Added support for deprecated POSIX functions on Windows.

Summary:
With the introduction of 8.0.1 We've stopped supporting in GHCi
the use of POSIX functions under their deprecated names on Windows.

This to be compatible with object and libraries from the most
popular compilers on the platform (Microsoft and Intel compilers).

However this brings a confusing disparity between the compiled and
interpreted behavior since MingW-W64 does support the deprecated names.

Also It seems clear that package writers won't update their packages to
properly support Windows. As such I have added redirects in the RTS
for the deprecated functions as listed on

https://msdn.microsoft.com/en-us/library/ms235384.aspx.

This won't export the functions (as in, they won't be in the symbol table
of compiled code for the RTS.) but we inject them into the symbol table
of the dynamic linker at startup.

Test Plan:
./validate
and

make test TEST="ffi017 ffi021"

Reviewers: thomie, simonmar, RyanGlScott, bgamari, austin, hvr, erikd

Reviewed By: simonmar, bgamari

Subscribers: RyanGlScott, #ghc_windows_task_force

Differential Revision: https://phabricator.haskell.org/D2500

GHC Trac Issues: #12209, #12497, #12496

1 files changed, 13 insertions, 0 deletions

diff --git a/rts/Linker.c b/rts/Linker.c
index b41bc1a641..f16fb83996 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -722,6 +722,7 @@ initLinker_ (int retain_cafs)
     initMutex(&dl_mutex);
 #endif
 #endif
+
     symhash = allocStrHashTable();
 
     /* populate the symbol table with stuff from the RTS */
@@ -1369,6 +1370,18 @@ static SymbolAddr* lookupSymbol_ (SymbolName* lbl)
         return NULL;
 #       endif
     } else {
+#if defined(mingw32_HOST_OS)
+            // If Windows, perform initialization of uninitialized
+            // Symbols from the C runtime which was loaded above.
+            // We do this on lookup to prevent the hit when
+            // The symbol isn't being used.
+            if (pinfo->value == (void*)0xBAADF00D)
+            {
+                char symBuffer[50];
+                sprintf(symBuffer, "_%s", lbl);
+                pinfo->value = GetProcAddress(GetModuleHandle("msvcrt"), symBuffer);
+            }
+#endif
         SymbolAddr* val = pinfo->value;
         IF_DEBUG(linker, debugBelch("lookupSymbol: value of %s is %p\n", lbl, val));