Make System.IO.openTempFile thread-safe on Windows

This calls out to the Win32 API `GetTempFileName` to generate
a temporary file. Using `uUnique = 0` guarantees that the file
we get back is unique and the file is "reserved" by creating it.

Test Plan:
./validate

I can't think of any sensible tests that shouldn't run for a while
to verify. So the example in #10731 was ran for a while and no
collisions in new code

Reviewers: hvr, bgamari, erikd

Reviewed By: bgamari

Subscribers: RyanGlScott, rwbarton, thomie, carter

GHC Trac Issues: #10731

Differential Revision: https://phabricator.haskell.org/D4278

1 files changed, 44 insertions, 1 deletions

diff --git a/libraries/base/cbits/Win32Utils.c b/libraries/base/cbits/Win32Utils.c
index 965adc2902..ce7ce97fc0 100644
--- a/libraries/base/cbits/Win32Utils.c
+++ b/libraries/base/cbits/Win32Utils.c
@@ -1,12 +1,16 @@
 /* ----------------------------------------------------------------------------
    (c) The University of Glasgow 2006
-   
+
    Useful Win32 bits
    ------------------------------------------------------------------------- */
 
 #if defined(_WIN32)
 
 #include "HsBase.h"
+#include <stdbool.h>
+#include <stdint.h>
+#include <wchar.h>
+#include <windows.h>
 
 /* This is the error table that defines the mapping between OS error
    codes and errno values */
@@ -148,4 +152,43 @@ BOOL file_exists(LPCTSTR path)
     return r != INVALID_FILE_ATTRIBUTES;
 }
 
+bool getTempFileNameErrorNo (wchar_t* pathName, wchar_t* prefix,
+                             wchar_t* suffix, uint32_t uUnique,
+                             wchar_t* tempFileName)
+{
+  if (!GetTempFileNameW(pathName, prefix, uUnique, tempFileName))
+    {
+      maperrno();
+      return false;
+    }
+
+  wchar_t* drive = malloc (sizeof(wchar_t) * _MAX_DRIVE);
+  wchar_t* dir   = malloc (sizeof(wchar_t) * _MAX_DIR);
+  wchar_t* fname = malloc (sizeof(wchar_t) * _MAX_FNAME);
+  bool success = true;
+  if (_wsplitpath_s (tempFileName, drive, _MAX_DRIVE, dir, _MAX_DIR,
+                     fname, _MAX_FNAME, NULL, 0) != 0)
+    {
+      success = false;
+      maperrno ();
+    }
+  else
+    {
+      wchar_t* temp = _wcsdup (tempFileName);
+      if (wcsnlen(drive, _MAX_DRIVE) == 0)
+        swprintf_s(tempFileName, MAX_PATH, L"%s\%s%s",
+                   dir, fname, suffix);
+      else
+        swprintf_s(tempFileName, MAX_PATH, L"%s\%s\%s%s",
+                   drive, dir, fname, suffix);
+      MoveFileW(temp, tempFileName);
+      free(temp);
+    }
+
+  free(drive);
+  free(dir);
+  free(fname);
+
+  return success;
+}
 #endif