1 files changed, 69 insertions, 0 deletions

diff --git a/lib-src/ntlib.c b/lib-src/ntlib.c
index 41b4e3a0cbc..ab7d8b590df 100644
--- a/lib-src/ntlib.c
+++ b/lib-src/ntlib.c
@@ -422,3 +422,72 @@ lstat (const char * path, struct stat * buf)
 {
   return stat (path, buf);
 }
+
+/* Implementation of mkostemp for MS-Windows, to avoid race conditions
+   when using mktemp.  Copied from w32.c.
+
+   This is used only in update-game-score.c.  It is overkill for that
+   use case, since update-game-score renames the temporary file into
+   the game score file, which isn't atomic on MS-Windows anyway, when
+   the game score already existed before running the program, which it
+   almost always does.  But using a simpler implementation just to
+   make a point is uneconomical...  */
+
+int
+mkostemp (char * template, int flags)
+{
+  char * p;
+  int i, fd = -1;
+  unsigned uid = GetCurrentThreadId ();
+  int save_errno = errno;
+  static char first_char[] = "abcdefghijklmnopqrstuvwyz0123456789!%-_@#";
+
+  errno = EINVAL;
+  if (template == NULL)
+    return -1;
+
+  p = template + strlen (template);
+  i = 5;
+  /* replace up to the last 5 X's with uid in decimal */
+  while (--p >= template && p[0] == 'X' && --i >= 0)
+    {
+      p[0] = '0' + uid % 10;
+      uid /= 10;
+    }
+
+  if (i < 0 && p[0] == 'X')
+    {
+      i = 0;
+      do
+        {
+          p[0] = first_char[i];
+          if ((fd = open (template,
+                          flags | _O_CREAT | _O_EXCL | _O_RDWR,
+                          S_IRUSR | S_IWUSR)) >= 0
+              || errno != EEXIST)
+            {
+              if (fd >= 0)
+                errno = save_errno;
+              return fd;
+            }
+        }
+      while (++i < sizeof (first_char));
+    }
+
+  /* Template is badly formed or else we can't generate a unique name.  */
+  return -1;
+}
+
+/* On Windows, you cannot rename into an existing file.  */
+int
+sys_rename (const char *from, const char *to)
+{
+  int retval = rename (from, to);
+
+  if (retval < 0 && errno == EEXIST)
+    {
+      if (unlink (to) == 0)
+        retval = rename (from, to);
+    }
+  return retval;
+}