Actually ... given this change, why don't we drop the initial stat()
call? Just try mkdir(), and move on if it succeeds. If not, but
there's already a directory there, we're good. That eliminates the
race condition without duplicating code.
regards, tom lane
diff --git a/src/port/pgmkdirp.c b/src/port/pgmkdirp.c
index 7d7cea4dd0e..3e6b06fce79 100644
--- a/src/port/pgmkdirp.c
+++ b/src/port/pgmkdirp.c
@@ -56,7 +56,6 @@
int
pg_mkdir_p(char *path, int omode)
{
- struct stat sb;
mode_t numask,
oumask;
int last,
@@ -119,24 +118,46 @@ pg_mkdir_p(char *path, int omode)
if (last)
(void) umask(oumask);
- /* check for pre-existing directory */
- if (stat(path, &sb) == 0)
+ if (mkdir(path, last ? omode : S_IRWXU | S_IRWXG | S_IRWXO) < 0)
{
- if (!S_ISDIR(sb.st_mode))
+ /*
+ * If we got EEXIST because there's already a directory there,
+ * don't complain.
+ */
+#ifndef WIN32
+ int save_errno = errno;
+ struct stat sb;
+
+ if (save_errno != EEXIST ||
+ stat(path, &sb) != 0 ||
+ !S_ISDIR(sb.st_mode))
{
- if (last)
- errno = EEXIST;
- else
- errno = ENOTDIR;
+ /* Don't let stat replace mkdir's errno */
+ errno = save_errno;
retval = -1;
break;
}
+#else /* WIN32 */
+ /*
+ * On Windows, stat() opens a handle and can transiently fail on a
+ * directory another process is concurrently creating. Probe with
+ * a path-based attribute query instead: it requests only
+ * FILE_READ_ATTRIBUTES and is exempt from share-mode denial, so
+ * it reliably sees a concurrently-created directory. We assume
+ * GetFileAttributes() won't change errno.
+ */
+ DWORD attr = GetFileAttributes(path);
+
+ if (errno != EEXIST ||
+ attr == INVALID_FILE_ATTRIBUTES ||
+ !(attr & FILE_ATTRIBUTE_DIRECTORY))
+ {
+ retval = -1;
+ break;
+ }
+#endif /* WIN32 */
}
- else if (mkdir(path, last ? omode : S_IRWXU | S_IRWXG | S_IRWXO) < 0)
- {
- retval = -1;
- break;
- }
+
if (!last)
*p = '/';
}
