Properly check for readdir/closedir() failures

Clear errno before calling readdir() and handle old MinGW errno bug
while adding full test coverage for readdir/closedir failures.

Backpatch through 8.4.

2 files changed, 9 insertions, 13 deletions

diff --git a/src/port/dirent.c b/src/port/dirent.c
index f9d93ea7d86..3bdc03e9b44 100644
--- a/src/port/dirent.c
+++ b/src/port/dirent.c
@@ -105,15 +105,19 @@ readdir(DIR *d)
 	strcpy(d->ret.d_name, fd.cFileName);		/* Both strings are MAX_PATH
 												 * long */
 	d->ret.d_namlen = strlen(d->ret.d_name);
+
 	return &d->ret;
 }
 
 int
 closedir(DIR *d)
 {
+	int ret = 0;
+
 	if (d->handle != INVALID_HANDLE_VALUE)
-		FindClose(d->handle);
+		ret = !FindClose(d->handle);
 	free(d->dirname);
 	free(d);
-	return 0;
+
+	return ret;
 }
diff --git a/src/port/pgcheckdir.c b/src/port/pgcheckdir.c
index fc97f8cc1da..502d4f377d9 100644
--- a/src/port/pgcheckdir.c
+++ b/src/port/pgcheckdir.c
@@ -33,14 +33,11 @@ pg_check_dir(const char *dir)
 	struct dirent *file;
 	bool		dot_found = false;
 
-	errno = 0;
-
 	chkdir = opendir(dir);
-
 	if (chkdir == NULL)
 		return (errno == ENOENT) ? 0 : -1;
 
-	while ((file = readdir(chkdir)) != NULL)
+	while (errno = 0, (file = readdir(chkdir)) != NULL)
 	{
 		if (strcmp(".", file->d_name) == 0 ||
 			strcmp("..", file->d_name) == 0)
@@ -68,17 +65,12 @@ pg_check_dir(const char *dir)
 	}
 
 #ifdef WIN32
-	/*
-	 * This fix is in mingw cvs (runtime/mingwex/dirent.c rev 1.4), but not in
-	 * released version
-	 */
+	/* Bug in old Mingw dirent.c;  fixed in mingw-runtime-3.2, 2003-10-10 */
 	if (GetLastError() == ERROR_NO_MORE_FILES)
 		errno = 0;
 #endif
 
-	closedir(chkdir);
-
-	if (errno != 0)
+	if (errno || closedir(chkdir))
 		result = -1;			/* some kind of I/O error? */
 
 	/* We report on dot-files if we _only_ find dot files */