From c57befe80d7e044bc9d48f72ff4c377e948f6ad7 Mon Sep 17 00:00:00 2001
From: Daniel Gibson <metalcaedes@gmail.com>
Date: Sat, 4 May 2019 19:39:24 +0200
Subject: [PATCH] When opening file make sure it's actually a file, fixes #394

... and not a directory, which can cause crashes.
---
 src/common/header/shared.h |  7 +------
 src/common/shared/shared.c | 27 +++++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/src/common/header/shared.h b/src/common/header/shared.h
index 117053a1..ae762532 100644
--- a/src/common/header/shared.h
+++ b/src/common/header/shared.h
@@ -254,13 +254,8 @@ int Q_strlcat(char *dst, const char *src, int size);
 
 /* ============================================= */
 
-/* Unicode wrappers around fopen(). */
-
-#ifdef _WIN32
+/* Unicode wrappers that also make sure it's a regular file around fopen(). */
 FILE *Q_fopen(const char *file, const char *mode);
-#else
-#define Q_fopen(file, mode) fopen(file, mode)
-#endif
 
 /* ============================================= */
 
diff --git a/src/common/shared/shared.c b/src/common/shared/shared.c
index 08da4d05..7de02faa 100644
--- a/src/common/shared/shared.c
+++ b/src/common/shared/shared.c
@@ -1149,7 +1149,9 @@ Q_strlcat(char *dst, const char *src, int size)
  */
 #ifdef _WIN32
 #include <windows.h>
-
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
 FILE *Q_fopen(const char *file, const char *mode)
 {
 	WCHAR wfile[MAX_OSPATH];
@@ -1161,12 +1163,33 @@ FILE *Q_fopen(const char *file, const char *mode)
 	{
 		if (MultiByteToWideChar(CP_UTF8, 0, mode, -1, wmode, 16) > 0)
 		{
-			return _wfopen(wfile, wmode);
+			// make sure it's a regular file and not a directory or sth, see #394
+			struct _stat buf;
+			int statret = _wstat(wfile, &buf);
+			if((statret == 0 && (buf.st_mode & _S_IFREG) != 0) || (statret == -1 && errno == ENOENT))
+			{
+				return _wfopen(wfile, wmode);
+			}
 		}
 	}
 
 	return NULL;
 }
+#else
+#include <sys/stat.h>
+#include <errno.h>
+FILE *Q_fopen(const char *file, const char *mode)
+{
+	// make sure it's a regular file and not a directory or sth, see #394
+	struct stat statbuf;
+	int statret = stat(file, &statbuf);
+	// (it's ok if it doesn't exist though, maybe we wanna write/create)
+	if((statret == -1 && errno != ENOENT) || (statret == 0 && (statbuf.st_mode & S_IFREG) == 0))
+	{
+		return NULL;
+	}
+	return fopen(file, mode);
+}
 #endif
 
 /*