[FFmpeg-devel] [PATCH] avformat/cache - delete cache file after closing handle

[Gyan]

The existing practice of unlinking path immediately after acquiring file 
handle was returning (unchecked) EPERM error on Windows. Switched to 
deletion after closing handle.
Confirmed that cache protocol temp files are deleted in Windows 7 when 
ffmpeg exits.

The cache protocol calls avutil/avpriv_tempfile(), which in turn, calls 
mkstemp (for me), so I don't see the provision to append O_TEMPORARY as 
a flag while opening. mkstemp only applies
_O_RDWR | _O_CREAT | _O_EXCL | _O_BINARY

Should be tested in other environments. If it works, supersedes 
https://patchwork.ffmpeg.org/patch/13242/

Thanks,
Gyan
-------------- next part --------------
From f1f17020dd96205a60195e310d8c3b53126c2e00 Mon Sep 17 00:00:00 2001
From: Gyan Doshi <ffmpeg at gyani.pro>
Date: Wed, 22 May 2019 18:05:04 +0530
Subject: [PATCH] avformat/cache - delete cache file after closing handle

Ensures cache file deletion on Windows, when compiled under MinGW.
---
 libavformat/cache.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavformat/cache.c b/libavformat/cache.c
index 66bbbf54c9..1db13ceefc 100644
--- a/libavformat/cache.c
+++ b/libavformat/cache.c
@@ -54,6 +54,7 @@ typedef struct CacheEntry {
 typedef struct Context {
     AVClass *class;
     int fd;
+    char *filename;
     struct AVTreeNode *root;
     int64_t logical_pos;
     int64_t cache_pos;
@@ -83,7 +84,7 @@ static int cache_open(URLContext *h, const char *arg, int flags, AVDictionary **
         return c->fd;
     }
 
-    unlink(buffername);
+    c->filename = av_strdup(buffername);
     av_freep(&buffername);
 
     return ffurl_open_whitelist(&c->inner, arg, flags, &h->interrupt_callback,
@@ -292,11 +293,15 @@ static int enu_free(void *opaque, void *elem)
 static int cache_close(URLContext *h)
 {
     Context *c= h->priv_data;
+    int ret;
 
     av_log(h, AV_LOG_INFO, "Statistics, cache hits:%"PRId64" cache misses:%"PRId64"\n",
            c->cache_hit, c->cache_miss);
 
     close(c->fd);
+    ret = avpriv_io_delete(c->filename);
+    if (ret < 0)
+        av_log(h, AV_LOG_ERROR, "Could not delete %s. Error is %s\n", c->filename, av_err2str(ret));
     ffurl_close(c->inner);
     av_tree_enumerate(c->root, NULL, NULL, enu_free);
     av_tree_destroy(c->root);
-- 
2.21.0