[FFmpeg-devel] [PATCH v2] libavformat/img2enc.c: rm warning ‘.tmp’ directive output may be truncated

[caifan0425 <caifan0425@163.com>]

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Signed-off-by: Cai Fan <caifan0425@163.com>---
 libavformat/img2enc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavformat/img2enc.c b/libavformat/img2enc.c
index 41638d92b8..a1eb0c688d 100644
--- a/libavformat/img2enc.c
+++ b/libavformat/img2enc.c
@@ -180,7 +180,12 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt)
     }
     for (i = 0; i < 4; i++) {
         av_dict_copy(&options, img->protocol_opts, 0);
-        snprintf(img->temp[i], sizeof(img->tmp[i]), "%s.tmp", filename);
+        int len = snprintf(img->tmp[i], sizeof(img->tmp[i]), "%s.tmp", filename);
+        if (len < 0 || len >= sizeof(img->tmp[i])) {
+            av_log(s, AV_LOG_ERROR, "filename '%s' exceeds buffer size %zu\n", filename, sizeof(img->tmp[i]));
+            ret = AVERROR(EINVAL);
+            goto fail;
+        }
         av_strlcpy(img->target[i], filename, sizeof(img->target[i]));
         if (s->io_open(s, &pb[i], img->use_rename ? img->tmp[i] : filename, AVIO_FLAG_WRITE, &options) < 0) {
             av_log(s, AV_LOG_ERROR, "Could not open file : %s\n", img->use_rename ? img->tmp[i] : filename);
-- 


> On Jul 31, 2025, at 10:13, Cai Fan <caifan0425@163.com> wrote:
> 
> Signed-off-by: Cai Fan <caifan0425@163.com>
> ---
> libavformat/img2enc.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/img2enc.c b/libavformat/img2enc.c
> index 41638d92b8..a1eb0c688d 100644
> --- a/libavformat/img2enc.c
> +++ b/libavformat/img2enc.c
> @@ -180,7 +180,12 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt)
>     }
>     for (i = 0; i < 4; i++) {
>         av_dict_copy(&options, img->protocol_opts, 0);
> -        snprintf(img->tmp[i], sizeof(img->tmp[i]), "%s.tmp", filename);
> +        int len = snprintf(img->tmp[i], sizeof(img->tmp[i]), "%s.tmp", filename);
> +        if (len < 0 || len >= sizeof(img->tmp[i])) {
> +            av_log(s, AV_LOG_ERROR, "Filename too long: %s\n", filename);

“filename exceeds buffer size %zu\n”.

> +            ret = AVERROR(EINVAL);
> +            goto fail;
> +        }
>         av_strlcpy(img->target[i], filename, sizeof(img->target[i]));
>         if (s->io_open(s, &pb[i], img->use_rename ? img->tmp[i] : filename, AVIO_FLAG_WRITE, &options) < 0) {
>             av_log(s, AV_LOG_ERROR, "Could not open file : %s\n", img->use_rename ? img->tmp[i] : filename);
> -- 
> 2.34.1
> 
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