[FFmpeg-devel] [PATCH 3/3] avformat/hlsenc: Fix path handling for Windows

[Marton Balint]

On Fri, 13 Jun 2025, softworkz wrote:

> From: softworkz <softworkz at hotmail.com>
>

Can you give an example where the path handling is wrong and where this 
patch fixes it? Is there a trac ticket?

> Signed-off-by: softworkz <softworkz at hotmail.com>
> ---
> libavformat/hlsenc.c | 43 ++++++++++++++++++++++++++++---------------
> 1 file changed, 28 insertions(+), 15 deletions(-)
>
> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
> index f81385d0b4..ba1e74e999 100644
> --- a/libavformat/hlsenc.c
> +++ b/libavformat/hlsenc.c
> @@ -329,6 +329,23 @@ static int hlsenc_io_close(AVFormatContext *s, AVIOContext **pb, char *filename)
>     return ret;
> }
>
> +static int get_last_separator_pos(const char *path)

size_t

> +{
> +    if (!path || *path == '\0')
> +        return -1;
> +
> +    char *p = strrchr(path, '/');
> +#if HAVE_DOS_PATHS
> +    char *q = strrchr(path, '\\');
> +    p = FFMAX(p, q);

You are comparing potentially NULL pointers here.

> +#endif
> +
> +    if (!p)
> +        return -1;
> +
> +    return p - path;
> +}
> +
> static void set_http_options(AVFormatContext *s, AVDictionary **options, HLSContext *c)
> {
>     int http_base_proto = ff_is_http_proto(s->url);
> @@ -1408,14 +1425,10 @@ static int hls_rename_temp_file(AVFormatContext *s, AVFormatContext *oc)
>
> static const char* get_relative_url(const char *master_url, const char *media_url)
> {
> -    const char *p = strrchr(master_url, '/');
> -    size_t base_len = 0;
> -
> -    if (!p) p = strrchr(master_url, '\\');
> +    int pos = get_last_separator_pos(master_url);

size_t, and you can keep using base_len variable, you don't have to 
rename, it is used for the same purpose as before.

>
> -    if (p) {
> -        base_len = p - master_url;
> -        if (av_strncasecmp(master_url, media_url, base_len)) {
> +    if (pos >= 0) {
> +        if (av_strncasecmp(master_url, media_url, pos)) {
>             av_log(NULL, AV_LOG_WARNING, "Unable to find relative url\n");
>             return NULL;
>         }
> @@ -1423,7 +1436,7 @@ static const char* get_relative_url(const char *master_url, const char *media_ur
>         return media_url;
>     }
>
> -    return media_url + base_len + 1;
> +    return media_url + pos + 1;
> }
>
> static int64_t get_stream_bit_rate(AVStream *stream)
> @@ -3151,13 +3164,13 @@ static int hls_init(AVFormatContext *s)
>                     vs->fmp4_init_filename = expanded;
>                 }
>
> -                p = strrchr(vs->m3u8_name, '/');
> -                if (p) {
> -                    char tmp = *(++p);
> -                    *p = '\0';
> -                    vs->base_output_dirname = av_asprintf("%s%s", vs->m3u8_name,
> -                                                          vs->fmp4_init_filename);
> -                    *p = tmp;
> +                int pos = get_last_separator_pos(vs->m3u8_name);
> +                if (pos >= 0) {
> +                    AVBPrint buf;
> +                    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
> +                    av_bprint_append_data(&buf, vs->m3u8_name, pos + 1);
> +                    av_bprintf(&buf, "%s", vs->fmp4_init_filename);
> +                    av_bprint_finalize(&buf, &vs->base_output_dirname);

av_bprintf here is unneeded, because in the end you have to malloc the 
result anyway. Keep using av_asprintf() with "%*s" to limit the length.

Regards,
Marton

>                 } else {
>                     vs->base_output_dirname = av_strdup(vs->fmp4_init_filename);
>                 }
> -- 
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