Re: [FFmpeg-devel] [PATCH 1/2] avformat/imfdec: do not use filesize when reading XML file

[Marton Balint]

On Sun, 9 Jan 2022, Pierre-Anthony Lemieux wrote:

On Sat, Jan 8, 2022 at 10:49 AM Marton Balint <c...@passwd.hu> wrote:



On Sat, 1 Jan 2022, Marton Balint wrote:

Signed-off-by: Marton Balint <c...@passwd.hu>
---
libavformat/imfdec.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/libavformat/imfdec.c b/libavformat/imfdec.c
index f17064cfcd..ef1e7cf206 100644
--- a/libavformat/imfdec.c
+++ b/libavformat/imfdec.c
@@ -73,8 +73,6 @@
#include <inttypes.h>
#include <libxml/parser.h>

-#define MAX_BPRINT_READ_SIZE (UINT_MAX - 1)
-#define DEFAULT_ASSETMAP_SIZE 8 * 1024
#define AVRATIONAL_FORMAT "%d/%d"
#define AVRATIONAL_ARG(rational) rational.num, rational.den

@@ -279,7 +277,6 @@ static int parse_assetmap(AVFormatContext *s, const char 
*url)
    const char *base_url;
    char *tmp_str = NULL;
    int ret;
-    int64_t filesize;

    av_log(s, AV_LOG_DEBUG, "Asset Map URL: %s\n", url);

@@ -289,13 +286,10 @@ static int parse_assetmap(AVFormatContext *s, const char 
*url)
    if (ret < 0)
        return ret;

-    filesize = avio_size(in);
-    filesize = filesize > 0 ? filesize : DEFAULT_ASSETMAP_SIZE;
+    av_bprint_init(&buf, 0, INT_MAX); // xmlReadMemory uses integer length

-    av_bprint_init(&buf, filesize + 1, AV_BPRINT_SIZE_UNLIMITED);
-
-    ret = avio_read_to_bprint(in, &buf, MAX_BPRINT_READ_SIZE);
-    if (ret < 0 || !avio_feof(in) || buf.len == 0) {
+    ret = avio_read_to_bprint(in, &buf, SIZE_MAX);
+    if (ret < 0 || !avio_feof(in)) {
        av_log(s, AV_LOG_ERROR, "Unable to read to asset map '%s'\n", url);
        if (ret == 0)
            ret = AVERROR_INVALIDDATA;
@@ -311,8 +305,7 @@ static int parse_assetmap(AVFormatContext *s, const char 
*url)
    }
    base_url = av_dirname(tmp_str);

-    filesize = buf.len;
-    doc = xmlReadMemory(buf.str, filesize, url, NULL, 0);
+    doc = xmlReadMemory(buf.str, buf.len, url, NULL, 0);

    ret = parse_imf_asset_map_from_xml_dom(s, doc, &c->asset_locator_map, 
base_url);
    if (!ret)

Will apply the series tomorrow.

It looks like the same code exists at libavformat/imf_cpl.c [1].

[1] 
https://github.com/FFmpeg/FFmpeg/blob/ce4d459db186a7d8ac842685cd6256c9ac1b7f25/libavformat/imf_cpl.c#L795

Does it need to be changed there as well?

Yes, preferably that should be changed as well. No that it matters too 
much, it just better/simpler not to depend on filesize.

Thanks,
Marton
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