From 71c908817ec6173afb9bfbae404c6ce824cd965c Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Fri, 17 May 2019 00:30:18 +0200 Subject: avformat/matroskadec: Accept more unknown-length elements II Up until now, one last kind of unknown-length element hasn't been properly handled: Unknown-length elements that are supposed to be skipped, i.e. the level 1 elements that might reside after the clusters. This commit changes this. To do this, ebml_parse got a mode that essentially tries to skip everything except when parsing is needed (namely for unknown-length elements for which parsing is necessary as they can't be skipped). This mode is selected by using a NULL as destination where the parsed data should be written to. It is used to parse the level 1 elements in matroska_parse_cluster. The syntax list used for parsing must of course include links to the syntax of all the master elements that might need to be parsed. In other words: Instead of matroska_clusters (which contained every level 1 element except clusters as EBML_NONE elements designated to be skipped) matroska_segment is needed and used; matroska_clusters has been removed. Furthermore, matroska_segment has been reordered so that clusters are at the front as this is now the most common case for this list. Signed-off-by: Andreas Rheinhardt --- libavformat/matroskadec.c | 24 ++++++++++-------------- 1 file changed, 10 insertions(+), 14 deletions(-) diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c index 24d3ef2b74..31bb6936eb 100644 --- a/libavformat/matroskadec.c +++ b/libavformat/matroskadec.c @@ -685,6 +685,7 @@ static const EbmlSyntax matroska_seekhead[] = { }; static const EbmlSyntax matroska_segment[] = { + { MATROSKA_ID_CLUSTER, EBML_STOP }, { MATROSKA_ID_INFO, EBML_LEVEL1, 0, 0, { .n = matroska_info } }, { MATROSKA_ID_TRACKS, EBML_LEVEL1, 0, 0, { .n = matroska_tracks } }, { MATROSKA_ID_ATTACHMENTS, EBML_LEVEL1, 0, 0, { .n = matroska_attachments } }, @@ -692,7 +693,6 @@ static const EbmlSyntax matroska_segment[] = { { MATROSKA_ID_CUES, EBML_LEVEL1, 0, 0, { .n = matroska_index } }, { MATROSKA_ID_TAGS, EBML_LEVEL1, 0, 0, { .n = matroska_tags } }, { MATROSKA_ID_SEEKHEAD, EBML_LEVEL1, 0, 0, { .n = matroska_seekhead } }, - { MATROSKA_ID_CLUSTER, EBML_STOP }, { 0 } /* We don't want to go back to level 0, so don't add the parent. */ }; @@ -740,18 +740,6 @@ static const EbmlSyntax matroska_cluster_enter[] = { { MATROSKA_ID_CLUSTER, EBML_NEST, 0, 0, { .n = &matroska_cluster_parsing[2] } }, { 0 } }; - -static const EbmlSyntax matroska_clusters[] = { - { MATROSKA_ID_CLUSTER, EBML_STOP }, - { MATROSKA_ID_CUES, EBML_NONE }, - { MATROSKA_ID_TAGS, EBML_NONE }, - { MATROSKA_ID_INFO, EBML_NONE }, - { MATROSKA_ID_TRACKS, EBML_NONE }, - { MATROSKA_ID_ATTACHMENTS, EBML_NONE }, - { MATROSKA_ID_CHAPTERS, EBML_NONE }, - { MATROSKA_ID_SEEKHEAD, EBML_NONE }, - { 0 } /* We don't want to go back to level 0, so don't add the parent. */ -}; #undef CHILD_OF static const char *const matroska_doctypes[] = { "matroska", "webm" }; @@ -1082,6 +1070,7 @@ static int ebml_parse_nest(MatroskaDemuxContext *matroska, EbmlSyntax *syntax, { int i, res; + if (data) { for (i = 0; syntax[i].id; i++) switch (syntax[i].type) { case EBML_UINT: @@ -1109,6 +1098,7 @@ static int ebml_parse_nest(MatroskaDemuxContext *matroska, EbmlSyntax *syntax, matroska->num_levels--; return 0; } + } do { res = ebml_parse(matroska, syntax, data); @@ -1238,6 +1228,7 @@ static int ebml_parse(MatroskaDemuxContext *matroska, update_pos = 0; /* Don't update resync_pos as an error might have happened. */ } + if (data) { data = (char *) data + syntax->data_offset; if (syntax->list_elem_size) { EbmlList *list = data; @@ -1250,6 +1241,7 @@ static int ebml_parse(MatroskaDemuxContext *matroska, memset(data, 0, syntax->list_elem_size); list->nb_elem++; } + } if (syntax->type != EBML_STOP) { matroska->current_id = 0; @@ -1366,6 +1358,9 @@ static int ebml_parse(MatroskaDemuxContext *matroska, // of the element as the "last known good" position. matroska->resync_pos = pos; } + + if (!data && length != EBML_UNKNOWN_LENGTH) + goto skip; } switch (syntax->type) { @@ -1404,6 +1399,7 @@ static int ebml_parse(MatroskaDemuxContext *matroska, break; case EBML_STOP: return 1; + skip: default: if (length) { int64_t res2; @@ -3671,7 +3667,7 @@ static int matroska_parse_cluster(MatroskaDemuxContext *matroska) av_assert0(matroska->num_levels <= 2); if (matroska->num_levels == 1) { - res = ebml_parse(matroska, matroska_clusters, NULL); + res = ebml_parse(matroska, matroska_segment, NULL); if (res == 1) { /* Found a cluster: subtract the size of the ID already read. */ -- cgit v1.2.3