avformat/id3v2: Avoid allocations for ID3v2ExtraMeta

Up until now, the ID3v2ExtraMeta structure (which is used when parsing
ID3v2 tags containing attached pictures, chapters etc.) contained a
pointer to separately allocated data that depended on the type of the
tag. Yet the difference of the sizes of the largest and the smallest of
these structures is fairly small, so that it is better to simply include
a union of all the possible types of tag-dependent structures in
ID3v2ExtraMeta. This commit implements this.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/hls.c

@@ -1004,7 +1004,7 @@ static void parse_id3(AVFormatContext *s, AVIOContext *pb,
     ff_id3v2_read_dict(pb, metadata, ID3v2_DEFAULT_MAGIC, extra_meta);
     for (meta = *extra_meta; meta; meta = meta->next) {
         if (!strcmp(meta->tag, "PRIV")) {
-            ID3v2ExtraMetaPRIV *priv = meta->data;
+            ID3v2ExtraMetaPRIV *priv = &meta->data.priv;
             if (priv->datasize == 8 && !strcmp(priv->owner, id3_priv_owner_ts)) {
                 /* 33-bit MPEG timestamp */
                 int64_t ts = AV_RB64(priv->data);
@@ -1015,7 +1015,7 @@ static void parse_id3(AVFormatContext *s, AVIOContext *pb,
                     av_log(s, AV_LOG_ERROR, "Invalid HLS ID3 audio timestamp %"PRId64"\n", ts);
             }
         } else if (!strcmp(meta->tag, "APIC") && apic)
-            *apic = meta->data;
+            *apic = &meta->data.apic;
     }
 }
 

libavformat/id3v2.c

@@ -225,7 +225,6 @@ static void free_geobtag(void *obj)
     av_freep(&geob->file_name);
     av_freep(&geob->description);
     av_freep(&geob->data);
-    av_free(geob);
 }
 
 /**
@@ -459,20 +458,15 @@ static void read_geobtag(AVFormatContext *s, AVIOContext *pb, int taglen,
     if (taglen < 1)
         return;
 
-    geob_data = av_mallocz(sizeof(ID3v2ExtraMetaGEOB));
-    if (!geob_data) {
-        av_log(s, AV_LOG_ERROR, "Failed to alloc %"SIZE_SPECIFIER" bytes\n",
-               sizeof(ID3v2ExtraMetaGEOB));
-        return;
-    }
-
     new_extra = av_mallocz(sizeof(ID3v2ExtraMeta));
     if (!new_extra) {
         av_log(s, AV_LOG_ERROR, "Failed to alloc %"SIZE_SPECIFIER" bytes\n",
                sizeof(ID3v2ExtraMeta));
-        goto fail;
+        return;
     }
 
+    geob_data = &new_extra->data.geob;
+
     /* read encoding type byte */
     encoding = avio_r8(pb);
     taglen--;
@@ -511,7 +505,6 @@ static void read_geobtag(AVFormatContext *s, AVIOContext *pb, int taglen,
 
     /* add data to the list */
     new_extra->tag  = "GEOB";
-    new_extra->data = geob_data;
     new_extra->next = *extra_meta;
     *extra_meta     = new_extra;
 
@@ -577,7 +570,6 @@ static void free_apic(void *obj)
     ID3v2ExtraMetaAPIC *apic = obj;
     av_buffer_unref(&apic->buf);
     av_freep(&apic->description);
-    av_freep(&apic);
 }
 
 static void rstrip_spaces(char *buf)
@@ -603,10 +595,11 @@ static void read_apic(AVFormatContext *s, AVIOContext *pb, int taglen,
         goto fail;
 
     new_extra = av_mallocz(sizeof(*new_extra));
-    apic      = av_mallocz(sizeof(*apic));
-    if (!new_extra || !apic)
+    if (!new_extra)
         goto fail;
 
+    apic = &new_extra->data.apic;
+
     enc = avio_r8(pb);
     taglen--;
 
@@ -658,7 +651,6 @@ static void read_apic(AVFormatContext *s, AVIOContext *pb, int taglen,
     memset(apic->buf->data + taglen, 0, AV_INPUT_BUFFER_PADDING_SIZE);
 
     new_extra->tag  = "APIC";
-    new_extra->data = apic;
     new_extra->next = *extra_meta;
     *extra_meta     = new_extra;
 
@@ -680,7 +672,6 @@ static void free_chapter(void *obj)
     ID3v2ExtraMetaCHAP *chap = obj;
     av_freep(&chap->element_id);
     av_dict_free(&chap->meta);
-    av_freep(&chap);
 }
 
 static void read_chapter(AVFormatContext *s, AVIOContext *pb, int len, const char *ttag, ID3v2ExtraMeta **extra_meta, int isv34)
@@ -691,10 +682,10 @@ static void read_chapter(AVFormatContext *s, AVIOContext *pb, int len, const cha
     ID3v2ExtraMetaCHAP *chap  = NULL;
 
     new_extra = av_mallocz(sizeof(*new_extra));
-    chap      = av_mallocz(sizeof(*chap));
+    if (!new_extra)
+        return;
 
-    if (!new_extra || !chap)
-        goto fail;
+    chap = &new_extra->data.chap;
 
     if (decode_str(s, pb, 0, &chap->element_id, &len) < 0)
         goto fail;
@@ -727,15 +718,13 @@ static void read_chapter(AVFormatContext *s, AVIOContext *pb, int len, const cha
     ff_metadata_conv(&chap->meta, NULL, ff_id3v2_4_metadata_conv);
 
     new_extra->tag  = "CHAP";
-    new_extra->data = chap;
     new_extra->next = *extra_meta;
     *extra_meta     = new_extra;
 
     return;
 
 fail:
-    if (chap)
-        free_chapter(chap);
+    free_chapter(chap);
     av_freep(&new_extra);
 }
 
@@ -744,7 +733,6 @@ static void free_priv(void *obj)
     ID3v2ExtraMetaPRIV *priv = obj;
     av_freep(&priv->owner);
     av_freep(&priv->data);
-    av_freep(&priv);
 }
 
 static void read_priv(AVFormatContext *s, AVIOContext *pb, int taglen,
@@ -754,10 +742,10 @@ static void read_priv(AVFormatContext *s, AVIOContext *pb, int taglen,
     ID3v2ExtraMetaPRIV *priv;
 
     meta = av_mallocz(sizeof(*meta));
-    priv = av_mallocz(sizeof(*priv));
+    if (!meta)
+        return;
 
-    if (!meta || !priv)
-        goto fail;
+    priv = &meta->data.priv;
 
     if (decode_str(s, pb, ID3v2_ENCODING_ISO8859, &priv->owner, &taglen) < 0)
         goto fail;
@@ -772,15 +760,13 @@ static void read_priv(AVFormatContext *s, AVIOContext *pb, int taglen,
         goto fail;
 
     meta->tag   = "PRIV";
-    meta->data  = priv;
     meta->next  = *extra_meta;
     *extra_meta = meta;
 
     return;
 
 fail:
-    if (priv)
-        free_priv(priv);
+    free_priv(priv);
     av_freep(&meta);
 }
 
@@ -1132,7 +1118,7 @@ void ff_id3v2_free_extra_meta(ID3v2ExtraMeta **extra_meta)
 
     while (current) {
         if ((extra_func = get_extra_meta_func(current->tag, 1)))
-            extra_func->free(current->data);
+            extra_func->free(&current->data);
         next = current->next;
         av_freep(&current);
         current = next;
@@ -1151,7 +1137,7 @@ int ff_id3v2_parse_apic(AVFormatContext *s, ID3v2ExtraMeta **extra_meta)
 
         if (strcmp(cur->tag, "APIC"))
             continue;
-        apic = cur->data;
+        apic = &cur->data.apic;
 
         if (!(st = avformat_new_stream(s, NULL)))
             return AVERROR(ENOMEM);
@@ -1197,7 +1183,7 @@ int ff_id3v2_parse_chapters(AVFormatContext *s, ID3v2ExtraMeta **extra_meta)
 
         if (strcmp(cur->tag, "CHAP"))
             continue;
-        chap = cur->data;
+        chap = &cur->data.chap;
 
         if ((ret = av_dynarray_add_nofree(&chapters, &num_chapters, chap)) < 0)
             goto end;
@@ -1239,7 +1225,7 @@ int ff_id3v2_parse_priv_dict(AVDictionary **metadata, ID3v2ExtraMeta **extra_met
 
     for (cur = *extra_meta; cur; cur = cur->next) {
         if (!strcmp(cur->tag, "PRIV")) {
-            ID3v2ExtraMetaPRIV *priv = cur->data;
+            ID3v2ExtraMetaPRIV *priv = &cur->data.priv;
             AVBPrint bprint;
             char *escaped, *key;
             int i, ret;

libavformat/id3v2.h

@@ -54,12 +54,6 @@ typedef struct ID3v2EncContext {
     int          len;       ///< size of the tag written so far
 } ID3v2EncContext;
 
-typedef struct ID3v2ExtraMeta {
-    const char *tag;
-    void *data;
-    struct ID3v2ExtraMeta *next;
-} ID3v2ExtraMeta;
-
 typedef struct ID3v2ExtraMetaGEOB {
     uint32_t datasize;
     uint8_t *mime_type;
@@ -87,6 +81,17 @@ typedef struct ID3v2ExtraMetaCHAP {
     AVDictionary *meta;
 } ID3v2ExtraMetaCHAP;
 
+typedef struct ID3v2ExtraMeta {
+    const char *tag;
+    struct ID3v2ExtraMeta *next;
+    union {
+        ID3v2ExtraMetaAPIC apic;
+        ID3v2ExtraMetaCHAP chap;
+        ID3v2ExtraMetaGEOB geob;
+        ID3v2ExtraMetaPRIV priv;
+    } data;
+} ID3v2ExtraMeta;
+
 /**
  * Detect ID3v2 Header.
  * @param buf   must be ID3v2_HEADER_SIZE byte long

libavformat/omadec.c

@@ -217,14 +217,13 @@ static int decrypt_init(AVFormatContext *s, ID3v2ExtraMeta *em, uint8_t *header)
     av_log(s, AV_LOG_INFO, "File is encrypted\n");
 
     /* find GEOB metadata */
-    while (em) {
-        if (!strcmp(em->tag, "GEOB") &&
-            (geob = em->data) &&
-            (!strcmp(geob->description, "OMG_LSI") ||
-             !strcmp(geob->description, "OMG_BKLSI"))) {
+    for (; em; em = em->next) {
+        if (strcmp(em->tag, "GEOB"))
+            continue;
+        geob = &em->data.geob;
+        if (!strcmp(geob->description, "OMG_LSI") ||
+            !strcmp(geob->description, "OMG_BKLSI"))
             break;
-        }
-        em = em->next;
     }
     if (!em) {
         av_log(s, AV_LOG_ERROR, "No encryption header found\n");