Support multiple extents in an ItemLocationBox
Fixes: #291
diff --git a/src/read.c b/src/read.c
index 97246ce..40bdb1b 100644
--- a/src/read.c
+++ b/src/read.c
@@ -118,21 +118,29 @@
return NULL;
}
+typedef struct avifDecoderItemExtent
+{
+ uint32_t offset;
+ uint32_t size;
+} avifDecoderItemExtent;
+AVIF_ARRAY_DECLARE(avifDecoderItemExtentArray, avifDecoderItemExtent, extent);
+
// one "item" worth for decoding (all iref, iloc, iprp, etc refer to one of these)
typedef struct avifDecoderItem
{
uint32_t id;
struct avifMeta * meta; // Unowned; A back-pointer for convenience
uint8_t type[4];
- uint32_t offset;
uint32_t size;
uint32_t idatID; // If non-zero, offset is relative to this idat box (iloc construction_method==1)
avifContentType contentType;
avifPropertyArray properties;
- uint32_t thumbnailForID; // if non-zero, this item is a thumbnail for Item #{thumbnailForID}
- uint32_t auxForID; // if non-zero, this item is an auxC plane for Item #{auxForID}
- uint32_t descForID; // if non-zero, this item is a content description for Item #{descForID}
- uint32_t dimgForID; // if non-zero, this item is a derived image for Item #{dimgForID}
+ avifDecoderItemExtentArray extents; // All extent offsets/sizes
+ avifRWData mergedExtents; // if populated, is a single contiguous block of this item's extents (unused when extents.count == 1)
+ uint32_t thumbnailForID; // if non-zero, this item is a thumbnail for Item #{thumbnailForID}
+ uint32_t auxForID; // if non-zero, this item is an auxC plane for Item #{auxForID}
+ uint32_t descForID; // if non-zero, this item is a content description for Item #{descForID}
+ uint32_t dimgForID; // if non-zero, this item is a derived image for Item #{dimgForID}
avifBool hasUnsupportedEssentialProperty; // If true, this item cites a property flagged as 'essential' that libavif doesn't support (yet). Ignore the item, if so.
} avifDecoderItem;
AVIF_ARRAY_DECLARE(avifDecoderItemArray, avifDecoderItem, item);
@@ -453,6 +461,8 @@
for (uint32_t i = 0; i < meta->items.count; ++i) {
avifDecoderItem * item = &meta->items.item[i];
avifArrayDestroy(&item->properties);
+ avifArrayDestroy(&item->extents);
+ avifRWDataFree(&item->mergedExtents);
}
avifArrayDestroy(&meta->items);
avifArrayDestroy(&meta->properties);
@@ -474,6 +484,7 @@
avifDecoderItem * item = (avifDecoderItem *)avifArrayPushPtr(&meta->items);
avifArrayCreate(&item->properties, sizeof(avifProperty), 16);
+ avifArrayCreate(&item->extents, sizeof(avifDecoderItemExtent), 1);
item->id = itemID;
item->meta = meta;
return item;
@@ -581,6 +592,12 @@
static const uint8_t * avifDecoderDataCalcItemPtr(avifDecoderData * data, avifDecoderItem * item)
{
+ if (item->mergedExtents.data) {
+ // Multiple extents have already been concatenated for this item, just return it
+ return item->mergedExtents.data;
+ }
+
+ // Find this item's source of all extents' data, based on the construction method
avifROData * offsetBuffer = NULL;
if (item->idatID == 0) {
// construction_method: file(0)
@@ -603,14 +620,48 @@
}
}
- if (item->offset > offsetBuffer->size) {
+ if (item->extents.count == 0) {
+ return NULL;
+ } else if (item->extents.count == 1) {
+ // A single extent; just use the pre-existing buffer
+
+ avifDecoderItemExtent * extent = &item->extents.extent[0];
+ if (extent->offset > offsetBuffer->size) {
+ return NULL;
+ }
+ uint64_t offsetSize = (uint64_t)extent->offset + (uint64_t)extent->size;
+ if (offsetSize > (uint64_t)offsetBuffer->size) {
+ return NULL;
+ }
+ return offsetBuffer->data + extent->offset;
+ }
+
+ // Multiple extents; merge them into a single contiguous buffer
+ avifRWDataRealloc(&item->mergedExtents, item->size);
+ uint8_t * front = item->mergedExtents.data;
+ size_t remainingBytes = item->mergedExtents.size;
+ for (uint32_t extentIter = 0; extentIter < item->extents.count; ++extentIter) {
+ avifDecoderItemExtent * extent = &item->extents.extent[extentIter];
+ if (extent->offset > offsetBuffer->size) {
+ return NULL;
+ }
+ uint64_t offsetSize = (uint64_t)extent->offset + (uint64_t)extent->size;
+ if (offsetSize > (uint64_t)offsetBuffer->size) {
+ return NULL;
+ }
+ if ((size_t)extent->size > remainingBytes) {
+ return NULL;
+ }
+
+ memcpy(front, offsetBuffer->data + extent->offset, extent->size);
+ front += extent->size;
+ remainingBytes -= extent->size;
+ }
+ if (remainingBytes != 0) {
+ // This should be impossible?
return NULL;
}
- uint64_t offsetSize = (uint64_t)item->offset + (uint64_t)item->size;
- if (offsetSize > (uint64_t)offsetBuffer->size) {
- return NULL;
- }
- return offsetBuffer->data + item->offset;
+ return item->mergedExtents.data;
}
static avifBool avifDecoderDataGenerateImageGridTiles(avifDecoderData * data, avifImageGrid * grid, avifDecoderItem * gridItem, avifBool alpha)
@@ -949,13 +1000,20 @@
}
}
+ avifDecoderItem * item = avifMetaFindItem(meta, itemID);
+ if (!item) {
+ return AVIF_FALSE;
+ }
+ item->id = itemID;
+ item->idatID = idatID;
+
uint16_t dataReferenceIndex; // unsigned int(16) data_ref rence_index;
CHECK(avifROStreamReadU16(&s, &dataReferenceIndex)); //
uint64_t baseOffset; // unsigned int(base_offset_size*8) base_offset;
CHECK(avifROStreamReadUX8(&s, &baseOffset, baseOffsetSize)); //
uint16_t extentCount; // unsigned int(16) extent_count;
CHECK(avifROStreamReadU16(&s, &extentCount)); //
- if (extentCount == 1) {
+ for (int extentIter = 0; extentIter < extentCount; ++extentIter) {
// If extent_index is ever supported, this spec must be implemented here:
// :: if (((version == 1) || (version == 2)) && (index_size > 0)) {
// :: unsigned int(index_size*8) extent_index;
@@ -966,17 +1024,10 @@
uint64_t extentLength; // unsigned int(offset_size*8) extent_length;
CHECK(avifROStreamReadUX8(&s, &extentLength, lengthSize));
- avifDecoderItem * item = avifMetaFindItem(meta, itemID);
- if (!item) {
- return AVIF_FALSE;
- }
- item->id = itemID;
- item->offset = (uint32_t)(baseOffset + extentOffset);
- item->size = (uint32_t)extentLength;
- item->idatID = idatID;
- } else {
- // TODO: support more than one extent
- return AVIF_FALSE;
+ avifDecoderItemExtent * extent = (avifDecoderItemExtent *)avifArrayPushPtr(&item->extents);
+ extent->offset = (uint32_t)(baseOffset + extentOffset);
+ extent->size = (uint32_t)extentLength;
+ item->size += extent->size;
}
}
return AVIF_TRUE;
