Validate the item properties for made up alpha grid
Also address the comments from the review here:
https://aomedia-review.googlesource.com/c/libavif/+/175421
diff --git a/src/read.c b/src/read.c
index 091b405..3c1c849 100644
--- a/src/read.c
+++ b/src/read.c
@@ -3563,20 +3563,20 @@
// Returns AVIF_TRUE if the item should be skipped. Items should be skipped for one of the following reasons:
// * Size is 0.
// * Has an essential property that isn't supported by libavif.
-// * Item is Exif or similar data.
+// * Item is Exif or similar metadata.
// * Item is a thumbnail.
-static avifBool avifDecoderDataShouldSkipItem(avifDecoderItem * item)
+static avifBool avifDecoderItemShouldBeSkipped(const avifDecoderItem * item)
{
return !item->size || item->hasUnsupportedEssentialProperty ||
(avifGetCodecType(item->type) == AVIF_CODEC_TYPE_UNKNOWN && memcmp(item->type, "grid", 4)) || item->thumbnailForID != 0;
}
-// Returns the color item if found, or NULL.
+// Returns the primary color item if found, or NULL.
static avifDecoderItem * avifDecoderDataFindColorItem(avifDecoderData * data)
{
for (uint32_t itemIndex = 0; itemIndex < data->meta->items.count; ++itemIndex) {
avifDecoderItem * item = &data->meta->items.item[itemIndex];
- if (avifDecoderDataShouldSkipItem(item)) {
+ if (avifDecoderItemShouldBeSkipped(item)) {
continue;
}
if (item->id == data->meta->primaryItemID) {
@@ -3586,19 +3586,22 @@
return NULL;
}
+// Returns AVIF_TRUE if item is an alpha auxiliary item of the parent color
+// item.
static avifBool avifDecoderItemIsAlphaAux(avifDecoderItem * item, uint32_t colorItemId)
{
if (item->auxForID != colorItemId)
return AVIF_FALSE;
- // Is this an alpha auxiliary item of the color item?
const avifProperty * auxCProp = avifPropertyArrayFind(&item->properties, "auxC");
return auxCProp && isAlphaURN(auxCProp->u.auxC.auxType);
}
// Finds the alpha item whose parent item is colorItem and sets it in the alphaItem output parameter. Returns AVIF_RESULT_OK on
// success. Note that *alphaItem can be NULL even if the return value is AVIF_RESULT_OK. If the colorItem is a grid and the alpha
-// item is represented as a set of auxl items to each color tile, then a fake item will be created and isAlphaItemInInput will be
-// set to AVIF_FALSE. Otherwise, isAlphaItemInInput will be set to AVIF_TRUE when *alphaItem is not NULL.
+// item is represented as a set of auxl items to each color tile, then a fake item will be created and *isAlphaItemInInput will be
+// set to AVIF_FALSE. In this case, the alpha item merely exists to hold the locations of the alpha tile items. The data of this
+// item need not be read and the pixi property cannot be validated. Otherwise, *isAlphaItemInInput will be set to AVIF_TRUE when
+// *alphaItem is not NULL.
static avifResult avifDecoderDataFindAlphaItem(avifDecoderData * data,
avifDecoderItem * colorItem,
avifDecoderItem ** alphaItem,
@@ -3606,7 +3609,7 @@
{
for (uint32_t itemIndex = 0; itemIndex < data->meta->items.count; ++itemIndex) {
avifDecoderItem * item = &data->meta->items.item[itemIndex];
- if (avifDecoderDataShouldSkipItem(item)) {
+ if (avifDecoderItemShouldBeSkipped(item)) {
continue;
}
if (avifDecoderItemIsAlphaAux(item, colorItem->id)) {
@@ -3615,55 +3618,60 @@
return AVIF_RESULT_OK;
}
}
- if (!memcmp(colorItem->type, "grid", 4)) {
- // If color item is a grid, check if there is an alpha channel which is represented as an auxl item to each color tile
- // item.
- uint32_t colorItemCount = data->color.grid.rows * data->color.grid.columns;
- if (colorItemCount <= 0) {
- *alphaItem = NULL;
- return AVIF_RESULT_OK;
- }
- uint32_t * alphaItemIndices = avifAlloc(colorItemCount * sizeof(uint32_t));
- AVIF_CHECKERR(alphaItemIndices, AVIF_RESULT_OUT_OF_MEMORY);
- uint32_t alphaItemCount = 0;
- uint32_t maxItemID = 0;
- for (uint32_t i = 0; i < colorItem->meta->items.count; ++i) {
- avifDecoderItem * item = &colorItem->meta->items.item[i];
- if (item->id > maxItemID) {
- maxItemID = item->id;
- }
- if (item->dimgForID == colorItem->id) {
- for (uint32_t j = 0; j < colorItem->meta->items.count; ++j) {
- avifDecoderItem * auxlItem = &colorItem->meta->items.item[j];
- if (avifDecoderItemIsAlphaAux(auxlItem, item->id)) {
- alphaItemIndices[alphaItemCount++] = j;
- }
- }
- }
- }
- if (alphaItemCount != colorItemCount) {
- // Not all the color items had an alpha auxiliary attached to it. Report this case as an image without alpha channel.
- avifFree(alphaItemIndices);
- *alphaItem = NULL;
- return AVIF_RESULT_OK;
- }
- *alphaItem = avifMetaFindItem(colorItem->meta, maxItemID + 1);
- if (*alphaItem == NULL) {
- avifFree(alphaItemIndices);
- return AVIF_RESULT_OUT_OF_MEMORY;
- }
- memcpy((*alphaItem)->type, "grid", 4);
- (*alphaItem)->width = colorItem->width;
- (*alphaItem)->height = colorItem->height;
- for (uint32_t i = 0; i < alphaItemCount; ++i) {
- avifDecoderItem * item = &colorItem->meta->items.item[alphaItemIndices[i]];
- item->dimgForID = (*alphaItem)->id;
- }
- avifFree(alphaItemIndices);
+ if (memcmp(colorItem->type, "grid", 4)) {
+ *alphaItem = NULL;
*isAlphaItemInInput = AVIF_FALSE;
return AVIF_RESULT_OK;
}
- *alphaItem = NULL;
+ // If color item is a grid, check if there is an alpha channel which is represented as an auxl item to each color tile
+ // item.
+ uint32_t colorItemCount = data->color.grid.rows * data->color.grid.columns;
+ if (colorItemCount == 0) {
+ *alphaItem = NULL;
+ *isAlphaItemInInput = AVIF_FALSE;
+ return AVIF_RESULT_OK;
+ }
+ uint32_t * alphaItemIndices = avifAlloc(colorItemCount * sizeof(uint32_t));
+ AVIF_CHECKERR(alphaItemIndices, AVIF_RESULT_OUT_OF_MEMORY);
+ uint32_t alphaItemCount = 0;
+ uint32_t maxItemID = 0;
+ for (uint32_t i = 0; i < colorItem->meta->items.count; ++i) {
+ avifDecoderItem * item = &colorItem->meta->items.item[i];
+ if (item->id > maxItemID) {
+ maxItemID = item->id;
+ }
+ if (item->dimgForID == colorItem->id) {
+ for (uint32_t j = 0; j < colorItem->meta->items.count; ++j) {
+ avifDecoderItem * auxlItem = &colorItem->meta->items.item[j];
+ if (avifDecoderItemIsAlphaAux(auxlItem, item->id)) {
+ alphaItemIndices[alphaItemCount++] = j;
+ }
+ }
+ }
+ }
+ if (alphaItemCount != colorItemCount) {
+ // Not all the color items had an alpha auxiliary attached to it. Report this case as an image without alpha channel.
+ avifFree(alphaItemIndices);
+ *alphaItem = NULL;
+ *isAlphaItemInInput = AVIF_FALSE;
+ return AVIF_RESULT_OK;
+ }
+ *alphaItem = avifMetaFindItem(colorItem->meta, maxItemID + 1);
+ if (*alphaItem == NULL) {
+ avifFree(alphaItemIndices);
+ *isAlphaItemInInput = AVIF_FALSE;
+ return AVIF_RESULT_OUT_OF_MEMORY;
+ }
+ memcpy((*alphaItem)->type, "grid", 4);
+ (*alphaItem)->width = colorItem->width;
+ (*alphaItem)->height = colorItem->height;
+ for (uint32_t i = 0; i < alphaItemCount; ++i) {
+ avifDecoderItem * item = &colorItem->meta->items.item[alphaItemIndices[i]];
+ item->dimgForID = (*alphaItem)->id;
+ }
+ avifFree(alphaItemIndices);
+ *isAlphaItemInInput = AVIF_FALSE;
+ data->alpha.grid = data->color.grid;
return AVIF_RESULT_OK;
}
@@ -3901,7 +3909,7 @@
assert(colorCodecType != AVIF_CODEC_TYPE_UNKNOWN);
}
- avifBool isAlphaItemInInput = AVIF_TRUE;
+ avifBool isAlphaItemInInput;
avifDecoderItem * alphaItem;
AVIF_CHECKRES(avifDecoderDataFindAlphaItem(data, colorItem, &alphaItem, &isAlphaItemInInput));
avifCodecType alphaCodecType = AVIF_CODEC_TYPE_UNKNOWN;
@@ -3917,9 +3925,6 @@
decoder->imageDimensionLimit,
data->diag),
AVIF_RESULT_INVALID_IMAGE_GRID);
- } else {
- // This item was not actually in the input. Just copy the color grid structure to the alpha grid.
- data->alpha.grid = data->color.grid;
}
alphaCodecType = avifDecoderItemGetGridCodecType(alphaItem);
if (alphaCodecType == AVIF_CODEC_TYPE_UNKNOWN) {
@@ -3975,11 +3980,15 @@
AVIF_CHECKRES(
avifDecoderItemValidateProperties(colorItem, avifGetConfigurationPropertyName(colorCodecType), &decoder->diag, decoder->strictFlags));
- if (alphaItem && isAlphaItemInInput) {
- AVIF_CHECKRES(avifDecoderItemValidateProperties(alphaItem,
- avifGetConfigurationPropertyName(alphaCodecType),
- &decoder->diag,
- decoder->strictFlags));
+ if (alphaItem) {
+ avifStrictFlags strictFlags = decoder->strictFlags;
+ if (!isAlphaItemInInput) {
+ // In this case, the made up grid item will not have a an associated pixi property. So validate everything else
+ // but the pixi property.
+ strictFlags &= ~AVIF_STRICT_PIXI_REQUIRED;
+ }
+ AVIF_CHECKRES(
+ avifDecoderItemValidateProperties(alphaItem, avifGetConfigurationPropertyName(alphaCodecType), &decoder->diag, strictFlags));
}
}
