GetFeatures: Detect invalid VP8X/VP8/VP8L data

This facilitates early error detection during decode/render.
Also, related refactoring.

Change-Id: Ia6c7cd91dec202a2a68dae2118f5981cf1eaa83d

src/mux/muxedit.c

@@ -422,20 +422,23 @@ static WebPMuxError GetFrameFragmentInfo(
   return WEBP_MUX_OK;
 }
 
-WebPMuxError MuxGetImageWidthHeight(const WebPChunk* const image_chunk,
+WebPMuxError MuxGetImageInfo(const WebPChunk* const image_chunk,
-                                    int* const width, int* const height) {
+                             int* const width, int* const height,
+                             int* const has_alpha) {
   const uint32_t tag = image_chunk->tag_;
   const WebPData* const data = &image_chunk->data_;
   int w, h;
+  int a = 0;
   int ok;
   assert(image_chunk != NULL);
   assert(tag == kChunks[IDX_VP8].tag || tag == kChunks[IDX_VP8L].tag);
   ok = (tag == kChunks[IDX_VP8].tag) ?
       VP8GetInfo(data->bytes, data->size, data->size, &w, &h) :
-      VP8LGetInfo(data->bytes, data->size, &w, &h, NULL);
+      VP8LGetInfo(data->bytes, data->size, &w, &h, &a);
   if (ok) {
-    *width = w;
+    if (width != NULL) *width = w;
-    *height = h;
+    if (height != NULL) *height = h;
+    if (has_alpha != NULL) *has_alpha = a;
     return WEBP_MUX_OK;
   } else {
     return WEBP_MUX_BAD_DATA;
@@ -455,7 +458,7 @@ static WebPMuxError GetImageInfo(const WebPMuxImage* const wpi,
   if (err != WEBP_MUX_OK) return err;
 
   // Get width and height from VP8/VP8L chunk.
-  return MuxGetImageWidthHeight(image_chunk, width, height);
+  return MuxGetImageInfo(image_chunk, width, height, NULL);
 }
 
 static WebPMuxError GetImageCanvasWidthHeight(
@@ -503,7 +506,7 @@ static WebPMuxError GetImageCanvasWidthHeight(
     // For a single image, extract the width & height from VP8/VP8L image-data.
     int w, h;
     const WebPChunk* const image_chunk = wpi->img_;
-    const WebPMuxError err = MuxGetImageWidthHeight(image_chunk, &w, &h);
+    const WebPMuxError err = MuxGetImageInfo(image_chunk, &w, &h, NULL);
     if (err != WEBP_MUX_OK) return err;
     *width = w;
     *height = h;

src/mux/muxi.h

@@ -149,9 +149,10 @@ size_t ChunksListDiskSize(const WebPChunk* chunk_list);
 // Write out the given list of chunks into 'dst'.
 uint8_t* ChunkListEmit(const WebPChunk* chunk_list, uint8_t* dst);
 
-// Get the width & height of image stored in 'image_chunk'.
+// Get the width, height and has_alpha info of image stored in 'image_chunk'.
-WebPMuxError MuxGetImageWidthHeight(const WebPChunk* const image_chunk,
+WebPMuxError MuxGetImageInfo(const WebPChunk* const image_chunk,
-                                    int* const width, int* const height);
+                             int* const width, int* const height,
+                             int* const has_alpha);
 
 //------------------------------------------------------------------------------
 // MuxImage object management.
@@ -233,12 +234,6 @@ uint8_t* MuxEmitRiffHeader(uint8_t* const data, size_t size);
 // or if 'id' is not known.
 WebPChunk** MuxGetChunkListFromId(const WebPMux* mux, WebPChunkId id);
 
-// Get the canvas width and height after validating that VP8X/VP8/VP8L chunk and
-// canvas size are valid. This method can be used for validation-only purposes
-// by passing 'width' and 'height' to be NULL.
-WebPMuxError MuxGetCanvasSize(const WebPMux* const mux, int* width,
-                              int* height);
-
 // Validates the given mux object.
 WebPMuxError MuxValidate(const WebPMux* const mux);
 

src/mux/muxinternal.c

@@ -486,10 +486,6 @@ WebPMuxError MuxValidate(const WebPMux* const mux) {
   // Verify mux has at least one image.
   if (mux->images_ == NULL) return WEBP_MUX_INVALID_ARGUMENT;
 
-  // Validate that VP8X/VP8/VP8L chunk and canvas size are valid.
-  err = MuxGetCanvasSize(mux, NULL, NULL);
-  if (err != WEBP_MUX_OK) return err;
-
   err = WebPMuxGetFeatures(mux, &flags);
   if (err != WEBP_MUX_OK) return err;
 

src/mux/muxread.c

@@ -278,27 +278,34 @@ static WebPMuxError ValidateForSingleImage(const WebPMux* const mux) {
   }
 }
 
-WebPMuxError MuxGetCanvasSize(const WebPMux* const mux, int* width,
+// Get the canvas width, height and flags after validating that VP8X/VP8/VP8L
-                              int* height) {
+// chunk and canvas size are valid.
+static WebPMuxError MuxGetCanvasInfo(const WebPMux* const mux,
+                                     int* width, int* height, uint32_t* flags) {
   int w, h;
+  uint32_t f = 0;
   WebPData data;
   assert(mux != NULL);
 
   // Check if VP8X chunk is present.
   if (MuxGet(mux, IDX_VP8X, 1, &data) == WEBP_MUX_OK) {
     if (data.size < VP8X_CHUNK_SIZE) return WEBP_MUX_BAD_DATA;
+    f = GetLE32(data.bytes);
     w = GetLE24(data.bytes + 4) + 1;
     h = GetLE24(data.bytes + 7) + 1;
   } else {  // Single image case.
+    int has_alpha;
     WebPMuxError err = ValidateForSingleImage(mux);
     if (err != WEBP_MUX_OK) return err;
-    err = MuxGetImageWidthHeight(mux->images_->img_, &w, &h);
+    err = MuxGetImageInfo(mux->images_->img_, &w, &h, &has_alpha);
     if (err != WEBP_MUX_OK) return err;
+    if (has_alpha) f |= ALPHA_FLAG;
   }
   if (w * (uint64_t)h >= MAX_IMAGE_AREA) return WEBP_MUX_BAD_DATA;
 
-  if (width) *width = w;
+  if (width != NULL) *width = w;
-  if (height) *height = h;
+  if (height != NULL) *height = h;
+  if (flags != NULL) *flags = f;
   return WEBP_MUX_OK;
 }
 
@@ -306,36 +313,12 @@ WebPMuxError WebPMuxGetCanvasSize(const WebPMux* mux, int* width, int* height) {
   if (mux == NULL || width == NULL || height == NULL) {
     return WEBP_MUX_INVALID_ARGUMENT;
   }
-  return MuxGetCanvasSize(mux, width, height);
+  return MuxGetCanvasInfo(mux, width, height, NULL);
 }
 
 WebPMuxError WebPMuxGetFeatures(const WebPMux* mux, uint32_t* flags) {
-  WebPData data;
-
   if (mux == NULL || flags == NULL) return WEBP_MUX_INVALID_ARGUMENT;
-  *flags = 0;
+  return MuxGetCanvasInfo(mux, NULL, NULL, flags);
-
-  // Check if VP8X chunk is present.
-  if (MuxGet(mux, IDX_VP8X, 1, &data) == WEBP_MUX_OK) {
-    if (data.size < CHUNK_SIZE_BYTES) return WEBP_MUX_BAD_DATA;
-    *flags = GetLE32(data.bytes);  // All OK. Fill up flags.
-  } else {
-    WebPMuxError err = ValidateForSingleImage(mux);  // Check for single image.
-    if (err != WEBP_MUX_OK) return err;
-    if (MuxHasLosslessImages(mux->images_)) {
-      const WebPData* const vp8l_data = &mux->images_->img_->data_;
-      int has_alpha = 0;
-      if (!VP8LGetInfo(vp8l_data->bytes, vp8l_data->size, NULL, NULL,
-                       &has_alpha)) {
-        return WEBP_MUX_BAD_DATA;
-      }
-      if (has_alpha) {
-        *flags = ALPHA_FLAG;
-      }
-    }
-  }
-
-  return WEBP_MUX_OK;
 }
 
 static uint8_t* EmitVP8XChunk(uint8_t* const dst, int width,
@@ -374,7 +357,7 @@ static WebPMuxError SynthesizeBitstream(const WebPMuxImage* const wpi,
     int w, h;
     WebPMuxError err;
     assert(wpi->img_ != NULL);
-    err = MuxGetImageWidthHeight(wpi->img_, &w, &h);
+    err = MuxGetImageInfo(wpi->img_, &w, &h, NULL);
     if (err != WEBP_MUX_OK) {
       free(data);
       return err;

src/webp/mux.h

@@ -329,7 +329,7 @@ WEBP_EXTERN(WebPMuxError) WebPMuxGetCanvasSize(const WebPMux* mux,
 //           Enum 'WebPFeatureFlags' can be used to test individual flag values.
 // Returns:
 //   WEBP_MUX_INVALID_ARGUMENT - if mux or flags is NULL.
-//   WEBP_MUX_BAD_DATA - if VP8X/VP8L chunk in mux is invalid.
+//   WEBP_MUX_BAD_DATA - if VP8X/VP8/VP8L chunk or canvas size is invalid.
 //   WEBP_MUX_OK - on success.
 WEBP_EXTERN(WebPMuxError) WebPMuxGetFeatures(const WebPMux* mux,
                                              uint32_t* flags);