commit fdaa89c27c53ca52c75b010de9620b22e1c09f08
author Wan-Teh Chang <wtc@google.com> Thu Mar 24 19:14:12 2022 -0700
committer Wan-Teh Chang <wtc@google.com> Fri Mar 25 09:20:41 2022 -0700
tree 390308563b9b930b86eab9deaff1425c93cba564
parent c3ea2e4561e83e5e7874f28346dc27448d1952a1

Reorder the if statements in avifDecoderNthImage

Reorder the if statements in avifDecoderNthImage so that the one that
may fall through is the last one, after the if statements that always
return.

src/read.c

diff --git a/src/read.c b/src/read.c
index 379b950..54a3c1e 100644
--- a/src/read.c
+++ b/src/read.c
@@ -3982,12 +3982,17 @@
         return AVIF_RESULT_NO_CONTENT;
     }
 
-    if (frameIndex > INT_MAX) {
+    if ((frameIndex > INT_MAX) || ((int)frameIndex >= decoder->imageCount)) {
         // Impossible index
         return AVIF_RESULT_NO_IMAGES_REMAINING;
     }
 
     int requestedIndex = (int)frameIndex;
+    if (requestedIndex == (decoder->imageIndex + 1)) {
+        // It's just the next image (already partially decoded or not at all), nothing special here
+        return avifDecoderNextImage(decoder);
+    }
+
     if (requestedIndex == decoder->imageIndex) {
         if ((decoder->data->decodedColorTileCount == decoder->data->colorTileCount) &&
             (decoder->data->decodedAlphaTileCount == decoder->data->alphaTileCount)) {
@@ -3999,16 +4004,6 @@
         // Fall through to flush and start decoding from the nearest key frame.
     }
 
-    if (requestedIndex == (decoder->imageIndex + 1)) {
-        // It's just the next image (already partially decoded or not at all), nothing special here
-        return avifDecoderNextImage(decoder);
-    }
-
-    if (requestedIndex >= decoder->imageCount) {
-        // Impossible index
-        return AVIF_RESULT_NO_IMAGES_REMAINING;
-    }
-
     int nearestKeyFrame = (int)avifDecoderNearestKeyframe(decoder, frameIndex);
     if ((nearestKeyFrame > (decoder->imageIndex + 1)) || (requestedIndex <= decoder->imageIndex)) {
         // If we get here, a decoder flush is necessary