Fix thumbnail store crashing on loading old files

third_party/android_opengl/etc1/etc1.cpp

Index: third_party/android_opengl/etc1/etc1.cpp
diff --git a/third_party/android_opengl/etc1/etc1.cpp b/third_party/android_opengl/etc1/etc1.cpp
index 7dd08d9883ebefe2935200d45f511160271e8bcb..99b5f1534194b1eed793f1c3ddf29704a5685e4e 100644
--- a/third_party/android_opengl/etc1/etc1.cpp
+++ b/third_party/android_opengl/etc1/etc1.cpp
@@ -587,3 +587,63 @@ bool etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 heig
     }
     return true;
 }
+
+static const char kMagic[] = { 'P', 'K', 'M', ' ', '1', '0' };
+
+static const etc1_uint32 ETC1_PKM_FORMAT_OFFSET = 6;
+static const etc1_uint32 ETC1_PKM_ENCODED_WIDTH_OFFSET = 8;
+static const etc1_uint32 ETC1_PKM_ENCODED_HEIGHT_OFFSET = 10;
+static const etc1_uint32 ETC1_PKM_WIDTH_OFFSET = 12;
+static const etc1_uint32 ETC1_PKM_HEIGHT_OFFSET = 14;
+
+static const etc1_uint32 ETC1_RGB_NO_MIPMAPS = 0;
+
+static void writeBEUint16(etc1_byte* pOut, etc1_uint32 data) {
+    pOut[0] = (etc1_byte) (data >> 8);
+    pOut[1] = (etc1_byte) data;
+}
+
+static etc1_uint32 readBEUint16(const etc1_byte* pIn) {
+    return (pIn[0] << 8) | pIn[1];
+}
+
+// Format a PKM header
+
+void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height) {
+    memcpy(pHeader, kMagic, sizeof(kMagic));
+    etc1_uint32 encodedWidth = (width + 3) & ~3;
+    etc1_uint32 encodedHeight = (height + 3) & ~3;
+    writeBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET, ETC1_RGB_NO_MIPMAPS);
+    writeBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET, encodedWidth);
+    writeBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET, encodedHeight);
+    writeBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET, width);
+    writeBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET, height);
+}
+
+// Check if a PKM header is correctly formatted.
+
+bool etc1_pkm_is_valid(const etc1_byte* pHeader) {
+    if (memcmp(pHeader, kMagic, sizeof(kMagic))) {
+        return false;
+    }
+    etc1_uint32 format = readBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET);
+    etc1_uint32 encodedWidth = readBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET);
+    etc1_uint32 encodedHeight = readBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET);
+    etc1_uint32 width = readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET);
+    etc1_uint32 height = readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET);
+    return format == ETC1_RGB_NO_MIPMAPS &&
+            encodedWidth >= width && encodedWidth - width < 4 &&
+            encodedHeight >= height && encodedHeight - height < 4;
+}
+
+// Read the image width from a PKM header
+
+etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader) {
+    return readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET);
+}
+
+// Read the image height from a PKM header
+
+etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader){
+    return readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET);
+}