prevent signed int overflow in left shift ops

force unsigned when shifting by 24.

Change-Id: Ie229d252e2e4078107cd705b09397e686a321ffd
(cherry picked from commit f4f90880a8de432cdead8baed1e2b04e1afb6128)

2 files changed, 5 insertions, 5 deletions

diff --git a/examples/cwebp.c b/examples/cwebp.c
index 300d2c4f..0aee03ea 100644
--- a/examples/cwebp.c
+++ b/examples/cwebp.c
@@ -109,15 +109,15 @@ typedef enum {
 
 static InputFileFormat GetImageType(FILE* in_file) {
   InputFileFormat format = UNSUPPORTED;
-  unsigned int magic;
-  unsigned char buf[4];
+  uint32_t magic;
+  uint8_t buf[4];
 
   if ((fread(&buf[0], 4, 1, in_file) != 1) ||
       (fseek(in_file, 0, SEEK_SET) != 0)) {
     return format;
   }
 
-  magic = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];
+  magic = ((uint32_t)buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];
   if (magic == 0x89504E47U) {
     format = PNG_;
   } else if (magic >= 0xFFD8FF00U && magic <= 0xFFD8FFFFU) {
diff --git a/src/enc/picture.c b/src/enc/picture.c
index ce8f59ad..e9f78e1e 100644
--- a/src/enc/picture.c
+++ b/src/enc/picture.c
@@ -710,7 +710,7 @@ static int Import(WebPPicture* const picture,
     for (y = 0; y < height; ++y) {
       for (x = 0; x < width; ++x) {
         const int offset = step * x + y * rgb_stride;
-        const uint32_t argb = (a_ptr[offset] << 24) |
+        const uint32_t argb = ((uint32_t)a_ptr[offset] << 24) |
                               (r_ptr[offset] << 16) |
                               (g_ptr[offset] <<  8) |
                               (b_ptr[offset]);
@@ -810,7 +810,7 @@ int WebPPictureYUVAToARGB(WebPPicture* picture) {
         const uint8_t* const src = picture->a + y * picture->a_stride;
         int x;
         for (x = 0; x < width; ++x) {
-          argb_dst[x] = (argb_dst[x] & 0x00ffffffu) | (src[x] << 24);
+          argb_dst[x] = (argb_dst[x] & 0x00ffffffu) | ((uint32_t)src[x] << 24);
         }
       }
     }