Merge branch 'libpng15' of git://github.com/jbowler/libpng into libpng15

4 files changed, 32 insertions, 27 deletions

diff --git a/contrib/libtests/pngvalid.c b/contrib/libtests/pngvalid.c
index 9b85c3ef3..330e26393 100644
--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -4010,8 +4010,11 @@ check_interlace_type(int const interlace_type)
 #  define do_own_interlace 1
 #endif /* WRITE_INTERLACING tests */
 
-#define CAN_WRITE_INTERLACE\
-   PNG_LIBPNG_VER >= 10700 || defined PNG_WRITE_INTERLACING_SUPPORTED
+#if PNG_LIBPNG_VER >= 10700 || defined PNG_WRITE_INTERLACING_SUPPORTED
+#   define CAN_WRITE_INTERLACE 1
+#else
+#   define CAN_WRITE_INTERLACE 0
+#endif
 
 /* Do the same thing for read interlacing; this controls whether read tests do
  * their own de-interlace or use libpng.
diff --git a/png.c b/png.c
index 6922200ac..0e394207d 100644
--- a/png.c
+++ b/png.c
@@ -776,6 +776,8 @@ png_access_version_number(void)
 
 /* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
 #  ifdef PNG_CHECK_cHRM_SUPPORTED
+static void png_64bit_product(long v1, long v2, long *hi_product,
+    unsigned long *lo_product);
 
 int /* PRIVATE */
 png_check_cHRM_fixed(png_structp png_ptr,
@@ -784,7 +786,8 @@ png_check_cHRM_fixed(png_structp png_ptr,
    png_fixed_point blue_x, png_fixed_point blue_y)
 {
    int ret = 1;
-   unsigned long xy_hi,xy_lo,yx_hi,yx_lo;
+   long xy_hi,yx_hi;
+   unsigned long xy_lo,yx_lo;
 
    png_debug(1, "in function png_check_cHRM_fixed");
 
@@ -2169,29 +2172,31 @@ png_reciprocal2(png_fixed_point a, png_fixed_point b)
  *    A and D, and X || Y is (X << 16) + Y.
 */
 
-void /* PRIVATE */
-png_64bit_product (long v1, long v2, unsigned long *hi_product,
+static void
+png_64bit_product(long v1, long v2, long *hi_product,
     unsigned long *lo_product)
 {
-   int a, b, c, d;
-   long lo, hi, x, y;
+   long a, b, c, d;
+   unsigned long lo;
+   long hi, x, y;
 
-   a = (v1 >> 16) & 0xffff;
+   a = v1 >> 16;
    b = v1 & 0xffff;
-   c = (v2 >> 16) & 0xffff;
+   c = v2 >> 16;
    d = v2 & 0xffff;
 
-   lo = b * d;                   /* BD */
+   lo = b;
+   lo *= d;                      /* BD */
    x = a * d + c * b;            /* AD + CB */
-   y = ((lo >> 16) & 0xffff) + x;
+   y = (lo >> 16) + x;
 
-   lo = (lo & 0xffff) | ((y & 0xffff) << 16);
-   hi = (y >> 16) & 0xffff;
+   lo = (lo & 0xffff) | ((y & 0xffffU) << 16);
 
+   hi = y >> 16;
    hi += a * c;                  /* AC */
 
-   *hi_product = (unsigned long)hi;
-   *lo_product = (unsigned long)lo;
+   *hi_product = hi;
+   *lo_product = lo;
 }
 #endif /* CHECK_cHRM */
 
diff --git a/pngpriv.h b/pngpriv.h
index 8bdccccaf..e6ca9bf0d 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -1362,13 +1362,6 @@ PNG_EXTERN int png_check_cHRM_fixed PNGARG((png_structp png_ptr,
     png_fixed_point int_blue_y));
 #endif
 
-#ifdef PNG_CHECK_cHRM_SUPPORTED
-/* Added at libpng version 1.2.34 and 1.4.0 */
-/* Currently only used by png_check_cHRM_fixed */
-PNG_EXTERN void png_64bit_product PNGARG((long v1, long v2,
-    unsigned long *hi_product, unsigned long *lo_product));
-#endif
-
 #ifdef PNG_cHRM_SUPPORTED
 /* Added at libpng version 1.5.5 */
 typedef struct png_xy
diff --git a/pngtrans.c b/pngtrans.c
index a5df5afe0..dcd4d98b4 100644
--- a/pngtrans.c
+++ b/pngtrans.c
@@ -629,12 +629,16 @@ png_do_check_palette_indexes(png_structp png_ptr, png_row_infop row_info)
       png_ptr->num_palette > 0) /* num_palette can be 0 in MNG files */
    {
       /* Calculations moved outside switch in an attempt to stop different
-       * compiler warnings.  'padding' is in *bits* within the last byte, it is
-       * an 'int' because pixel_depth becomes an 'int' in the expression below,
-       * and this calculation is used because it avoids warnings that other
-       * forms produced on either GCC or MSVC.
+       * compiler warnings.
+       *
+       * 1.5.28: This rewritten version attempts to remove the unsigned integer
+       * overflow from the prior version.  While this was well defined it
+       * resulted in unsigned overflow detection in clang.  Since the result is
+       * always in the range 0..7 only the low three bits of of the various
+       * intermediates are every required, so:
        */
-      int padding = (-row_info->pixel_depth * row_info->width) & 7;
+      unsigned int padding =
+          ((8 - (row_info->pixel_depth & 7)) * (row_info->width & 7)) & 7;
       png_bytep rp = png_ptr->row_buf + row_info->rowbytes;
 
       switch (row_info->bit_depth)