[lipng17] Do not build png_product2() when it is unused and work around

one more Coverity-scan dead-code warning.

ANNOUNCE

@@ -1,5 +1,5 @@
 
-Libpng 1.7.0beta48 - January 29, 2015
+Libpng 1.7.0beta48 - February 7, 2015
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -697,7 +697,9 @@ Version 1.7.0beta47 [January 29, 2015]
   Added #ifndef __COVERITY__ where needed in png.c, pngrutil.c and
     pngset.c to avoid warnings about dead code.
 
-Version 1.7.0beta48 [January 29, 2015]
+Version 1.7.0beta48 [February 7, 2015]
+  Work around one more Coverity-scan dead-code warning.
+  Do not build png_product2() when it is unused.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -4986,7 +4986,9 @@ Version 1.7.0beta47 [January 29, 2015]
   Added #ifndef __COVERITY__ where needed in png.c, pngrutil.c and
     pngset.c to avoid warnings about dead code.
 
-Version 1.7.0beta48 [January 29, 2015]
+Version 1.7.0beta48 [February 7, 2015]
+  Work around one more Coverity-scan dead-code warning.
+  Do not build png_product2() when it is unused.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

png.c

@@ -694,13 +694,13 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-     "libpng version 1.7.0beta48 - February 4, 2015" PNG_STRING_NEWLINE \
+     "libpng version 1.7.0beta48 - February 7, 2015" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE;
 #  else
-      return "libpng version 1.7.0beta48 - February 4, 2015\
+      return "libpng version 1.7.0beta48 - February 7, 2015\
       Copyright (c) 1998-2015 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -3319,34 +3319,28 @@ png_gamma_significant(png_fixed_point gamma_val)
 #endif
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
-#if defined(PNG_16BIT_SUPPORTED) || !defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
+#ifdef PNG_16BIT_SUPPORTED
+#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
 /* A local convenience routine. */
 static png_fixed_point
 png_product2(png_fixed_point a, png_fixed_point b)
 {
    /* The required result is 1/a * 1/b; the following preserves accuracy. */
-#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
-   double r = a * 1E-5;
-   r *= b;
-   r = floor(r+.5);
-
-   if (r <= 2147483647. && r >= -2147483648.)
-      return (png_fixed_point)r;
-#else
    png_fixed_point res;
 
    if (png_muldiv(&res, a, b, 100000) != 0)
       return res;
-#endif
 
    return 0; /* overflow */
 }
-#endif /* 16BIT || !FLOATING_ARITHMETIC */
+#endif /* FLOATING_ARITHMETIC */
+#endif /* 16BIT */
 
 /* The inverse of the above. */
 png_fixed_point
 png_reciprocal2(png_fixed_point a, png_fixed_point b)
 {
+#ifdef PNG_16BIT_SUPPORTED
    /* The required result is 1/a * 1/b; the following preserves accuracy. */
 #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
    if (a != 0 && b != 0)
@@ -3357,6 +3351,7 @@ png_reciprocal2(png_fixed_point a, png_fixed_point b)
 
       if (r <= 2147483647. && r >= -2147483648.)
          return (png_fixed_point)r;
+   }
 #else
    /* This may overflow because the range of png_fixed_point isn't
     * symmetric, but this API is only used for the product of file and
@@ -3368,7 +3363,7 @@ png_reciprocal2(png_fixed_point a, png_fixed_point b)
    if (res != 0)
       return png_reciprocal(res);
 #endif
-   }
+#endif /* 16BIT */
 
    return 0; /* overflow */
 }

pngread.c

@@ -2285,8 +2285,14 @@ png_image_read_colormap(png_voidp argument)
                      output_processing = PNG_CMAP_NONE;
                      break;
                   }
-
+#ifdef __COVERITY__
+                 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
+                  * here.
+                  */
+                  back_alpha = 255;
+#else
                   back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
+#endif
                }
 
                /* output_processing means that the libpng-processed row will be
@@ -2411,7 +2417,14 @@ png_image_read_colormap(png_voidp argument)
                 */
                background_index = i;
                png_create_colormap_entry(display, i++, back_r, back_g, back_b,
-                  output_encoding == P_LINEAR ? 65535U : 255U, output_encoding);
+#ifdef __COVERITY__
+                 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
+                  * here.
+                  */ 255U,
+#else
+                  output_encoding == P_LINEAR ? 65535U : 255U,
+#endif
+                  output_encoding);
 
                /* For non-opaque input composite on the sRGB background - this
                 * requires inverting the encoding for each component.  The input

pngrtran.c

@@ -2991,18 +2991,11 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
             for (i = 0; i < row_width; i++)
             {
                png_uint_16 red, green, blue, w;
-
-#if 0 /* Coverity doesn't like this */
-               red   = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               blue  = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-#else
                png_byte hi,lo;
 
                hi=*(sp)++; lo=*(sp)++; red   = (png_uint_16)((hi << 8) | (lo));
                hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
                hi=*(sp)++; lo=*(sp)++; blue  = (png_uint_16)((hi << 8) | (lo));
-#endif
 
                if (red == green && red == blue)
                {
@@ -3047,10 +3040,11 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
             for (i = 0; i < row_width; i++)
             {
                png_uint_16 red, green, blue, gray16;
+               png_byte hi,lo;
 
-               red   = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
+               hi=*(sp)++; lo=*(sp)++; red   = (png_uint_16)((hi << 8) | (lo));
-               green = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
+               hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
-               blue  = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
+               hi=*(sp)++; lo=*(sp)++; blue  = (png_uint_16)((hi << 8) | (lo));
 
                if (red != green || red != blue)
                   rgb_error |= 1;