diff options
Diffstat (limited to 'src/video/SDL_pixels.c')
| -rw-r--r-- | src/video/SDL_pixels.c | 41 |
1 files changed, 34 insertions, 7 deletions
diff --git a/src/video/SDL_pixels.c b/src/video/SDL_pixels.c index 1a7fd518f1..44626b7494 100644 --- a/src/video/SDL_pixels.c +++ b/src/video/SDL_pixels.c @@ -286,26 +286,53 @@ void SDL_DitherColors(SDL_Color *colors, int bpp) } } /* - * Calculate the pad-aligned scanline width of a surface + * Calculate the pad-aligned scanline width of a surface. Return 0 in case of + * an error. */ Uint16 SDL_CalculatePitch(SDL_Surface *surface) { - Uint16 pitch; + unsigned int pitch = 0; /* Surface should be 4-byte aligned for speed */ - pitch = surface->w*surface->format->BytesPerPixel; + /* The code tries to prevent from an Uint16 overflow. */; + for (Uint8 byte = surface->format->BytesPerPixel; byte; byte--) { + pitch += (unsigned int)surface->w; + if (pitch < surface->w) { + SDL_SetError("A scanline is too wide"); + return(0); + } + } switch (surface->format->BitsPerPixel) { case 1: - pitch = (pitch+7)/8; + if (pitch % 8) { + pitch = pitch / 8 + 1; + } else { + pitch = pitch / 8; + } break; case 4: - pitch = (pitch+1)/2; + if (pitch % 2) { + pitch = pitch / 2 + 1; + } else { + pitch = pitch / 2; + } break; default: break; } - pitch = (pitch + 3) & ~3; /* 4-byte aligning */ - return(pitch); + /* 4-byte aligning */ + if (pitch & 3) { + if (pitch + 3 < pitch) { + SDL_SetError("A scanline is too wide"); + return(0); + } + pitch = (pitch + 3) & ~3; + } + if (pitch > 0xFFFF) { + SDL_SetError("A scanline is too wide"); + return(0); + } + return((Uint16)pitch); } /* * Match an RGB value to a particular palette index |