def png_invalid_bad_palette_reference():
"""Refer to a nonexistent palette entry."""
palette = ''.join([pngforge.rgb(i,i,i) for i in range(64)])
return (pngforge.sig() +
pngforge.ihdr(width=1, height=1,
color_type=pngforge.COLOR_INDEXED) +
pngforge.chunk('PLTE', palette) +
pngforge.idat(pngforge.scanline(0, chr(64))) +
pngforge.iend())
def png_invalid_short_palette():
"""Construct a palette that isn't a multiple of 3 bytes long."""
palette = ''.join([pngforge.rgb(i,i,i) for i in range(2)])[0:5]
return (pngforge.sig() +
pngforge.ihdr(width=1, height=1,
color_type=pngforge.COLOR_INDEXED) +
pngforge.chunk('PLTE', palette) +
pngforge.idat(pngforge.scanline(0, '\0')) +
pngforge.iend())
def png_invalid_short_idat():
"""Create a image with a too-short IDAT."""
return (pngforge.sig() + pngforge.ihdr(1, 1) +
pngforge.chunk('IDAT', '') +
pngforge.iend())
def png_invalid_bad_crc():
"""Return a chunk with a bad CRC."""
return pngforge.sig() + pngforge.chunk('ABCD', crc=1)
def png_invalid_chunk_size_big():
"""Return a chunk that claims to be 1gb."""
return pngforge.sig() + pngforge.chunk('BIGC', length=2**30)
def png_invalid_chunk_size_overflow():
"""Overflow a signed integer for the chunk size."""
return pngforge.sig() + pngforge.chunk('BIGC', length=2**31)
