Comment 6 for bug 931496

Added the attached printfs. Here's the output:

** WARNING **: scanner.vala:1204: Scan completed with 1584 lines, expected 2250 lines
allocated: data_length = 711000, height = 2250, width = 1264
shift_count: offset 711000 >= data_length 711000 (x = 1263, width = 1264)
simple-scan: malloc.c:2453: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed.
Aborted (core dumped)

This is a buffer overrun by one byte. You can see clearly that all the other color depths (besides DeviceGray) add an extra byte to account for this overflow. Only the DeviceGray one does not, adding one to the data_length calculations for DeviceGray fixes the problem.

Please let me know if you want any other printfs or information in specific places.