Matt Sarett | 96be908 | 2016-05-03 13:29:54 -0400 | [diff] [blame] | 1 | /* Fake a PNG - just write it out directly. |
| 2 | * |
| 3 | * COPYRIGHT: Written by John Cunningham Bowler, 2014. |
| 4 | * To the extent possible under law, the author has waived all copyright and |
| 5 | * related or neighboring rights to this work. This work is published from: |
| 6 | * United States. |
| 7 | * |
| 8 | */ |
| 9 | |
Chris Craik | ca2bf81 | 2013-07-29 15:28:30 -0700 | [diff] [blame] | 10 | #include <stdio.h> |
| 11 | #include <zlib.h> /* for crc32 */ |
| 12 | |
| 13 | void |
| 14 | put_uLong(uLong val) |
| 15 | { |
| 16 | putchar(val >> 24); |
| 17 | putchar(val >> 16); |
| 18 | putchar(val >> 8); |
| 19 | putchar(val >> 0); |
| 20 | } |
| 21 | |
| 22 | void |
| 23 | put_chunk(const unsigned char *chunk, uInt length) |
| 24 | { |
| 25 | uLong crc; |
| 26 | |
| 27 | put_uLong(length-4); /* Exclude the tag */ |
| 28 | |
| 29 | fwrite(chunk, length, 1, stdout); |
| 30 | |
| 31 | crc = crc32(0, Z_NULL, 0); |
| 32 | put_uLong(crc32(crc, chunk, length)); |
| 33 | } |
| 34 | |
| 35 | const unsigned char signature[] = |
| 36 | { |
| 37 | 137, 80, 78, 71, 13, 10, 26, 10 |
| 38 | }; |
| 39 | |
| 40 | const unsigned char IHDR[] = |
| 41 | { |
| 42 | 73, 72, 68, 82, /* IHDR */ |
| 43 | 0, 0, 0, 1, /* width */ |
| 44 | 0, 0, 0, 1, /* height */ |
| 45 | 1, /* bit depth */ |
| 46 | 0, /* color type: greyscale */ |
| 47 | 0, /* compression method */ |
| 48 | 0, /* filter method */ |
| 49 | 0 /* interlace method: none */ |
| 50 | }; |
| 51 | |
| 52 | const unsigned char unknown[] = |
| 53 | { |
| 54 | 'u', 'n', 'K', 'n' /* "unKn" - private safe to copy */ |
| 55 | }; |
| 56 | |
| 57 | int |
| 58 | main(void) |
| 59 | { |
| 60 | fwrite(signature, sizeof signature, 1, stdout); |
| 61 | put_chunk(IHDR, sizeof IHDR); |
| 62 | |
Matt Sarett | 96be908 | 2016-05-03 13:29:54 -0400 | [diff] [blame] | 63 | for (;;) |
Chris Craik | ca2bf81 | 2013-07-29 15:28:30 -0700 | [diff] [blame] | 64 | put_chunk(unknown, sizeof unknown); |
| 65 | } |