Simple C functions that replicates the behaviour of the hexdump -C command
HexDump comes with two functions:
void hexdump(void *mem, size_t length);
void hexdump_to(FILE *stream, void *mem, size_t length);Pass a pointer to your data and its length to both functions. The first one dumps to stderr meanwhile the other let you provide a stream to dump to.
Through #defines in the header file, you can:
- Skip or not duplicate lines
- Set the number of columns
- Set the number of bytes per column
There's actually a difference between this hexdump and the original one: this one separates the ASCII dump in columns to match the hex dump's number of columns. I feel like it enhances data readability.
Here's what it looks like, with 3 columns of 4 bytes each:
$> ./hexdump main.c
00000000 2f 2a 0d 0a 2a 2a 20 45 50 49 54 45 |/*..|** E|PITE|
0000000c 43 48 20 50 52 4f 4a 45 43 54 2c 20 |CH P|ROJE|CT, |
00000018 32 30 31 38 0d 0a 2a 2a 20 48 65 78 |2018|..**| Hex|
00000024 44 75 6d 70 0d 0a 2a 2a 20 46 69 6c |Dump|..**| Fil|
00000030 65 20 64 65 73 63 72 69 70 74 69 6f |e de|scri|ptio|
0000003c 6e 3a 0d 0a 2a 2a 20 45 78 61 6d 70 |n:..|** E|xamp|
00000048 6c 65 20 6d 61 69 6e 20 66 75 6e 63 |le m|ain |func|
00000054 74 69 6f 6e 0d 0a 2a 2f 0d 0a 0d 0a |tion|..*/|....|
00000060 23 69 6e 63 6c 75 64 65 20 22 68 65 |#inc|lude| "he|
0000006c 78 64 75 6d 70 2e 68 22 0d 0a 0d 0a |xdum|p.h"|....|
00000078 69 6e 74 20 6d 61 69 6e 28 69 6e 74 |int |main|(int|
00000084 20 61 63 2c 20 63 68 61 72 20 2a 61 | ac,| cha|r *a|
00000090 76 5b 5d 29 0d 0a 7b 0d 0a 09 69 66 |v[])|..{.|..if|
0000009c 20 28 61 63 20 21 3d 20 32 29 0d 0a | (ac| != |2)..|
000000a8 09 09 72 65 74 75 72 6e 20 45 58 49 |..re|turn| EXI|
000000b4 54 5f 46 41 49 4c 55 52 45 3b 0d 0a |T_FA|ILUR|E;..|
000000c0 0d 0a 09 46 49 4c 45 20 2a 66 70 20 |...F|ILE |*fp |
000000cc 3d 20 66 6f 70 65 6e 28 61 76 5b 31 |= fo|pen(|av[1|
000000d8 5d 2c 20 22 72 22 29 3b 0d 0a 09 69 |], "|r");|...i|
000000e4 66 20 28 21 66 70 29 0d 0a 09 09 72 |f (!|fp).|...r|
000000f0 65 74 75 72 6e 20 45 58 49 54 5f 46 |etur|n EX|IT_F|
000000fc 41 49 4c 55 52 45 3b 0d 0a 0d 0a 09 |AILU|RE;.|....|
00000108 66 73 65 65 6b 28 66 70 2c 20 30 2c |fsee|k(fp|, 0,|
00000114 20 53 45 45 4b 5f 45 4e 44 29 3b 0d | SEE|K_EN|D);.|
00000120 0a 09 73 69 7a 65 5f 74 20 6c 65 6e |..si|ze_t| len|
0000012c 67 74 68 20 3d 20 66 74 65 6c 6c 28 |gth |= ft|ell(|
00000138 66 70 29 3b 0d 0a 09 66 73 65 65 6b |fp);|...f|seek|
00000144 28 66 70 2c 20 30 2c 20 53 45 45 4b |(fp,| 0, |SEEK|
00000150 5f 53 45 54 29 3b 0d 0a 0d 0a 09 75 |_SET|);..|...u|
0000015c 69 6e 74 38 5f 74 20 64 61 74 61 5b |int8|_t d|ata[|
00000168 6c 65 6e 67 74 68 5d 3b 0d 0a 09 6d |leng|th];|...m|
00000174 65 6d 73 65 74 28 64 61 74 61 2c 20 |emse|t(da|ta, |
00000180 30 2c 20 6c 65 6e 67 74 68 29 3b 0d |0, l|engt|h);.|
0000018c 0a 0d 0a 09 69 66 20 28 66 72 65 61 |....|if (|frea|
00000198 64 28 64 61 74 61 2c 20 73 69 7a 65 |d(da|ta, |size|
000001a4 6f 66 28 75 69 6e 74 38 5f 74 29 2c |of(u|int8|_t),|
000001b0 20 6c 65 6e 67 74 68 2c 20 66 70 29 | len|gth,| fp)|
000001bc 20 21 3d 20 6c 65 6e 67 74 68 29 20 | != |leng|th) |
000001c8 7b 0d 0a 09 09 66 63 6c 6f 73 65 28 |{...|.fcl|ose(|
000001d4 66 70 29 3b 0d 0a 09 09 72 65 74 75 |fp);|....|retu|
000001e0 72 6e 20 45 58 49 54 5f 46 41 49 4c |rn E|XIT_|FAIL|
000001ec 55 52 45 3b 0d 0a 09 7d 0d 0a 0d 0a |URE;|...}|....|
000001f8 09 68 65 78 64 75 6d 70 5f 74 6f 28 |.hex|dump|_to(|
00000204 73 74 64 6f 75 74 2c 20 64 61 74 61 |stdo|ut, |data|
00000210 2c 20 6c 65 6e 67 74 68 29 3b 0d 0a |, le|ngth|);..|
0000021c 0d 0a 09 66 63 6c 6f 73 65 28 66 70 |...f|clos|e(fp|
00000228 29 3b 0d 0a 09 72 65 74 75 72 6e 20 |);..|.ret|urn |
00000234 45 58 49 54 5f 53 55 43 43 45 53 53 |EXIT|_SUC|CESS|
00000240 3b 0d 0a 7d |;..}|
00000244