chiark / gitweb /
DisOrder 3.0
[disorder] / lib / hex.c
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460b9539 1/*
2 * This file is part of DisOrder
5aff007d 3 * Copyright (C) 2004, 2005, 2007, 2008 Richard Kettlewell
460b9539 4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
18 * USA
19 */
ed422be7 20/** @file lib/hex.c @brief Hexadecimal encoding and decoding */
460b9539 21
22#include <config.h>
23#include "types.h"
24
25#include <stdio.h>
26#include <string.h>
27
28#include "hex.h"
29#include "mem.h"
30#include "log.h"
31
ed422be7
RK
32/** @brief Convert a byte sequence to hex
33 * @param ptr Pointer to first byte
34 * @param n Number of bytes
35 * @return Allocated string containing hexdump
36 */
460b9539 37char *hex(const uint8_t *ptr, size_t n) {
38 char *buf = xmalloc_noptr(n * 2 + 1), *p = buf;
39
40 while(n-- > 0)
41 p += sprintf(p, "%02x", (unsigned)*ptr++);
ef582771 42 *p = 0;
460b9539 43 return buf;
44}
45
ed422be7
RK
46/** @brief Convert a character to its value as a hex digit
47 * @param c Character code
48 * @return Value has hex digit or -1
49 *
50 * The 'q' stands for 'quiet' - this function does not report errors.
51 */
460b9539 52int unhexdigitq(int c) {
53 switch(c) {
54 case '0': return 0;
55 case '1': return 1;
56 case '2': return 2;
57 case '3': return 3;
58 case '4': return 4;
59 case '5': return 5;
60 case '6': return 6;
61 case '7': return 7;
62 case '8': return 8;
63 case '9': return 9;
64 case 'a': case 'A': return 10;
65 case 'b': case 'B': return 11;
66 case 'c': case 'C': return 12;
67 case 'd': case 'D': return 13;
68 case 'e': case 'E': return 14;
69 case 'f': case 'F': return 15;
70 default: return -1;
71 }
72}
73
ed422be7
RK
74/** @brief Convert a character to its value as a hex digit
75 * @param c Character code
76 * @return Value has hex digit or -1
77 *
78 * If the character is not a valid hex digit then an error is logged.
79 * See @ref unhexdigitq() if that is a problem.
80 */
460b9539 81int unhexdigit(int c) {
82 int d;
83
84 if((d = unhexdigitq(c)) < 0) error(0, "invalid hex digit");
85 return d;
86}
87
ed422be7
RK
88/** @brief Convert a hex string to bytes
89 * @param s Pointer to hex string
90 * @param np Where to store byte string length or NULL
91 * @return Allocated buffer, or 0
92 *
93 * @p s should point to a 0-terminated string containing an even number
94 * of hex digits. They are converted to bytes and returned via the return
95 * value and optionally the length via @p np.
96 *
97 * On any error a message is logged and a null pointer is returned.
98 */
460b9539 99uint8_t *unhex(const char *s, size_t *np) {
100 size_t l;
101 uint8_t *buf, *p;
102 int d1, d2;
103
104 if((l = strlen(s)) & 1) {
105 error(0, "hex string has odd length");
106 return 0;
107 }
108 p = buf = xmalloc_noptr(l / 2);
109 while(*s) {
110 if((d1 = unhexdigit(*s++)) < 0) return 0;
111 if((d2 = unhexdigit(*s++)) < 0) return 0;
112 *p++ = d1 * 16 + d2;
113 }
114 if(np)
115 *np = l / 2;
116 return buf;
117}
118
119/*
120Local Variables:
121c-basic-offset:2
122comment-column:40
123End:
124*/