xref: /openbmc/linux/lib/hexdump.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * lib/hexdump.c
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation. See README and COPYING for
7  * more details.
8  */
9 
10 #include <linux/types.h>
11 #include <linux/ctype.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 
15 /**
16  * hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory
17  * @buf: data blob to dump
18  * @len: number of bytes in the @buf
19  * @linebuf: where to put the converted data
20  * @linebuflen: total size of @linebuf, including space for terminating NUL
21  *
22  * hex_dump_to_buffer() works on one "line" of output at a time, i.e.,
23  * 16 bytes of input data converted to hex + ASCII output.
24  *
25  * Given a buffer of u8 data, hex_dump_to_buffer() converts the input data
26  * to a hex + ASCII dump at the supplied memory location.
27  * The converted output is always NUL-terminated.
28  *
29  * E.g.:
30  *	hex_dump_to_buffer(frame->data, frame->len, linebuf, sizeof(linebuf));
31  *
32  * example output buffer:
33  * 40414243 44454647 48494a4b 4c4d4e4f  @ABCDEFGHIJKLMNO
34  */
35 void hex_dump_to_buffer(const void *buf, size_t len, char *linebuf,
36 			size_t linebuflen)
37 {
38 	const u8 *ptr = buf;
39 	u8 ch;
40 	int j, lx = 0;
41 
42 	for (j = 0; (j < 16) && (j < len) && (lx + 3) < linebuflen; j++) {
43 		if (j && !(j % 4))
44 			linebuf[lx++] = ' ';
45 		ch = ptr[j];
46 		linebuf[lx++] = hex_asc(ch >> 4);
47 		linebuf[lx++] = hex_asc(ch & 0x0f);
48 	}
49 	if ((lx + 2) < linebuflen) {
50 		linebuf[lx++] = ' ';
51 		linebuf[lx++] = ' ';
52 	}
53 	for (j = 0; (j < 16) && (j < len) && (lx + 2) < linebuflen; j++)
54 		linebuf[lx++] = isprint(ptr[j]) ? ptr[j] : '.';
55 	linebuf[lx++] = '\0';
56 }
57 EXPORT_SYMBOL(hex_dump_to_buffer);
58 
59 /**
60  * print_hex_dump - print a text hex dump to syslog for a binary blob of data
61  * @level: kernel log level (e.g. KERN_DEBUG)
62  * @prefix_type: controls whether prefix of an offset, address, or none
63  *  is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
64  * @buf: data blob to dump
65  * @len: number of bytes in the @buf
66  *
67  * Given a buffer of u8 data, print_hex_dump() prints a hex + ASCII dump
68  * to the kernel log at the specified kernel log level, with an optional
69  * leading prefix.
70  *
71  * E.g.:
72  *   print_hex_dump(KERN_DEBUG, DUMP_PREFIX_ADDRESS, frame->data, frame->len);
73  *
74  * Example output using %DUMP_PREFIX_OFFSET:
75  * 0009ab42: 40414243 44454647 48494a4b 4c4d4e4f  @ABCDEFGHIJKLMNO
76  * Example output using %DUMP_PREFIX_ADDRESS:
77  * ffffffff88089af0: 70717273 74757677 78797a7b 7c7d7e7f  pqrstuvwxyz{|}~.
78  */
79 void print_hex_dump(const char *level, int prefix_type, void *buf, size_t len)
80 {
81 	u8 *ptr = buf;
82 	int i, linelen, remaining = len;
83 	unsigned char linebuf[100];
84 
85 	for (i = 0; i < len; i += 16) {
86 		linelen = min(remaining, 16);
87 		remaining -= 16;
88 		hex_dump_to_buffer(ptr + i, linelen, linebuf, sizeof(linebuf));
89 
90 		switch (prefix_type) {
91 		case DUMP_PREFIX_ADDRESS:
92 			printk("%s%*p: %s\n", level,
93 				(int)(2 * sizeof(void *)), ptr + i, linebuf);
94 			break;
95 		case DUMP_PREFIX_OFFSET:
96 			printk("%s%.8x: %s\n", level, i, linebuf);
97 			break;
98 		default:
99 			printk("%s%s\n", level, linebuf);
100 			break;
101 		}
102 	}
103 }
104 EXPORT_SYMBOL(print_hex_dump);
105