1 /* xxd.c - hexdump.
2 *
3 * Copyright 2015 The Android Open Source Project
4 *
5 * No obvious standard, output looks like:
6 * 0000000: 4c69 6e75 7820 7665 7273 696f 6e20 332e Linux version 3.
7
8 USE_XXD(NEWTOY(xxd, ">1c#<1>4096=16l#g#<1=2prs#[!rs]", TOYFLAG_USR|TOYFLAG_BIN))
9
10 config XXD
11 bool "xxd"
12 default y
13 help
14 usage: xxd [-c n] [-g n] [-l n] [-p] [-r] [-s n] [file]
15
16 Hexdump a file to stdout. If no file is listed, copy from stdin.
17 Filename "-" is a synonym for stdin.
18
19 -c n Show n bytes per line (default 16)
20 -g n Group bytes by adding a ' ' every n bytes (default 2)
21 -l n Limit of n bytes before stopping (default is no limit)
22 -p Plain hexdump (30 bytes/line, no grouping)
23 -r Reverse operation: turn a hexdump into a binary file
24 -s n Skip to offset n
25 */
26
27 #define FOR_xxd
28 #include "toys.h"
29
GLOBALS(long s;long g;long l;long c;)30 GLOBALS(
31 long s;
32 long g;
33 long l;
34 long c;
35 )
36
37 static void do_xxd(int fd, char *name)
38 {
39 long long pos = 0;
40 long long limit = TT.l;
41 int i, len, space;
42
43 if (toys.optflags&FLAG_s) {
44 xlseek(fd, TT.s, SEEK_SET);
45 pos = TT.s;
46 if (limit) limit += TT.s;
47 }
48
49 while (0<(len = readall(fd, toybuf,
50 (limit && limit-pos<TT.c)?limit-pos:TT.c))) {
51 if (!(toys.optflags&FLAG_p)) printf("%08llx: ", pos);
52 pos += len;
53 space = 2*TT.c+TT.c/TT.g+1;
54
55 for (i=0; i<len;) {
56 space -= printf("%02x", toybuf[i]);
57 if (!(++i%TT.g)) {
58 putchar(' ');
59 space--;
60 }
61 }
62
63 if (!(toys.optflags&FLAG_p)) {
64 printf("%*s", space, "");
65 for (i=0; i<len; i++)
66 putchar((toybuf[i]>=' ' && toybuf[i]<='~') ? toybuf[i] : '.');
67 }
68 putchar('\n');
69 }
70 if (len<0) perror_exit("read");
71 }
72
dehex(char ch)73 static int dehex(char ch)
74 {
75 if (ch >= '0' && ch <= '9') return ch - '0';
76 if (ch >= 'a' && ch <= 'f') return ch - 'a' + 10;
77 if (ch >= 'A' && ch <= 'F') return ch - 'a' + 10;
78 return (ch == '\n') ? -2 : -1;
79 }
80
do_xxd_reverse(int fd,char * name)81 static void do_xxd_reverse(int fd, char *name)
82 {
83 FILE *fp = xfdopen(fd, "r");
84
85 while (!feof(fp)) {
86 int col = 0;
87 int tmp;
88
89 // Each line of a non-plain hexdump starts with an offset/address.
90 if (!(toys.optflags&FLAG_p)) {
91 long long pos;
92
93 if (fscanf(fp, "%llx: ", &pos) == 1) {
94 if (fseek(stdout, pos, SEEK_SET) != 0) {
95 // TODO: just write out zeros if non-seekable?
96 perror_exit("%s: seek failed", name);
97 }
98 }
99 }
100
101 // A plain hexdump can have as many bytes per line as you like,
102 // but a non-plain hexdump assumes garbage after it's seen the
103 // specified number of bytes.
104 while (toys.optflags&FLAG_p || col < TT.c) {
105 int n1, n2;
106
107 // If we're at EOF or EOL or we read some non-hex...
108 if ((n1 = n2 = dehex(fgetc(fp))) < 0 || (n2 = dehex(fgetc(fp))) < 0) {
109 // If we're at EOL, start on that line.
110 if (n1 == -2 || n2 == -2) continue;
111 // Otherwise, skip to the next line.
112 break;
113 }
114
115 fputc((n1 << 4) | (n2 & 0xf), stdout);
116 col++;
117
118 // Is there any grouping going on? Ignore a single space.
119 tmp = fgetc(fp);
120 if (tmp != ' ') ungetc(tmp, fp);
121 }
122
123 // Skip anything else on this line (such as the ASCII dump).
124 while ((tmp = fgetc(fp)) != EOF && tmp != '\n')
125 ;
126 }
127 if (ferror(fp)) perror_msg_raw(name);
128
129 fclose(fp);
130 }
131
xxd_main(void)132 void xxd_main(void)
133 {
134 // Plain style is 30 bytes/line, no grouping.
135 if (toys.optflags&FLAG_p) TT.c = TT.g = 30;
136
137 loopfiles(toys.optargs, toys.optflags&FLAG_r ? do_xxd_reverse : do_xxd);
138 }
139