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Eric Andersencff3fe32000-09-20 19:22:26 +00001/*
2 * Mini unrpm implementation for busybox
3 *
4 * rpmunpack.c - Utility program to unpack an RPM archive
5 *
6 * Gero Kuhlmann <gero@gkminix.han.de> 1998
7 *
8 * This program is public domain software; you can do whatever you like
9 * with this source, including modifying and redistributing it.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
14 */
15
Eric Andersen3570a342000-09-25 21:45:58 +000016#include "busybox.h"
Eric Andersencff3fe32000-09-20 19:22:26 +000017#include <unistd.h>
18#include <stdio.h>
19#include <stdlib.h>
20#include <fcntl.h>
21#include <string.h>
22
23/*
24 * Some general definitions
25 */
26#define BUFSIZE 512
27#define RPM_MAGIC "\355\253\356\333"
28#define GZ_MAGIC_1 '\037'
29#define GZ_MAGIC_2 '\213'
30
31/*
32 * Global variables
33 */
34static char buffer[BUFSIZE];
35static char *progname;
36static int infile, outfile;
37
38/*
39 * Read a specified number of bytes from input file
40 */
41static void myread(int num)
42{
43 int err;
44
45 if ((err = read(infile, buffer, num)) != num) {
46 if (err < 0)
47 perror(progname);
48 else
49 fprintf(stderr, "unexpected end of input file\n");
50 exit(1);
51 }
52}
53
54/*
55 * Main program
56 */
57int unrpm_main(int argc, char **argv)
58{
59 int len, status = 0;
60
61 /* Get our own program name */
62 if ((progname = strrchr(argv[0], '/')) == NULL)
63 progname = argv[0];
64 else
65 progname++;
66
67 /* Check for command line parameters */
68 if (argc>=2 && *argv[1]=='-') {
69 usage(unrpm_usage);
70 }
71
72 /* Open input file */
73 if (argc == 1)
74 infile = STDIN_FILENO;
75 else if ((infile = open(argv[1], O_RDONLY)) < 0) {
76 perror(progname);
77 exit(1);
78 }
79
80 /* Read magic ID and output filename */
81 myread(4);
82 if (strncmp(buffer, RPM_MAGIC, 4)) {
83 fprintf(stderr, "input file is not in RPM format\n");
84 exit(1);
85 }
86 myread(6); /* Skip flags */
87 myread(64);
88 buffer[64] = '\0';
89
90 /* Open output file */
91 strcat(buffer, ".cpio.gz");
92 if (infile == STDIN_FILENO)
93 outfile = STDOUT_FILENO;
94 else if ((outfile = open(buffer, O_WRONLY | O_CREAT | O_TRUNC, 0644)) < 0) {
95 perror(progname);
96 exit(1);
97 }
98
99 /*
100 * Now search for the GZIP signature. This is rather awkward, but I don't
101 * know any other way how to find out the exact starting position of the
102 * archive within the input file. There are a couple of data structures
103 * and texts (obviously descriptions, installation shell scripts etc.)
104 * coming before the archive, but even they start at different offsets
105 * with different RPM files. However, it looks like the GZIP signature
106 * never appears before offset 0x200, so we skip these first couple of
107 * bytes to make the signature scan a little more reliable.
108 */
109 myread(0x200 - 74);
110 while (status < 2) {
111 myread(1);
112 if (status == 0 && buffer[0] == GZ_MAGIC_1)
113 status++;
114 else if (status == 1 && buffer[0] == GZ_MAGIC_2)
115 status++;
116 else
117 status = 0;
118 }
119 buffer[0] = GZ_MAGIC_1;
120 buffer[1] = GZ_MAGIC_2;
121 if (write(outfile, buffer, 2) < 0) {
122 perror(progname);
123 exit(1);
124 }
125
126 /* Now simply copy the GZIP archive into the output file */
127 while ((len = read(infile, buffer, BUFSIZE)) > 0) {
128 if (write(outfile, buffer, len) < 0) {
129 perror(progname);
130 exit(1);
131 }
132 }
133 if (len < 0) {
134 perror(progname);
135 exit(1);
136 }
137 close(outfile);
138 close(infile);
139 exit(0);
140}