2 * rpmunpack for busybox
4 * rpmunpack.c - Utility program to unpack an RPM archive
6 * Gero Kuhlmann <gero@gkminix.han.de> 1998
8 * This program is public domain software; you can do whatever you like
9 * with this source, including modifying and redistributing it.
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.
23 * Some general definitions
26 #define RPM_MAGIC "\355\253\356\333"
27 #define GZ_MAGIC_1 '\037'
28 #define GZ_MAGIC_2 '\213'
33 static char *progname;
34 static int infile, outfile;
37 * Read a specified number of bytes from input file
39 static void myread(int num, char *buffer)
43 if ((err = read(infile, buffer, num)) != num) {
45 perror_msg_and_die(progname);
47 error_msg_and_die("Unexpected end of input file!\n");
54 int rpmunpack_main(int argc, char **argv)
57 RESERVE_BB_BUFFER(buffer, BUFSIZ);
59 /* Get our own program name */
60 if ((progname = strrchr(argv[0], '/')) == NULL)
65 /* Check for command line parameters */
66 if (argc>=2 && *argv[1]=='-') {
67 usage(rpmunpack_usage);
72 infile = STDIN_FILENO;
73 else if ((infile = open(argv[1], O_RDONLY)) < 0)
74 perror_msg_and_die("%s", argv[1]);
76 /* Read magic ID and output filename */
78 if (strncmp(buffer, RPM_MAGIC, 4)) {
79 fprintf(stderr, "Input file is not in RPM format!\n");
82 myread(6, buffer); /* Skip flags */
86 /* Open output file */
87 strcat(buffer, ".cpio.gz");
88 if (infile == STDIN_FILENO)
89 outfile = STDOUT_FILENO;
90 else if ((outfile = open(buffer, O_WRONLY | O_CREAT | O_TRUNC, 0644)) < 0)
91 perror_msg_and_die("%s", buffer);
94 * Now search for the GZIP signature. This is rather awkward, but I don't
95 * know any other way how to find out the exact starting position of the
96 * archive within the input file. There are a couple of data structures
97 * and texts (obviously descriptions, installation shell scripts etc.)
98 * coming before the archive, but even they start at different offsets
99 * with different RPM files. However, it looks like the GZIP signature
100 * never appears before offset 0x200, so we skip these first couple of
101 * bytes to make the signature scan a little more reliable.
103 myread(0x200 - 74, buffer);
106 if (status == 0 && buffer[0] == GZ_MAGIC_1)
108 else if (status == 1 && buffer[0] == GZ_MAGIC_2)
113 buffer[0] = GZ_MAGIC_1;
114 buffer[1] = GZ_MAGIC_2;
115 if (write(outfile, buffer, 2) < 0)
116 perror_msg_and_die("write");
118 /* Now simply copy the GZIP archive into the output file */
119 while ((len = read(infile, buffer, BUFSIZ)) > 0) {
120 if (write(outfile, buffer, len) < 0)
121 perror_msg_and_die("write");
124 perror_msg_and_die("read");