141 lines
3.2 KiB
C
141 lines
3.2 KiB
C
/*
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* Mini unrpm implementation for busybox
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*
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* rpmunpack.c - Utility program to unpack an RPM archive
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*
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* Gero Kuhlmann <gero@gkminix.han.de> 1998
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*
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* This program is public domain software; you can do whatever you like
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* with this source, including modifying and redistributing it.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include "busybox.h"
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <string.h>
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/*
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* Some general definitions
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*/
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#define BUFSIZE 512
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#define RPM_MAGIC "\355\253\356\333"
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#define GZ_MAGIC_1 '\037'
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#define GZ_MAGIC_2 '\213'
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/*
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* Global variables
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*/
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static char buffer[BUFSIZE];
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static char *progname;
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static int infile, outfile;
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/*
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* Read a specified number of bytes from input file
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*/
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static void myread(int num)
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{
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int err;
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if ((err = read(infile, buffer, num)) != num) {
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if (err < 0)
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perror(progname);
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else
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fprintf(stderr, "unexpected end of input file\n");
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exit(1);
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}
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}
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/*
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* Main program
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*/
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int unrpm_main(int argc, char **argv)
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{
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int len, status = 0;
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/* Get our own program name */
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if ((progname = strrchr(argv[0], '/')) == NULL)
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progname = argv[0];
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else
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progname++;
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/* Check for command line parameters */
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if (argc>=2 && *argv[1]=='-') {
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usage(unrpm_usage);
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}
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/* Open input file */
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if (argc == 1)
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infile = STDIN_FILENO;
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else if ((infile = open(argv[1], O_RDONLY)) < 0) {
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perror(progname);
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exit(1);
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}
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/* Read magic ID and output filename */
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myread(4);
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if (strncmp(buffer, RPM_MAGIC, 4)) {
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fprintf(stderr, "input file is not in RPM format\n");
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exit(1);
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}
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myread(6); /* Skip flags */
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myread(64);
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buffer[64] = '\0';
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/* Open output file */
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strcat(buffer, ".cpio.gz");
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if (infile == STDIN_FILENO)
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outfile = STDOUT_FILENO;
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else if ((outfile = open(buffer, O_WRONLY | O_CREAT | O_TRUNC, 0644)) < 0) {
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perror(progname);
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exit(1);
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}
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/*
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* Now search for the GZIP signature. This is rather awkward, but I don't
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* know any other way how to find out the exact starting position of the
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* archive within the input file. There are a couple of data structures
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* and texts (obviously descriptions, installation shell scripts etc.)
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* coming before the archive, but even they start at different offsets
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* with different RPM files. However, it looks like the GZIP signature
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* never appears before offset 0x200, so we skip these first couple of
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* bytes to make the signature scan a little more reliable.
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*/
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myread(0x200 - 74);
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while (status < 2) {
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myread(1);
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if (status == 0 && buffer[0] == GZ_MAGIC_1)
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status++;
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else if (status == 1 && buffer[0] == GZ_MAGIC_2)
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status++;
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else
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status = 0;
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}
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buffer[0] = GZ_MAGIC_1;
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buffer[1] = GZ_MAGIC_2;
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if (write(outfile, buffer, 2) < 0) {
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perror(progname);
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exit(1);
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}
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/* Now simply copy the GZIP archive into the output file */
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while ((len = read(infile, buffer, BUFSIZE)) > 0) {
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if (write(outfile, buffer, len) < 0) {
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perror(progname);
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exit(1);
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}
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}
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if (len < 0) {
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perror(progname);
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exit(1);
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}
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close(outfile);
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close(infile);
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exit(0);
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}
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