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