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/*
* compress routines:
* zmagic() - returns 0 if not recognized, uncompresses and prints
* information if recognized
* uncompress(method, old, n, newch) - uncompress old into new,
* using method, return sizeof new
*/
#include "file.h"
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif
#ifndef lint
FILE_RCSID("@(#)$Id: compress.c,v 1.19 2001/03/20 04:22:02 christos Exp $")
#endif
static struct {
const char *magic;
int maglen;
const char *const argv[3];
int silent;
} compr[] = {
{ "\037\235", 2, { "gzip", "-cdq", NULL }, 1 }, /* compressed */
/* Uncompress can get stuck; so use gzip first if we have it
* Idea from Damien Clark, thanks! */
{ "\037\235", 2, { "uncompress", "-c", NULL }, 1 }, /* compressed */
{ "\037\213", 2, { "gzip", "-cdq", NULL }, 1 }, /* gzipped */
{ "\037\236", 2, { "gzip", "-cdq", NULL }, 1 }, /* frozen */
{ "\037\240", 2, { "gzip", "-cdq", NULL }, 1 }, /* SCO LZH */
/* the standard pack utilities do not accept standard input */
{ "\037\036", 2, { "gzip", "-cdq", NULL }, 0 }, /* packed */
{ "BZh", 3, { "bzip2", "-d", NULL }, 1 }, /* bzip2-ed */
};
static int ncompr = sizeof(compr) / sizeof(compr[0]);
static int uncompress __P((int, const unsigned char *, unsigned char **, int));
static int swrite __P((int, const void *, size_t));
static int sread __P((int, void *, size_t));
int
zmagic(buf, nbytes)
unsigned char *buf;
int nbytes;
{
unsigned char *newbuf;
int newsize;
int i;
for (i = 0; i < ncompr; i++) {
if (nbytes < compr[i].maglen)
continue;
if (memcmp(buf, compr[i].magic, compr[i].maglen) == 0 &&
(newsize = uncompress(i, buf, &newbuf, nbytes)) != 0) {
tryit(newbuf, newsize, 1);
free(newbuf);
printf(" (");
tryit(buf, nbytes, 0);
printf(")");
return 1;
}
}
if (i == ncompr)
return 0;
return 1;
}
/*
* `safe' write for sockets and pipes.
*/
static int
swrite(fd, buf, n)
int fd;
const void *buf;
size_t n;
{
int rv;
size_t rn = n;
do
switch (rv = write(fd, buf, n)) {
case -1:
if (errno == EINTR)
continue;
return -1;
default:
n -= rv;
buf = ((char *)buf) + rv;
break;
}
while (n > 0);
return rn;
}
/*
* `safe' read for sockets and pipes.
*/
static int
sread(fd, buf, n)
int fd;
void *buf;
size_t n;
{
int rv;
size_t rn = n;
do
switch (rv = read(fd, buf, n)) {
case -1:
if (errno == EINTR)
continue;
return -1;
default:
n -= rv;
buf = ((char *)buf) + rv;
break;
}
while (n > 0);
return rn;
}
static int
uncompress(method, old, newch, n)
int method;
const unsigned char *old;
unsigned char **newch;
int n;
{
int fdin[2], fdout[2];
if (pipe(fdin) == -1 || pipe(fdout) == -1) {
error("cannot create pipe (%s).\n", strerror(errno));
/*NOTREACHED*/
}
switch (fork()) {
case 0: /* child */
(void) close(0);
(void) dup(fdin[0]);
(void) close(fdin[0]);
(void) close(fdin[1]);
(void) close(1);
(void) dup(fdout[1]);
(void) close(fdout[0]);
(void) close(fdout[1]);
if (compr[method].silent)
(void) close(2);
execvp(compr[method].argv[0],
(char *const *)compr[method].argv);
exit(1);
/*NOTREACHED*/
case -1:
error("could not fork (%s).\n", strerror(errno));
/*NOTREACHED*/
default: /* parent */
(void) close(fdin[0]);
(void) close(fdout[1]);
if (swrite(fdin[1], old, n) != n) {
n = 0;
goto err;
}
(void) close(fdin[1]);
fdin[1] = -1;
if ((*newch = (unsigned char *) malloc(n)) == NULL) {
n = 0;
goto err;
}
if ((n = sread(fdout[0], *newch, n)) <= 0) {
free(*newch);
n = 0;
goto err;
}
err:
if (fdin[1] != -1)
(void) close(fdin[1]);
(void) close(fdout[0]);
(void) wait(NULL);
return n;
}
}
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