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/* $OpenBSD: compress.c,v 1.4 1998/07/10 15:05:19 mickey Exp $ */
/*
* 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 <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <err.h>
#include "file.h"
static struct {
char *magic;
int maglen;
char *argv[3];
int silent;
} compr[] = {
{ "\037\235", 2, { "uncompress", "-c", NULL }, 0 }, /* 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 */
};
static int ncompr = sizeof(compr) / sizeof(compr[0]);
static int uncompress __P((int, const unsigned char *, unsigned char **, int));
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)
break;
}
if (i == ncompr)
return 0;
if ((newsize = uncompress(i, buf, &newbuf, nbytes)) != 0) {
tryit(newbuf, newsize, 1);
free(newbuf);
printf(" (");
tryit(buf, nbytes, 0);
printf(")");
}
return 1;
}
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) {
err(1, "cannot create pipe");
/*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], compr[method].argv);
err(1, "could not execute `%s'", compr[method].argv[0]);
/*NOTREACHED*/
case -1:
err(1, "could not fork");
/*NOTREACHED*/
default: /* parent */
(void) close(fdin[0]);
(void) close(fdout[1]);
if (write(fdin[1], old, n) != n) {
err(1, "write failed");
/*NOTREACHED*/
}
(void) close(fdin[1]);
if ((*newch = (unsigned char *) malloc(n)) == NULL) {
err(1, "malloc");
/*NOTREACHED*/
}
if ((n = read(fdout[0], *newch, n)) <= 0) {
free(*newch);
err(1, "read failed");
/*NOTREACHED*/
}
(void) close(fdout[0]);
(void) wait(NULL);
return n;
}
}
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