123 lines
2.8 KiB
C
123 lines
2.8 KiB
C
/*
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* compress routines:
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* zmagic() - returns 0 if not recognized, uncompresses and prints
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* information if recognized
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* uncompress(method, old, n, newch) - uncompress old into new,
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* using method, return sizeof new
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* $Id: compress.c,v 1.4 1995/05/21 00:13:28 christos Exp $
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <sys/wait.h>
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#include "file.h"
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static struct {
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char *magic;
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int maglen;
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char *argv[3];
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int silent;
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} compr[] = {
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{ "\037\235", 2, { "uncompress", "-c", NULL }, 0 }, /* compressed */
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{ "\037\213", 2, { "gzip", "-cdq", NULL }, 1 }, /* gzipped */
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{ "\037\236", 2, { "gzip", "-cdq", NULL }, 1 }, /* frozen */
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{ "\037\240", 2, { "gzip", "-cdq", NULL }, 1 }, /* SCO LZH */
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/* the standard pack utilities do not accept standard input */
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{ "\037\036", 2, { "gzip", "-cdq", NULL }, 0 }, /* packed */
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};
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static int ncompr = sizeof(compr) / sizeof(compr[0]);
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static int uncompress __P((int, const unsigned char *, unsigned char **, int));
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int
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zmagic(buf, nbytes)
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unsigned char *buf;
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int nbytes;
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{
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unsigned char *newbuf;
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int newsize;
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int i;
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for (i = 0; i < ncompr; i++) {
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if (nbytes < compr[i].maglen)
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continue;
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if (memcmp(buf, compr[i].magic, compr[i].maglen) == 0)
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break;
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}
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if (i == ncompr)
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return 0;
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if ((newsize = uncompress(i, buf, &newbuf, nbytes)) != 0) {
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tryit(newbuf, newsize, 1);
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free(newbuf);
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printf(" (");
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tryit(buf, nbytes, 0);
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printf(")");
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}
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return 1;
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}
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static int
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uncompress(method, old, newch, n)
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int method;
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const unsigned char *old;
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unsigned char **newch;
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int n;
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{
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int fdin[2], fdout[2];
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if (pipe(fdin) == -1 || pipe(fdout) == -1) {
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error("cannot create pipe (%s).\n", strerror(errno));
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/*NOTREACHED*/
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}
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switch (fork()) {
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case 0: /* child */
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(void) close(0);
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(void) dup(fdin[0]);
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(void) close(fdin[0]);
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(void) close(fdin[1]);
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(void) close(1);
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(void) dup(fdout[1]);
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(void) close(fdout[0]);
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(void) close(fdout[1]);
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if (compr[method].silent)
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(void) close(2);
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execvp(compr[method].argv[0], compr[method].argv);
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error("could not execute `%s' (%s).\n",
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compr[method].argv[0], strerror(errno));
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/*NOTREACHED*/
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case -1:
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error("could not fork (%s).\n", strerror(errno));
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/*NOTREACHED*/
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default: /* parent */
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(void) close(fdin[0]);
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(void) close(fdout[1]);
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if (write(fdin[1], old, n) != n) {
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error("write failed (%s).\n", strerror(errno));
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/*NOTREACHED*/
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}
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(void) close(fdin[1]);
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if ((*newch = (unsigned char *) malloc(n)) == NULL) {
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error("out of memory.\n");
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/*NOTREACHED*/
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}
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if ((n = read(fdout[0], *newch, n)) <= 0) {
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free(*newch);
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error("read failed (%s).\n", strerror(errno));
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/*NOTREACHED*/
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}
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(void) close(fdout[0]);
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(void) wait(NULL);
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return n;
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}
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}
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