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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 1.20 2001/07/22 21:04:15 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", "-cd", 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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