BSD 4_4_Lite2 development

[unix-history] / usr / src / contrib / file-3.12 / compress.c

/*
* 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
* $Id: compress.c,v 1.7 1993/10/27 20:59:05 christos Exp $
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/wait.h>

#include "file.h"

static struct {
  char *magic;
  int   maglen;
  char *argv[3];
  int   silent;
} compr[] = {
   { "\037\235", 2, { "uncompress", "-c", NULL }, 0 },
   { "\037\213", 2, { "gzip", "-dq", NULL }, 1 },
#if 0
   /* XXX pcat does not work, cause I don't know how to make it read stdin */
   { "\037\036", 2, { "pcat", NULL, NULL }, 0 },
#endif
};

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) {
               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], compr[method].argv);
               error("could not execute `%s' (%s).\n", 
                     compr[method].argv[0], strerror(errno));
               /*NOTREACHED*/
       case -1:
               error("could not fork (%s).\n", strerror(errno));
               /*NOTREACHED*/

       default: /* parent */
               (void) close(fdin[0]);
               (void) close(fdout[1]);
               if (write(fdin[1], old, n) != n) {
                       error("write failed (%s).\n", strerror(errno));
                       /*NOTREACHED*/
               }
               (void) close(fdin[1]);
               if ((*newch = (unsigned char *) malloc(n)) == NULL) {
                       error("out of memory.\n");
                       /*NOTREACHED*/
               }
               if ((n = read(fdout[0], *newch, n)) <= 0) {
                       free(*newch);
                       error("read failed (%s).\n", strerror(errno));
                       /*NOTREACHED*/
               }
               (void) close(fdout[0]);
               (void) wait(NULL);
               return n;
       }
}