Fix gross spelling and typographical errors pointed out by Keith Bostic.

[unix-history] / usr.bin / file / compress.c

/*
* compress routines:
*      is_compress() returns 0 if uncompressed, number of bits if compressed.
*      uncompress(old, n, newch) - uncompress old into new, return sizeof new
* compress.c,v 1.1 1993/06/10 00:38:05 jtc Exp
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/wait.h>

#include "file.h"

/* Check for compression, return nbits. Algorithm, in magic(4) format:
* 0       string          \037\235        compressed data
* >2      byte&0x80       >0              block compressed
* >2      byte&0x1f       x               %d bits
*/
int
is_compress(p, b)
const unsigned char *p;
int *b;
{

       if (*p != '\037' || *(/*signed*/ char*)(p+1) != '\235')
               return 0;       /* not compress()ed */

       *b = *(p+2) & 0x80;
       return *(p+2) & 0x1f;
}

int
uncompress(old, newch, n)
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]);

               execlp("uncompress", "uncompress", "-c", NULL);
               error("could not execute `uncompress' (%s).\n", 
                     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;
       }
}