file_cmds-60.tar.gz

[apple/file_cmds.git] / file / compress.c

diff --git a/file/compress.c b/file/compress.c
new file mode 100644 (file)
index 0000000..4088f2d
--- /dev/null
+++ b/file/compress.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
+ * Reserved.  This file contains Original Code and/or Modifications of
+ * Original Code as defined in and that are subject to the Apple Public
+ * Source License Version 1.1 (the "License").  You may not use this file
+ * except in compliance with the License.  Please obtain a copy of the
+ * License at http://www.apple.com/publicsource and read it before using
+ * this file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
+ * License for the specific language governing rights and limitations
+ * under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+/*     $OpenBSD: compress.c,v 1.3 1997/02/09 23:58:19 millert 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 <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 },        /* 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) {
+               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;
+       }
+}