file_cmds-60.tar.gz

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

diff --git a/file/ascmagic.c b/file/ascmagic.c
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+/*
+ * 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: ascmagic.c,v 1.3 1997/02/09 23:58:18 millert Exp $    */
+
+/*
+ * ASCII magic -- file types that we know based on keywords
+ * that can appear anywhere in the file.
+ *
+ * Copyright (c) Ian F. Darwin, 1987.
+ * Written by Ian F. Darwin.
+ *
+ * This software is not subject to any license of the American Telephone
+ * and Telegraph Company or of the Regents of the University of California.
+ *
+ * Permission is granted to anyone to use this software for any purpose on
+ * any computer system, and to alter it and redistribute it freely, subject
+ * to the following restrictions:
+ *
+ * 1. The author is not responsible for the consequences of use of this
+ *    software, no matter how awful, even if they arise from flaws in it.
+ *
+ * 2. The origin of this software must not be misrepresented, either by
+ *    explicit claim or by omission.  Since few users ever read sources,
+ *    credits must appear in the documentation.
+ *
+ * 3. Altered versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.  Since few users
+ *    ever read sources, credits must appear in the documentation.
+ *
+ * 4. This notice may not be removed or altered.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "file.h"
+#include "names.h"
+
+#ifndef        lint
+#if 0
+static char *moduleid = "$OpenBSD: ascmagic.c,v 1.3 1997/02/09 23:58:18 millert Exp $";
+#endif
+#endif /* lint */
+
+                       /* an optimisation over plain strcmp() */
+#define        STREQ(a, b)     (*(a) == *(b) && strcmp((a), (b)) == 0)
+
+int
+ascmagic(buf, nbytes)
+unsigned char *buf;
+int nbytes;    /* size actually read */
+{
+       int i, has_escapes = 0;
+       unsigned char *s;
+       char nbuf[HOWMANY+1];   /* one extra for terminating '\0' */
+       char *token;
+       register struct names *p;
+
+       /*
+        * Do the tar test first, because if the first file in the tar
+        * archive starts with a dot, we can confuse it with an nroff file.
+        */
+       switch (is_tar(buf, nbytes)) {
+       case 1:
+               ckfputs("tar archive", stdout);
+               return 1;
+       case 2:
+               ckfputs("POSIX tar archive", stdout);
+               return 1;
+       }
+
+       /*
+        * for troff, look for . + letter + letter or .\";
+        * this must be done to disambiguate tar archives' ./file
+        * and other trash from real troff input.
+        */
+       if (*buf == '.') {
+               unsigned char *tp = buf + 1;
+
+               while (isascii(*tp) && isspace(*tp))
+                       ++tp;   /* skip leading whitespace */
+               if ((isascii(*tp) && (isalnum(*tp) || *tp=='\\') &&
+                   isascii(tp[1]) && (isalnum(tp[1]) || tp[1] == '"'))) {
+                       ckfputs("troff or preprocessor input text", stdout);
+                       return 1;
+               }
+       }
+       if ((*buf == 'c' || *buf == 'C') && 
+           isascii(buf[1]) && isspace(buf[1])) {
+               ckfputs("fortran program text", stdout);
+               return 1;
+       }
+
+
+       /* Make sure we are dealing with ascii text before looking for tokens */
+       for (i = 0; i < nbytes; i++) {
+               if (!isascii(buf[i]))
+                       return 0;       /* not all ASCII */
+       }
+
+       /* look for tokens from names.h - this is expensive! */
+       /* make a copy of the buffer here because strtok() will destroy it */
+       s = (unsigned char*) memcpy(nbuf, buf, nbytes);
+       s[nbytes] = '\0';
+       has_escapes = (memchr(s, '\033', nbytes) != NULL);
+       while ((token = strtok((char *) s, " \t\n\r\f")) != NULL) {
+               s = NULL;       /* make strtok() keep on tokin' */
+               for (p = names; p < names + NNAMES; p++) {
+                       if (STREQ(p->name, token)) {
+                               ckfputs(types[p->type], stdout);
+                               if (has_escapes)
+                                       ckfputs(" (with escape sequences)", 
+                                               stdout);
+                               return 1;
+                       }
+               }
+       }
+
+       /* all else fails, but it is ASCII... */
+       ckfputs("ASCII text", stdout);
+       if (has_escapes) {
+               ckfputs(" (with escape sequences)", stdout);
+       }
+       return 1;
+}
+
+