1 files changed, 120 insertions, 0 deletions
diff --git a/usr.bin/file/ascmagic.c b/usr.bin/file/ascmagic.c
new file mode 100644
index 0000000..600b0ab
--- /dev/null
+++ b/usr.bin/file/ascmagic.c
@@ -0,0 +1,120 @@
+/*
+ * 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
+static char *moduleid = 
+	"@(#)$Id: ascmagic.c,v 1.17 1994/01/21 01:25:30 christos Exp $";
+#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, isblock, has_escapes = 0;
+	unsigned char *s;
+	char nbuf[HOWMANY+1];	/* one extra for terminating '\0' */
+	char *token;
+	register struct names *p;
+
+	/* these are easy, do them first */
+
+	/*
+	 * 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=='"'))) {
+			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;
+	}
+
+	/* 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;
+			}
+		}
+	}
+
+	switch (is_tar(buf, nbytes)) {
+	case 1:
+		ckfputs("tar archive", stdout);
+		return 1;
+	case 2:
+		ckfputs("POSIX tar archive", stdout);
+		return 1;
+	}
+
+	for (i = 0; i < nbytes; i++) {
+		if (!isascii(*(buf+i)))
+			return 0;	/* not all ascii */
+	}
+
+	/* all else fails, but it is ascii... */
+	ckfputs("ascii text", stdout);
+	if (has_escapes) {
+		ckfputs(" (with escape sequences)", stdout);
+	}
+	return 1;
+}
+
+