diff options
Diffstat (limited to 'usr.bin/file/ascmagic.c')
-rw-r--r-- | usr.bin/file/ascmagic.c | 120 |
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; +} + + |