projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 66a734b3 WJ |
1 | /* |
| 2 | * Ascii magic -- file types that we know based on keywords | |
| 3 | * that can appear anywhere in the file. | |
| 4 | * | |
| 5 | * Copyright (c) Ian F. Darwin, 1987. | |
| 6 | * Written by Ian F. Darwin. | |
| 7 | * | |
| 8 | * This software is not subject to any license of the American Telephone | |
| 9 | * and Telegraph Company or of the Regents of the University of California. | |
| 10 | * | |
| 11 | * Permission is granted to anyone to use this software for any purpose on | |
| 12 | * any computer system, and to alter it and redistribute it freely, subject | |
| 13 | * to the following restrictions: | |
| 14 | * | |
| 15 | * 1. The author is not responsible for the consequences of use of this | |
| 16 | * software, no matter how awful, even if they arise from flaws in it. | |
| 17 | * | |
| 18 | * 2. The origin of this software must not be misrepresented, either by | |
| 19 | * explicit claim or by omission. Since few users ever read sources, | |
| 20 | * credits must appear in the documentation. | |
| 21 | * | |
| 22 | * 3. Altered versions must be plainly marked as such, and must not be | |
| 23 | * misrepresented as being the original software. Since few users | |
| 24 | * ever read sources, credits must appear in the documentation. | |
| 25 | * | |
| 26 | * 4. This notice may not be removed or altered. | |
| 27 | */ | |
| 28 | ||
| 29 | #include <stdio.h> | |
| 30 | #include <ctype.h> | |
| 31 | #include "file.h" | |
| 32 | #include "names.h" | |
| 33 | ||
| 34 | #ifndef lint | |
| 35 | static char *moduleid = | |
| 36 | "@(#)$Header: ascmagic.c,v 1.5 87/09/16 14:44:45 ian Exp $"; | |
| 37 | #endif /* lint */ | |
| 38 | ||
| 39 | char *ckfmsg = "write error on output"; | |
| 40 | ||
| 41 | /* an optimisation over plain strcmp() */ | |
| 42 | #define STREQ(a, b) (*(a) == *(b) && strcmp((a), (b)) == 0) | |
| 43 | ||
| 44 | ascmagic(buf) | |
| 45 | register char *buf; | |
| 46 | { | |
| 47 | register int i; | |
| 48 | char *s, *strtok(), *token; | |
| 49 | register struct names *p; | |
| 50 | extern int nbytes; | |
| 51 | short has_escapes = 0; | |
| 52 | ||
| 53 | /* these are easy, do them first */ | |
| 54 | ||
| 55 | /* | |
| 56 | * for troff, look for . + letter + letter; | |
| 57 | * this must be done to disambiguate tar archives' ./file | |
| 58 | * and other trash from real troff input. | |
| 59 | */ | |
| 60 | if (*buf == '.' && | |
| 61 | isascii(*(buf+1)) && isalnum(*(buf+1)) && | |
| 62 | isascii(*(buf+2)) && isalnum(*(buf+2))){ | |
| 63 | ckfputs("troff or preprocessor input text", stdout); | |
| 64 | return 1; | |
| 65 | } | |
| 66 | if ((*buf == 'c' || *buf == 'C') && | |
| 67 | isascii(*(buf + 1)) && isspace(*(buf + 1))) { | |
| 68 | ckfputs("fortran program text", stdout); | |
| 69 | return 1; | |
| 70 | } | |
| 71 | ||
| 72 | /* look for tokens from names.h - this is expensive! */ | |
| 73 | s = buf; | |
| 74 | while ((token = strtok(s, " \t\n\r\f")) != NULL) { | |
| 75 | s = NULL; /* make strtok() keep on tokin' */ | |
| 76 | for (p = names; p < names + NNAMES; p++) { | |
| 77 | if (STREQ(p->name, token)) { | |
| 78 | ckfputs(types[p->type], stdout); | |
| 79 | return 1; | |
| 80 | } | |
| 81 | } | |
| 82 | } | |
| 83 | ||
| 84 | switch (is_tar(buf)) { | |
| 85 | case 1: | |
| 86 | ckfputs("tar archive", stdout); | |
| 87 | return 1; | |
| 88 | case 2: | |
| 89 | ckfputs("POSIX tar archive", stdout); | |
| 90 | return 1; | |
| 91 | } | |
| 92 | ||
| 93 | for (i = 0; i < nbytes; i++) { | |
| 94 | if (!isascii(*(buf+i))) | |
| 95 | return 0; /* not all ascii */ | |
| 96 | if (*(buf+i) == '\033') /* ascii ESCAPE */ | |
| 97 | has_escapes ++; | |
| 98 | } | |
| 99 | ||
| 100 | /* all else fails, but it is ascii... */ | |
| 101 | if (has_escapes){ | |
| 102 | ckfputs("ascii text (with escape sequences)", stdout); | |
| 103 | } | |
| 104 | else { | |
| 105 | ckfputs("ascii text", stdout); | |
| 106 | } | |
| 107 | return 1; | |
| 108 | } | |
| 109 | ||
| 110 |