Annotation of embedaddon/php/ext/fileinfo/libmagic/is_tar.c, revision 1.1.1.1
1.1 misho 1: /*
2: * Copyright (c) Ian F. Darwin 1986-1995.
3: * Software written by Ian F. Darwin and others;
4: * maintained 1995-present by Christos Zoulas and others.
5: *
6: * Redistribution and use in source and binary forms, with or without
7: * modification, are permitted provided that the following conditions
8: * are met:
9: * 1. Redistributions of source code must retain the above copyright
10: * notice immediately at the beginning of the file, without modification,
11: * this list of conditions, and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: *
16: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20: * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26: * SUCH DAMAGE.
27: */
28: /*
29: * is_tar() -- figure out whether file is a tar archive.
30: *
31: * Stolen (by the author!) from the public domain tar program:
32: * Public Domain version written 26 Aug 1985 John Gilmore (ihnp4!hoptoad!gnu).
33: *
34: * @(#)list.c 1.18 9/23/86 Public Domain - gnu
35: *
36: * Comments changed and some code/comments reformatted
37: * for file command by Ian Darwin.
38: */
39:
40: #include "file.h"
41:
42: #ifndef lint
43: FILE_RCSID("@(#)$File: is_tar.c,v 1.36 2009/02/03 20:27:51 christos Exp $")
44: #endif
45:
46: #include "magic.h"
47: #include <string.h>
48: #include <ctype.h>
49: #include "tar.h"
50:
51: #define isodigit(c) ( ((c) >= '0') && ((c) <= '7') )
52:
53: private int is_tar(const unsigned char *, size_t);
54: private int from_oct(int, const char *); /* Decode octal number */
55:
56: static const char tartype[][32] = {
57: "tar archive",
58: "POSIX tar archive",
59: "POSIX tar archive (GNU)",
60: };
61:
62: protected int
63: file_is_tar(struct magic_set *ms, const unsigned char *buf, size_t nbytes)
64: {
65: /*
66: * Do the tar test first, because if the first file in the tar
67: * archive starts with a dot, we can confuse it with an nroff file.
68: */
69: int tar;
70: int mime = ms->flags & MAGIC_MIME;
71:
72: if ((ms->flags & MAGIC_APPLE) != 0)
73: return 0;
74:
75: tar = is_tar(buf, nbytes);
76: if (tar < 1 || tar > 3)
77: return 0;
78:
79: if (file_printf(ms, "%s", mime ? "application/x-tar" :
80: tartype[tar - 1]) == -1)
81: return -1;
82: return 1;
83: }
84:
85: /*
86: * Return
87: * 0 if the checksum is bad (i.e., probably not a tar archive),
88: * 1 for old UNIX tar file,
89: * 2 for Unix Std (POSIX) tar file,
90: * 3 for GNU tar file.
91: */
92: private int
93: is_tar(const unsigned char *buf, size_t nbytes)
94: {
95: const union record *header = (const union record *)(const void *)buf;
96: int i;
97: int sum, recsum;
98: const char *p;
99:
100: if (nbytes < sizeof(union record))
101: return 0;
102:
103: recsum = from_oct(8, header->header.chksum);
104:
105: sum = 0;
106: p = header->charptr;
107: for (i = sizeof(union record); --i >= 0;) {
108: /*
109: * We cannot use unsigned char here because of old compilers,
110: * e.g. V7.
111: */
112: sum += 0xFF & *p++;
113: }
114:
115: /* Adjust checksum to count the "chksum" field as blanks. */
116: for (i = sizeof(header->header.chksum); --i >= 0;)
117: sum -= 0xFF & header->header.chksum[i];
118: sum += ' '* sizeof header->header.chksum;
119:
120: if (sum != recsum)
121: return 0; /* Not a tar archive */
122:
123: if (strcmp(header->header.magic, GNUTMAGIC) == 0)
124: return 3; /* GNU Unix Standard tar archive */
125: if (strcmp(header->header.magic, TMAGIC) == 0)
126: return 2; /* Unix Standard tar archive */
127:
128: return 1; /* Old fashioned tar archive */
129: }
130:
131:
132: /*
133: * Quick and dirty octal conversion.
134: *
135: * Result is -1 if the field is invalid (all blank, or nonoctal).
136: */
137: private int
138: from_oct(int digs, const char *where)
139: {
140: int value;
141:
142: while (isspace((unsigned char)*where)) { /* Skip spaces */
143: where++;
144: if (--digs <= 0)
145: return -1; /* All blank field */
146: }
147: value = 0;
148: while (digs > 0 && isodigit(*where)) { /* Scan til nonoctal */
149: value = (value << 3) | (*where++ - '0');
150: --digs;
151: }
152:
153: if (digs > 0 && *where && !isspace((unsigned char)*where))
154: return -1; /* Ended on non-space/nul */
155:
156: return value;
157: }
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