Annotation of embedaddon/php/ext/fileinfo/libmagic/is_tar.c, revision 1.1.1.2
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.
1.1.1.2 ! misho 5: *
1.1 misho 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.
1.1.1.2 ! misho 15: *
1.1 misho 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
1.1.1.2 ! misho 43: FILE_RCSID("@(#)$File: is_tar.c,v 1.37 2010/11/30 14:58:53 rrt Exp $")
1.1 misho 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: /*
1.1.1.2 ! misho 86: * Return
! 87: * 0 if the checksum is bad (i.e., probably not a tar archive),
1.1 misho 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;
1.1.1.2 ! misho 98: const unsigned char *p;
1.1 misho 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;
1.1.1.2 ! misho 107: for (i = sizeof(union record); --i >= 0;)
! 108: sum += *p++;
1.1 misho 109:
110: /* Adjust checksum to count the "chksum" field as blanks. */
111: for (i = sizeof(header->header.chksum); --i >= 0;)
1.1.1.2 ! misho 112: sum -= header->header.chksum[i];
! 113: sum += ' ' * sizeof header->header.chksum;
1.1 misho 114:
115: if (sum != recsum)
116: return 0; /* Not a tar archive */
1.1.1.2 ! misho 117:
! 118: if (strcmp(header->header.magic, GNUTMAGIC) == 0)
1.1 misho 119: return 3; /* GNU Unix Standard tar archive */
1.1.1.2 ! misho 120: if (strcmp(header->header.magic, TMAGIC) == 0)
1.1 misho 121: return 2; /* Unix Standard tar archive */
122:
123: return 1; /* Old fashioned tar archive */
124: }
125:
126:
127: /*
128: * Quick and dirty octal conversion.
129: *
1.1.1.2 ! misho 130: * Result is -1 if the field is invalid (all blank, or non-octal).
1.1 misho 131: */
132: private int
133: from_oct(int digs, const char *where)
134: {
135: int value;
136:
137: while (isspace((unsigned char)*where)) { /* Skip spaces */
138: where++;
139: if (--digs <= 0)
140: return -1; /* All blank field */
141: }
142: value = 0;
1.1.1.2 ! misho 143: while (digs > 0 && isodigit(*where)) { /* Scan til non-octal */
1.1 misho 144: value = (value << 3) | (*where++ - '0');
145: --digs;
146: }
147:
148: if (digs > 0 && *where && !isspace((unsigned char)*where))
1.1.1.2 ! misho 149: return -1; /* Ended on non-(space/NUL) */
1.1 misho 150:
151: return value;
152: }
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