fsmagic.c revision 175296
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 * fsmagic - magic based on filesystem info - directory, special files, etc. 30 */ 31 32#include "file.h" 33#include "magic.h" 34#include <string.h> 35#ifdef HAVE_UNISTD_H 36#include <unistd.h> 37#endif 38#include <stdlib.h> 39#include <sys/stat.h> 40/* Since major is a function on SVR4, we cannot use `ifndef major'. */ 41#ifdef MAJOR_IN_MKDEV 42# include <sys/mkdev.h> 43# define HAVE_MAJOR 44#endif 45#ifdef MAJOR_IN_SYSMACROS 46# include <sys/sysmacros.h> 47# define HAVE_MAJOR 48#endif 49#ifdef major /* Might be defined in sys/types.h. */ 50# define HAVE_MAJOR 51#endif 52 53#ifndef HAVE_MAJOR 54# define major(dev) (((dev) >> 8) & 0xff) 55# define minor(dev) ((dev) & 0xff) 56#endif 57#undef HAVE_MAJOR 58 59#ifndef lint 60FILE_RCSID("@(#)$File: fsmagic.c,v 1.48 2007/10/17 19:33:31 christos Exp $") 61#endif /* lint */ 62 63protected int 64file_fsmagic(struct magic_set *ms, const char *fn, struct stat *sb) 65{ 66 int ret = 0; 67 int mime = ms->flags & MAGIC_MIME; 68#ifdef S_IFLNK 69 char buf[BUFSIZ+4]; 70 int nch; 71 struct stat tstatbuf; 72#endif 73 74 if (fn == NULL) 75 return 0; 76 77 /* 78 * Fstat is cheaper but fails for files you don't have read perms on. 79 * On 4.2BSD and similar systems, use lstat() to identify symlinks. 80 */ 81#ifdef S_IFLNK 82 if ((ms->flags & MAGIC_SYMLINK) == 0) 83 ret = lstat(fn, sb); 84 else 85#endif 86 ret = stat(fn, sb); /* don't merge into if; see "ret =" above */ 87 88 if (ret) { 89 if (ms->flags & MAGIC_ERROR) { 90 file_error(ms, errno, "cannot stat `%s'", fn); 91 return -1; 92 } 93 if (file_printf(ms, "cannot open `%s' (%s)", 94 fn, strerror(errno)) == -1) 95 return -1; 96 return 1; 97 } 98 99 if (mime) { 100 if ((sb->st_mode & S_IFMT) != S_IFREG) { 101 if ((mime & MAGIC_MIME_TYPE) && 102 file_printf(ms, "application/x-not-regular-file") 103 == -1) 104 return -1; 105 return 1; 106 } 107 } 108 else { 109#ifdef S_ISUID 110 if (sb->st_mode & S_ISUID) 111 if (file_printf(ms, "setuid ") == -1) 112 return -1; 113#endif 114#ifdef S_ISGID 115 if (sb->st_mode & S_ISGID) 116 if (file_printf(ms, "setgid ") == -1) 117 return -1; 118#endif 119#ifdef S_ISVTX 120 if (sb->st_mode & S_ISVTX) 121 if (file_printf(ms, "sticky ") == -1) 122 return -1; 123#endif 124 } 125 126 switch (sb->st_mode & S_IFMT) { 127 case S_IFDIR: 128 if (file_printf(ms, "directory") == -1) 129 return -1; 130 return 1; 131#ifdef S_IFCHR 132 case S_IFCHR: 133 /* 134 * If -s has been specified, treat character special files 135 * like ordinary files. Otherwise, just report that they 136 * are block special files and go on to the next file. 137 */ 138 if ((ms->flags & MAGIC_DEVICES) != 0) 139 break; 140#ifdef HAVE_ST_RDEV 141# ifdef dv_unit 142 if (file_printf(ms, "character special (%d/%d/%d)", 143 major(sb->st_rdev), dv_unit(sb->st_rdev), 144 dv_subunit(sb->st_rdev)) == -1) 145 return -1; 146# else 147 if (file_printf(ms, "character special (%ld/%ld)", 148 (long) major(sb->st_rdev), (long) minor(sb->st_rdev)) == -1) 149 return -1; 150# endif 151#else 152 if (file_printf(ms, "character special") == -1) 153 return -1; 154#endif 155 return 1; 156#endif 157#ifdef S_IFBLK 158 case S_IFBLK: 159 /* 160 * If -s has been specified, treat block special files 161 * like ordinary files. Otherwise, just report that they 162 * are block special files and go on to the next file. 163 */ 164 if ((ms->flags & MAGIC_DEVICES) != 0) 165 break; 166#ifdef HAVE_ST_RDEV 167# ifdef dv_unit 168 if (file_printf(ms, "block special (%d/%d/%d)", 169 major(sb->st_rdev), dv_unit(sb->st_rdev), 170 dv_subunit(sb->st_rdev)) == -1) 171 return -1; 172# else 173 if (file_printf(ms, "block special (%ld/%ld)", 174 (long)major(sb->st_rdev), (long)minor(sb->st_rdev)) == -1) 175 return -1; 176# endif 177#else 178 if (file_printf(ms, "block special") == -1) 179 return -1; 180#endif 181 return 1; 182#endif 183 /* TODO add code to handle V7 MUX and Blit MUX files */ 184#ifdef S_IFIFO 185 case S_IFIFO: 186 if((ms->flags & MAGIC_DEVICES) != 0) 187 break; 188 if (file_printf(ms, "fifo (named pipe)") == -1) 189 return -1; 190 return 1; 191#endif 192#ifdef S_IFDOOR 193 case S_IFDOOR: 194 if (file_printf(ms, "door") == -1) 195 return -1; 196 return 1; 197#endif 198#ifdef S_IFLNK 199 case S_IFLNK: 200 if ((nch = readlink(fn, buf, BUFSIZ-1)) <= 0) { 201 if (ms->flags & MAGIC_ERROR) { 202 file_error(ms, errno, "unreadable symlink `%s'", 203 fn); 204 return -1; 205 } 206 if (file_printf(ms, 207 "unreadable symlink `%s' (%s)", fn, 208 strerror(errno)) == -1) 209 return -1; 210 return 1; 211 } 212 buf[nch] = '\0'; /* readlink(2) forgets this */ 213 214 /* If broken symlink, say so and quit early. */ 215 if (*buf == '/') { 216 if (stat(buf, &tstatbuf) < 0) { 217 if (ms->flags & MAGIC_ERROR) { 218 file_error(ms, errno, 219 "broken symbolic link to `%s'", buf); 220 return -1; 221 } 222 if (file_printf(ms, "broken symbolic link to `%s'", 223 buf) == -1) 224 return -1; 225 return 1; 226 } 227 } 228 else { 229 char *tmp; 230 char buf2[BUFSIZ+BUFSIZ+4]; 231 232 if ((tmp = strrchr(fn, '/')) == NULL) { 233 tmp = buf; /* in current directory anyway */ 234 } else { 235 if (tmp - fn + 1 > BUFSIZ) { 236 if (ms->flags & MAGIC_ERROR) { 237 file_error(ms, 0, 238 "path too long: `%s'", buf); 239 return -1; 240 } 241 if (file_printf(ms, 242 "path too long: `%s'", fn) == -1) 243 return -1; 244 return 1; 245 } 246 (void)strcpy(buf2, fn); /* take dir part */ 247 buf2[tmp - fn + 1] = '\0'; 248 (void)strcat(buf2, buf); /* plus (rel) link */ 249 tmp = buf2; 250 } 251 if (stat(tmp, &tstatbuf) < 0) { 252 if (ms->flags & MAGIC_ERROR) { 253 file_error(ms, errno, 254 "broken symbolic link to `%s'", 255 buf); 256 return -1; 257 } 258 if (file_printf(ms, 259 "broken symbolic link to `%s'", buf) == -1) 260 return -1; 261 return 1; 262 } 263 } 264 265 /* Otherwise, handle it. */ 266 if ((ms->flags & MAGIC_SYMLINK) != 0) { 267 const char *p; 268 ms->flags &= MAGIC_SYMLINK; 269 p = magic_file(ms, buf); 270 ms->flags |= MAGIC_SYMLINK; 271 return p != NULL ? 1 : -1; 272 } else { /* just print what it points to */ 273 if (file_printf(ms, "symbolic link to `%s'", 274 buf) == -1) 275 return -1; 276 } 277 return 1; 278#endif 279#ifdef S_IFSOCK 280#ifndef __COHERENT__ 281 case S_IFSOCK: 282 if (file_printf(ms, "socket") == -1) 283 return -1; 284 return 1; 285#endif 286#endif 287 case S_IFREG: 288 break; 289 default: 290 file_error(ms, 0, "invalid mode 0%o", sb->st_mode); 291 return -1; 292 /*NOTREACHED*/ 293 } 294 295 /* 296 * regular file, check next possibility 297 * 298 * If stat() tells us the file has zero length, report here that 299 * the file is empty, so we can skip all the work of opening and 300 * reading the file. 301 * But if the -s option has been given, we skip this optimization, 302 * since on some systems, stat() reports zero size for raw disk 303 * partitions. (If the block special device really has zero length, 304 * the fact that it is empty will be detected and reported correctly 305 * when we read the file.) 306 */ 307 if ((ms->flags & MAGIC_DEVICES) == 0 && sb->st_size == 0) { 308 if ((!mime || (mime & MAGIC_MIME_TYPE)) && 309 file_printf(ms, mime ? "application/x-empty" : 310 "empty") == -1) 311 return -1; 312 return 1; 313 } 314 return 0; 315} 316