1 /* 2 * Copyright (c) Christos Zoulas 2003. 3 * All Rights Reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR 19 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include "file.h" 29 30 #ifndef lint 31 FILE_RCSID("@(#)$File: magic.c,v 1.62 2009/03/20 21:25:41 christos Exp $") 32 #endif /* lint */ 33 34 #include "magic.h" 35 36 #include <stdlib.h> 37 #include <unistd.h> 38 #include <string.h> 39 #ifdef QUICK 40 #include <sys/mman.h> 41 #endif 42 #ifdef HAVE_LIMITS_H 43 #include <limits.h> /* for PIPE_BUF */ 44 #endif 45 46 #if defined(HAVE_UTIMES) 47 # include <sys/time.h> 48 #elif defined(HAVE_UTIME) 49 # if defined(HAVE_SYS_UTIME_H) 50 # include <sys/utime.h> 51 # elif defined(HAVE_UTIME_H) 52 # include <utime.h> 53 # endif 54 #endif 55 56 #ifdef HAVE_UNISTD_H 57 #include <unistd.h> /* for read() */ 58 #endif 59 60 #include <netinet/in.h> /* for byte swapping */ 61 62 #include "patchlevel.h" 63 64 #ifndef PIPE_BUF 65 /* Get the PIPE_BUF from pathconf */ 66 #ifdef _PC_PIPE_BUF 67 #define PIPE_BUF pathconf(".", _PC_PIPE_BUF) 68 #else 69 #define PIPE_BUF 512 70 #endif 71 #endif 72 73 private void free_mlist(struct mlist *); 74 private void close_and_restore(const struct magic_set *, const char *, int, 75 const struct stat *); 76 private int unreadable_info(struct magic_set *, mode_t, const char *); 77 #ifndef COMPILE_ONLY 78 private const char *file_or_fd(struct magic_set *, const char *, int); 79 #endif 80 81 #ifndef STDIN_FILENO 82 #define STDIN_FILENO 0 83 #endif 84 85 public struct magic_set * 86 magic_open(int flags) 87 { 88 struct magic_set *ms; 89 size_t len; 90 91 if ((ms = CAST(magic_set *, calloc((size_t)1, 92 sizeof(struct magic_set)))) == NULL) 93 return NULL; 94 95 if (magic_setflags(ms, flags) == -1) { 96 errno = EINVAL; 97 goto free; 98 } 99 100 ms->o.buf = ms->o.pbuf = NULL; 101 len = (ms->c.len = 10) * sizeof(*ms->c.li); 102 103 if ((ms->c.li = CAST(struct level_info *, malloc(len))) == NULL) 104 goto free; 105 106 ms->event_flags = 0; 107 ms->error = -1; 108 ms->mlist = NULL; 109 ms->file = "unknown"; 110 ms->line = 0; 111 return ms; 112 free: 113 free(ms); 114 return NULL; 115 } 116 117 private void 118 free_mlist(struct mlist *mlist) 119 { 120 struct mlist *ml; 121 122 if (mlist == NULL) 123 return; 124 125 for (ml = mlist->next; ml != mlist;) { 126 struct mlist *next = ml->next; 127 struct magic *mg = ml->magic; 128 file_delmagic(mg, ml->mapped, ml->nmagic); 129 free(ml); 130 ml = next; 131 } 132 free(ml); 133 } 134 135 private int 136 unreadable_info(struct magic_set *ms, mode_t md, const char *file) 137 { 138 /* We cannot open it, but we were able to stat it. */ 139 if (access(file, W_OK) == 0) 140 if (file_printf(ms, "writable, ") == -1) 141 return -1; 142 if (access(file, X_OK) == 0) 143 if (file_printf(ms, "executable, ") == -1) 144 return -1; 145 if (S_ISREG(md)) 146 if (file_printf(ms, "regular file, ") == -1) 147 return -1; 148 if (file_printf(ms, "no read permission") == -1) 149 return -1; 150 return 0; 151 } 152 153 public void 154 magic_close(struct magic_set *ms) 155 { 156 free_mlist(ms->mlist); 157 free(ms->o.pbuf); 158 free(ms->o.buf); 159 free(ms->c.li); 160 free(ms); 161 } 162 163 /* 164 * load a magic file 165 */ 166 public int 167 magic_load(struct magic_set *ms, const char *magicfile) 168 { 169 struct mlist *ml = file_apprentice(ms, magicfile, FILE_LOAD); 170 if (ml) { 171 free_mlist(ms->mlist); 172 ms->mlist = ml; 173 return 0; 174 } 175 return -1; 176 } 177 178 public int 179 magic_compile(struct magic_set *ms, const char *magicfile) 180 { 181 struct mlist *ml = file_apprentice(ms, magicfile, FILE_COMPILE); 182 free_mlist(ml); 183 return ml ? 0 : -1; 184 } 185 186 public int 187 magic_check(struct magic_set *ms, const char *magicfile) 188 { 189 struct mlist *ml = file_apprentice(ms, magicfile, FILE_CHECK); 190 free_mlist(ml); 191 return ml ? 0 : -1; 192 } 193 194 private void 195 close_and_restore(const struct magic_set *ms, const char *name, int fd, 196 const struct stat *sb) 197 { 198 if (fd == STDIN_FILENO) 199 return; 200 (void) close(fd); 201 202 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 203 /* 204 * Try to restore access, modification times if read it. 205 * This is really *bad* because it will modify the status 206 * time of the file... And of course this will affect 207 * backup programs 208 */ 209 #ifdef HAVE_UTIMES 210 struct timeval utsbuf[2]; 211 (void)memset(utsbuf, 0, sizeof(utsbuf)); 212 utsbuf[0].tv_sec = sb->st_atime; 213 utsbuf[1].tv_sec = sb->st_mtime; 214 215 (void) utimes(name, utsbuf); /* don't care if loses */ 216 #elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 217 struct utimbuf utbuf; 218 219 (void)memset(&utbuf, 0, sizeof(utbuf)); 220 utbuf.actime = sb->st_atime; 221 utbuf.modtime = sb->st_mtime; 222 (void) utime(name, &utbuf); /* don't care if loses */ 223 #endif 224 } 225 } 226 227 #ifndef COMPILE_ONLY 228 229 /* 230 * find type of descriptor 231 */ 232 public const char * 233 magic_descriptor(struct magic_set *ms, int fd) 234 { 235 return file_or_fd(ms, NULL, fd); 236 } 237 238 /* 239 * find type of named file 240 */ 241 public const char * 242 magic_file(struct magic_set *ms, const char *inname) 243 { 244 return file_or_fd(ms, inname, STDIN_FILENO); 245 } 246 247 private const char * 248 file_or_fd(struct magic_set *ms, const char *inname, int fd) 249 { 250 int rv = -1; 251 unsigned char *buf; 252 struct stat sb; 253 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 254 int ispipe = 0; 255 256 /* 257 * one extra for terminating '\0', and 258 * some overlapping space for matches near EOF 259 */ 260 #define SLOP (1 + sizeof(union VALUETYPE)) 261 if ((buf = CAST(unsigned char *, malloc(HOWMANY + SLOP))) == NULL) 262 return NULL; 263 264 if (file_reset(ms) == -1) 265 goto done; 266 267 switch (file_fsmagic(ms, inname, &sb)) { 268 case -1: /* error */ 269 goto done; 270 case 0: /* nothing found */ 271 break; 272 default: /* matched it and printed type */ 273 rv = 0; 274 goto done; 275 } 276 277 if (inname == NULL) { 278 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) 279 ispipe = 1; 280 } else { 281 int flags = O_RDONLY|O_BINARY; 282 283 if (stat(inname, &sb) == 0 && S_ISFIFO(sb.st_mode)) { 284 flags |= O_NONBLOCK; 285 ispipe = 1; 286 } 287 288 errno = 0; 289 if ((fd = open(inname, flags)) < 0) { 290 if (unreadable_info(ms, sb.st_mode, inname) == -1) 291 goto done; 292 rv = 0; 293 goto done; 294 } 295 #ifdef O_NONBLOCK 296 if ((flags = fcntl(fd, F_GETFL)) != -1) { 297 flags &= ~O_NONBLOCK; 298 (void)fcntl(fd, F_SETFL, flags); 299 } 300 #endif 301 } 302 303 /* 304 * try looking at the first HOWMANY bytes 305 */ 306 if (ispipe) { 307 ssize_t r = 0; 308 309 while ((r = sread(fd, (void *)&buf[nbytes], 310 (size_t)(HOWMANY - nbytes), 1)) > 0) { 311 nbytes += r; 312 if (r < PIPE_BUF) break; 313 } 314 315 if (nbytes == 0) { 316 /* We can not read it, but we were able to stat it. */ 317 if (unreadable_info(ms, sb.st_mode, inname) == -1) 318 goto done; 319 rv = 0; 320 goto done; 321 } 322 323 } else { 324 if ((nbytes = read(fd, (char *)buf, HOWMANY)) == -1) { 325 file_error(ms, errno, "cannot read `%s'", inname); 326 goto done; 327 } 328 } 329 330 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 331 if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) 332 goto done; 333 rv = 0; 334 done: 335 free(buf); 336 close_and_restore(ms, inname, fd, &sb); 337 return rv == 0 ? file_getbuffer(ms) : NULL; 338 } 339 340 341 public const char * 342 magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 343 { 344 if (file_reset(ms) == -1) 345 return NULL; 346 /* 347 * The main work is done here! 348 * We have the file name and/or the data buffer to be identified. 349 */ 350 if (file_buffer(ms, -1, NULL, buf, nb) == -1) { 351 return NULL; 352 } 353 return file_getbuffer(ms); 354 } 355 #endif 356 357 public const char * 358 magic_error(struct magic_set *ms) 359 { 360 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 361 } 362 363 public int 364 magic_errno(struct magic_set *ms) 365 { 366 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 367 } 368 369 public int 370 magic_setflags(struct magic_set *ms, int flags) 371 { 372 #if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 373 if (flags & MAGIC_PRESERVE_ATIME) 374 return -1; 375 #endif 376 ms->flags = flags; 377 return 0; 378 } 379