1 /* $NetBSD: magic.c,v 1.5 2013/01/03 23:05:38 christos Exp $ */ 2 3 /* 4 * Copyright (c) Christos Zoulas 2003. 5 * All Rights Reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice immediately at the beginning of the file, without modification, 12 * this list of conditions, and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR 21 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #ifdef WIN32 31 #include <windows.h> 32 #include <shlwapi.h> 33 #endif 34 35 #include "file.h" 36 37 #ifndef lint 38 #if 0 39 FILE_RCSID("@(#)$File: magic.c,v 1.77 2012/10/31 17:20:06 christos Exp $") 40 #else 41 __RCSID("$NetBSD: magic.c,v 1.5 2013/01/03 23:05:38 christos Exp $"); 42 #endif 43 #endif /* lint */ 44 45 #include "magic.h" 46 47 #include <stdlib.h> 48 #include <unistd.h> 49 #include <string.h> 50 #ifdef QUICK 51 #include <sys/mman.h> 52 #endif 53 #ifdef HAVE_LIMITS_H 54 #include <limits.h> /* for PIPE_BUF */ 55 #endif 56 57 #if defined(HAVE_UTIMES) 58 # include <sys/time.h> 59 #elif defined(HAVE_UTIME) 60 # if defined(HAVE_SYS_UTIME_H) 61 # include <sys/utime.h> 62 # elif defined(HAVE_UTIME_H) 63 # include <utime.h> 64 # endif 65 #endif 66 67 #ifdef HAVE_UNISTD_H 68 #include <unistd.h> /* for read() */ 69 #endif 70 71 #ifndef PIPE_BUF 72 /* Get the PIPE_BUF from pathconf */ 73 #ifdef _PC_PIPE_BUF 74 #define PIPE_BUF pathconf(".", _PC_PIPE_BUF) 75 #else 76 #define PIPE_BUF 512 77 #endif 78 #endif 79 80 private void close_and_restore(const struct magic_set *, const char *, int, 81 const struct stat *); 82 private int unreadable_info(struct magic_set *, mode_t, const char *); 83 private const char* get_default_magic(void); 84 #ifndef COMPILE_ONLY 85 private const char *file_or_fd(struct magic_set *, const char *, int); 86 #endif 87 88 #ifndef STDIN_FILENO 89 #define STDIN_FILENO 0 90 #endif 91 92 private const char * 93 get_default_magic(void) 94 { 95 static const char hmagic[] = "/.magic/magic.mgc"; 96 static char *default_magic; 97 char *home, *hmagicpath; 98 99 #ifndef WIN32 100 struct stat st; 101 102 if (default_magic) { 103 free(default_magic); 104 default_magic = NULL; 105 } 106 if ((home = getenv("HOME")) == NULL) 107 return MAGIC; 108 109 if (asprintf(&hmagicpath, "%s/.magic.mgc", home) < 0) 110 return MAGIC; 111 if (stat(hmagicpath, &st) == -1) { 112 free(hmagicpath); 113 if (asprintf(&hmagicpath, "%s/.magic", home) < 0) 114 return MAGIC; 115 if (stat(hmagicpath, &st) == -1) 116 goto out; 117 if (S_ISDIR(st.st_mode)) { 118 free(hmagicpath); 119 if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0) 120 return MAGIC; 121 if (access(hmagicpath, R_OK) == -1) 122 goto out; 123 } 124 } 125 126 if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0) 127 goto out; 128 free(hmagicpath); 129 return default_magic; 130 out: 131 default_magic = NULL; 132 free(hmagicpath); 133 return MAGIC; 134 #else 135 char *hmagicp = hmagicpath; 136 char *tmppath = NULL; 137 138 #define APPENDPATH() \ 139 do { \ 140 if (tmppath && access(tmppath, R_OK) != -1) { \ 141 if (hmagicpath == NULL) \ 142 hmagicpath = tmppath; \ 143 else { \ 144 if (asprintf(&hmagicp, "%s%c%s", hmagicpath, \ 145 PATHSEP, tmppath) >= 0) { \ 146 free(hmagicpath); \ 147 hmagicpath = hmagicp; \ 148 } \ 149 free(tmppath); \ 150 } \ 151 tmppath = NULL; \ 152 } \ 153 } while (/*CONSTCOND*/0) 154 155 if (default_magic) { 156 free(default_magic); 157 default_magic = NULL; 158 } 159 160 /* First, try to get user-specific magic file */ 161 if ((home = getenv("LOCALAPPDATA")) == NULL) { 162 if ((home = getenv("USERPROFILE")) != NULL) 163 if (asprintf(&tmppath, 164 "%s/Local Settings/Application Data%s", home, 165 hmagic) < 0) 166 tmppath = NULL; 167 } else { 168 if (asprintf(&tmppath, "%s%s", home, hmagic) < 0) 169 tmppath = NULL; 170 } 171 172 APPENDPATH(); 173 174 /* Second, try to get a magic file from Common Files */ 175 if ((home = getenv("COMMONPROGRAMFILES")) != NULL) { 176 if (asprintf(&tmppath, "%s%s", home, hmagic) >= 0) 177 APPENDPATH(); 178 } 179 180 /* Third, try to get magic file relative to dll location */ 181 LPTSTR dllpath = malloc(sizeof(*dllpath) * (MAX_PATH + 1)); 182 dllpath[MAX_PATH] = 0; /* just in case long path gets truncated and not null terminated */ 183 if (GetModuleFileNameA(NULL, dllpath, MAX_PATH)){ 184 PathRemoveFileSpecA(dllpath); 185 if (strlen(dllpath) > 3 && 186 stricmp(&dllpath[strlen(dllpath) - 3], "bin") == 0) { 187 if (asprintf(&tmppath, 188 "%s/../share/misc/magic.mgc", dllpath) >= 0) 189 APPENDPATH(); 190 } else { 191 if (asprintf(&tmppath, 192 "%s/share/misc/magic.mgc", dllpath) >= 0) 193 APPENDPATH(); 194 else if (asprintf(&tmppath, 195 "%s/magic.mgc", dllpath) >= 0) 196 APPENDPATH(); 197 } 198 } 199 200 /* Don't put MAGIC constant - it likely points to a file within MSys 201 tree */ 202 default_magic = hmagicpath; 203 return default_magic; 204 #endif 205 } 206 207 public const char * 208 magic_getpath(const char *magicfile, int action) 209 { 210 if (magicfile != NULL) 211 return magicfile; 212 213 magicfile = getenv("MAGIC"); 214 if (magicfile != NULL) 215 return magicfile; 216 217 return action == FILE_LOAD ? get_default_magic() : MAGIC; 218 } 219 220 public struct magic_set * 221 magic_open(int flags) 222 { 223 return file_ms_alloc(flags); 224 } 225 226 private int 227 unreadable_info(struct magic_set *ms, mode_t md, const char *file) 228 { 229 /* We cannot open it, but we were able to stat it. */ 230 if (access(file, W_OK) == 0) 231 if (file_printf(ms, "writable, ") == -1) 232 return -1; 233 if (access(file, X_OK) == 0) 234 if (file_printf(ms, "executable, ") == -1) 235 return -1; 236 if (S_ISREG(md)) 237 if (file_printf(ms, "regular file, ") == -1) 238 return -1; 239 if (file_printf(ms, "no read permission") == -1) 240 return -1; 241 return 0; 242 } 243 244 public void 245 magic_close(struct magic_set *ms) 246 { 247 if (ms == NULL) 248 return; 249 file_ms_free(ms); 250 } 251 252 /* 253 * load a magic file 254 */ 255 public int 256 magic_load(struct magic_set *ms, const char *magicfile) 257 { 258 if (ms == NULL) 259 return -1; 260 return file_apprentice(ms, magicfile, FILE_LOAD); 261 } 262 263 public int 264 magic_compile(struct magic_set *ms, const char *magicfile) 265 { 266 if (ms == NULL) 267 return -1; 268 return file_apprentice(ms, magicfile, FILE_COMPILE); 269 } 270 271 public int 272 magic_check(struct magic_set *ms, const char *magicfile) 273 { 274 if (ms == NULL) 275 return -1; 276 return file_apprentice(ms, magicfile, FILE_CHECK); 277 } 278 279 public int 280 magic_list(struct magic_set *ms, const char *magicfile) 281 { 282 if (ms == NULL) 283 return -1; 284 return file_apprentice(ms, magicfile, FILE_LIST); 285 } 286 287 private void 288 close_and_restore(const struct magic_set *ms, const char *name, int fd, 289 const struct stat *sb) 290 { 291 if (fd == STDIN_FILENO) 292 return; 293 (void) close(fd); 294 295 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 296 /* 297 * Try to restore access, modification times if read it. 298 * This is really *bad* because it will modify the status 299 * time of the file... And of course this will affect 300 * backup programs 301 */ 302 #ifdef HAVE_UTIMES 303 struct timeval utsbuf[2]; 304 (void)memset(utsbuf, 0, sizeof(utsbuf)); 305 utsbuf[0].tv_sec = sb->st_atime; 306 utsbuf[1].tv_sec = sb->st_mtime; 307 308 (void) utimes(name, utsbuf); /* don't care if loses */ 309 #elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 310 struct utimbuf utbuf; 311 312 (void)memset(&utbuf, 0, sizeof(utbuf)); 313 utbuf.actime = sb->st_atime; 314 utbuf.modtime = sb->st_mtime; 315 (void) utime(name, &utbuf); /* don't care if loses */ 316 #endif 317 } 318 } 319 320 #ifndef COMPILE_ONLY 321 322 /* 323 * find type of descriptor 324 */ 325 public const char * 326 magic_descriptor(struct magic_set *ms, int fd) 327 { 328 if (ms == NULL) 329 return NULL; 330 return file_or_fd(ms, NULL, fd); 331 } 332 333 /* 334 * find type of named file 335 */ 336 public const char * 337 magic_file(struct magic_set *ms, const char *inname) 338 { 339 if (ms == NULL) 340 return NULL; 341 return file_or_fd(ms, inname, STDIN_FILENO); 342 } 343 344 private const char * 345 file_or_fd(struct magic_set *ms, const char *inname, int fd) 346 { 347 int rv = -1; 348 unsigned char *buf; 349 struct stat sb; 350 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 351 int ispipe = 0; 352 353 /* 354 * one extra for terminating '\0', and 355 * some overlapping space for matches near EOF 356 */ 357 #define SLOP (1 + sizeof(union VALUETYPE)) 358 if ((buf = CAST(unsigned char *, malloc(HOWMANY + SLOP))) == NULL) 359 return NULL; 360 361 if (file_reset(ms) == -1) 362 goto done; 363 364 switch (file_fsmagic(ms, inname, &sb)) { 365 case -1: /* error */ 366 goto done; 367 case 0: /* nothing found */ 368 break; 369 default: /* matched it and printed type */ 370 rv = 0; 371 goto done; 372 } 373 374 if (inname == NULL) { 375 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) 376 ispipe = 1; 377 } else { 378 int flags = O_RDONLY|O_BINARY; 379 380 if (stat(inname, &sb) == 0 && S_ISFIFO(sb.st_mode)) { 381 #ifdef O_NONBLOCK 382 flags |= O_NONBLOCK; 383 #endif 384 ispipe = 1; 385 } 386 387 errno = 0; 388 if ((fd = open(inname, flags)) < 0) { 389 if (unreadable_info(ms, sb.st_mode, inname) == -1) 390 goto done; 391 rv = 0; 392 goto done; 393 } 394 #ifdef O_NONBLOCK 395 if ((flags = fcntl(fd, F_GETFL)) != -1) { 396 flags &= ~O_NONBLOCK; 397 (void)fcntl(fd, F_SETFL, flags); 398 } 399 #endif 400 } 401 402 /* 403 * try looking at the first HOWMANY bytes 404 */ 405 if (ispipe) { 406 ssize_t r = 0; 407 408 while ((r = sread(fd, (void *)&buf[nbytes], 409 (size_t)(HOWMANY - nbytes), 1)) > 0) { 410 nbytes += r; 411 if (r < PIPE_BUF) break; 412 } 413 414 if (nbytes == 0) { 415 /* We can not read it, but we were able to stat it. */ 416 if (unreadable_info(ms, sb.st_mode, inname) == -1) 417 goto done; 418 rv = 0; 419 goto done; 420 } 421 422 } else { 423 if ((nbytes = read(fd, (char *)buf, HOWMANY)) == -1) { 424 file_error(ms, errno, "cannot read `%s'", inname); 425 goto done; 426 } 427 } 428 429 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 430 if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) 431 goto done; 432 rv = 0; 433 done: 434 free(buf); 435 close_and_restore(ms, inname, fd, &sb); 436 return rv == 0 ? file_getbuffer(ms) : NULL; 437 } 438 439 440 public const char * 441 magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 442 { 443 if (ms == NULL) 444 return NULL; 445 if (file_reset(ms) == -1) 446 return NULL; 447 /* 448 * The main work is done here! 449 * We have the file name and/or the data buffer to be identified. 450 */ 451 if (file_buffer(ms, -1, NULL, buf, nb) == -1) { 452 return NULL; 453 } 454 return file_getbuffer(ms); 455 } 456 #endif 457 458 public const char * 459 magic_error(struct magic_set *ms) 460 { 461 if (ms == NULL) 462 return "Magic database is not open"; 463 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 464 } 465 466 public int 467 magic_errno(struct magic_set *ms) 468 { 469 if (ms == NULL) 470 return EINVAL; 471 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 472 } 473 474 public int 475 magic_setflags(struct magic_set *ms, int flags) 476 { 477 if (ms == NULL) 478 return -1; 479 #if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 480 if (flags & MAGIC_PRESERVE_ATIME) 481 return -1; 482 #endif 483 ms->flags = flags; 484 return 0; 485 } 486