1 /* $NetBSD: magic.c,v 1.9 2014/10/10 20:15:02 christos Exp $ */ 2 /* 3 * Copyright (c) Christos Zoulas 2003. 4 * All Rights Reserved. 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 #ifdef WIN32 30 #include <windows.h> 31 #include <shlwapi.h> 32 #endif 33 34 #include "file.h" 35 36 #ifndef lint 37 #if 0 38 FILE_RCSID("@(#)$File: magic.c,v 1.85 2014/08/04 06:19:44 christos Exp $") 39 #else 40 __RCSID("$NetBSD: magic.c,v 1.9 2014/10/10 20:15:02 christos Exp $"); 41 #endif 42 #endif /* lint */ 43 44 #include "magic.h" 45 46 #include <stdlib.h> 47 #include <unistd.h> 48 #include <string.h> 49 #ifdef QUICK 50 #include <sys/mman.h> 51 #endif 52 #ifdef HAVE_LIMITS_H 53 #include <limits.h> /* for PIPE_BUF */ 54 #endif 55 56 #if defined(HAVE_UTIMES) 57 # include <sys/time.h> 58 #elif defined(HAVE_UTIME) 59 # if defined(HAVE_SYS_UTIME_H) 60 # include <sys/utime.h> 61 # elif defined(HAVE_UTIME_H) 62 # include <utime.h> 63 # endif 64 #endif 65 66 #ifdef HAVE_UNISTD_H 67 #include <unistd.h> /* for read() */ 68 #endif 69 70 #ifndef PIPE_BUF 71 /* Get the PIPE_BUF from pathconf */ 72 #ifdef _PC_PIPE_BUF 73 #define PIPE_BUF pathconf(".", _PC_PIPE_BUF) 74 #else 75 #define PIPE_BUF 512 76 #endif 77 #endif 78 79 private void close_and_restore(const struct magic_set *, const char *, int, 80 const struct stat *); 81 private int unreadable_info(struct magic_set *, mode_t, const char *); 82 private const char* get_default_magic(void); 83 #ifndef COMPILE_ONLY 84 private const char *file_or_fd(struct magic_set *, const char *, int); 85 #endif 86 87 #ifndef STDIN_FILENO 88 #define STDIN_FILENO 0 89 #endif 90 91 private const char * 92 get_default_magic(void) 93 { 94 static const char hmagic[] = "/.magic/magic.mgc"; 95 static char *default_magic; 96 char *home, *hmagicpath; 97 98 #ifndef WIN32 99 struct stat st; 100 101 if (default_magic) { 102 free(default_magic); 103 default_magic = NULL; 104 } 105 if ((home = getenv("HOME")) == NULL) 106 return MAGIC; 107 108 if (asprintf(&hmagicpath, "%s/.magic.mgc", home) < 0) 109 return MAGIC; 110 if (stat(hmagicpath, &st) == -1) { 111 free(hmagicpath); 112 if (asprintf(&hmagicpath, "%s/.magic", home) < 0) 113 return MAGIC; 114 if (stat(hmagicpath, &st) == -1) 115 goto out; 116 if (S_ISDIR(st.st_mode)) { 117 free(hmagicpath); 118 if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0) 119 return MAGIC; 120 if (access(hmagicpath, R_OK) == -1) 121 goto out; 122 } 123 } 124 125 if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0) 126 goto out; 127 free(hmagicpath); 128 return default_magic; 129 out: 130 default_magic = NULL; 131 free(hmagicpath); 132 return MAGIC; 133 #else 134 char *hmagicp; 135 char *tmppath = NULL; 136 hmagicpath = 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 if (file) { 230 /* We cannot open it, but we were able to stat it. */ 231 if (access(file, W_OK) == 0) 232 if (file_printf(ms, "writable, ") == -1) 233 return -1; 234 if (access(file, X_OK) == 0) 235 if (file_printf(ms, "executable, ") == -1) 236 return -1; 237 } 238 if (S_ISREG(md)) 239 if (file_printf(ms, "regular file, ") == -1) 240 return -1; 241 if (file_printf(ms, "no read permission") == -1) 242 return -1; 243 return 0; 244 } 245 246 public void 247 magic_close(struct magic_set *ms) 248 { 249 if (ms == NULL) 250 return; 251 file_ms_free(ms); 252 } 253 254 /* 255 * load a magic file 256 */ 257 public int 258 magic_load(struct magic_set *ms, const char *magicfile) 259 { 260 if (ms == NULL) 261 return -1; 262 return file_apprentice(ms, magicfile, FILE_LOAD); 263 } 264 265 #ifndef COMPILE_ONLY 266 /* 267 * Install a set of compiled magic buffers. 268 */ 269 public int 270 magic_load_buffers(struct magic_set *ms, void **bufs, size_t *sizes, 271 size_t nbufs) 272 { 273 if (ms == NULL) 274 return -1; 275 return buffer_apprentice(ms, (struct magic **)bufs, sizes, nbufs); 276 } 277 #endif 278 279 public int 280 magic_compile(struct magic_set *ms, const char *magicfile) 281 { 282 if (ms == NULL) 283 return -1; 284 return file_apprentice(ms, magicfile, FILE_COMPILE); 285 } 286 287 public int 288 magic_check(struct magic_set *ms, const char *magicfile) 289 { 290 if (ms == NULL) 291 return -1; 292 return file_apprentice(ms, magicfile, FILE_CHECK); 293 } 294 295 public int 296 magic_list(struct magic_set *ms, const char *magicfile) 297 { 298 if (ms == NULL) 299 return -1; 300 return file_apprentice(ms, magicfile, FILE_LIST); 301 } 302 303 private void 304 close_and_restore(const struct magic_set *ms, const char *name, int fd, 305 const struct stat *sb) 306 { 307 if (fd == STDIN_FILENO || name == NULL) 308 return; 309 (void) close(fd); 310 311 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 312 /* 313 * Try to restore access, modification times if read it. 314 * This is really *bad* because it will modify the status 315 * time of the file... And of course this will affect 316 * backup programs 317 */ 318 #ifdef HAVE_UTIMES 319 struct timeval utsbuf[2]; 320 (void)memset(utsbuf, 0, sizeof(utsbuf)); 321 utsbuf[0].tv_sec = sb->st_atime; 322 utsbuf[1].tv_sec = sb->st_mtime; 323 324 (void) utimes(name, utsbuf); /* don't care if loses */ 325 #elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 326 struct utimbuf utbuf; 327 328 (void)memset(&utbuf, 0, sizeof(utbuf)); 329 utbuf.actime = sb->st_atime; 330 utbuf.modtime = sb->st_mtime; 331 (void) utime(name, &utbuf); /* don't care if loses */ 332 #endif 333 } 334 } 335 336 #ifndef COMPILE_ONLY 337 338 /* 339 * find type of descriptor 340 */ 341 public const char * 342 magic_descriptor(struct magic_set *ms, int fd) 343 { 344 if (ms == NULL) 345 return NULL; 346 return file_or_fd(ms, NULL, fd); 347 } 348 349 /* 350 * find type of named file 351 */ 352 public const char * 353 magic_file(struct magic_set *ms, const char *inname) 354 { 355 if (ms == NULL) 356 return NULL; 357 return file_or_fd(ms, inname, STDIN_FILENO); 358 } 359 360 private const char * 361 file_or_fd(struct magic_set *ms, const char *inname, int fd) 362 { 363 int rv = -1; 364 unsigned char *buf; 365 struct stat sb; 366 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 367 int ispipe = 0; 368 off_t pos = (off_t)-1; 369 370 if (file_reset(ms) == -1) 371 goto out; 372 373 /* 374 * one extra for terminating '\0', and 375 * some overlapping space for matches near EOF 376 */ 377 #define SLOP (1 + sizeof(union VALUETYPE)) 378 if ((buf = CAST(unsigned char *, malloc(HOWMANY + SLOP))) == NULL) 379 return NULL; 380 381 switch (file_fsmagic(ms, inname, &sb)) { 382 case -1: /* error */ 383 goto done; 384 case 0: /* nothing found */ 385 break; 386 default: /* matched it and printed type */ 387 rv = 0; 388 goto done; 389 } 390 391 #ifdef WIN32 392 /* Place stdin in binary mode, so EOF (Ctrl+Z) doesn't stop early. */ 393 if (fd == STDIN_FILENO) 394 _setmode(STDIN_FILENO, O_BINARY); 395 #endif 396 397 if (inname == NULL) { 398 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) 399 ispipe = 1; 400 else 401 pos = lseek(fd, (off_t)0, SEEK_CUR); 402 } else { 403 int flags = O_RDONLY|O_BINARY; 404 int okstat = stat(inname, &sb) == 0; 405 406 if (okstat && S_ISFIFO(sb.st_mode)) { 407 #ifdef O_NONBLOCK 408 flags |= O_NONBLOCK; 409 #endif 410 ispipe = 1; 411 } 412 413 errno = 0; 414 if ((fd = open(inname, flags)) < 0) { 415 #ifdef WIN32 416 /* 417 * Can't stat, can't open. It may have been opened in 418 * fsmagic, so if the user doesn't have read permission, 419 * allow it to say so; otherwise an error was probably 420 * displayed in fsmagic. 421 */ 422 if (!okstat && errno == EACCES) { 423 sb.st_mode = S_IFBLK; 424 okstat = 1; 425 } 426 #endif 427 if (okstat && 428 unreadable_info(ms, sb.st_mode, inname) == -1) 429 goto done; 430 rv = 0; 431 goto done; 432 } 433 #ifdef O_NONBLOCK 434 if ((flags = fcntl(fd, F_GETFL)) != -1) { 435 flags &= ~O_NONBLOCK; 436 (void)fcntl(fd, F_SETFL, flags); 437 } 438 #endif 439 } 440 441 /* 442 * try looking at the first HOWMANY bytes 443 */ 444 if (ispipe) { 445 ssize_t r = 0; 446 447 while ((r = sread(fd, (void *)&buf[nbytes], 448 (size_t)(HOWMANY - nbytes), 1)) > 0) { 449 nbytes += r; 450 if (r < PIPE_BUF) break; 451 } 452 453 if (nbytes == 0) { 454 /* We can not read it, but we were able to stat it. */ 455 if (unreadable_info(ms, sb.st_mode, inname) == -1) 456 goto done; 457 rv = 0; 458 goto done; 459 } 460 461 } else { 462 /* Windows refuses to read from a big console buffer. */ 463 size_t howmany = 464 #if defined(WIN32) && HOWMANY > 8 * 1024 465 _isatty(fd) ? 8 * 1024 : 466 #endif 467 HOWMANY; 468 if ((nbytes = read(fd, (char *)buf, howmany)) == -1) { 469 if (inname == NULL && fd != STDIN_FILENO) 470 file_error(ms, errno, "cannot read fd %d", fd); 471 else 472 file_error(ms, errno, "cannot read `%s'", 473 inname == NULL ? "/dev/stdin" : inname); 474 goto done; 475 } 476 } 477 478 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 479 if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) 480 goto done; 481 rv = 0; 482 done: 483 free(buf); 484 if (pos != (off_t)-1) 485 (void)lseek(fd, pos, SEEK_SET); 486 close_and_restore(ms, inname, fd, &sb); 487 out: 488 return rv == 0 ? file_getbuffer(ms) : NULL; 489 } 490 491 492 public const char * 493 magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 494 { 495 if (ms == NULL) 496 return NULL; 497 if (file_reset(ms) == -1) 498 return NULL; 499 /* 500 * The main work is done here! 501 * We have the file name and/or the data buffer to be identified. 502 */ 503 if (file_buffer(ms, -1, NULL, buf, nb) == -1) { 504 return NULL; 505 } 506 return file_getbuffer(ms); 507 } 508 #endif 509 510 public const char * 511 magic_error(struct magic_set *ms) 512 { 513 if (ms == NULL) 514 return "Magic database is not open"; 515 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 516 } 517 518 public int 519 magic_errno(struct magic_set *ms) 520 { 521 if (ms == NULL) 522 return EINVAL; 523 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 524 } 525 526 public int 527 magic_setflags(struct magic_set *ms, int flags) 528 { 529 if (ms == NULL) 530 return -1; 531 #if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 532 if (flags & MAGIC_PRESERVE_ATIME) 533 return -1; 534 #endif 535 ms->flags = flags; 536 return 0; 537 } 538 539 public int 540 magic_version(void) 541 { 542 return MAGIC_VERSION; 543 } 544