1 /* $NetBSD: magic.c,v 1.11 2017/02/10 17:53:24 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 1.100 2016/07/18 11:43:05 christos Exp $") 40 #else 41 __RCSID("$NetBSD: magic.c,v 1.11 2017/02/10 17:53:24 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 #ifdef WIN32 93 /* HINSTANCE of this shared library. Needed for get_default_magic() */ 94 static HINSTANCE _w32_dll_instance = NULL; 95 96 static void 97 _w32_append_path(char **hmagicpath, const char *fmt, ...) 98 { 99 char *tmppath; 100 char *newpath; 101 va_list ap; 102 103 va_start(ap, fmt); 104 if (vasprintf(&tmppath, fmt, ap) < 0) { 105 va_end(ap); 106 return; 107 } 108 va_end(ap); 109 110 if (access(tmppath, R_OK) == -1) 111 goto out; 112 113 if (*hmagicpath == NULL) { 114 *hmagicpath = tmppath; 115 return; 116 } 117 118 if (asprintf(&newpath, "%s%c%s", *hmagicpath, PATHSEP, tmppath) < 0) 119 goto out; 120 121 free(*hmagicpath); 122 free(tmppath); 123 *hmagicpath = newpath; 124 return; 125 out: 126 free(tmppath); 127 } 128 129 static void 130 _w32_get_magic_relative_to(char **hmagicpath, HINSTANCE module) 131 { 132 static const char *trypaths[] = { 133 "%s/share/misc/magic.mgc", 134 "%s/magic.mgc", 135 }; 136 LPSTR dllpath; 137 size_t sp; 138 139 dllpath = calloc(MAX_PATH + 1, sizeof(*dllpath)); 140 141 if (!GetModuleFileNameA(module, dllpath, MAX_PATH)) 142 goto out; 143 144 PathRemoveFileSpecA(dllpath); 145 146 if (module) { 147 char exepath[MAX_PATH]; 148 GetModuleFileNameA(NULL, exepath, MAX_PATH); 149 PathRemoveFileSpecA(exepath); 150 if (stricmp(exepath, dllpath) == 0) 151 goto out; 152 } 153 154 sp = strlen(dllpath); 155 if (sp > 3 && stricmp(&dllpath[sp - 3], "bin") == 0) { 156 _w32_append_path(hmagicpath, 157 "%s/../share/misc/magic.mgc", dllpath); 158 goto out; 159 } 160 161 for (sp = 0; sp < __arraycount(trypaths); sp++) 162 _w32_append_path(hmagicpath, trypaths[sp], dllpath); 163 out: 164 free(dllpath); 165 } 166 167 /* Placate GCC by offering a sacrificial previous prototype */ 168 BOOL WINAPI DllMain(HINSTANCE, DWORD, LPVOID); 169 170 BOOL WINAPI 171 DllMain(HINSTANCE hinstDLL, DWORD fdwReason, 172 LPVOID lpvReserved __attribute__((__unused__))) 173 { 174 if (fdwReason == DLL_PROCESS_ATTACH) 175 _w32_dll_instance = hinstDLL; 176 return TRUE; 177 } 178 #endif 179 180 private const char * 181 get_default_magic(void) 182 { 183 static const char hmagic[] = "/.magic/magic.mgc"; 184 static char *default_magic; 185 char *home, *hmagicpath; 186 187 #ifndef WIN32 188 struct stat st; 189 190 if (default_magic) { 191 free(default_magic); 192 default_magic = NULL; 193 } 194 if ((home = getenv("HOME")) == NULL) 195 return MAGIC; 196 197 if (asprintf(&hmagicpath, "%s/.magic.mgc", home) < 0) 198 return MAGIC; 199 if (stat(hmagicpath, &st) == -1) { 200 free(hmagicpath); 201 if (asprintf(&hmagicpath, "%s/.magic", home) < 0) 202 return MAGIC; 203 if (stat(hmagicpath, &st) == -1) 204 goto out; 205 if (S_ISDIR(st.st_mode)) { 206 free(hmagicpath); 207 if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0) 208 return MAGIC; 209 if (access(hmagicpath, R_OK) == -1) 210 goto out; 211 } 212 } 213 214 if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0) 215 goto out; 216 free(hmagicpath); 217 return default_magic; 218 out: 219 default_magic = NULL; 220 free(hmagicpath); 221 return MAGIC; 222 #else 223 hmagicpath = NULL; 224 225 if (default_magic) { 226 free(default_magic); 227 default_magic = NULL; 228 } 229 230 /* First, try to get a magic file from user-application data */ 231 if ((home = getenv("LOCALAPPDATA")) != NULL) 232 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 233 234 /* Second, try to get a magic file from the user profile data */ 235 if ((home = getenv("USERPROFILE")) != NULL) 236 _w32_append_path(&hmagicpath, 237 "%s/Local Settings/Application Data%s", home, hmagic); 238 239 /* Third, try to get a magic file from Common Files */ 240 if ((home = getenv("COMMONPROGRAMFILES")) != NULL) 241 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 242 243 /* Fourth, try to get magic file relative to exe location */ 244 _w32_get_magic_relative_to(&hmagicpath, NULL); 245 246 /* Fifth, try to get magic file relative to dll location */ 247 _w32_get_magic_relative_to(&hmagicpath, _w32_dll_instance); 248 249 /* Avoid MAGIC constant - it likely points to a file within MSys tree */ 250 default_magic = hmagicpath; 251 return default_magic; 252 #endif 253 } 254 255 public const char * 256 magic_getpath(const char *magicfile, int action) 257 { 258 if (magicfile != NULL) 259 return magicfile; 260 261 magicfile = getenv("MAGIC"); 262 if (magicfile != NULL) 263 return magicfile; 264 265 return action == FILE_LOAD ? get_default_magic() : MAGIC; 266 } 267 268 public struct magic_set * 269 magic_open(int flags) 270 { 271 return file_ms_alloc(flags); 272 } 273 274 private int 275 unreadable_info(struct magic_set *ms, mode_t md, const char *file) 276 { 277 if (file) { 278 /* We cannot open it, but we were able to stat it. */ 279 if (access(file, W_OK) == 0) 280 if (file_printf(ms, "writable, ") == -1) 281 return -1; 282 if (access(file, X_OK) == 0) 283 if (file_printf(ms, "executable, ") == -1) 284 return -1; 285 } 286 if (S_ISREG(md)) 287 if (file_printf(ms, "regular file, ") == -1) 288 return -1; 289 if (file_printf(ms, "no read permission") == -1) 290 return -1; 291 return 0; 292 } 293 294 public void 295 magic_close(struct magic_set *ms) 296 { 297 if (ms == NULL) 298 return; 299 file_ms_free(ms); 300 } 301 302 /* 303 * load a magic file 304 */ 305 public int 306 magic_load(struct magic_set *ms, const char *magicfile) 307 { 308 if (ms == NULL) 309 return -1; 310 return file_apprentice(ms, magicfile, FILE_LOAD); 311 } 312 313 #ifndef COMPILE_ONLY 314 /* 315 * Install a set of compiled magic buffers. 316 */ 317 public int 318 magic_load_buffers(struct magic_set *ms, void **bufs, size_t *sizes, 319 size_t nbufs) 320 { 321 if (ms == NULL) 322 return -1; 323 return buffer_apprentice(ms, (struct magic **)bufs, sizes, nbufs); 324 } 325 #endif 326 327 public int 328 magic_compile(struct magic_set *ms, const char *magicfile) 329 { 330 if (ms == NULL) 331 return -1; 332 return file_apprentice(ms, magicfile, FILE_COMPILE); 333 } 334 335 public int 336 magic_check(struct magic_set *ms, const char *magicfile) 337 { 338 if (ms == NULL) 339 return -1; 340 return file_apprentice(ms, magicfile, FILE_CHECK); 341 } 342 343 public int 344 magic_list(struct magic_set *ms, const char *magicfile) 345 { 346 if (ms == NULL) 347 return -1; 348 return file_apprentice(ms, magicfile, FILE_LIST); 349 } 350 351 private void 352 close_and_restore(const struct magic_set *ms, const char *name, int fd, 353 const struct stat *sb) 354 { 355 if (fd == STDIN_FILENO || name == NULL) 356 return; 357 (void) close(fd); 358 359 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 360 /* 361 * Try to restore access, modification times if read it. 362 * This is really *bad* because it will modify the status 363 * time of the file... And of course this will affect 364 * backup programs 365 */ 366 #ifdef HAVE_UTIMES 367 struct timeval utsbuf[2]; 368 (void)memset(utsbuf, 0, sizeof(utsbuf)); 369 utsbuf[0].tv_sec = sb->st_atime; 370 utsbuf[1].tv_sec = sb->st_mtime; 371 372 (void) utimes(name, utsbuf); /* don't care if loses */ 373 #elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 374 struct utimbuf utbuf; 375 376 (void)memset(&utbuf, 0, sizeof(utbuf)); 377 utbuf.actime = sb->st_atime; 378 utbuf.modtime = sb->st_mtime; 379 (void) utime(name, &utbuf); /* don't care if loses */ 380 #endif 381 } 382 } 383 384 #ifndef COMPILE_ONLY 385 386 /* 387 * find type of descriptor 388 */ 389 public const char * 390 magic_descriptor(struct magic_set *ms, int fd) 391 { 392 if (ms == NULL) 393 return NULL; 394 return file_or_fd(ms, NULL, fd); 395 } 396 397 /* 398 * find type of named file 399 */ 400 public const char * 401 magic_file(struct magic_set *ms, const char *inname) 402 { 403 if (ms == NULL) 404 return NULL; 405 return file_or_fd(ms, inname, STDIN_FILENO); 406 } 407 408 private const char * 409 file_or_fd(struct magic_set *ms, const char *inname, int fd) 410 { 411 int rv = -1; 412 unsigned char *buf; 413 struct stat sb; 414 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 415 int ispipe = 0; 416 off_t pos = (off_t)-1; 417 418 if (file_reset(ms) == -1) 419 goto out; 420 421 /* 422 * one extra for terminating '\0', and 423 * some overlapping space for matches near EOF 424 */ 425 #define SLOP (1 + sizeof(union VALUETYPE)) 426 if ((buf = CAST(unsigned char *, malloc(ms->bytes_max + SLOP))) == NULL) 427 return NULL; 428 429 switch (file_fsmagic(ms, inname, &sb)) { 430 case -1: /* error */ 431 goto done; 432 case 0: /* nothing found */ 433 break; 434 default: /* matched it and printed type */ 435 rv = 0; 436 goto done; 437 } 438 439 #ifdef WIN32 440 /* Place stdin in binary mode, so EOF (Ctrl+Z) doesn't stop early. */ 441 if (fd == STDIN_FILENO) 442 _setmode(STDIN_FILENO, O_BINARY); 443 #endif 444 445 if (inname == NULL) { 446 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) 447 ispipe = 1; 448 else 449 pos = lseek(fd, (off_t)0, SEEK_CUR); 450 } else { 451 int flags = O_RDONLY|O_BINARY; 452 int okstat = stat(inname, &sb) == 0; 453 454 if (okstat && S_ISFIFO(sb.st_mode)) { 455 #ifdef O_NONBLOCK 456 flags |= O_NONBLOCK; 457 #endif 458 ispipe = 1; 459 } 460 461 errno = 0; 462 if ((fd = open(inname, flags)) < 0) { 463 #ifdef WIN32 464 /* 465 * Can't stat, can't open. It may have been opened in 466 * fsmagic, so if the user doesn't have read permission, 467 * allow it to say so; otherwise an error was probably 468 * displayed in fsmagic. 469 */ 470 if (!okstat && errno == EACCES) { 471 sb.st_mode = S_IFBLK; 472 okstat = 1; 473 } 474 #endif 475 if (okstat && 476 unreadable_info(ms, sb.st_mode, inname) == -1) 477 goto done; 478 rv = 0; 479 goto done; 480 } 481 #ifdef O_NONBLOCK 482 if ((flags = fcntl(fd, F_GETFL)) != -1) { 483 flags &= ~O_NONBLOCK; 484 (void)fcntl(fd, F_SETFL, flags); 485 } 486 #endif 487 } 488 489 /* 490 * try looking at the first ms->bytes_max bytes 491 */ 492 if (ispipe) { 493 ssize_t r = 0; 494 495 while ((r = sread(fd, (void *)&buf[nbytes], 496 (size_t)(ms->bytes_max - nbytes), 1)) > 0) { 497 nbytes += r; 498 if (r < PIPE_BUF) break; 499 } 500 501 if (nbytes == 0 && inname) { 502 /* We can not read it, but we were able to stat it. */ 503 if (unreadable_info(ms, sb.st_mode, inname) == -1) 504 goto done; 505 rv = 0; 506 goto done; 507 } 508 509 } else { 510 /* Windows refuses to read from a big console buffer. */ 511 size_t howmany = 512 #if defined(WIN32) 513 _isatty(fd) ? 8 * 1024 : 514 #endif 515 ms->bytes_max; 516 if ((nbytes = read(fd, (char *)buf, howmany)) == -1) { 517 if (inname == NULL && fd != STDIN_FILENO) 518 file_error(ms, errno, "cannot read fd %d", fd); 519 else 520 file_error(ms, errno, "cannot read `%s'", 521 inname == NULL ? "/dev/stdin" : inname); 522 goto done; 523 } 524 } 525 526 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 527 if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) 528 goto done; 529 rv = 0; 530 done: 531 free(buf); 532 if (fd != -1) { 533 if (pos != (off_t)-1) 534 (void)lseek(fd, pos, SEEK_SET); 535 close_and_restore(ms, inname, fd, &sb); 536 } 537 out: 538 return rv == 0 ? file_getbuffer(ms) : NULL; 539 } 540 541 542 public const char * 543 magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 544 { 545 if (ms == NULL) 546 return NULL; 547 if (file_reset(ms) == -1) 548 return NULL; 549 /* 550 * The main work is done here! 551 * We have the file name and/or the data buffer to be identified. 552 */ 553 if (file_buffer(ms, -1, NULL, buf, nb) == -1) { 554 return NULL; 555 } 556 return file_getbuffer(ms); 557 } 558 #endif 559 560 public const char * 561 magic_error(struct magic_set *ms) 562 { 563 if (ms == NULL) 564 return "Magic database is not open"; 565 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 566 } 567 568 public int 569 magic_errno(struct magic_set *ms) 570 { 571 if (ms == NULL) 572 return EINVAL; 573 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 574 } 575 576 public int 577 magic_setflags(struct magic_set *ms, int flags) 578 { 579 if (ms == NULL) 580 return -1; 581 #if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 582 if (flags & MAGIC_PRESERVE_ATIME) 583 return -1; 584 #endif 585 ms->flags = flags; 586 return 0; 587 } 588 589 public int 590 magic_version(void) 591 { 592 return MAGIC_VERSION; 593 } 594 595 public int 596 magic_setparam(struct magic_set *ms, int param, const void *val) 597 { 598 switch (param) { 599 case MAGIC_PARAM_INDIR_MAX: 600 ms->indir_max = (uint16_t)*(const size_t *)val; 601 return 0; 602 case MAGIC_PARAM_NAME_MAX: 603 ms->name_max = (uint16_t)*(const size_t *)val; 604 return 0; 605 case MAGIC_PARAM_ELF_PHNUM_MAX: 606 ms->elf_phnum_max = (uint16_t)*(const size_t *)val; 607 return 0; 608 case MAGIC_PARAM_ELF_SHNUM_MAX: 609 ms->elf_shnum_max = (uint16_t)*(const size_t *)val; 610 return 0; 611 case MAGIC_PARAM_ELF_NOTES_MAX: 612 ms->elf_notes_max = (uint16_t)*(const size_t *)val; 613 return 0; 614 case MAGIC_PARAM_REGEX_MAX: 615 ms->elf_notes_max = (uint16_t)*(const size_t *)val; 616 return 0; 617 case MAGIC_PARAM_BYTES_MAX: 618 ms->bytes_max = *(const size_t *)val; 619 return 0; 620 default: 621 errno = EINVAL; 622 return -1; 623 } 624 } 625 626 public int 627 magic_getparam(struct magic_set *ms, int param, void *val) 628 { 629 switch (param) { 630 case MAGIC_PARAM_INDIR_MAX: 631 *(size_t *)val = ms->indir_max; 632 return 0; 633 case MAGIC_PARAM_NAME_MAX: 634 *(size_t *)val = ms->name_max; 635 return 0; 636 case MAGIC_PARAM_ELF_PHNUM_MAX: 637 *(size_t *)val = ms->elf_phnum_max; 638 return 0; 639 case MAGIC_PARAM_ELF_SHNUM_MAX: 640 *(size_t *)val = ms->elf_shnum_max; 641 return 0; 642 case MAGIC_PARAM_ELF_NOTES_MAX: 643 *(size_t *)val = ms->elf_notes_max; 644 return 0; 645 case MAGIC_PARAM_REGEX_MAX: 646 *(size_t *)val = ms->regex_max; 647 return 0; 648 case MAGIC_PARAM_BYTES_MAX: 649 *(size_t *)val = ms->bytes_max; 650 return 0; 651 default: 652 errno = EINVAL; 653 return -1; 654 } 655 } 656