magic.c revision 309848
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#ifdef WIN32 29#include <windows.h> 30#include <shlwapi.h> 31#endif 32 33#include "file.h" 34 35#ifndef lint 36FILE_RCSID("@(#)$File: magic.c,v 1.100 2016/07/18 11:43:05 christos Exp $") 37#endif /* lint */ 38 39#include "magic.h" 40 41#include <stdlib.h> 42#include <unistd.h> 43#include <string.h> 44#ifdef QUICK 45#include <sys/mman.h> 46#endif 47#ifdef HAVE_LIMITS_H 48#include <limits.h> /* for PIPE_BUF */ 49#endif 50 51#if defined(HAVE_UTIMES) 52# include <sys/time.h> 53#elif defined(HAVE_UTIME) 54# if defined(HAVE_SYS_UTIME_H) 55# include <sys/utime.h> 56# elif defined(HAVE_UTIME_H) 57# include <utime.h> 58# endif 59#endif 60 61#ifdef HAVE_UNISTD_H 62#include <unistd.h> /* for read() */ 63#endif 64 65#ifndef PIPE_BUF 66/* Get the PIPE_BUF from pathconf */ 67#ifdef _PC_PIPE_BUF 68#define PIPE_BUF pathconf(".", _PC_PIPE_BUF) 69#else 70#define PIPE_BUF 512 71#endif 72#endif 73 74private void close_and_restore(const struct magic_set *, const char *, int, 75 const struct stat *); 76private int unreadable_info(struct magic_set *, mode_t, const char *); 77private const char* get_default_magic(void); 78#ifndef COMPILE_ONLY 79private const char *file_or_fd(struct magic_set *, const char *, int); 80#endif 81 82#ifndef STDIN_FILENO 83#define STDIN_FILENO 0 84#endif 85 86#ifdef WIN32 87/* HINSTANCE of this shared library. Needed for get_default_magic() */ 88static HINSTANCE _w32_dll_instance = NULL; 89 90static void 91_w32_append_path(char **hmagicpath, const char *fmt, ...) 92{ 93 char *tmppath; 94 char *newpath; 95 va_list ap; 96 97 va_start(ap, fmt); 98 if (vasprintf(&tmppath, fmt, ap) < 0) { 99 va_end(ap); 100 return; 101 } 102 va_end(ap); 103 104 if (access(tmppath, R_OK) == -1) 105 goto out; 106 107 if (*hmagicpath == NULL) { 108 *hmagicpath = tmppath; 109 return; 110 } 111 112 if (asprintf(&newpath, "%s%c%s", *hmagicpath, PATHSEP, tmppath) < 0) 113 goto out; 114 115 free(*hmagicpath); 116 free(tmppath); 117 *hmagicpath = newpath; 118 return; 119out: 120 free(tmppath); 121} 122 123static void 124_w32_get_magic_relative_to(char **hmagicpath, HINSTANCE module) 125{ 126 static const char *trypaths[] = { 127 "%s/share/misc/magic.mgc", 128 "%s/magic.mgc", 129 }; 130 LPSTR dllpath; 131 size_t sp; 132 133 dllpath = calloc(MAX_PATH + 1, sizeof(*dllpath)); 134 135 if (!GetModuleFileNameA(module, dllpath, MAX_PATH)) 136 goto out; 137 138 PathRemoveFileSpecA(dllpath); 139 140 if (module) { 141 char exepath[MAX_PATH]; 142 GetModuleFileNameA(NULL, exepath, MAX_PATH); 143 PathRemoveFileSpecA(exepath); 144 if (stricmp(exepath, dllpath) == 0) 145 goto out; 146 } 147 148 sp = strlen(dllpath); 149 if (sp > 3 && stricmp(&dllpath[sp - 3], "bin") == 0) { 150 _w32_append_path(hmagicpath, 151 "%s/../share/misc/magic.mgc", dllpath); 152 goto out; 153 } 154 155 for (sp = 0; sp < __arraycount(trypaths); sp++) 156 _w32_append_path(hmagicpath, trypaths[sp], dllpath); 157out: 158 free(dllpath); 159} 160 161/* Placate GCC by offering a sacrificial previous prototype */ 162BOOL WINAPI DllMain(HINSTANCE, DWORD, LPVOID); 163 164BOOL WINAPI 165DllMain(HINSTANCE hinstDLL, DWORD fdwReason, 166 LPVOID lpvReserved __attribute__((__unused__))) 167{ 168 if (fdwReason == DLL_PROCESS_ATTACH) 169 _w32_dll_instance = hinstDLL; 170 return TRUE; 171} 172#endif 173 174private const char * 175get_default_magic(void) 176{ 177 static const char hmagic[] = "/.magic/magic.mgc"; 178 static char *default_magic; 179 char *home, *hmagicpath; 180 181#ifndef WIN32 182 struct stat st; 183 184 if (default_magic) { 185 free(default_magic); 186 default_magic = NULL; 187 } 188 if ((home = getenv("HOME")) == NULL) 189 return MAGIC; 190 191 if (asprintf(&hmagicpath, "%s/.magic.mgc", home) < 0) 192 return MAGIC; 193 if (stat(hmagicpath, &st) == -1) { 194 free(hmagicpath); 195 if (asprintf(&hmagicpath, "%s/.magic", home) < 0) 196 return MAGIC; 197 if (stat(hmagicpath, &st) == -1) 198 goto out; 199 if (S_ISDIR(st.st_mode)) { 200 free(hmagicpath); 201 if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0) 202 return MAGIC; 203 if (access(hmagicpath, R_OK) == -1) 204 goto out; 205 } 206 } 207 208 if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0) 209 goto out; 210 free(hmagicpath); 211 return default_magic; 212out: 213 default_magic = NULL; 214 free(hmagicpath); 215 return MAGIC; 216#else 217 hmagicpath = NULL; 218 219 if (default_magic) { 220 free(default_magic); 221 default_magic = NULL; 222 } 223 224 /* First, try to get a magic file from user-application data */ 225 if ((home = getenv("LOCALAPPDATA")) != NULL) 226 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 227 228 /* Second, try to get a magic file from the user profile data */ 229 if ((home = getenv("USERPROFILE")) != NULL) 230 _w32_append_path(&hmagicpath, 231 "%s/Local Settings/Application Data%s", home, hmagic); 232 233 /* Third, try to get a magic file from Common Files */ 234 if ((home = getenv("COMMONPROGRAMFILES")) != NULL) 235 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 236 237 /* Fourth, try to get magic file relative to exe location */ 238 _w32_get_magic_relative_to(&hmagicpath, NULL); 239 240 /* Fifth, try to get magic file relative to dll location */ 241 _w32_get_magic_relative_to(&hmagicpath, _w32_dll_instance); 242 243 /* Avoid MAGIC constant - it likely points to a file within MSys tree */ 244 default_magic = hmagicpath; 245 return default_magic; 246#endif 247} 248 249public const char * 250magic_getpath(const char *magicfile, int action) 251{ 252 if (magicfile != NULL) 253 return magicfile; 254 255 magicfile = getenv("MAGIC"); 256 if (magicfile != NULL) 257 return magicfile; 258 259 return action == FILE_LOAD ? get_default_magic() : MAGIC; 260} 261 262public struct magic_set * 263magic_open(int flags) 264{ 265 return file_ms_alloc(flags); 266} 267 268private int 269unreadable_info(struct magic_set *ms, mode_t md, const char *file) 270{ 271 if (file) { 272 /* We cannot open it, but we were able to stat it. */ 273 if (access(file, W_OK) == 0) 274 if (file_printf(ms, "writable, ") == -1) 275 return -1; 276 if (access(file, X_OK) == 0) 277 if (file_printf(ms, "executable, ") == -1) 278 return -1; 279 } 280 if (S_ISREG(md)) 281 if (file_printf(ms, "regular file, ") == -1) 282 return -1; 283 if (file_printf(ms, "no read permission") == -1) 284 return -1; 285 return 0; 286} 287 288public void 289magic_close(struct magic_set *ms) 290{ 291 if (ms == NULL) 292 return; 293 file_ms_free(ms); 294} 295 296/* 297 * load a magic file 298 */ 299public int 300magic_load(struct magic_set *ms, const char *magicfile) 301{ 302 if (ms == NULL) 303 return -1; 304 return file_apprentice(ms, magicfile, FILE_LOAD); 305} 306 307#ifndef COMPILE_ONLY 308/* 309 * Install a set of compiled magic buffers. 310 */ 311public int 312magic_load_buffers(struct magic_set *ms, void **bufs, size_t *sizes, 313 size_t nbufs) 314{ 315 if (ms == NULL) 316 return -1; 317 return buffer_apprentice(ms, (struct magic **)bufs, sizes, nbufs); 318} 319#endif 320 321public int 322magic_compile(struct magic_set *ms, const char *magicfile) 323{ 324 if (ms == NULL) 325 return -1; 326 return file_apprentice(ms, magicfile, FILE_COMPILE); 327} 328 329public int 330magic_check(struct magic_set *ms, const char *magicfile) 331{ 332 if (ms == NULL) 333 return -1; 334 return file_apprentice(ms, magicfile, FILE_CHECK); 335} 336 337public int 338magic_list(struct magic_set *ms, const char *magicfile) 339{ 340 if (ms == NULL) 341 return -1; 342 return file_apprentice(ms, magicfile, FILE_LIST); 343} 344 345private void 346close_and_restore(const struct magic_set *ms, const char *name, int fd, 347 const struct stat *sb) 348{ 349 if (fd == STDIN_FILENO || name == NULL) 350 return; 351 (void) close(fd); 352 353 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 354 /* 355 * Try to restore access, modification times if read it. 356 * This is really *bad* because it will modify the status 357 * time of the file... And of course this will affect 358 * backup programs 359 */ 360#ifdef HAVE_UTIMES 361 struct timeval utsbuf[2]; 362 (void)memset(utsbuf, 0, sizeof(utsbuf)); 363 utsbuf[0].tv_sec = sb->st_atime; 364 utsbuf[1].tv_sec = sb->st_mtime; 365 366 (void) utimes(name, utsbuf); /* don't care if loses */ 367#elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 368 struct utimbuf utbuf; 369 370 (void)memset(&utbuf, 0, sizeof(utbuf)); 371 utbuf.actime = sb->st_atime; 372 utbuf.modtime = sb->st_mtime; 373 (void) utime(name, &utbuf); /* don't care if loses */ 374#endif 375 } 376} 377 378#ifndef COMPILE_ONLY 379 380/* 381 * find type of descriptor 382 */ 383public const char * 384magic_descriptor(struct magic_set *ms, int fd) 385{ 386 if (ms == NULL) 387 return NULL; 388 return file_or_fd(ms, NULL, fd); 389} 390 391/* 392 * find type of named file 393 */ 394public const char * 395magic_file(struct magic_set *ms, const char *inname) 396{ 397 if (ms == NULL) 398 return NULL; 399 return file_or_fd(ms, inname, STDIN_FILENO); 400} 401 402private const char * 403file_or_fd(struct magic_set *ms, const char *inname, int fd) 404{ 405 int rv = -1; 406 unsigned char *buf; 407 struct stat sb; 408 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 409 int ispipe = 0; 410 off_t pos = (off_t)-1; 411 412 if (file_reset(ms) == -1) 413 goto out; 414 415 /* 416 * one extra for terminating '\0', and 417 * some overlapping space for matches near EOF 418 */ 419#define SLOP (1 + sizeof(union VALUETYPE)) 420 if ((buf = CAST(unsigned char *, malloc(ms->bytes_max + SLOP))) == NULL) 421 return NULL; 422 423 switch (file_fsmagic(ms, inname, &sb)) { 424 case -1: /* error */ 425 goto done; 426 case 0: /* nothing found */ 427 break; 428 default: /* matched it and printed type */ 429 rv = 0; 430 goto done; 431 } 432 433#ifdef WIN32 434 /* Place stdin in binary mode, so EOF (Ctrl+Z) doesn't stop early. */ 435 if (fd == STDIN_FILENO) 436 _setmode(STDIN_FILENO, O_BINARY); 437#endif 438 439 if (inname == NULL) { 440 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) 441 ispipe = 1; 442 else 443 pos = lseek(fd, (off_t)0, SEEK_CUR); 444 } else { 445 int flags = O_RDONLY|O_BINARY; 446 int okstat = stat(inname, &sb) == 0; 447 448 if (okstat && S_ISFIFO(sb.st_mode)) { 449#ifdef O_NONBLOCK 450 flags |= O_NONBLOCK; 451#endif 452 ispipe = 1; 453 } 454 455 errno = 0; 456 if ((fd = open(inname, flags)) < 0) { 457#ifdef WIN32 458 /* 459 * Can't stat, can't open. It may have been opened in 460 * fsmagic, so if the user doesn't have read permission, 461 * allow it to say so; otherwise an error was probably 462 * displayed in fsmagic. 463 */ 464 if (!okstat && errno == EACCES) { 465 sb.st_mode = S_IFBLK; 466 okstat = 1; 467 } 468#endif 469 if (okstat && 470 unreadable_info(ms, sb.st_mode, inname) == -1) 471 goto done; 472 rv = 0; 473 goto done; 474 } 475#ifdef O_NONBLOCK 476 if ((flags = fcntl(fd, F_GETFL)) != -1) { 477 flags &= ~O_NONBLOCK; 478 (void)fcntl(fd, F_SETFL, flags); 479 } 480#endif 481 } 482 483 /* 484 * try looking at the first ms->bytes_max bytes 485 */ 486 if (ispipe) { 487 ssize_t r = 0; 488 489 while ((r = sread(fd, (void *)&buf[nbytes], 490 (size_t)(ms->bytes_max - nbytes), 1)) > 0) { 491 nbytes += r; 492 if (r < PIPE_BUF) break; 493 } 494 495 if (nbytes == 0 && inname) { 496 /* We can not read it, but we were able to stat it. */ 497 if (unreadable_info(ms, sb.st_mode, inname) == -1) 498 goto done; 499 rv = 0; 500 goto done; 501 } 502 503 } else { 504 /* Windows refuses to read from a big console buffer. */ 505 size_t howmany = 506#if defined(WIN32) 507 _isatty(fd) ? 8 * 1024 : 508#endif 509 ms->bytes_max; 510 if ((nbytes = read(fd, (char *)buf, howmany)) == -1) { 511 if (inname == NULL && fd != STDIN_FILENO) 512 file_error(ms, errno, "cannot read fd %d", fd); 513 else 514 file_error(ms, errno, "cannot read `%s'", 515 inname == NULL ? "/dev/stdin" : inname); 516 goto done; 517 } 518 } 519 520 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 521 if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) 522 goto done; 523 rv = 0; 524done: 525 free(buf); 526 if (fd != -1) { 527 if (pos != (off_t)-1) 528 (void)lseek(fd, pos, SEEK_SET); 529 close_and_restore(ms, inname, fd, &sb); 530 } 531out: 532 return rv == 0 ? file_getbuffer(ms) : NULL; 533} 534 535 536public const char * 537magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 538{ 539 if (ms == NULL) 540 return NULL; 541 if (file_reset(ms) == -1) 542 return NULL; 543 /* 544 * The main work is done here! 545 * We have the file name and/or the data buffer to be identified. 546 */ 547 if (file_buffer(ms, -1, NULL, buf, nb) == -1) { 548 return NULL; 549 } 550 return file_getbuffer(ms); 551} 552#endif 553 554public const char * 555magic_error(struct magic_set *ms) 556{ 557 if (ms == NULL) 558 return "Magic database is not open"; 559 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 560} 561 562public int 563magic_errno(struct magic_set *ms) 564{ 565 if (ms == NULL) 566 return EINVAL; 567 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 568} 569 570public int 571magic_setflags(struct magic_set *ms, int flags) 572{ 573 if (ms == NULL) 574 return -1; 575#if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 576 if (flags & MAGIC_PRESERVE_ATIME) 577 return -1; 578#endif 579 ms->flags = flags; 580 return 0; 581} 582 583public int 584magic_version(void) 585{ 586 return MAGIC_VERSION; 587} 588 589public int 590magic_setparam(struct magic_set *ms, int param, const void *val) 591{ 592 switch (param) { 593 case MAGIC_PARAM_INDIR_MAX: 594 ms->indir_max = (uint16_t)*(const size_t *)val; 595 return 0; 596 case MAGIC_PARAM_NAME_MAX: 597 ms->name_max = (uint16_t)*(const size_t *)val; 598 return 0; 599 case MAGIC_PARAM_ELF_PHNUM_MAX: 600 ms->elf_phnum_max = (uint16_t)*(const size_t *)val; 601 return 0; 602 case MAGIC_PARAM_ELF_SHNUM_MAX: 603 ms->elf_shnum_max = (uint16_t)*(const size_t *)val; 604 return 0; 605 case MAGIC_PARAM_ELF_NOTES_MAX: 606 ms->elf_notes_max = (uint16_t)*(const size_t *)val; 607 return 0; 608 case MAGIC_PARAM_REGEX_MAX: 609 ms->elf_notes_max = (uint16_t)*(const size_t *)val; 610 return 0; 611 case MAGIC_PARAM_BYTES_MAX: 612 ms->bytes_max = *(const size_t *)val; 613 return 0; 614 default: 615 errno = EINVAL; 616 return -1; 617 } 618} 619 620public int 621magic_getparam(struct magic_set *ms, int param, void *val) 622{ 623 switch (param) { 624 case MAGIC_PARAM_INDIR_MAX: 625 *(size_t *)val = ms->indir_max; 626 return 0; 627 case MAGIC_PARAM_NAME_MAX: 628 *(size_t *)val = ms->name_max; 629 return 0; 630 case MAGIC_PARAM_ELF_PHNUM_MAX: 631 *(size_t *)val = ms->elf_phnum_max; 632 return 0; 633 case MAGIC_PARAM_ELF_SHNUM_MAX: 634 *(size_t *)val = ms->elf_shnum_max; 635 return 0; 636 case MAGIC_PARAM_ELF_NOTES_MAX: 637 *(size_t *)val = ms->elf_notes_max; 638 return 0; 639 case MAGIC_PARAM_REGEX_MAX: 640 *(size_t *)val = ms->regex_max; 641 return 0; 642 case MAGIC_PARAM_BYTES_MAX: 643 *(size_t *)val = ms->bytes_max; 644 return 0; 645 default: 646 errno = EINVAL; 647 return -1; 648 } 649} 650