magic.c revision 284778
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 1.93 2015/04/15 23:47:58 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 sp = strlen(dllpath); 141 if (sp > 3 && stricmp(&dllpath[sp - 3], "bin") == 0) { 142 _w32_append_path(hmagicpath, 143 "%s/../share/misc/magic.mgc", dllpath); 144 goto out; 145 } 146 147 for (sp = 0; sp < __arraycount(trypaths); sp++) 148 _w32_append_path(hmagicpath, trypaths[sp], dllpath); 149out: 150 free(dllpath); 151} 152 153/* Placate GCC by offering a sacrificial previous prototype */ 154BOOL WINAPI DllMain(HINSTANCE, DWORD, LPVOID); 155 156BOOL WINAPI 157DllMain(HINSTANCE hinstDLL, DWORD fdwReason, 158 LPVOID lpvReserved __attribute__((__unused__))) 159{ 160 if (fdwReason == DLL_PROCESS_ATTACH) 161 _w32_dll_instance = hinstDLL; 162 return TRUE; 163} 164#endif 165 166private const char * 167get_default_magic(void) 168{ 169 static const char hmagic[] = "/.magic/magic.mgc"; 170 static char *default_magic; 171 char *home, *hmagicpath; 172 173#ifndef WIN32 174 struct stat st; 175 176 if (default_magic) { 177 free(default_magic); 178 default_magic = NULL; 179 } 180 if ((home = getenv("HOME")) == NULL) 181 return MAGIC; 182 183 if (asprintf(&hmagicpath, "%s/.magic.mgc", home) < 0) 184 return MAGIC; 185 if (stat(hmagicpath, &st) == -1) { 186 free(hmagicpath); 187 if (asprintf(&hmagicpath, "%s/.magic", home) < 0) 188 return MAGIC; 189 if (stat(hmagicpath, &st) == -1) 190 goto out; 191 if (S_ISDIR(st.st_mode)) { 192 free(hmagicpath); 193 if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0) 194 return MAGIC; 195 if (access(hmagicpath, R_OK) == -1) 196 goto out; 197 } 198 } 199 200 if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0) 201 goto out; 202 free(hmagicpath); 203 return default_magic; 204out: 205 default_magic = NULL; 206 free(hmagicpath); 207 return MAGIC; 208#else 209 hmagicpath = NULL; 210 211 if (default_magic) { 212 free(default_magic); 213 default_magic = NULL; 214 } 215 216 /* First, try to get a magic file from user-application data */ 217 if ((home = getenv("LOCALAPPDATA")) != NULL) 218 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 219 220 /* Second, try to get a magic file from the user profile data */ 221 if ((home = getenv("USERPROFILE")) != NULL) 222 _w32_append_path(&hmagicpath, 223 "%s/Local Settings/Application Data%s", home, hmagic); 224 225 /* Third, try to get a magic file from Common Files */ 226 if ((home = getenv("COMMONPROGRAMFILES")) != NULL) 227 _w32_append_path(&hmagicpath, "%s%s", home, hmagic); 228 229 /* Fourth, try to get magic file relative to exe location */ 230 _w32_get_magic_relative_to(&hmagicpath, NULL); 231 232 /* Fifth, try to get magic file relative to dll location */ 233 _w32_get_magic_relative_to(&hmagicpath, _w32_dll_instance); 234 235 /* Avoid MAGIC constant - it likely points to a file within MSys tree */ 236 default_magic = hmagicpath; 237 return default_magic; 238#endif 239} 240 241public const char * 242magic_getpath(const char *magicfile, int action) 243{ 244 if (magicfile != NULL) 245 return magicfile; 246 247 magicfile = getenv("MAGIC"); 248 if (magicfile != NULL) 249 return magicfile; 250 251 return action == FILE_LOAD ? get_default_magic() : MAGIC; 252} 253 254public struct magic_set * 255magic_open(int flags) 256{ 257 return file_ms_alloc(flags); 258} 259 260private int 261unreadable_info(struct magic_set *ms, mode_t md, const char *file) 262{ 263 if (file) { 264 /* We cannot open it, but we were able to stat it. */ 265 if (access(file, W_OK) == 0) 266 if (file_printf(ms, "writable, ") == -1) 267 return -1; 268 if (access(file, X_OK) == 0) 269 if (file_printf(ms, "executable, ") == -1) 270 return -1; 271 } 272 if (S_ISREG(md)) 273 if (file_printf(ms, "regular file, ") == -1) 274 return -1; 275 if (file_printf(ms, "no read permission") == -1) 276 return -1; 277 return 0; 278} 279 280public void 281magic_close(struct magic_set *ms) 282{ 283 if (ms == NULL) 284 return; 285 file_ms_free(ms); 286} 287 288/* 289 * load a magic file 290 */ 291public int 292magic_load(struct magic_set *ms, const char *magicfile) 293{ 294 if (ms == NULL) 295 return -1; 296 return file_apprentice(ms, magicfile, FILE_LOAD); 297} 298 299#ifndef COMPILE_ONLY 300/* 301 * Install a set of compiled magic buffers. 302 */ 303public int 304magic_load_buffers(struct magic_set *ms, void **bufs, size_t *sizes, 305 size_t nbufs) 306{ 307 if (ms == NULL) 308 return -1; 309 return buffer_apprentice(ms, (struct magic **)bufs, sizes, nbufs); 310} 311#endif 312 313public int 314magic_compile(struct magic_set *ms, const char *magicfile) 315{ 316 if (ms == NULL) 317 return -1; 318 return file_apprentice(ms, magicfile, FILE_COMPILE); 319} 320 321public int 322magic_check(struct magic_set *ms, const char *magicfile) 323{ 324 if (ms == NULL) 325 return -1; 326 return file_apprentice(ms, magicfile, FILE_CHECK); 327} 328 329public int 330magic_list(struct magic_set *ms, const char *magicfile) 331{ 332 if (ms == NULL) 333 return -1; 334 return file_apprentice(ms, magicfile, FILE_LIST); 335} 336 337private void 338close_and_restore(const struct magic_set *ms, const char *name, int fd, 339 const struct stat *sb) 340{ 341 if (fd == STDIN_FILENO || name == NULL) 342 return; 343 (void) close(fd); 344 345 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 346 /* 347 * Try to restore access, modification times if read it. 348 * This is really *bad* because it will modify the status 349 * time of the file... And of course this will affect 350 * backup programs 351 */ 352#ifdef HAVE_UTIMES 353 struct timeval utsbuf[2]; 354 (void)memset(utsbuf, 0, sizeof(utsbuf)); 355 utsbuf[0].tv_sec = sb->st_atime; 356 utsbuf[1].tv_sec = sb->st_mtime; 357 358 (void) utimes(name, utsbuf); /* don't care if loses */ 359#elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 360 struct utimbuf utbuf; 361 362 (void)memset(&utbuf, 0, sizeof(utbuf)); 363 utbuf.actime = sb->st_atime; 364 utbuf.modtime = sb->st_mtime; 365 (void) utime(name, &utbuf); /* don't care if loses */ 366#endif 367 } 368} 369 370#ifndef COMPILE_ONLY 371 372/* 373 * find type of descriptor 374 */ 375public const char * 376magic_descriptor(struct magic_set *ms, int fd) 377{ 378 if (ms == NULL) 379 return NULL; 380 return file_or_fd(ms, NULL, fd); 381} 382 383/* 384 * find type of named file 385 */ 386public const char * 387magic_file(struct magic_set *ms, const char *inname) 388{ 389 if (ms == NULL) 390 return NULL; 391 return file_or_fd(ms, inname, STDIN_FILENO); 392} 393 394private const char * 395file_or_fd(struct magic_set *ms, const char *inname, int fd) 396{ 397 int rv = -1; 398 unsigned char *buf; 399 struct stat sb; 400 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 401 int ispipe = 0; 402 off_t pos = (off_t)-1; 403 404 if (file_reset(ms) == -1) 405 goto out; 406 407 /* 408 * one extra for terminating '\0', and 409 * some overlapping space for matches near EOF 410 */ 411#define SLOP (1 + sizeof(union VALUETYPE)) 412 if ((buf = CAST(unsigned char *, malloc(HOWMANY + SLOP))) == NULL) 413 return NULL; 414 415 switch (file_fsmagic(ms, inname, &sb)) { 416 case -1: /* error */ 417 goto done; 418 case 0: /* nothing found */ 419 break; 420 default: /* matched it and printed type */ 421 rv = 0; 422 goto done; 423 } 424 425#ifdef WIN32 426 /* Place stdin in binary mode, so EOF (Ctrl+Z) doesn't stop early. */ 427 if (fd == STDIN_FILENO) 428 _setmode(STDIN_FILENO, O_BINARY); 429#endif 430 431 if (inname == NULL) { 432 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) 433 ispipe = 1; 434 else 435 pos = lseek(fd, (off_t)0, SEEK_CUR); 436 } else { 437 int flags = O_RDONLY|O_BINARY; 438 int okstat = stat(inname, &sb) == 0; 439 440 if (okstat && S_ISFIFO(sb.st_mode)) { 441#ifdef O_NONBLOCK 442 flags |= O_NONBLOCK; 443#endif 444 ispipe = 1; 445 } 446 447 errno = 0; 448 if ((fd = open(inname, flags)) < 0) { 449#ifdef WIN32 450 /* 451 * Can't stat, can't open. It may have been opened in 452 * fsmagic, so if the user doesn't have read permission, 453 * allow it to say so; otherwise an error was probably 454 * displayed in fsmagic. 455 */ 456 if (!okstat && errno == EACCES) { 457 sb.st_mode = S_IFBLK; 458 okstat = 1; 459 } 460#endif 461 if (okstat && 462 unreadable_info(ms, sb.st_mode, inname) == -1) 463 goto done; 464 rv = 0; 465 goto done; 466 } 467#ifdef O_NONBLOCK 468 if ((flags = fcntl(fd, F_GETFL)) != -1) { 469 flags &= ~O_NONBLOCK; 470 (void)fcntl(fd, F_SETFL, flags); 471 } 472#endif 473 } 474 475 /* 476 * try looking at the first HOWMANY bytes 477 */ 478 if (ispipe) { 479 ssize_t r = 0; 480 481 while ((r = sread(fd, (void *)&buf[nbytes], 482 (size_t)(HOWMANY - nbytes), 1)) > 0) { 483 nbytes += r; 484 if (r < PIPE_BUF) break; 485 } 486 487 if (nbytes == 0) { 488 /* We can not read it, but we were able to stat it. */ 489 if (unreadable_info(ms, sb.st_mode, inname) == -1) 490 goto done; 491 rv = 0; 492 goto done; 493 } 494 495 } else { 496 /* Windows refuses to read from a big console buffer. */ 497 size_t howmany = 498#if defined(WIN32) && HOWMANY > 8 * 1024 499 _isatty(fd) ? 8 * 1024 : 500#endif 501 HOWMANY; 502 if ((nbytes = read(fd, (char *)buf, howmany)) == -1) { 503 if (inname == NULL && fd != STDIN_FILENO) 504 file_error(ms, errno, "cannot read fd %d", fd); 505 else 506 file_error(ms, errno, "cannot read `%s'", 507 inname == NULL ? "/dev/stdin" : inname); 508 goto done; 509 } 510 } 511 512 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 513 if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) 514 goto done; 515 rv = 0; 516done: 517 free(buf); 518 if (pos != (off_t)-1) 519 (void)lseek(fd, pos, SEEK_SET); 520 close_and_restore(ms, inname, fd, &sb); 521out: 522 return rv == 0 ? file_getbuffer(ms) : NULL; 523} 524 525 526public const char * 527magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 528{ 529 if (ms == NULL) 530 return NULL; 531 if (file_reset(ms) == -1) 532 return NULL; 533 /* 534 * The main work is done here! 535 * We have the file name and/or the data buffer to be identified. 536 */ 537 if (file_buffer(ms, -1, NULL, buf, nb) == -1) { 538 return NULL; 539 } 540 return file_getbuffer(ms); 541} 542#endif 543 544public const char * 545magic_error(struct magic_set *ms) 546{ 547 if (ms == NULL) 548 return "Magic database is not open"; 549 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 550} 551 552public int 553magic_errno(struct magic_set *ms) 554{ 555 if (ms == NULL) 556 return EINVAL; 557 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 558} 559 560public int 561magic_setflags(struct magic_set *ms, int flags) 562{ 563 if (ms == NULL) 564 return -1; 565#if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 566 if (flags & MAGIC_PRESERVE_ATIME) 567 return -1; 568#endif 569 ms->flags = flags; 570 return 0; 571} 572 573public int 574magic_version(void) 575{ 576 return MAGIC_VERSION; 577} 578 579public int 580magic_setparam(struct magic_set *ms, int param, const void *val) 581{ 582 switch (param) { 583 case MAGIC_PARAM_INDIR_MAX: 584 ms->indir_max = (uint16_t)*(const size_t *)val; 585 return 0; 586 case MAGIC_PARAM_NAME_MAX: 587 ms->name_max = (uint16_t)*(const size_t *)val; 588 return 0; 589 case MAGIC_PARAM_ELF_PHNUM_MAX: 590 ms->elf_phnum_max = (uint16_t)*(const size_t *)val; 591 return 0; 592 case MAGIC_PARAM_ELF_SHNUM_MAX: 593 ms->elf_shnum_max = (uint16_t)*(const size_t *)val; 594 return 0; 595 case MAGIC_PARAM_ELF_NOTES_MAX: 596 ms->elf_notes_max = (uint16_t)*(const size_t *)val; 597 return 0; 598 default: 599 errno = EINVAL; 600 return -1; 601 } 602} 603 604public int 605magic_getparam(struct magic_set *ms, int param, void *val) 606{ 607 switch (param) { 608 case MAGIC_PARAM_INDIR_MAX: 609 *(size_t *)val = ms->indir_max; 610 return 0; 611 case MAGIC_PARAM_NAME_MAX: 612 *(size_t *)val = ms->name_max; 613 return 0; 614 case MAGIC_PARAM_ELF_PHNUM_MAX: 615 *(size_t *)val = ms->elf_phnum_max; 616 return 0; 617 case MAGIC_PARAM_ELF_SHNUM_MAX: 618 *(size_t *)val = ms->elf_shnum_max; 619 return 0; 620 case MAGIC_PARAM_ELF_NOTES_MAX: 621 *(size_t *)val = ms->elf_notes_max; 622 return 0; 623 default: 624 errno = EINVAL; 625 return -1; 626 } 627} 628