magic.c revision 276415
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 1.90 2014/12/04 15:56:46 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 86private const char * 87get_default_magic(void) 88{ 89 static const char hmagic[] = "/.magic/magic.mgc"; 90 static char *default_magic; 91 char *home, *hmagicpath; 92 93#ifndef WIN32 94 struct stat st; 95 96 if (default_magic) { 97 free(default_magic); 98 default_magic = NULL; 99 } 100 if ((home = getenv("HOME")) == NULL) 101 return MAGIC; 102 103 if (asprintf(&hmagicpath, "%s/.magic.mgc", home) < 0) 104 return MAGIC; 105 if (stat(hmagicpath, &st) == -1) { 106 free(hmagicpath); 107 if (asprintf(&hmagicpath, "%s/.magic", home) < 0) 108 return MAGIC; 109 if (stat(hmagicpath, &st) == -1) 110 goto out; 111 if (S_ISDIR(st.st_mode)) { 112 free(hmagicpath); 113 if (asprintf(&hmagicpath, "%s/%s", home, hmagic) < 0) 114 return MAGIC; 115 if (access(hmagicpath, R_OK) == -1) 116 goto out; 117 } 118 } 119 120 if (asprintf(&default_magic, "%s:%s", hmagicpath, MAGIC) < 0) 121 goto out; 122 free(hmagicpath); 123 return default_magic; 124out: 125 default_magic = NULL; 126 free(hmagicpath); 127 return MAGIC; 128#else 129 char *hmagicp; 130 char *tmppath = NULL; 131 LPTSTR dllpath; 132 hmagicpath = NULL; 133 134#define APPENDPATH() \ 135 do { \ 136 if (tmppath && access(tmppath, R_OK) != -1) { \ 137 if (hmagicpath == NULL) \ 138 hmagicpath = tmppath; \ 139 else { \ 140 if (asprintf(&hmagicp, "%s%c%s", hmagicpath, \ 141 PATHSEP, tmppath) >= 0) { \ 142 free(hmagicpath); \ 143 hmagicpath = hmagicp; \ 144 } \ 145 free(tmppath); \ 146 } \ 147 tmppath = NULL; \ 148 } \ 149 } while (/*CONSTCOND*/0) 150 151 if (default_magic) { 152 free(default_magic); 153 default_magic = NULL; 154 } 155 156 /* First, try to get user-specific magic file */ 157 if ((home = getenv("LOCALAPPDATA")) == NULL) { 158 if ((home = getenv("USERPROFILE")) != NULL) 159 if (asprintf(&tmppath, 160 "%s/Local Settings/Application Data%s", home, 161 hmagic) < 0) 162 tmppath = NULL; 163 } else { 164 if (asprintf(&tmppath, "%s%s", home, hmagic) < 0) 165 tmppath = NULL; 166 } 167 168 APPENDPATH(); 169 170 /* Second, try to get a magic file from Common Files */ 171 if ((home = getenv("COMMONPROGRAMFILES")) != NULL) { 172 if (asprintf(&tmppath, "%s%s", home, hmagic) >= 0) 173 APPENDPATH(); 174 } 175 176 /* Third, try to get magic file relative to dll location */ 177 dllpath = malloc(sizeof(*dllpath) * (MAX_PATH + 1)); 178 dllpath[MAX_PATH] = 0; /* just in case long path gets truncated and not null terminated */ 179 if (GetModuleFileNameA(NULL, dllpath, MAX_PATH)){ 180 PathRemoveFileSpecA(dllpath); 181 if (strlen(dllpath) > 3 && 182 stricmp(&dllpath[strlen(dllpath) - 3], "bin") == 0) { 183 if (asprintf(&tmppath, 184 "%s/../share/misc/magic.mgc", dllpath) >= 0) 185 APPENDPATH(); 186 } else { 187 if (asprintf(&tmppath, 188 "%s/share/misc/magic.mgc", dllpath) >= 0) 189 APPENDPATH(); 190 else if (asprintf(&tmppath, 191 "%s/magic.mgc", dllpath) >= 0) 192 APPENDPATH(); 193 } 194 } 195 196 /* Don't put MAGIC constant - it likely points to a file within MSys 197 tree */ 198 default_magic = hmagicpath; 199 return default_magic; 200#endif 201} 202 203public const char * 204magic_getpath(const char *magicfile, int action) 205{ 206 if (magicfile != NULL) 207 return magicfile; 208 209 magicfile = getenv("MAGIC"); 210 if (magicfile != NULL) 211 return magicfile; 212 213 return action == FILE_LOAD ? get_default_magic() : MAGIC; 214} 215 216public struct magic_set * 217magic_open(int flags) 218{ 219 return file_ms_alloc(flags); 220} 221 222private int 223unreadable_info(struct magic_set *ms, mode_t md, const char *file) 224{ 225 if (file) { 226 /* We cannot open it, but we were able to stat it. */ 227 if (access(file, W_OK) == 0) 228 if (file_printf(ms, "writable, ") == -1) 229 return -1; 230 if (access(file, X_OK) == 0) 231 if (file_printf(ms, "executable, ") == -1) 232 return -1; 233 } 234 if (S_ISREG(md)) 235 if (file_printf(ms, "regular file, ") == -1) 236 return -1; 237 if (file_printf(ms, "no read permission") == -1) 238 return -1; 239 return 0; 240} 241 242public void 243magic_close(struct magic_set *ms) 244{ 245 if (ms == NULL) 246 return; 247 file_ms_free(ms); 248} 249 250/* 251 * load a magic file 252 */ 253public int 254magic_load(struct magic_set *ms, const char *magicfile) 255{ 256 if (ms == NULL) 257 return -1; 258 return file_apprentice(ms, magicfile, FILE_LOAD); 259} 260 261#ifndef COMPILE_ONLY 262/* 263 * Install a set of compiled magic buffers. 264 */ 265public int 266magic_load_buffers(struct magic_set *ms, void **bufs, size_t *sizes, 267 size_t nbufs) 268{ 269 if (ms == NULL) 270 return -1; 271 return buffer_apprentice(ms, (struct magic **)bufs, sizes, nbufs); 272} 273#endif 274 275public int 276magic_compile(struct magic_set *ms, const char *magicfile) 277{ 278 if (ms == NULL) 279 return -1; 280 return file_apprentice(ms, magicfile, FILE_COMPILE); 281} 282 283public int 284magic_check(struct magic_set *ms, const char *magicfile) 285{ 286 if (ms == NULL) 287 return -1; 288 return file_apprentice(ms, magicfile, FILE_CHECK); 289} 290 291public int 292magic_list(struct magic_set *ms, const char *magicfile) 293{ 294 if (ms == NULL) 295 return -1; 296 return file_apprentice(ms, magicfile, FILE_LIST); 297} 298 299private void 300close_and_restore(const struct magic_set *ms, const char *name, int fd, 301 const struct stat *sb) 302{ 303 if (fd == STDIN_FILENO || name == NULL) 304 return; 305 (void) close(fd); 306 307 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 308 /* 309 * Try to restore access, modification times if read it. 310 * This is really *bad* because it will modify the status 311 * time of the file... And of course this will affect 312 * backup programs 313 */ 314#ifdef HAVE_UTIMES 315 struct timeval utsbuf[2]; 316 (void)memset(utsbuf, 0, sizeof(utsbuf)); 317 utsbuf[0].tv_sec = sb->st_atime; 318 utsbuf[1].tv_sec = sb->st_mtime; 319 320 (void) utimes(name, utsbuf); /* don't care if loses */ 321#elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 322 struct utimbuf utbuf; 323 324 (void)memset(&utbuf, 0, sizeof(utbuf)); 325 utbuf.actime = sb->st_atime; 326 utbuf.modtime = sb->st_mtime; 327 (void) utime(name, &utbuf); /* don't care if loses */ 328#endif 329 } 330} 331 332#ifndef COMPILE_ONLY 333 334/* 335 * find type of descriptor 336 */ 337public const char * 338magic_descriptor(struct magic_set *ms, int fd) 339{ 340 if (ms == NULL) 341 return NULL; 342 return file_or_fd(ms, NULL, fd); 343} 344 345/* 346 * find type of named file 347 */ 348public const char * 349magic_file(struct magic_set *ms, const char *inname) 350{ 351 if (ms == NULL) 352 return NULL; 353 return file_or_fd(ms, inname, STDIN_FILENO); 354} 355 356private const char * 357file_or_fd(struct magic_set *ms, const char *inname, int fd) 358{ 359 int rv = -1; 360 unsigned char *buf; 361 struct stat sb; 362 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 363 int ispipe = 0; 364 off_t pos = (off_t)-1; 365 366 if (file_reset(ms) == -1) 367 goto out; 368 369 /* 370 * one extra for terminating '\0', and 371 * some overlapping space for matches near EOF 372 */ 373#define SLOP (1 + sizeof(union VALUETYPE)) 374 if ((buf = CAST(unsigned char *, malloc(HOWMANY + SLOP))) == NULL) 375 return NULL; 376 377 switch (file_fsmagic(ms, inname, &sb)) { 378 case -1: /* error */ 379 goto done; 380 case 0: /* nothing found */ 381 break; 382 default: /* matched it and printed type */ 383 rv = 0; 384 goto done; 385 } 386 387#ifdef WIN32 388 /* Place stdin in binary mode, so EOF (Ctrl+Z) doesn't stop early. */ 389 if (fd == STDIN_FILENO) 390 _setmode(STDIN_FILENO, O_BINARY); 391#endif 392 393 if (inname == NULL) { 394 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) 395 ispipe = 1; 396 else 397 pos = lseek(fd, (off_t)0, SEEK_CUR); 398 } else { 399 int flags = O_RDONLY|O_BINARY; 400 int okstat = stat(inname, &sb) == 0; 401 402 if (okstat && S_ISFIFO(sb.st_mode)) { 403#ifdef O_NONBLOCK 404 flags |= O_NONBLOCK; 405#endif 406 ispipe = 1; 407 } 408 409 errno = 0; 410 if ((fd = open(inname, flags)) < 0) { 411#ifdef WIN32 412 /* 413 * Can't stat, can't open. It may have been opened in 414 * fsmagic, so if the user doesn't have read permission, 415 * allow it to say so; otherwise an error was probably 416 * displayed in fsmagic. 417 */ 418 if (!okstat && errno == EACCES) { 419 sb.st_mode = S_IFBLK; 420 okstat = 1; 421 } 422#endif 423 if (okstat && 424 unreadable_info(ms, sb.st_mode, inname) == -1) 425 goto done; 426 rv = 0; 427 goto done; 428 } 429#ifdef O_NONBLOCK 430 if ((flags = fcntl(fd, F_GETFL)) != -1) { 431 flags &= ~O_NONBLOCK; 432 (void)fcntl(fd, F_SETFL, flags); 433 } 434#endif 435 } 436 437 /* 438 * try looking at the first HOWMANY bytes 439 */ 440 if (ispipe) { 441 ssize_t r = 0; 442 443 while ((r = sread(fd, (void *)&buf[nbytes], 444 (size_t)(HOWMANY - nbytes), 1)) > 0) { 445 nbytes += r; 446 if (r < PIPE_BUF) break; 447 } 448 449 if (nbytes == 0) { 450 /* We can not read it, but we were able to stat it. */ 451 if (unreadable_info(ms, sb.st_mode, inname) == -1) 452 goto done; 453 rv = 0; 454 goto done; 455 } 456 457 } else { 458 /* Windows refuses to read from a big console buffer. */ 459 size_t howmany = 460#if defined(WIN32) && HOWMANY > 8 * 1024 461 _isatty(fd) ? 8 * 1024 : 462#endif 463 HOWMANY; 464 if ((nbytes = read(fd, (char *)buf, howmany)) == -1) { 465 if (inname == NULL && fd != STDIN_FILENO) 466 file_error(ms, errno, "cannot read fd %d", fd); 467 else 468 file_error(ms, errno, "cannot read `%s'", 469 inname == NULL ? "/dev/stdin" : inname); 470 goto done; 471 } 472 } 473 474 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 475 if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) 476 goto done; 477 rv = 0; 478done: 479 free(buf); 480 if (pos != (off_t)-1) 481 (void)lseek(fd, pos, SEEK_SET); 482 close_and_restore(ms, inname, fd, &sb); 483out: 484 return rv == 0 ? file_getbuffer(ms) : NULL; 485} 486 487 488public const char * 489magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 490{ 491 if (ms == NULL) 492 return NULL; 493 if (file_reset(ms) == -1) 494 return NULL; 495 /* 496 * The main work is done here! 497 * We have the file name and/or the data buffer to be identified. 498 */ 499 if (file_buffer(ms, -1, NULL, buf, nb) == -1) { 500 return NULL; 501 } 502 return file_getbuffer(ms); 503} 504#endif 505 506public const char * 507magic_error(struct magic_set *ms) 508{ 509 if (ms == NULL) 510 return "Magic database is not open"; 511 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 512} 513 514public int 515magic_errno(struct magic_set *ms) 516{ 517 if (ms == NULL) 518 return EINVAL; 519 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 520} 521 522public int 523magic_setflags(struct magic_set *ms, int flags) 524{ 525 if (ms == NULL) 526 return -1; 527#if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 528 if (flags & MAGIC_PRESERVE_ATIME) 529 return -1; 530#endif 531 ms->flags = flags; 532 return 0; 533} 534 535public int 536magic_version(void) 537{ 538 return MAGIC_VERSION; 539} 540 541public int 542magic_setparam(struct magic_set *ms, int param, const void *val) 543{ 544 switch (param) { 545 case MAGIC_PARAM_INDIR_MAX: 546 ms->indir_max = *(const size_t *)val; 547 return 0; 548 case MAGIC_PARAM_NAME_MAX: 549 ms->name_max = *(const size_t *)val; 550 return 0; 551 case MAGIC_PARAM_ELF_PHNUM_MAX: 552 ms->elf_phnum_max = *(const size_t *)val; 553 return 0; 554 case MAGIC_PARAM_ELF_SHNUM_MAX: 555 ms->elf_shnum_max = *(const size_t *)val; 556 return 0; 557 default: 558 errno = EINVAL; 559 return -1; 560 } 561} 562 563public int 564magic_getparam(struct magic_set *ms, int param, void *val) 565{ 566 switch (param) { 567 case MAGIC_PARAM_INDIR_MAX: 568 *(size_t *)val = ms->indir_max; 569 return 0; 570 case MAGIC_PARAM_NAME_MAX: 571 *(size_t *)val = ms->name_max; 572 return 0; 573 case MAGIC_PARAM_ELF_PHNUM_MAX: 574 *(size_t *)val = ms->elf_phnum_max; 575 return 0; 576 case MAGIC_PARAM_ELF_SHNUM_MAX: 577 *(size_t *)val = ms->elf_shnum_max; 578 return 0; 579 default: 580 errno = EINVAL; 581 return -1; 582 } 583} 584