1 /* $NetBSD: magic.c,v 1.8 2014/06/13 02:08:06 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 1.84 2014/05/14 23:15:42 christos Exp $") 39 #else 40 __RCSID("$NetBSD: magic.c,v 1.8 2014/06/13 02:08:06 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 public int 266 magic_compile(struct magic_set *ms, const char *magicfile) 267 { 268 if (ms == NULL) 269 return -1; 270 return file_apprentice(ms, magicfile, FILE_COMPILE); 271 } 272 273 public int 274 magic_check(struct magic_set *ms, const char *magicfile) 275 { 276 if (ms == NULL) 277 return -1; 278 return file_apprentice(ms, magicfile, FILE_CHECK); 279 } 280 281 public int 282 magic_list(struct magic_set *ms, const char *magicfile) 283 { 284 if (ms == NULL) 285 return -1; 286 return file_apprentice(ms, magicfile, FILE_LIST); 287 } 288 289 private void 290 close_and_restore(const struct magic_set *ms, const char *name, int fd, 291 const struct stat *sb) 292 { 293 if (fd == STDIN_FILENO || name == NULL) 294 return; 295 (void) close(fd); 296 297 if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) { 298 /* 299 * Try to restore access, modification times if read it. 300 * This is really *bad* because it will modify the status 301 * time of the file... And of course this will affect 302 * backup programs 303 */ 304 #ifdef HAVE_UTIMES 305 struct timeval utsbuf[2]; 306 (void)memset(utsbuf, 0, sizeof(utsbuf)); 307 utsbuf[0].tv_sec = sb->st_atime; 308 utsbuf[1].tv_sec = sb->st_mtime; 309 310 (void) utimes(name, utsbuf); /* don't care if loses */ 311 #elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H) 312 struct utimbuf utbuf; 313 314 (void)memset(&utbuf, 0, sizeof(utbuf)); 315 utbuf.actime = sb->st_atime; 316 utbuf.modtime = sb->st_mtime; 317 (void) utime(name, &utbuf); /* don't care if loses */ 318 #endif 319 } 320 } 321 322 #ifndef COMPILE_ONLY 323 324 /* 325 * find type of descriptor 326 */ 327 public const char * 328 magic_descriptor(struct magic_set *ms, int fd) 329 { 330 if (ms == NULL) 331 return NULL; 332 return file_or_fd(ms, NULL, fd); 333 } 334 335 /* 336 * find type of named file 337 */ 338 public const char * 339 magic_file(struct magic_set *ms, const char *inname) 340 { 341 if (ms == NULL) 342 return NULL; 343 return file_or_fd(ms, inname, STDIN_FILENO); 344 } 345 346 private const char * 347 file_or_fd(struct magic_set *ms, const char *inname, int fd) 348 { 349 int rv = -1; 350 unsigned char *buf; 351 struct stat sb; 352 ssize_t nbytes = 0; /* number of bytes read from a datafile */ 353 int ispipe = 0; 354 off_t pos = (off_t)-1; 355 356 if (file_reset(ms) == -1) 357 goto out; 358 359 /* 360 * one extra for terminating '\0', and 361 * some overlapping space for matches near EOF 362 */ 363 #define SLOP (1 + sizeof(union VALUETYPE)) 364 if ((buf = CAST(unsigned char *, malloc(HOWMANY + SLOP))) == NULL) 365 return NULL; 366 367 switch (file_fsmagic(ms, inname, &sb)) { 368 case -1: /* error */ 369 goto done; 370 case 0: /* nothing found */ 371 break; 372 default: /* matched it and printed type */ 373 rv = 0; 374 goto done; 375 } 376 377 #ifdef WIN32 378 /* Place stdin in binary mode, so EOF (Ctrl+Z) doesn't stop early. */ 379 if (fd == STDIN_FILENO) 380 _setmode(STDIN_FILENO, O_BINARY); 381 #endif 382 383 if (inname == NULL) { 384 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode)) 385 ispipe = 1; 386 else 387 pos = lseek(fd, (off_t)0, SEEK_CUR); 388 } else { 389 int flags = O_RDONLY|O_BINARY; 390 int okstat = stat(inname, &sb) == 0; 391 392 if (okstat && S_ISFIFO(sb.st_mode)) { 393 #ifdef O_NONBLOCK 394 flags |= O_NONBLOCK; 395 #endif 396 ispipe = 1; 397 } 398 399 errno = 0; 400 if ((fd = open(inname, flags)) < 0) { 401 #ifdef WIN32 402 /* 403 * Can't stat, can't open. It may have been opened in 404 * fsmagic, so if the user doesn't have read permission, 405 * allow it to say so; otherwise an error was probably 406 * displayed in fsmagic. 407 */ 408 if (!okstat && errno == EACCES) { 409 sb.st_mode = S_IFBLK; 410 okstat = 1; 411 } 412 #endif 413 if (okstat && 414 unreadable_info(ms, sb.st_mode, inname) == -1) 415 goto done; 416 rv = 0; 417 goto done; 418 } 419 #ifdef O_NONBLOCK 420 if ((flags = fcntl(fd, F_GETFL)) != -1) { 421 flags &= ~O_NONBLOCK; 422 (void)fcntl(fd, F_SETFL, flags); 423 } 424 #endif 425 } 426 427 /* 428 * try looking at the first HOWMANY bytes 429 */ 430 if (ispipe) { 431 ssize_t r = 0; 432 433 while ((r = sread(fd, (void *)&buf[nbytes], 434 (size_t)(HOWMANY - nbytes), 1)) > 0) { 435 nbytes += r; 436 if (r < PIPE_BUF) break; 437 } 438 439 if (nbytes == 0) { 440 /* We can not read it, but we were able to stat it. */ 441 if (unreadable_info(ms, sb.st_mode, inname) == -1) 442 goto done; 443 rv = 0; 444 goto done; 445 } 446 447 } else { 448 /* Windows refuses to read from a big console buffer. */ 449 size_t howmany = 450 #if defined(WIN32) && HOWMANY > 8 * 1024 451 _isatty(fd) ? 8 * 1024 : 452 #endif 453 HOWMANY; 454 if ((nbytes = read(fd, (char *)buf, howmany)) == -1) { 455 if (inname == NULL && fd != STDIN_FILENO) 456 file_error(ms, errno, "cannot read fd %d", fd); 457 else 458 file_error(ms, errno, "cannot read `%s'", 459 inname == NULL ? "/dev/stdin" : inname); 460 goto done; 461 } 462 } 463 464 (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */ 465 if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1) 466 goto done; 467 rv = 0; 468 done: 469 free(buf); 470 if (pos != (off_t)-1) 471 (void)lseek(fd, pos, SEEK_SET); 472 close_and_restore(ms, inname, fd, &sb); 473 out: 474 return rv == 0 ? file_getbuffer(ms) : NULL; 475 } 476 477 478 public const char * 479 magic_buffer(struct magic_set *ms, const void *buf, size_t nb) 480 { 481 if (ms == NULL) 482 return NULL; 483 if (file_reset(ms) == -1) 484 return NULL; 485 /* 486 * The main work is done here! 487 * We have the file name and/or the data buffer to be identified. 488 */ 489 if (file_buffer(ms, -1, NULL, buf, nb) == -1) { 490 return NULL; 491 } 492 return file_getbuffer(ms); 493 } 494 #endif 495 496 public const char * 497 magic_error(struct magic_set *ms) 498 { 499 if (ms == NULL) 500 return "Magic database is not open"; 501 return (ms->event_flags & EVENT_HAD_ERR) ? ms->o.buf : NULL; 502 } 503 504 public int 505 magic_errno(struct magic_set *ms) 506 { 507 if (ms == NULL) 508 return EINVAL; 509 return (ms->event_flags & EVENT_HAD_ERR) ? ms->error : 0; 510 } 511 512 public int 513 magic_setflags(struct magic_set *ms, int flags) 514 { 515 if (ms == NULL) 516 return -1; 517 #if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES) 518 if (flags & MAGIC_PRESERVE_ATIME) 519 return -1; 520 #endif 521 ms->flags = flags; 522 return 0; 523 } 524 525 public int 526 magic_version(void) 527 { 528 return MAGIC_VERSION; 529 } 530