contrib/file-4/src/magic.c

   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 #include "file.h"
  29 #include "magic.h"
  30
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <unistd.h>
  34 #include <string.h>
  35 #include <sys/types.h>
  36 #include <sys/param.h>  /* for MAXPATHLEN */
  37 #include <sys/stat.h>
  38 #ifdef QUICK
  39 #include <sys/mman.h>
  40 #endif
  41 #include <limits.h>     /* for PIPE_BUF */
  42
  43 #if defined(HAVE_UTIMES)
  44 # include <sys/time.h>
  45 #elif defined(HAVE_UTIME)
  46 # if defined(HAVE_SYS_UTIME_H)
  47 #  include <sys/utime.h>
  48 # elif defined(HAVE_UTIME_H)
  49 #  include <utime.h>
  50 # endif
  51 #endif
  52
  53 #ifdef HAVE_UNISTD_H
  54 #include <unistd.h>     /* for read() */
  55 #endif
  56
  57 #ifdef HAVE_LOCALE_H
  58 #include <locale.h>
  59 #endif
  60
  61 #include <netinet/in.h>         /* for byte swapping */
  62
  63 #include "patchlevel.h"
  64
  65 #ifndef lint
  66 FILE_RCSID("@(#)$File: magic.c,v 1.45 2007/12/27 16:35:59 christos Exp $")
  67 #endif  /* lint */
  68
  69 #ifdef __EMX__
  70 private char *apptypeName = NULL;
  71 protected int file_os2_apptype(struct magic_set *ms, const char *fn,
  72     const void *buf, size_t nb);
  73 #endif /* __EMX__ */
  74
  75 private void free_mlist(struct mlist *);
  76 private void close_and_restore(const struct magic_set *, const char *, int,
  77     const struct stat *);
  78 private int info_from_stat(struct magic_set *, mode_t);
  79 #ifndef COMPILE_ONLY
  80 private const char *file_or_fd(struct magic_set *, const char *, int);
  81 #endif
  82
  83 #ifndef STDIN_FILENO
  84 #define STDIN_FILENO    0
  85 #endif
  86
  87 public struct magic_set *
  88 magic_open(int flags)
  89 {
  90         struct magic_set *ms;
  91
  92         if ((ms = calloc((size_t)1, sizeof(struct magic_set))) == NULL)
  93                 return NULL;
  94
  95         if (magic_setflags(ms, flags) == -1) {
  96                 errno = EINVAL;
  97                 goto free1;
  98         }
  99
 100         ms->o.ptr = ms->o.buf = malloc(ms->o.left = ms->o.size = 1024);
 101         if (ms->o.buf == NULL)
 102                 goto free1;
 103
 104         ms->o.pbuf = malloc(ms->o.psize = 1024);
 105         if (ms->o.pbuf == NULL)
 106                 goto free2;
 107
 108         ms->c.li = malloc((ms->c.len = 10) * sizeof(*ms->c.li));
 109         if (ms->c.li == NULL)
 110                 goto free3;
 111
 112         ms->haderr = 0;
 113         ms->error = -1;
 114         ms->mlist = NULL;
 115         ms->file = "unknown";
 116         ms->line = 0;
 117         return ms;
 118 free3:
 119         free(ms->o.pbuf);
 120 free2:
 121         free(ms->o.buf);
 122 free1:
 123         free(ms);
 124         return NULL;
 125 }
 126
 127 private void
 128 free_mlist(struct mlist *mlist)
 129 {
 130         struct mlist *ml;
 131
 132         if (mlist == NULL)
 133                 return;
 134
 135         for (ml = mlist->next; ml != mlist;) {
 136                 struct mlist *next = ml->next;
 137                 struct magic *mg = ml->magic;
 138                 file_delmagic(mg, ml->mapped, ml->nmagic);
 139                 free(ml);
 140                 ml = next;
 141         }
 142         free(ml);
 143 }
 144
 145 private int
 146 info_from_stat(struct magic_set *ms, mode_t md)
 147 {
 148         /* We cannot open it, but we were able to stat it. */
 149         if (md & 0222)
 150                 if (file_printf(ms, "writable, ") == -1)
 151                         return -1;
 152         if (md & 0111)
 153                 if (file_printf(ms, "executable, ") == -1)
 154                         return -1;
 155         if (S_ISREG(md))
 156                 if (file_printf(ms, "regular file, ") == -1)
 157                         return -1;
 158         if (file_printf(ms, "no read permission") == -1)
 159                 return -1;
 160         return 0;
 161 }
 162
 163 public void
 164 magic_close(struct magic_set *ms)
 165 {
 166         free_mlist(ms->mlist);
 167         free(ms->o.pbuf);
 168         free(ms->o.buf);
 169         free(ms->c.li);
 170         free(ms);
 171 }
 172
 173 /*
 174  * load a magic file
 175  */
 176 public int
 177 magic_load(struct magic_set *ms, const char *magicfile)
 178 {
 179         struct mlist *ml = file_apprentice(ms, magicfile, FILE_LOAD);
 180         if (ml) {
 181                 free_mlist(ms->mlist);
 182                 ms->mlist = ml;
 183                 return 0;
 184         }
 185         return -1;
 186 }
 187
 188 public int
 189 magic_compile(struct magic_set *ms, const char *magicfile)
 190 {
 191         struct mlist *ml = file_apprentice(ms, magicfile, FILE_COMPILE);
 192         free_mlist(ml);
 193         return ml ? 0 : -1;
 194 }
 195
 196 public int
 197 magic_check(struct magic_set *ms, const char *magicfile)
 198 {
 199         struct mlist *ml = file_apprentice(ms, magicfile, FILE_CHECK);
 200         free_mlist(ml);
 201         return ml ? 0 : -1;
 202 }
 203
 204 private void
 205 close_and_restore(const struct magic_set *ms, const char *name, int fd,
 206     const struct stat *sb)
 207 {
 208         if (fd == STDIN_FILENO)
 209                 return;
 210         (void) close(fd);
 211
 212         if ((ms->flags & MAGIC_PRESERVE_ATIME) != 0) {
 213                 /*
 214                  * Try to restore access, modification times if read it.
 215                  * This is really *bad* because it will modify the status
 216                  * time of the file... And of course this will affect
 217                  * backup programs
 218                  */
 219 #ifdef HAVE_UTIMES
 220                 struct timeval  utsbuf[2];
 221                 utsbuf[0].tv_sec = sb->st_atime;
 222                 utsbuf[1].tv_sec = sb->st_mtime;
 223
 224                 (void) utimes(name, utsbuf); /* don't care if loses */
 225 #elif defined(HAVE_UTIME_H) || defined(HAVE_SYS_UTIME_H)
 226                 struct utimbuf  utbuf;
 227
 228                 utbuf.actime = sb->st_atime;
 229                 utbuf.modtime = sb->st_mtime;
 230                 (void) utime(name, &utbuf); /* don't care if loses */
 231 #endif
 232         }
 233 }
 234
 235 #ifndef COMPILE_ONLY
 236
 237 /*
 238  * find type of descriptor
 239  */
 240 public const char *
 241 magic_descriptor(struct magic_set *ms, int fd)
 242 {
 243         return file_or_fd(ms, NULL, fd);
 244 }
 245
 246 /*
 247  * find type of named file
 248  */
 249 public const char *
 250 magic_file(struct magic_set *ms, const char *inname)
 251 {
 252         return file_or_fd(ms, inname, STDIN_FILENO);
 253 }
 254
 255 private const char *
 256 file_or_fd(struct magic_set *ms, const char *inname, int fd)
 257 {
 258         int     rv = -1;
 259         unsigned char *buf;
 260         struct stat     sb;
 261         ssize_t nbytes = 0;     /* number of bytes read from a datafile */
 262         int     ispipe = 0;
 263
 264         /*
 265          * one extra for terminating '\0', and
 266          * some overlapping space for matches near EOF
 267          */
 268 #define SLOP (1 + sizeof(union VALUETYPE))
 269         if ((buf = malloc(HOWMANY + SLOP)) == NULL)
 270                 return NULL;
 271
 272         if (file_reset(ms) == -1)
 273                 goto done;
 274
 275         switch (file_fsmagic(ms, inname, &sb)) {
 276         case -1:                /* error */
 277                 goto done;
 278         case 0:                 /* nothing found */
 279                 break;
 280         default:                /* matched it and printed type */
 281                 rv = 0;
 282                 goto done;
 283         }
 284
 285         if (inname == NULL) {
 286                 if (fstat(fd, &sb) == 0 && S_ISFIFO(sb.st_mode))
 287                         ispipe = 1;
 288         } else {
 289                 int flags = O_RDONLY|O_BINARY;
 290
 291                 if (stat(inname, &sb) == 0 && S_ISFIFO(sb.st_mode)) {
 292                         flags |= O_NONBLOCK;
 293                         ispipe = 1;
 294                 }
 295
 296                 errno = 0;
 297                 if ((fd = open(inname, flags)) < 0) {
 298 #ifdef __CYGWIN__
 299                         char *tmp = alloca(strlen(inname) + 5);
 300                         (void)strcat(strcpy(tmp, inname), ".exe");
 301                         if ((fd = open(tmp, flags)) < 0) {
 302 #endif
 303                                 if (info_from_stat(ms, sb.st_mode) == -1)
 304                                         goto done;
 305                                 rv = 0;
 306                                 goto done;
 307 #ifdef __CYGWIN__
 308                         }
 309 #endif
 310                 }
 311 #ifdef O_NONBLOCK
 312                 if ((flags = fcntl(fd, F_GETFL)) != -1) {
 313                         flags &= ~O_NONBLOCK;
 314                         (void)fcntl(fd, F_SETFL, flags);
 315                 }
 316 #endif
 317         }
 318
 319         /*
 320          * try looking at the first HOWMANY bytes
 321          */
 322         if (ispipe) {
 323                 ssize_t r = 0;
 324
 325                 while ((r = sread(fd, (void *)&buf[nbytes],
 326                     (size_t)(HOWMANY - nbytes), 1)) > 0) {
 327                         nbytes += r;
 328                         if (r < PIPE_BUF) break;
 329                 }
 330
 331                 if (nbytes == 0) {
 332                         /* We can not read it, but we were able to stat it. */
 333                         if (info_from_stat(ms, sb.st_mode) == -1)
 334                                 goto done;
 335                         rv = 0;
 336                         goto done;
 337                 }
 338
 339         } else {
 340                 if ((nbytes = read(fd, (char *)buf, HOWMANY)) == -1) {
 341                         file_error(ms, errno, "cannot read `%s'", inname);
 342                         goto done;
 343                 }
 344         }
 345
 346         (void)memset(buf + nbytes, 0, SLOP); /* NUL terminate */
 347         if (file_buffer(ms, fd, inname, buf, (size_t)nbytes) == -1)
 348                 goto done;
 349         rv = 0;
 350 done:
 351         free(buf);
 352         close_and_restore(ms, inname, fd, &sb);
 353         return rv == 0 ? file_getbuffer(ms) : NULL;
 354 }
 355
 356
 357 public const char *
 358 magic_buffer(struct magic_set *ms, const void *buf, size_t nb)
 359 {
 360         if (file_reset(ms) == -1)
 361                 return NULL;
 362         /*
 363          * The main work is done here!
 364          * We have the file name and/or the data buffer to be identified.
 365          */
 366         if (file_buffer(ms, -1, NULL, buf, nb) == -1) {
 367                 return NULL;
 368         }
 369         return file_getbuffer(ms);
 370 }
 371 #endif
 372
 373 public const char *
 374 magic_error(struct magic_set *ms)
 375 {
 376         return ms->haderr ? ms->o.buf : NULL;
 377 }
 378
 379 public int
 380 magic_errno(struct magic_set *ms)
 381 {
 382         return ms->haderr ? ms->error : 0;
 383 }
 384
 385 public int
 386 magic_setflags(struct magic_set *ms, int flags)
 387 {
 388 #if !defined(HAVE_UTIME) && !defined(HAVE_UTIMES)
 389         if (flags & MAGIC_PRESERVE_ATIME)
 390                 return -1;
 391 #endif
 392         ms->flags = flags;
 393         return 0;
 394 }