contrib/file-4/src/compress.c

   1 /*
   2  * Copyright (c) Ian F. Darwin 1986-1995.
   3  * Software written by Ian F. Darwin and others;
   4  * maintained 1995-present by Christos Zoulas and others.
   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  * compress routines:
  30  *      zmagic() - returns 0 if not recognized, uncompresses and prints
  31  *                 information if recognized
  32  *      uncompress(method, old, n, newch) - uncompress old into new,
  33  *                                          using method, return sizeof new
  34  */
  35 #include "file.h"
  36 #include "magic.h"
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #ifdef HAVE_UNISTD_H
  40 #include <unistd.h>
  41 #endif
  42 #include <string.h>
  43 #include <errno.h>
  44 #include <sys/types.h>
  45 #ifdef HAVE_SYS_WAIT_H
  46 #include <sys/wait.h>
  47 #endif
  48 #ifdef HAVE_LIBZ
  49 #include <zlib.h>
  50 #endif
  51
  52 #ifndef lint
  53 FILE_RCSID("@(#)$Id: compress.c,v 1.41 2005/01/07 19:17:26 christos Exp $")
  54 #endif
  55
  56
  57 private struct {
  58         const char *magic;
  59         size_t maglen;
  60         const char *const argv[3];
  61         int silent;
  62 } compr[] = {
  63         { "\037\235", 2, { "gzip", "-cdq", NULL }, 1 },         /* compressed */
  64         /* Uncompress can get stuck; so use gzip first if we have it
  65          * Idea from Damien Clark, thanks! */
  66         { "\037\235", 2, { "uncompress", "-c", NULL }, 1 },     /* compressed */
  67         { "\037\213", 2, { "gzip", "-cdq", NULL }, 1 },         /* gzipped */
  68         { "\037\236", 2, { "gzip", "-cdq", NULL }, 1 },         /* frozen */
  69         { "\037\240", 2, { "gzip", "-cdq", NULL }, 1 },         /* SCO LZH */
  70         /* the standard pack utilities do not accept standard input */
  71         { "\037\036", 2, { "gzip", "-cdq", NULL }, 0 },         /* packed */
  72         { "BZh",      3, { "bzip2", "-cd", NULL }, 1 },         /* bzip2-ed */
  73 };
  74
  75 private int ncompr = sizeof(compr) / sizeof(compr[0]);
  76
  77
  78 private ssize_t swrite(int, const void *, size_t);
  79 private ssize_t sread(int, void *, size_t);
  80 private size_t uncompressbuf(struct magic_set *, int, size_t,
  81     const unsigned char *, unsigned char **, size_t);
  82 #ifdef HAVE_LIBZ
  83 private size_t uncompressgzipped(struct magic_set *, const unsigned char *,
  84     unsigned char **, size_t);
  85 #endif
  86
  87 protected int
  88 file_zmagic(struct magic_set *ms, int fd, const unsigned char *buf,
  89     size_t nbytes)
  90 {
  91         unsigned char *newbuf = NULL;
  92         size_t i, nsz;
  93         int rv = 0;
  94
  95         if ((ms->flags & MAGIC_COMPRESS) == 0)
  96                 return 0;
  97
  98         for (i = 0; i < ncompr; i++) {
  99                 if (nbytes < compr[i].maglen)
 100                         continue;
 101                 if (memcmp(buf, compr[i].magic, compr[i].maglen) == 0 &&
 102                     (nsz = uncompressbuf(ms, fd, i, buf, &newbuf,
 103                     nbytes)) != 0) {
 104                         ms->flags &= ~MAGIC_COMPRESS;
 105                         rv = -1;
 106                         if (file_buffer(ms, -1, newbuf, nsz) == -1)
 107                                 goto error;
 108                         if (file_printf(ms, " (") == -1)
 109                                 goto error;
 110                         if (file_buffer(ms, -1, buf, nbytes) == -1)
 111                                 goto error;
 112                         if (file_printf(ms, ")") == -1)
 113                                 goto error;
 114                         rv = 1;
 115                         break;
 116                 }
 117         }
 118 error:
 119         if (newbuf)
 120                 free(newbuf);
 121         ms->flags |= MAGIC_COMPRESS;
 122         return rv;
 123 }
 124
 125 /*
 126  * `safe' write for sockets and pipes.
 127  */
 128 private ssize_t
 129 swrite(int fd, const void *buf, size_t n)
 130 {
 131         int rv;
 132         size_t rn = n;
 133
 134         do
 135                 switch (rv = write(fd, buf, n)) {
 136                 case -1:
 137                         if (errno == EINTR)
 138                                 continue;
 139                         return -1;
 140                 default:
 141                         n -= rv;
 142                         buf = ((const char *)buf) + rv;
 143                         break;
 144                 }
 145         while (n > 0);
 146         return rn;
 147 }
 148
 149
 150 /*
 151  * `safe' read for sockets and pipes.
 152  */
 153 private ssize_t
 154 sread(int fd, void *buf, size_t n)
 155 {
 156         int rv;
 157         size_t rn = n;
 158
 159         do
 160                 switch (rv = read(fd, buf, n)) {
 161                 case -1:
 162                         if (errno == EINTR)
 163                                 continue;
 164                         return -1;
 165                 case 0:
 166                         return rn - n;
 167                 default:
 168                         n -= rv;
 169                         buf = ((char *)buf) + rv;
 170                         break;
 171                 }
 172         while (n > 0);
 173         return rn;
 174 }
 175
 176 protected int
 177 file_pipe2file(struct magic_set *ms, int fd, const void *startbuf,
 178     size_t nbytes)
 179 {
 180         char buf[4096];
 181         int r, tfd;
 182
 183         (void)strcpy(buf, "/tmp/file.XXXXXX");
 184 #ifndef HAVE_MKSTEMP
 185         {
 186                 char *ptr = mktemp(buf);
 187                 tfd = open(ptr, O_RDWR|O_TRUNC|O_EXCL|O_CREAT, 0600);
 188                 r = errno;
 189                 (void)unlink(ptr);
 190                 errno = r;
 191         }
 192 #else
 193         tfd = mkstemp(buf);
 194         r = errno;
 195         (void)unlink(buf);
 196         errno = r;
 197 #endif
 198         if (tfd == -1) {
 199                 file_error(ms, errno,
 200                     "cannot create temporary file for pipe copy");
 201                 return -1;
 202         }
 203
 204         if (swrite(tfd, startbuf, nbytes) != (ssize_t)nbytes)
 205                 r = 1;
 206         else {
 207                 while ((r = sread(fd, buf, sizeof(buf))) > 0)
 208                         if (swrite(tfd, buf, (size_t)r) != r)
 209                                 break;
 210         }
 211
 212         switch (r) {
 213         case -1:
 214                 file_error(ms, errno, "error copying from pipe to temp file");
 215                 return -1;
 216         case 0:
 217                 break;
 218         default:
 219                 file_error(ms, errno, "error while writing to temp file");
 220                 return -1;
 221         }
 222
 223         /*
 224          * We duplicate the file descriptor, because fclose on a
 225          * tmpfile will delete the file, but any open descriptors
 226          * can still access the phantom inode.
 227          */
 228         if ((fd = dup2(tfd, fd)) == -1) {
 229                 file_error(ms, errno, "could not dup descriptor for temp file");
 230                 return -1;
 231         }
 232         (void)close(tfd);
 233         if (lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) {
 234                 file_badseek(ms);
 235                 return -1;
 236         }
 237         return fd;
 238 }
 239
 240 #ifdef HAVE_LIBZ
 241
 242 #define FHCRC           (1 << 1)
 243 #define FEXTRA          (1 << 2)
 244 #define FNAME           (1 << 3)
 245 #define FCOMMENT        (1 << 4)
 246
 247 private size_t
 248 uncompressgzipped(struct magic_set *ms, const unsigned char *old,
 249     unsigned char **newch, size_t n)
 250 {
 251         unsigned char flg = old[3];
 252         size_t data_start = 10;
 253         z_stream z;
 254         int rc;
 255
 256         if (flg & FEXTRA) {
 257                 if (data_start+1 >= n)
 258                         return 0;
 259                 data_start += 2 + old[data_start] + old[data_start + 1] * 256;
 260         }
 261         if (flg & FNAME) {
 262                 while(data_start < n && old[data_start])
 263                         data_start++;
 264                 data_start++;
 265         }
 266         if(flg & FCOMMENT) {
 267                 while(data_start < n && old[data_start])
 268                         data_start++;
 269                 data_start++;
 270         }
 271         if(flg & FHCRC)
 272                 data_start += 2;
 273
 274         if (data_start >= n)
 275                 return 0;
 276         if ((*newch = (unsigned char *)malloc(HOWMANY + 1)) == NULL) {
 277                 return 0;
 278         }
 279
 280         /* XXX: const castaway, via strchr */
 281         z.next_in = (Bytef *)strchr((const char *)old + data_start,
 282             old[data_start]);
 283         z.avail_in = n - data_start;
 284         z.next_out = *newch;
 285         z.avail_out = HOWMANY;
 286         z.zalloc = Z_NULL;
 287         z.zfree = Z_NULL;
 288         z.opaque = Z_NULL;
 289
 290         rc = inflateInit2(&z, -15);
 291         if (rc != Z_OK) {
 292                 file_error(ms, 0, "zlib: %s", z.msg);
 293                 return 0;
 294         }
 295
 296         rc = inflate(&z, Z_SYNC_FLUSH);
 297         if (rc != Z_OK && rc != Z_STREAM_END) {
 298                 file_error(ms, 0, "zlib: %s", z.msg);
 299                 return 0;
 300         }
 301
 302         n = (size_t)z.total_out;
 303         inflateEnd(&z);
 304
 305         /* let's keep the nul-terminate tradition */
 306         (*newch)[n++] = '\0';
 307
 308         return n;
 309 }
 310 #endif
 311
 312 private size_t
 313 uncompressbuf(struct magic_set *ms, int fd, size_t method,
 314     const unsigned char *old, unsigned char **newch, size_t n)
 315 {
 316         int fdin[2], fdout[2];
 317         int r;
 318
 319 #ifdef HAVE_LIBZ
 320         if (method == 2)
 321                 return uncompressgzipped(ms, old, newch, n);
 322 #endif
 323         (void)fflush(stdout);
 324         (void)fflush(stderr);
 325
 326         if ((fd != -1 && pipe(fdin) == -1) || pipe(fdout) == -1) {
 327                 file_error(ms, errno, "cannot create pipe");
 328                 return 0;
 329         }
 330         switch (fork()) {
 331         case 0: /* child */
 332                 (void) close(0);
 333                 if (fd != -1) {
 334                     (void) dup(fd);
 335                     (void) lseek(0, (off_t)0, SEEK_SET);
 336                 } else {
 337                     (void) dup(fdin[0]);
 338                     (void) close(fdin[0]);
 339                     (void) close(fdin[1]);
 340                 }
 341
 342                 (void) close(1);
 343                 (void) dup(fdout[1]);
 344                 (void) close(fdout[0]);
 345                 (void) close(fdout[1]);
 346 #ifndef DEBUG
 347                 if (compr[method].silent)
 348                         (void)close(2);
 349 #endif
 350
 351                 execvp(compr[method].argv[0],
 352                        (char *const *)compr[method].argv);
 353 #ifdef DEBUG
 354                 (void)fprintf(stderr, "exec `%s' failed (%s)\n",
 355                     compr[method].argv[0], strerror(errno));
 356 #endif
 357                 exit(1);
 358                 /*NOTREACHED*/
 359         case -1:
 360                 file_error(ms, errno, "could not fork");
 361                 return 0;
 362
 363         default: /* parent */
 364                 (void) close(fdout[1]);
 365                 if (fd == -1) {
 366                         (void) close(fdin[0]);
 367                         /*
 368                          * fork again, to avoid blocking because both
 369                          * pipes filled
 370                          */
 371                         switch (fork()) {
 372                         case 0: /* child */
 373                                 (void)close(fdout[0]);
 374                                 if (swrite(fdin[1], old, n) != n) {
 375 #ifdef DEBUG
 376                                         (void)fprintf(stderr,
 377                                             "Write failed (%s)\n",
 378                                             strerror(errno));
 379 #endif
 380                                         exit(1);
 381                                 }
 382                                 exit(0);
 383                                 /*NOTREACHED*/
 384
 385                         case -1:
 386 #ifdef DEBUG
 387                                 (void)fprintf(stderr, "Fork failed (%s)\n",
 388                                     strerror(errno));
 389 #endif
 390                                 exit(1);
 391                                 /*NOTREACHED*/
 392
 393                         default:  /* parent */
 394                                 break;
 395                         }
 396                         (void) close(fdin[1]);
 397                         fdin[1] = -1;
 398                 }
 399
 400                 if ((*newch = (unsigned char *) malloc(HOWMANY + 1)) == NULL) {
 401 #ifdef DEBUG
 402                         (void)fprintf(stderr, "Malloc failed (%s)\n",
 403                             strerror(errno));
 404 #endif
 405                         n = 0;
 406                         goto err;
 407                 }
 408                 if ((r = sread(fdout[0], *newch, HOWMANY)) <= 0) {
 409 #ifdef DEBUG
 410                         (void)fprintf(stderr, "Read failed (%s)\n",
 411                             strerror(errno));
 412 #endif
 413                         free(*newch);
 414                         n = 0;
 415                         newch[0] = '\0';
 416                         goto err;
 417                 } else {
 418                         n = r;
 419                 }
 420                 /* NUL terminate, as every buffer is handled here. */
 421                 (*newch)[n++] = '\0';
 422 err:
 423                 if (fdin[1] != -1)
 424                         (void) close(fdin[1]);
 425                 (void) close(fdout[0]);
 426 #ifdef WNOHANG
 427                 while (waitpid(-1, NULL, WNOHANG) != -1)
 428                         continue;
 429 #else
 430                 (void)wait(NULL);
 431 #endif
 432                 return n;
 433         }
 434 }