coreutils/dd.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini dd implementation for busybox
   4  *
   5  *
   6  * Copyright (C) 2000,2001  Matt Kraai
   7  *
   8  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9  */
  10
  11 //config:config DD
  12 //config:       bool "dd"
  13 //config:       default y
  14 //config:       help
  15 //config:         dd copies a file (from standard input to standard output,
  16 //config:         by default) using specific input and output blocksizes,
  17 //config:         while optionally performing conversions on it.
  18 //config:
  19 //config:config FEATURE_DD_SIGNAL_HANDLING
  20 //config:       bool "Enable signal handling for status reporting"
  21 //config:       default y
  22 //config:       depends on DD
  23 //config:       help
  24 //config:         Sending a SIGUSR1 signal to a running `dd' process makes it
  25 //config:         print to standard error the number of records read and written
  26 //config:         so far, then to resume copying.
  27 //config:
  28 //config:         $ dd if=/dev/zero of=/dev/null &
  29 //config:         $ pid=$!; kill -USR1 $pid; sleep 1; kill $pid
  30 //config:         10899206+0 records in
  31 //config:         10899206+0 records out
  32 //config:
  33 //config:config FEATURE_DD_THIRD_STATUS_LINE
  34 //config:       bool "Enable the third status line upon signal"
  35 //config:       default y
  36 //config:       depends on DD && FEATURE_DD_SIGNAL_HANDLING
  37 //config:       help
  38 //config:         Displays a coreutils-like third status line with transferred bytes,
  39 //config:         elapsed time and speed.
  40 //config:
  41 //config:config FEATURE_DD_IBS_OBS
  42 //config:       bool "Enable ibs, obs and conv options"
  43 //config:       default y
  44 //config:       depends on DD
  45 //config:       help
  46 //config:         Enables support for writing a certain number of bytes in and out,
  47 //config:         at a time, and performing conversions on the data stream.
  48 //config:
  49 //config:config FEATURE_DD_STATUS
  50 //config:       bool "Enable status display options"
  51 //config:       default y
  52 //config:       depends on DD
  53 //config:       help
  54 //config:         Enables support for status=noxfer/none option.
  55
  56 //usage:#define dd_trivial_usage
  57 //usage:       "[if=FILE] [of=FILE] " IF_FEATURE_DD_IBS_OBS("[ibs=N] [obs=N] ") "[bs=N] [count=N] [skip=N]\n"
  58 //usage:       "        [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync]")
  59 //usage:#define dd_full_usage "\n\n"
  60 //usage:       "Copy a file with converting and formatting\n"
  61 //usage:     "\n        if=FILE         Read from FILE instead of stdin"
  62 //usage:     "\n        of=FILE         Write to FILE instead of stdout"
  63 //usage:     "\n        bs=N            Read and write N bytes at a time"
  64 //usage:        IF_FEATURE_DD_IBS_OBS(
  65 //usage:     "\n        ibs=N           Read N bytes at a time"
  66 //usage:        )
  67 //usage:        IF_FEATURE_DD_IBS_OBS(
  68 //usage:     "\n        obs=N           Write N bytes at a time"
  69 //usage:        )
  70 //usage:     "\n        count=N         Copy only N input blocks"
  71 //usage:     "\n        skip=N          Skip N input blocks"
  72 //usage:     "\n        seek=N          Skip N output blocks"
  73 //usage:        IF_FEATURE_DD_IBS_OBS(
  74 //usage:     "\n        conv=notrunc    Don't truncate output file"
  75 //usage:     "\n        conv=noerror    Continue after read errors"
  76 //usage:     "\n        conv=sync       Pad blocks with zeros"
  77 //usage:     "\n        conv=fsync      Physically write data out before finishing"
  78 //usage:     "\n        conv=swab       Swap every pair of bytes"
  79 //usage:        )
  80 //usage:        IF_FEATURE_DD_STATUS(
  81 //usage:     "\n        status=noxfer   Suppress rate output"
  82 //usage:     "\n        status=none     Suppress all output"
  83 //usage:        )
  84 //usage:     "\n"
  85 //usage:     "\nN may be suffixed by c (1), w (2), b (512), kB (1000), k (1024), MB, M, GB, G"
  86 //usage:
  87 //usage:#define dd_example_usage
  88 //usage:       "$ dd if=/dev/zero of=/dev/ram1 bs=1M count=4\n"
  89 //usage:       "4+0 records in\n"
  90 //usage:       "4+0 records out\n"
  91
  92 #include "libbb.h"
  93
  94 /* This is a NOEXEC applet. Be very careful! */
  95
  96
  97 enum {
  98         ifd = STDIN_FILENO,
  99         ofd = STDOUT_FILENO,
 100 };
 101
 102 struct globals {
 103         off_t out_full, out_part, in_full, in_part;
 104 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 105         unsigned long long total_bytes;
 106         unsigned long long begin_time_us;
 107 #endif
 108         int flags;
 109 } FIX_ALIASING;
 110 #define G (*(struct globals*)&bb_common_bufsiz1)
 111 #define INIT_G() do { \
 112         /* we have to zero it out because of NOEXEC */ \
 113         memset(&G, 0, sizeof(G)); \
 114 } while (0)
 115
 116 enum {
 117         /* Must be in the same order as OP_conv_XXX! */
 118         /* (see "flags |= (1 << what)" below) */
 119         FLAG_NOTRUNC = (1 << 0) * ENABLE_FEATURE_DD_IBS_OBS,
 120         FLAG_SYNC    = (1 << 1) * ENABLE_FEATURE_DD_IBS_OBS,
 121         FLAG_NOERROR = (1 << 2) * ENABLE_FEATURE_DD_IBS_OBS,
 122         FLAG_FSYNC   = (1 << 3) * ENABLE_FEATURE_DD_IBS_OBS,
 123         FLAG_SWAB    = (1 << 4) * ENABLE_FEATURE_DD_IBS_OBS,
 124         /* end of conv flags */
 125         FLAG_TWOBUFS = (1 << 5) * ENABLE_FEATURE_DD_IBS_OBS,
 126         FLAG_COUNT   = 1 << 6,
 127         FLAG_STATUS  = 1 << 7,
 128         FLAG_STATUS_NONE = 1 << 7,
 129         FLAG_STATUS_NOXFER = 1 << 8,
 130 };
 131
 132 static void dd_output_status(int UNUSED_PARAM cur_signal)
 133 {
 134 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 135         double seconds;
 136         unsigned long long bytes_sec;
 137         unsigned long long now_us = monotonic_us(); /* before fprintf */
 138 #endif
 139
 140         /* Deliberately using %u, not %d */
 141         fprintf(stderr, "%"OFF_FMT"u+%"OFF_FMT"u records in\n"
 142                         "%"OFF_FMT"u+%"OFF_FMT"u records out\n",
 143                         G.in_full, G.in_part,
 144                         G.out_full, G.out_part);
 145
 146 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 147 # if ENABLE_FEATURE_DD_STATUS
 148         if (G.flags & FLAG_STATUS_NOXFER) /* status=noxfer active? */
 149                 return;
 150         //TODO: should status=none make dd stop reacting to USR1 entirely?
 151         //So far we react to it (we print the stats),
 152         //status=none only suppresses final, non-USR1 generated status message.
 153 # endif
 154         fprintf(stderr, "%llu bytes (%sB) copied, ",
 155                         G.total_bytes,
 156                         /* show fractional digit, use suffixes */
 157                         make_human_readable_str(G.total_bytes, 1, 0)
 158         );
 159         /* Corner cases:
 160          * ./busybox dd </dev/null >/dev/null
 161          * ./busybox dd bs=1M count=2000 </dev/zero >/dev/null
 162          * (echo DONE) | ./busybox dd >/dev/null
 163          * (sleep 1; echo DONE) | ./busybox dd >/dev/null
 164          */
 165         seconds = (now_us - G.begin_time_us) / 1000000.0;
 166         bytes_sec = G.total_bytes / seconds;
 167         fprintf(stderr, "%f seconds, %sB/s\n",
 168                         seconds,
 169                         /* show fractional digit, use suffixes */
 170                         make_human_readable_str(bytes_sec, 1, 0)
 171         );
 172 #endif
 173 }
 174
 175 static ssize_t full_write_or_warn(const void *buf, size_t len,
 176         const char *const filename)
 177 {
 178         ssize_t n = full_write(ofd, buf, len);
 179         if (n < 0)
 180                 bb_perror_msg("writing '%s'", filename);
 181         return n;
 182 }
 183
 184 static bool write_and_stats(const void *buf, size_t len, size_t obs,
 185         const char *filename)
 186 {
 187         ssize_t n = full_write_or_warn(buf, len, filename);
 188         if (n < 0)
 189                 return 1;
 190         if ((size_t)n == obs)
 191                 G.out_full++;
 192         else if (n) /* > 0 */
 193                 G.out_part++;
 194 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 195         G.total_bytes += n;
 196 #endif
 197         return 0;
 198 }
 199
 200 #if ENABLE_LFS
 201 # define XATOU_SFX xatoull_sfx
 202 #else
 203 # define XATOU_SFX xatoul_sfx
 204 #endif
 205
 206 int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 207 int dd_main(int argc UNUSED_PARAM, char **argv)
 208 {
 209         static const char keywords[] ALIGN1 =
 210                 "bs\0""count\0""seek\0""skip\0""if\0""of\0"IF_FEATURE_DD_STATUS("status\0")
 211 #if ENABLE_FEATURE_DD_IBS_OBS
 212                 "ibs\0""obs\0""conv\0"
 213 #endif
 214                 ;
 215 #if ENABLE_FEATURE_DD_IBS_OBS
 216         static const char conv_words[] ALIGN1 =
 217                 "notrunc\0""sync\0""noerror\0""fsync\0""swab\0";
 218 #endif
 219 #if ENABLE_FEATURE_DD_STATUS
 220         static const char status_words[] ALIGN1 =
 221                 "none\0""noxfer\0";
 222 #endif
 223         enum {
 224                 OP_bs = 0,
 225                 OP_count,
 226                 OP_seek,
 227                 OP_skip,
 228                 OP_if,
 229                 OP_of,
 230                 IF_FEATURE_DD_STATUS(OP_status,)
 231 #if ENABLE_FEATURE_DD_IBS_OBS
 232                 OP_ibs,
 233                 OP_obs,
 234                 OP_conv,
 235                 /* Must be in the same order as FLAG_XXX! */
 236                 OP_conv_notrunc = 0,
 237                 OP_conv_sync,
 238                 OP_conv_noerror,
 239                 OP_conv_fsync,
 240                 OP_conv_swab,
 241         /* Unimplemented conv=XXX: */
 242         //nocreat       do not create the output file
 243         //excl          fail if the output file already exists
 244         //fdatasync     physically write output file data before finishing
 245         //lcase         change upper case to lower case
 246         //ucase         change lower case to upper case
 247         //block         pad newline-terminated records with spaces to cbs-size
 248         //unblock       replace trailing spaces in cbs-size records with newline
 249         //ascii         from EBCDIC to ASCII
 250         //ebcdic        from ASCII to EBCDIC
 251         //ibm           from ASCII to alternate EBCDIC
 252         /* Partially implemented: */
 253         //swab          swap every pair of input bytes: will abort on non-even reads
 254 #endif
 255         };
 256         smallint exitcode = EXIT_FAILURE;
 257         int i;
 258         size_t ibs = 512;
 259         char *ibuf;
 260 #if ENABLE_FEATURE_DD_IBS_OBS
 261         size_t obs = 512;
 262         char *obuf;
 263 #else
 264 # define obs  ibs
 265 # define obuf ibuf
 266 #endif
 267         /* These are all zeroed at once! */
 268         struct {
 269                 size_t oc;
 270                 ssize_t prev_read_size; /* for detecting swab failure */
 271                 off_t count;
 272                 off_t seek, skip;
 273                 const char *infile, *outfile;
 274         } Z;
 275 #define oc      (Z.oc     )
 276 #define prev_read_size (Z.prev_read_size)
 277 #define count   (Z.count  )
 278 #define seek    (Z.seek   )
 279 #define skip    (Z.skip   )
 280 #define infile  (Z.infile )
 281 #define outfile (Z.outfile)
 282
 283         memset(&Z, 0, sizeof(Z));
 284         INIT_G();
 285         //fflush_all(); - is this needed because of NOEXEC?
 286
 287         for (i = 1; argv[i]; i++) {
 288                 int what;
 289                 char *val;
 290                 char *arg = argv[i];
 291
 292 #if ENABLE_DESKTOP
 293                 /* "dd --". NB: coreutils 6.9 will complain if they see
 294                  * more than one of them. We wouldn't. */
 295                 if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
 296                         continue;
 297 #endif
 298                 val = strchr(arg, '=');
 299                 if (val == NULL)
 300                         bb_show_usage();
 301                 *val = '\0';
 302                 what = index_in_strings(keywords, arg);
 303                 if (what < 0)
 304                         bb_show_usage();
 305                 /* *val = '='; - to preserve ps listing? */
 306                 val++;
 307 #if ENABLE_FEATURE_DD_IBS_OBS
 308                 if (what == OP_ibs) {
 309                         /* Must fit into positive ssize_t */
 310                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 311                         /*continue;*/
 312                 }
 313                 if (what == OP_obs) {
 314                         obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 315                         /*continue;*/
 316                 }
 317                 if (what == OP_conv) {
 318                         while (1) {
 319                                 int n;
 320                                 /* find ',', replace them with NUL so we can use val for
 321                                  * index_in_strings() without copying.
 322                                  * We rely on val being non-null, else strchr would fault.
 323                                  */
 324                                 arg = strchr(val, ',');
 325                                 if (arg)
 326                                         *arg = '\0';
 327                                 n = index_in_strings(conv_words, val);
 328                                 if (n < 0)
 329                                         bb_error_msg_and_die(bb_msg_invalid_arg, val, "conv");
 330                                 G.flags |= (1 << n);
 331                                 if (!arg) /* no ',' left, so this was the last specifier */
 332                                         break;
 333                                 /* *arg = ','; - to preserve ps listing? */
 334                                 val = arg + 1; /* skip this keyword and ',' */
 335                         }
 336                         /*continue;*/
 337                 }
 338 #endif
 339                 if (what == OP_bs) {
 340                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 341                         obs = ibs;
 342                         /*continue;*/
 343                 }
 344                 /* These can be large: */
 345                 if (what == OP_count) {
 346                         G.flags |= FLAG_COUNT;
 347                         count = XATOU_SFX(val, cwbkMG_suffixes);
 348                         /*continue;*/
 349                 }
 350                 if (what == OP_seek) {
 351                         seek = XATOU_SFX(val, cwbkMG_suffixes);
 352                         /*continue;*/
 353                 }
 354                 if (what == OP_skip) {
 355                         skip = XATOU_SFX(val, cwbkMG_suffixes);
 356                         /*continue;*/
 357                 }
 358                 if (what == OP_if) {
 359                         infile = val;
 360                         /*continue;*/
 361                 }
 362                 if (what == OP_of) {
 363                         outfile = val;
 364                         /*continue;*/
 365                 }
 366 #if ENABLE_FEATURE_DD_STATUS
 367                 if (what == OP_status) {
 368                         int n;
 369                         n = index_in_strings(status_words, val);
 370                         if (n < 0)
 371                                 bb_error_msg_and_die(bb_msg_invalid_arg, val, "status");
 372                         G.flags |= FLAG_STATUS << n;
 373                         /*continue;*/
 374                 }
 375 #endif
 376         } /* end of "for (argv[i])" */
 377
 378 //XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
 379         ibuf = xmalloc(ibs);
 380         obuf = ibuf;
 381 #if ENABLE_FEATURE_DD_IBS_OBS
 382         if (ibs != obs) {
 383                 G.flags |= FLAG_TWOBUFS;
 384                 obuf = xmalloc(obs);
 385         }
 386 #endif
 387
 388 #if ENABLE_FEATURE_DD_SIGNAL_HANDLING
 389         signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
 390 #endif
 391 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 392         G.begin_time_us = monotonic_us();
 393 #endif
 394
 395         if (infile) {
 396                 xmove_fd(xopen(infile, O_RDONLY), ifd);
 397         } else {
 398                 infile = bb_msg_standard_input;
 399         }
 400         if (outfile) {
 401                 int oflag = O_WRONLY | O_CREAT;
 402
 403                 if (!seek && !(G.flags & FLAG_NOTRUNC))
 404                         oflag |= O_TRUNC;
 405
 406                 xmove_fd(xopen(outfile, oflag), ofd);
 407
 408                 if (seek && !(G.flags & FLAG_NOTRUNC)) {
 409                         if (ftruncate(ofd, seek * obs) < 0) {
 410                                 struct stat st;
 411
 412                                 if (fstat(ofd, &st) < 0
 413                                  || S_ISREG(st.st_mode)
 414                                  || S_ISDIR(st.st_mode)
 415                                 ) {
 416                                         goto die_outfile;
 417                                 }
 418                         }
 419                 }
 420         } else {
 421                 outfile = bb_msg_standard_output;
 422         }
 423         if (skip) {
 424                 if (lseek(ifd, skip * ibs, SEEK_CUR) < 0) {
 425                         do {
 426                                 ssize_t n = safe_read(ifd, ibuf, ibs);
 427                                 if (n < 0)
 428                                         goto die_infile;
 429                                 if (n == 0)
 430                                         break;
 431                         } while (--skip != 0);
 432                 }
 433         }
 434         if (seek) {
 435                 if (lseek(ofd, seek * obs, SEEK_CUR) < 0)
 436                         goto die_outfile;
 437         }
 438
 439         while (!(G.flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
 440                 ssize_t n;
 441
 442                 n = safe_read(ifd, ibuf, ibs);
 443                 if (n == 0)
 444                         break;
 445                 if (n < 0) {
 446                         /* "Bad block" */
 447                         if (!(G.flags & FLAG_NOERROR))
 448                                 goto die_infile;
 449                         bb_simple_perror_msg(infile);
 450                         /* GNU dd with conv=noerror skips over bad blocks */
 451                         xlseek(ifd, ibs, SEEK_CUR);
 452                         /* conv=noerror,sync writes NULs,
 453                          * conv=noerror just ignores input bad blocks */
 454                         n = 0;
 455                 }
 456                 if (G.flags & FLAG_SWAB) {
 457                         uint16_t *p16;
 458                         ssize_t n2;
 459
 460                         /* Our code allows only last read to be odd-sized */
 461                         if (prev_read_size & 1)
 462                                 bb_error_msg_and_die("can't swab %lu byte buffer",
 463                                                 (unsigned long)prev_read_size);
 464                         prev_read_size = n;
 465
 466                         /* If n is odd, last byte is not swapped:
 467                          *  echo -n "qwe" | dd conv=swab
 468                          * prints "wqe".
 469                          */
 470                         p16 = (void*) ibuf;
 471                         n2 = (n >> 1);
 472                         while (--n2 >= 0) {
 473                                 *p16 = bswap_16(*p16);
 474                                 p16++;
 475                         }
 476                 }
 477                 if ((size_t)n == ibs)
 478                         G.in_full++;
 479                 else {
 480                         G.in_part++;
 481                         if (G.flags & FLAG_SYNC) {
 482                                 memset(ibuf + n, 0, ibs - n);
 483                                 n = ibs;
 484                         }
 485                 }
 486                 if (G.flags & FLAG_TWOBUFS) {
 487                         char *tmp = ibuf;
 488                         while (n) {
 489                                 size_t d = obs - oc;
 490
 491                                 if (d > (size_t)n)
 492                                         d = n;
 493                                 memcpy(obuf + oc, tmp, d);
 494                                 n -= d;
 495                                 tmp += d;
 496                                 oc += d;
 497                                 if (oc == obs) {
 498                                         if (write_and_stats(obuf, obs, obs, outfile))
 499                                                 goto out_status;
 500                                         oc = 0;
 501                                 }
 502                         }
 503                 } else {
 504                         if (write_and_stats(ibuf, n, obs, outfile))
 505                                 goto out_status;
 506                 }
 507
 508                 if (G.flags & FLAG_FSYNC) {
 509                         if (fsync(ofd) < 0)
 510                                 goto die_outfile;
 511                 }
 512         }
 513
 514         if (ENABLE_FEATURE_DD_IBS_OBS && oc) {
 515                 if (write_and_stats(obuf, oc, obs, outfile))
 516                         goto out_status;
 517         }
 518         if (close(ifd) < 0) {
 519  die_infile:
 520                 bb_simple_perror_msg_and_die(infile);
 521         }
 522
 523         if (close(ofd) < 0) {
 524  die_outfile:
 525                 bb_simple_perror_msg_and_die(outfile);
 526         }
 527
 528         exitcode = EXIT_SUCCESS;
 529  out_status:
 530         if (!ENABLE_FEATURE_DD_STATUS || !(G.flags & FLAG_STATUS_NONE))
 531                 dd_output_status(0);
 532
 533         if (ENABLE_FEATURE_CLEAN_UP) {
 534                 free(obuf);
 535                 if (G.flags & FLAG_TWOBUFS)
 536                         free(ibuf);
 537         }
 538
 539         return exitcode;
 540 }