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] [iflag=skip_bytes]")
  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:     "\n        iflag=skip_bytes        skip=N is in bytes"
  80 //usage:        )
  81 //usage:        IF_FEATURE_DD_STATUS(
  82 //usage:     "\n        status=noxfer   Suppress rate output"
  83 //usage:     "\n        status=none     Suppress all output"
  84 //usage:        )
  85 //usage:     "\n"
  86 //usage:     "\nN may be suffixed by c (1), w (2), b (512), kB (1000), k (1024), MB, M, GB, G"
  87 //usage:
  88 //usage:#define dd_example_usage
  89 //usage:       "$ dd if=/dev/zero of=/dev/ram1 bs=1M count=4\n"
  90 //usage:       "4+0 records in\n"
  91 //usage:       "4+0 records out\n"
  92
  93 #include "libbb.h"
  94 #include "common_bufsiz.h"
  95
  96 /* This is a NOEXEC applet. Be very careful! */
  97
  98
  99 enum {
 100         ifd = STDIN_FILENO,
 101         ofd = STDOUT_FILENO,
 102 };
 103
 104 struct globals {
 105         off_t out_full, out_part, in_full, in_part;
 106 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 107         unsigned long long total_bytes;
 108         unsigned long long begin_time_us;
 109 #endif
 110         int flags;
 111 } FIX_ALIASING;
 112 #define G (*(struct globals*)bb_common_bufsiz1)
 113 #define INIT_G() do { \
 114         setup_common_bufsiz(); \
 115         /* we have to zero it out because of NOEXEC */ \
 116         memset(&G, 0, sizeof(G)); \
 117 } while (0)
 118
 119 enum {
 120         /* Must be in the same order as OP_conv_XXX! */
 121         /* (see "flags |= (1 << what)" below) */
 122         FLAG_NOTRUNC = (1 << 0) * ENABLE_FEATURE_DD_IBS_OBS,
 123         FLAG_SYNC    = (1 << 1) * ENABLE_FEATURE_DD_IBS_OBS,
 124         FLAG_NOERROR = (1 << 2) * ENABLE_FEATURE_DD_IBS_OBS,
 125         FLAG_FSYNC   = (1 << 3) * ENABLE_FEATURE_DD_IBS_OBS,
 126         FLAG_SWAB    = (1 << 4) * ENABLE_FEATURE_DD_IBS_OBS,
 127         /* end of conv flags */
 128         /* start of input flags */
 129         FLAG_IFLAG_SHIFT = 5,
 130         FLAG_SKIP_BYTES = (1 << 5) * ENABLE_FEATURE_DD_IBS_OBS,
 131         /* end of input flags */
 132         FLAG_TWOBUFS = (1 << 6) * ENABLE_FEATURE_DD_IBS_OBS,
 133         FLAG_COUNT   = 1 << 7,
 134         FLAG_STATUS  = 1 << 8,
 135         FLAG_STATUS_NONE = 1 << 9,
 136         FLAG_STATUS_NOXFER = 1 << 10,
 137 };
 138
 139 static void dd_output_status(int UNUSED_PARAM cur_signal)
 140 {
 141 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 142         double seconds;
 143         unsigned long long bytes_sec;
 144         unsigned long long now_us = monotonic_us(); /* before fprintf */
 145 #endif
 146
 147         /* Deliberately using %u, not %d */
 148         fprintf(stderr, "%"OFF_FMT"u+%"OFF_FMT"u records in\n"
 149                         "%"OFF_FMT"u+%"OFF_FMT"u records out\n",
 150                         G.in_full, G.in_part,
 151                         G.out_full, G.out_part);
 152
 153 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 154 # if ENABLE_FEATURE_DD_STATUS
 155         if (G.flags & FLAG_STATUS_NOXFER) /* status=noxfer active? */
 156                 return;
 157         //TODO: should status=none make dd stop reacting to USR1 entirely?
 158         //So far we react to it (we print the stats),
 159         //status=none only suppresses final, non-USR1 generated status message.
 160 # endif
 161         fprintf(stderr, "%llu bytes (%sB) copied, ",
 162                         G.total_bytes,
 163                         /* show fractional digit, use suffixes */
 164                         make_human_readable_str(G.total_bytes, 1, 0)
 165         );
 166         /* Corner cases:
 167          * ./busybox dd </dev/null >/dev/null
 168          * ./busybox dd bs=1M count=2000 </dev/zero >/dev/null
 169          * (echo DONE) | ./busybox dd >/dev/null
 170          * (sleep 1; echo DONE) | ./busybox dd >/dev/null
 171          */
 172         seconds = (now_us - G.begin_time_us) / 1000000.0;
 173         bytes_sec = G.total_bytes / seconds;
 174         fprintf(stderr, "%f seconds, %sB/s\n",
 175                         seconds,
 176                         /* show fractional digit, use suffixes */
 177                         make_human_readable_str(bytes_sec, 1, 0)
 178         );
 179 #endif
 180 }
 181
 182 static ssize_t full_write_or_warn(const void *buf, size_t len,
 183         const char *const filename)
 184 {
 185         ssize_t n = full_write(ofd, buf, len);
 186         if (n < 0)
 187                 bb_perror_msg("writing '%s'", filename);
 188         return n;
 189 }
 190
 191 static bool write_and_stats(const void *buf, size_t len, size_t obs,
 192         const char *filename)
 193 {
 194         ssize_t n = full_write_or_warn(buf, len, filename);
 195         if (n < 0)
 196                 return 1;
 197         if ((size_t)n == obs)
 198                 G.out_full++;
 199         else if (n) /* > 0 */
 200                 G.out_part++;
 201 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 202         G.total_bytes += n;
 203 #endif
 204         return 0;
 205 }
 206
 207 #if ENABLE_LFS
 208 # define XATOU_SFX xatoull_sfx
 209 #else
 210 # define XATOU_SFX xatoul_sfx
 211 #endif
 212
 213 #if ENABLE_FEATURE_DD_IBS_OBS
 214 static int parse_comma_flags(char *val, const char *words, const char *error_in)
 215 {
 216         int flags = 0;
 217         while (1) {
 218                 int n;
 219                 char *arg;
 220                 /* find ',', replace them with NUL so we can use val for
 221                  * index_in_strings() without copying.
 222                  * We rely on val being non-null, else strchr would fault.
 223                  */
 224                 arg = strchr(val, ',');
 225                 if (arg)
 226                         *arg = '\0';
 227                 n = index_in_strings(words, val);
 228                 if (n < 0)
 229                         bb_error_msg_and_die(bb_msg_invalid_arg_to, val, error_in);
 230                 flags |= (1 << n);
 231                 if (!arg) /* no ',' left, so this was the last specifier */
 232                         break;
 233                 *arg = ','; /* to preserve ps listing */
 234                 val = arg + 1; /* skip this keyword and ',' */
 235         }
 236         return flags;
 237 }
 238 #endif
 239
 240 int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 241 int dd_main(int argc UNUSED_PARAM, char **argv)
 242 {
 243         static const char keywords[] ALIGN1 =
 244                 "bs\0""count\0""seek\0""skip\0""if\0""of\0"IF_FEATURE_DD_STATUS("status\0")
 245 #if ENABLE_FEATURE_DD_IBS_OBS
 246                 "ibs\0""obs\0""conv\0""iflag\0"
 247 #endif
 248                 ;
 249 #if ENABLE_FEATURE_DD_IBS_OBS
 250         static const char conv_words[] ALIGN1 =
 251                 "notrunc\0""sync\0""noerror\0""fsync\0""swab\0";
 252         static const char iflag_words[] ALIGN1 =
 253                 "skip_bytes\0";
 254 #endif
 255 #if ENABLE_FEATURE_DD_STATUS
 256         static const char status_words[] ALIGN1 =
 257                 "none\0""noxfer\0";
 258 #endif
 259         enum {
 260                 OP_bs = 0,
 261                 OP_count,
 262                 OP_seek,
 263                 OP_skip,
 264                 OP_if,
 265                 OP_of,
 266                 IF_FEATURE_DD_STATUS(OP_status,)
 267 #if ENABLE_FEATURE_DD_IBS_OBS
 268                 OP_ibs,
 269                 OP_obs,
 270                 OP_conv,
 271                 OP_iflag,
 272                 /* Must be in the same order as FLAG_XXX! */
 273                 OP_conv_notrunc = 0,
 274                 OP_conv_sync,
 275                 OP_conv_noerror,
 276                 OP_conv_fsync,
 277                 OP_conv_swab,
 278         /* Unimplemented conv=XXX: */
 279         //nocreat       do not create the output file
 280         //excl          fail if the output file already exists
 281         //fdatasync     physically write output file data before finishing
 282         //lcase         change upper case to lower case
 283         //ucase         change lower case to upper case
 284         //block         pad newline-terminated records with spaces to cbs-size
 285         //unblock       replace trailing spaces in cbs-size records with newline
 286         //ascii         from EBCDIC to ASCII
 287         //ebcdic        from ASCII to EBCDIC
 288         //ibm           from ASCII to alternate EBCDIC
 289         /* Partially implemented: */
 290         //swab          swap every pair of input bytes: will abort on non-even reads
 291                 OP_iflag_skip_bytes,
 292 #endif
 293         };
 294         smallint exitcode = EXIT_FAILURE;
 295         int i;
 296         size_t ibs = 512;
 297         char *ibuf;
 298 #if ENABLE_FEATURE_DD_IBS_OBS
 299         size_t obs = 512;
 300         char *obuf;
 301 #else
 302 # define obs  ibs
 303 # define obuf ibuf
 304 #endif
 305         /* These are all zeroed at once! */
 306         struct {
 307                 size_t oc;
 308                 ssize_t prev_read_size; /* for detecting swab failure */
 309                 off_t count;
 310                 off_t seek, skip;
 311                 const char *infile, *outfile;
 312         } Z;
 313 #define oc      (Z.oc     )
 314 #define prev_read_size (Z.prev_read_size)
 315 #define count   (Z.count  )
 316 #define seek    (Z.seek   )
 317 #define skip    (Z.skip   )
 318 #define infile  (Z.infile )
 319 #define outfile (Z.outfile)
 320
 321         memset(&Z, 0, sizeof(Z));
 322         INIT_G();
 323         //fflush_all(); - is this needed because of NOEXEC?
 324
 325         for (i = 1; argv[i]; i++) {
 326                 int what;
 327                 char *val;
 328                 char *arg = argv[i];
 329
 330 #if ENABLE_DESKTOP
 331                 /* "dd --". NB: coreutils 6.9 will complain if they see
 332                  * more than one of them. We wouldn't. */
 333                 if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
 334                         continue;
 335 #endif
 336                 val = strchr(arg, '=');
 337                 if (val == NULL)
 338                         bb_show_usage();
 339                 *val = '\0';
 340                 what = index_in_strings(keywords, arg);
 341                 if (what < 0)
 342                         bb_show_usage();
 343                 /* *val = '='; - to preserve ps listing? */
 344                 val++;
 345 #if ENABLE_FEATURE_DD_IBS_OBS
 346                 if (what == OP_ibs) {
 347                         /* Must fit into positive ssize_t */
 348                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 349                         /*continue;*/
 350                 }
 351                 if (what == OP_obs) {
 352                         obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 353                         /*continue;*/
 354                 }
 355                 if (what == OP_conv) {
 356                         G.flags |= parse_comma_flags(val, conv_words, "conv");
 357                         /*continue;*/
 358                 }
 359                 if (what == OP_iflag) {
 360                         G.flags |= parse_comma_flags(val, iflag_words, "iflag") << FLAG_IFLAG_SHIFT;
 361                         /*continue;*/
 362                 }
 363 #endif
 364                 if (what == OP_bs) {
 365                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 366                         obs = ibs;
 367                         /*continue;*/
 368                 }
 369                 /* These can be large: */
 370                 if (what == OP_count) {
 371                         G.flags |= FLAG_COUNT;
 372                         count = XATOU_SFX(val, cwbkMG_suffixes);
 373                         /*continue;*/
 374                 }
 375                 if (what == OP_seek) {
 376                         seek = XATOU_SFX(val, cwbkMG_suffixes);
 377                         /*continue;*/
 378                 }
 379                 if (what == OP_skip) {
 380                         skip = XATOU_SFX(val, cwbkMG_suffixes);
 381                         /*continue;*/
 382                 }
 383                 if (what == OP_if) {
 384                         infile = val;
 385                         /*continue;*/
 386                 }
 387                 if (what == OP_of) {
 388                         outfile = val;
 389                         /*continue;*/
 390                 }
 391 #if ENABLE_FEATURE_DD_STATUS
 392                 if (what == OP_status) {
 393                         int n;
 394                         n = index_in_strings(status_words, val);
 395                         if (n < 0)
 396                                 bb_error_msg_and_die(bb_msg_invalid_arg_to, val, "status");
 397                         G.flags |= FLAG_STATUS << n;
 398                         /*continue;*/
 399                 }
 400 #endif
 401         } /* end of "for (argv[i])" */
 402
 403 //XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
 404         ibuf = xmalloc(ibs);
 405         obuf = ibuf;
 406 #if ENABLE_FEATURE_DD_IBS_OBS
 407         if (ibs != obs) {
 408                 G.flags |= FLAG_TWOBUFS;
 409                 obuf = xmalloc(obs);
 410         }
 411 #endif
 412
 413 #if ENABLE_FEATURE_DD_SIGNAL_HANDLING
 414         signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
 415 #endif
 416 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 417         G.begin_time_us = monotonic_us();
 418 #endif
 419
 420         if (infile) {
 421                 xmove_fd(xopen(infile, O_RDONLY), ifd);
 422         } else {
 423                 infile = bb_msg_standard_input;
 424         }
 425         if (outfile) {
 426                 int oflag = O_WRONLY | O_CREAT;
 427
 428                 if (!seek && !(G.flags & FLAG_NOTRUNC))
 429                         oflag |= O_TRUNC;
 430
 431                 xmove_fd(xopen(outfile, oflag), ofd);
 432
 433                 if (seek && !(G.flags & FLAG_NOTRUNC)) {
 434                         if (ftruncate(ofd, seek * obs) < 0) {
 435                                 struct stat st;
 436
 437                                 if (fstat(ofd, &st) < 0
 438                                  || S_ISREG(st.st_mode)
 439                                  || S_ISDIR(st.st_mode)
 440                                 ) {
 441                                         goto die_outfile;
 442                                 }
 443                         }
 444                 }
 445         } else {
 446                 outfile = bb_msg_standard_output;
 447         }
 448         if (skip) {
 449                 size_t blocksz = (G.flags & FLAG_SKIP_BYTES) ? 1 : ibs;
 450                 if (lseek(ifd, skip * blocksz, SEEK_CUR) < 0) {
 451                         do {
 452                                 ssize_t n = safe_read(ifd, ibuf, blocksz);
 453                                 if (n < 0)
 454                                         goto die_infile;
 455                                 if (n == 0)
 456                                         break;
 457                         } while (--skip != 0);
 458                 }
 459         }
 460         if (seek) {
 461                 if (lseek(ofd, seek * obs, SEEK_CUR) < 0)
 462                         goto die_outfile;
 463         }
 464
 465         while (!(G.flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
 466                 ssize_t n;
 467
 468                 n = safe_read(ifd, ibuf, ibs);
 469                 if (n == 0)
 470                         break;
 471                 if (n < 0) {
 472                         /* "Bad block" */
 473                         if (!(G.flags & FLAG_NOERROR))
 474                                 goto die_infile;
 475                         bb_simple_perror_msg(infile);
 476                         /* GNU dd with conv=noerror skips over bad blocks */
 477                         xlseek(ifd, ibs, SEEK_CUR);
 478                         /* conv=noerror,sync writes NULs,
 479                          * conv=noerror just ignores input bad blocks */
 480                         n = 0;
 481                 }
 482                 if (G.flags & FLAG_SWAB) {
 483                         uint16_t *p16;
 484                         ssize_t n2;
 485
 486                         /* Our code allows only last read to be odd-sized */
 487                         if (prev_read_size & 1)
 488                                 bb_error_msg_and_die("can't swab %lu byte buffer",
 489                                                 (unsigned long)prev_read_size);
 490                         prev_read_size = n;
 491
 492                         /* If n is odd, last byte is not swapped:
 493                          *  echo -n "qwe" | dd conv=swab
 494                          * prints "wqe".
 495                          */
 496                         p16 = (void*) ibuf;
 497                         n2 = (n >> 1);
 498                         while (--n2 >= 0) {
 499                                 *p16 = bswap_16(*p16);
 500                                 p16++;
 501                         }
 502                 }
 503                 if ((size_t)n == ibs)
 504                         G.in_full++;
 505                 else {
 506                         G.in_part++;
 507                         if (G.flags & FLAG_SYNC) {
 508                                 memset(ibuf + n, 0, ibs - n);
 509                                 n = ibs;
 510                         }
 511                 }
 512                 if (G.flags & FLAG_TWOBUFS) {
 513                         char *tmp = ibuf;
 514                         while (n) {
 515                                 size_t d = obs - oc;
 516
 517                                 if (d > (size_t)n)
 518                                         d = n;
 519                                 memcpy(obuf + oc, tmp, d);
 520                                 n -= d;
 521                                 tmp += d;
 522                                 oc += d;
 523                                 if (oc == obs) {
 524                                         if (write_and_stats(obuf, obs, obs, outfile))
 525                                                 goto out_status;
 526                                         oc = 0;
 527                                 }
 528                         }
 529                 } else {
 530                         if (write_and_stats(ibuf, n, obs, outfile))
 531                                 goto out_status;
 532                 }
 533
 534                 if (G.flags & FLAG_FSYNC) {
 535                         if (fsync(ofd) < 0)
 536                                 goto die_outfile;
 537                 }
 538         }
 539
 540         if (ENABLE_FEATURE_DD_IBS_OBS && oc) {
 541                 if (write_and_stats(obuf, oc, obs, outfile))
 542                         goto out_status;
 543         }
 544         if (close(ifd) < 0) {
 545  die_infile:
 546                 bb_simple_perror_msg_and_die(infile);
 547         }
 548
 549         if (close(ofd) < 0) {
 550  die_outfile:
 551                 bb_simple_perror_msg_and_die(outfile);
 552         }
 553
 554         exitcode = EXIT_SUCCESS;
 555  out_status:
 556         if (!ENABLE_FEATURE_DD_STATUS || !(G.flags & FLAG_STATUS_NONE))
 557                 dd_output_status(0);
 558
 559         if (ENABLE_FEATURE_CLEAN_UP) {
 560                 free(obuf);
 561                 if (G.flags & FLAG_TWOBUFS)
 562                         free(ibuf);
 563         }
 564
 565         return exitcode;
 566 }