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 static const struct suffix_mult dd_suffixes[] = {
 103         { "c", 1 },
 104         { "w", 2 },
 105         { "b", 512 },
 106         { "kB", 1000 },
 107         { "kD", 1000 },
 108         { "k", 1024 },
 109         { "K", 1024 },  /* compat with coreutils dd (it also accepts KB and KD, TODO?) */
 110         { "MB", 1000000 },
 111         { "MD", 1000000 },
 112         { "M", 1024*1024 },
 113         { "GB", 1000000000 },
 114         { "GD", 1000000000 },
 115         { "G", 1024*1024*1024 },
 116         /* "D" suffix for decimal is not in coreutils manpage, looks like it's deprecated */
 117         /* coreutils also understands TPEZY suffixes for tera- and so on, with B suffix for decimal */
 118         { "", 0 }
 119 };
 120
 121 struct globals {
 122         off_t out_full, out_part, in_full, in_part;
 123 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 124         unsigned long long total_bytes;
 125         unsigned long long begin_time_us;
 126 #endif
 127         int flags;
 128 } FIX_ALIASING;
 129 #define G (*(struct globals*)&bb_common_bufsiz1)
 130 #define INIT_G() do { \
 131         /* we have to zero it out because of NOEXEC */ \
 132         memset(&G, 0, sizeof(G)); \
 133 } while (0)
 134
 135 enum {
 136         /* Must be in the same order as OP_conv_XXX! */
 137         /* (see "flags |= (1 << what)" below) */
 138         FLAG_NOTRUNC = (1 << 0) * ENABLE_FEATURE_DD_IBS_OBS,
 139         FLAG_SYNC    = (1 << 1) * ENABLE_FEATURE_DD_IBS_OBS,
 140         FLAG_NOERROR = (1 << 2) * ENABLE_FEATURE_DD_IBS_OBS,
 141         FLAG_FSYNC   = (1 << 3) * ENABLE_FEATURE_DD_IBS_OBS,
 142         FLAG_SWAB    = (1 << 4) * ENABLE_FEATURE_DD_IBS_OBS,
 143         /* end of conv flags */
 144         FLAG_TWOBUFS = (1 << 5) * ENABLE_FEATURE_DD_IBS_OBS,
 145         FLAG_COUNT   = 1 << 6,
 146         FLAG_STATUS  = 1 << 7,
 147         FLAG_STATUS_NONE = 1 << 7,
 148         FLAG_STATUS_NOXFER = 1 << 8,
 149 };
 150
 151 static void dd_output_status(int UNUSED_PARAM cur_signal)
 152 {
 153 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 154         double seconds;
 155         unsigned long long bytes_sec;
 156         unsigned long long now_us = monotonic_us(); /* before fprintf */
 157 #endif
 158
 159         /* Deliberately using %u, not %d */
 160         fprintf(stderr, "%"OFF_FMT"u+%"OFF_FMT"u records in\n"
 161                         "%"OFF_FMT"u+%"OFF_FMT"u records out\n",
 162                         G.in_full, G.in_part,
 163                         G.out_full, G.out_part);
 164
 165 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 166 # if ENABLE_FEATURE_DD_STATUS
 167         if (G.flags & FLAG_STATUS_NOXFER) /* status=noxfer active? */
 168                 return;
 169         //TODO: should status=none make dd stop reacting to USR1 entirely?
 170         //So far we react to it (we print the stats),
 171         //status=none only suppresses final, non-USR1 generated status message.
 172 # endif
 173         fprintf(stderr, "%llu bytes (%sB) copied, ",
 174                         G.total_bytes,
 175                         /* show fractional digit, use suffixes */
 176                         make_human_readable_str(G.total_bytes, 1, 0)
 177         );
 178         /* Corner cases:
 179          * ./busybox dd </dev/null >/dev/null
 180          * ./busybox dd bs=1M count=2000 </dev/zero >/dev/null
 181          * (echo DONE) | ./busybox dd >/dev/null
 182          * (sleep 1; echo DONE) | ./busybox dd >/dev/null
 183          */
 184         seconds = (now_us - G.begin_time_us) / 1000000.0;
 185         bytes_sec = G.total_bytes / seconds;
 186         fprintf(stderr, "%f seconds, %sB/s\n",
 187                         seconds,
 188                         /* show fractional digit, use suffixes */
 189                         make_human_readable_str(bytes_sec, 1, 0)
 190         );
 191 #endif
 192 }
 193
 194 static ssize_t full_write_or_warn(const void *buf, size_t len,
 195         const char *const filename)
 196 {
 197         ssize_t n = full_write(ofd, buf, len);
 198         if (n < 0)
 199                 bb_perror_msg("writing '%s'", filename);
 200         return n;
 201 }
 202
 203 static bool write_and_stats(const void *buf, size_t len, size_t obs,
 204         const char *filename)
 205 {
 206         ssize_t n = full_write_or_warn(buf, len, filename);
 207         if (n < 0)
 208                 return 1;
 209         if ((size_t)n == obs)
 210                 G.out_full++;
 211         else if (n) /* > 0 */
 212                 G.out_part++;
 213 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 214         G.total_bytes += n;
 215 #endif
 216         return 0;
 217 }
 218
 219 #if ENABLE_LFS
 220 # define XATOU_SFX xatoull_sfx
 221 #else
 222 # define XATOU_SFX xatoul_sfx
 223 #endif
 224
 225 int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 226 int dd_main(int argc UNUSED_PARAM, char **argv)
 227 {
 228         static const char keywords[] ALIGN1 =
 229                 "bs\0""count\0""seek\0""skip\0""if\0""of\0"IF_FEATURE_DD_STATUS("status\0")
 230 #if ENABLE_FEATURE_DD_IBS_OBS
 231                 "ibs\0""obs\0""conv\0"
 232 #endif
 233                 ;
 234 #if ENABLE_FEATURE_DD_IBS_OBS
 235         static const char conv_words[] ALIGN1 =
 236                 "notrunc\0""sync\0""noerror\0""fsync\0""swab\0";
 237 #endif
 238 #if ENABLE_FEATURE_DD_STATUS
 239         static const char status_words[] ALIGN1 =
 240                 "none\0""noxfer\0";
 241 #endif
 242         enum {
 243                 OP_bs = 0,
 244                 OP_count,
 245                 OP_seek,
 246                 OP_skip,
 247                 OP_if,
 248                 OP_of,
 249                 IF_FEATURE_DD_STATUS(OP_status,)
 250 #if ENABLE_FEATURE_DD_IBS_OBS
 251                 OP_ibs,
 252                 OP_obs,
 253                 OP_conv,
 254                 /* Must be in the same order as FLAG_XXX! */
 255                 OP_conv_notrunc = 0,
 256                 OP_conv_sync,
 257                 OP_conv_noerror,
 258                 OP_conv_fsync,
 259                 OP_conv_swab,
 260         /* Unimplemented conv=XXX: */
 261         //nocreat       do not create the output file
 262         //excl          fail if the output file already exists
 263         //fdatasync     physically write output file data before finishing
 264         //lcase         change upper case to lower case
 265         //ucase         change lower case to upper case
 266         //block         pad newline-terminated records with spaces to cbs-size
 267         //unblock       replace trailing spaces in cbs-size records with newline
 268         //ascii         from EBCDIC to ASCII
 269         //ebcdic        from ASCII to EBCDIC
 270         //ibm           from ASCII to alternate EBCDIC
 271         /* Partially implemented: */
 272         //swab          swap every pair of input bytes: will abort on non-even reads
 273 #endif
 274         };
 275         smallint exitcode = EXIT_FAILURE;
 276         int i;
 277         size_t ibs = 512;
 278         char *ibuf;
 279 #if ENABLE_FEATURE_DD_IBS_OBS
 280         size_t obs = 512;
 281         char *obuf;
 282 #else
 283 # define obs  ibs
 284 # define obuf ibuf
 285 #endif
 286         /* These are all zeroed at once! */
 287         struct {
 288                 size_t oc;
 289                 ssize_t prev_read_size; /* for detecting swab failure */
 290                 off_t count;
 291                 off_t seek, skip;
 292                 const char *infile, *outfile;
 293         } Z;
 294 #define oc      (Z.oc     )
 295 #define prev_read_size (Z.prev_read_size)
 296 #define count   (Z.count  )
 297 #define seek    (Z.seek   )
 298 #define skip    (Z.skip   )
 299 #define infile  (Z.infile )
 300 #define outfile (Z.outfile)
 301
 302         memset(&Z, 0, sizeof(Z));
 303         INIT_G();
 304         //fflush_all(); - is this needed because of NOEXEC?
 305
 306         for (i = 1; argv[i]; i++) {
 307                 int what;
 308                 char *val;
 309                 char *arg = argv[i];
 310
 311 #if ENABLE_DESKTOP
 312                 /* "dd --". NB: coreutils 6.9 will complain if they see
 313                  * more than one of them. We wouldn't. */
 314                 if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
 315                         continue;
 316 #endif
 317                 val = strchr(arg, '=');
 318                 if (val == NULL)
 319                         bb_show_usage();
 320                 *val = '\0';
 321                 what = index_in_strings(keywords, arg);
 322                 if (what < 0)
 323                         bb_show_usage();
 324                 /* *val = '='; - to preserve ps listing? */
 325                 val++;
 326 #if ENABLE_FEATURE_DD_IBS_OBS
 327                 if (what == OP_ibs) {
 328                         /* Must fit into positive ssize_t */
 329                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 330                         /*continue;*/
 331                 }
 332                 if (what == OP_obs) {
 333                         obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 334                         /*continue;*/
 335                 }
 336                 if (what == OP_conv) {
 337                         while (1) {
 338                                 int n;
 339                                 /* find ',', replace them with NUL so we can use val for
 340                                  * index_in_strings() without copying.
 341                                  * We rely on val being non-null, else strchr would fault.
 342                                  */
 343                                 arg = strchr(val, ',');
 344                                 if (arg)
 345                                         *arg = '\0';
 346                                 n = index_in_strings(conv_words, val);
 347                                 if (n < 0)
 348                                         bb_error_msg_and_die(bb_msg_invalid_arg, val, "conv");
 349                                 G.flags |= (1 << n);
 350                                 if (!arg) /* no ',' left, so this was the last specifier */
 351                                         break;
 352                                 /* *arg = ','; - to preserve ps listing? */
 353                                 val = arg + 1; /* skip this keyword and ',' */
 354                         }
 355                         /*continue;*/
 356                 }
 357 #endif
 358                 if (what == OP_bs) {
 359                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 360                         obs = ibs;
 361                         /*continue;*/
 362                 }
 363                 /* These can be large: */
 364                 if (what == OP_count) {
 365                         G.flags |= FLAG_COUNT;
 366                         count = XATOU_SFX(val, dd_suffixes);
 367                         /*continue;*/
 368                 }
 369                 if (what == OP_seek) {
 370                         seek = XATOU_SFX(val, dd_suffixes);
 371                         /*continue;*/
 372                 }
 373                 if (what == OP_skip) {
 374                         skip = XATOU_SFX(val, dd_suffixes);
 375                         /*continue;*/
 376                 }
 377                 if (what == OP_if) {
 378                         infile = val;
 379                         /*continue;*/
 380                 }
 381                 if (what == OP_of) {
 382                         outfile = val;
 383                         /*continue;*/
 384                 }
 385 #if ENABLE_FEATURE_DD_STATUS
 386                 if (what == OP_status) {
 387                         int n;
 388                         n = index_in_strings(status_words, val);
 389                         if (n < 0)
 390                                 bb_error_msg_and_die(bb_msg_invalid_arg, val, "status");
 391                         G.flags |= FLAG_STATUS << n;
 392                         /*continue;*/
 393                 }
 394 #endif
 395         } /* end of "for (argv[i])" */
 396
 397 //XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
 398         ibuf = xmalloc(ibs);
 399         obuf = ibuf;
 400 #if ENABLE_FEATURE_DD_IBS_OBS
 401         if (ibs != obs) {
 402                 G.flags |= FLAG_TWOBUFS;
 403                 obuf = xmalloc(obs);
 404         }
 405 #endif
 406
 407 #if ENABLE_FEATURE_DD_SIGNAL_HANDLING
 408         signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
 409 #endif
 410 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 411         G.begin_time_us = monotonic_us();
 412 #endif
 413
 414         if (infile) {
 415                 xmove_fd(xopen(infile, O_RDONLY), ifd);
 416         } else {
 417                 infile = bb_msg_standard_input;
 418         }
 419         if (outfile) {
 420                 int oflag = O_WRONLY | O_CREAT;
 421
 422                 if (!seek && !(G.flags & FLAG_NOTRUNC))
 423                         oflag |= O_TRUNC;
 424
 425                 xmove_fd(xopen(outfile, oflag), ofd);
 426
 427                 if (seek && !(G.flags & FLAG_NOTRUNC)) {
 428                         if (ftruncate(ofd, seek * obs) < 0) {
 429                                 struct stat st;
 430
 431                                 if (fstat(ofd, &st) < 0
 432                                  || S_ISREG(st.st_mode)
 433                                  || S_ISDIR(st.st_mode)
 434                                 ) {
 435                                         goto die_outfile;
 436                                 }
 437                         }
 438                 }
 439         } else {
 440                 outfile = bb_msg_standard_output;
 441         }
 442         if (skip) {
 443                 if (lseek(ifd, skip * ibs, SEEK_CUR) < 0) {
 444                         do {
 445                                 ssize_t n = safe_read(ifd, ibuf, ibs);
 446                                 if (n < 0)
 447                                         goto die_infile;
 448                                 if (n == 0)
 449                                         break;
 450                         } while (--skip != 0);
 451                 }
 452         }
 453         if (seek) {
 454                 if (lseek(ofd, seek * obs, SEEK_CUR) < 0)
 455                         goto die_outfile;
 456         }
 457
 458         while (!(G.flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
 459                 ssize_t n;
 460
 461                 n = safe_read(ifd, ibuf, ibs);
 462                 if (n == 0)
 463                         break;
 464                 if (n < 0) {
 465                         /* "Bad block" */
 466                         if (!(G.flags & FLAG_NOERROR))
 467                                 goto die_infile;
 468                         bb_simple_perror_msg(infile);
 469                         /* GNU dd with conv=noerror skips over bad blocks */
 470                         xlseek(ifd, ibs, SEEK_CUR);
 471                         /* conv=noerror,sync writes NULs,
 472                          * conv=noerror just ignores input bad blocks */
 473                         n = 0;
 474                 }
 475                 if (G.flags & FLAG_SWAB) {
 476                         uint16_t *p16;
 477                         ssize_t n2;
 478
 479                         /* Our code allows only last read to be odd-sized */
 480                         if (prev_read_size & 1)
 481                                 bb_error_msg_and_die("can't swab %lu byte buffer",
 482                                                 (unsigned long)prev_read_size);
 483                         prev_read_size = n;
 484
 485                         /* If n is odd, last byte is not swapped:
 486                          *  echo -n "qwe" | dd conv=swab
 487                          * prints "wqe".
 488                          */
 489                         p16 = (void*) ibuf;
 490                         n2 = (n >> 1);
 491                         while (--n2 >= 0) {
 492                                 *p16 = bswap_16(*p16);
 493                                 p16++;
 494                         }
 495                 }
 496                 if ((size_t)n == ibs)
 497                         G.in_full++;
 498                 else {
 499                         G.in_part++;
 500                         if (G.flags & FLAG_SYNC) {
 501                                 memset(ibuf + n, 0, ibs - n);
 502                                 n = ibs;
 503                         }
 504                 }
 505                 if (G.flags & FLAG_TWOBUFS) {
 506                         char *tmp = ibuf;
 507                         while (n) {
 508                                 size_t d = obs - oc;
 509
 510                                 if (d > (size_t)n)
 511                                         d = n;
 512                                 memcpy(obuf + oc, tmp, d);
 513                                 n -= d;
 514                                 tmp += d;
 515                                 oc += d;
 516                                 if (oc == obs) {
 517                                         if (write_and_stats(obuf, obs, obs, outfile))
 518                                                 goto out_status;
 519                                         oc = 0;
 520                                 }
 521                         }
 522                 } else {
 523                         if (write_and_stats(ibuf, n, obs, outfile))
 524                                 goto out_status;
 525                 }
 526
 527                 if (G.flags & FLAG_FSYNC) {
 528                         if (fsync(ofd) < 0)
 529                                 goto die_outfile;
 530                 }
 531         }
 532
 533         if (ENABLE_FEATURE_DD_IBS_OBS && oc) {
 534                 if (write_and_stats(obuf, oc, obs, outfile))
 535                         goto out_status;
 536         }
 537         if (close(ifd) < 0) {
 538  die_infile:
 539                 bb_simple_perror_msg_and_die(infile);
 540         }
 541
 542         if (close(ofd) < 0) {
 543  die_outfile:
 544                 bb_simple_perror_msg_and_die(outfile);
 545         }
 546
 547         exitcode = EXIT_SUCCESS;
 548  out_status:
 549         if (!ENABLE_FEATURE_DD_STATUS || !(G.flags & FLAG_STATUS_NONE))
 550                 dd_output_status(0);
 551
 552         if (ENABLE_FEATURE_CLEAN_UP) {
 553                 free(obuf);
 554                 if (G.flags & FLAG_TWOBUFS)
 555                         free(ibuf);
 556         }
 557
 558         return exitcode;
 559 }