coreutils/dd.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini dd implementation for busybox
   4  *
   5  * Copyright (C) 2000,2001  Matt Kraai
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9 //config:config DD
  10 //config:       bool "dd"
  11 //config:       default y
  12 //config:       help
  13 //config:         dd copies a file (from standard input to standard output,
  14 //config:         by default) using specific input and output blocksizes,
  15 //config:         while optionally performing conversions on it.
  16 //config:
  17 //config:config FEATURE_DD_SIGNAL_HANDLING
  18 //config:       bool "Enable signal handling for status reporting"
  19 //config:       default y
  20 //config:       depends on DD
  21 //config:       help
  22 //config:         Sending a SIGUSR1 signal to a running `dd' process makes it
  23 //config:         print to standard error the number of records read and written
  24 //config:         so far, then to resume copying.
  25 //config:
  26 //config:         $ dd if=/dev/zero of=/dev/null &
  27 //config:         $ pid=$!; kill -USR1 $pid; sleep 1; kill $pid
  28 //config:         10899206+0 records in
  29 //config:         10899206+0 records out
  30 //config:
  31 //config:config FEATURE_DD_THIRD_STATUS_LINE
  32 //config:       bool "Enable the third status line upon signal"
  33 //config:       default y
  34 //config:       depends on DD && FEATURE_DD_SIGNAL_HANDLING
  35 //config:       help
  36 //config:         Displays a coreutils-like third status line with transferred bytes,
  37 //config:         elapsed time and speed.
  38 //config:
  39 //config:config FEATURE_DD_IBS_OBS
  40 //config:       bool "Enable ibs, obs and conv options"
  41 //config:       default y
  42 //config:       depends on DD
  43 //config:       help
  44 //config:         Enable support for writing a certain number of bytes in and out,
  45 //config:         at a time, and performing conversions on the data stream.
  46 //config:
  47 //config:config FEATURE_DD_STATUS
  48 //config:       bool "Enable status display options"
  49 //config:       default y
  50 //config:       depends on DD
  51 //config:       help
  52 //config:         Enable support for status=noxfer/none option.
  53
  54 //applet:IF_DD(APPLET_NOEXEC(dd, dd, BB_DIR_BIN, BB_SUID_DROP, dd))
  55
  56 //kbuild:lib-$(CONFIG_DD) += dd.o
  57
  58 //usage:#define dd_trivial_usage
  59 //usage:       "[if=FILE] [of=FILE] " IF_FEATURE_DD_IBS_OBS("[ibs=N] [obs=N] ") "[bs=N] [count=N] [skip=N]\n"
  60 //usage:       "        [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync] [iflag=skip_bytes]")
  61 //usage:#define dd_full_usage "\n\n"
  62 //usage:       "Copy a file with converting and formatting\n"
  63 //usage:     "\n        if=FILE         Read from FILE instead of stdin"
  64 //usage:     "\n        of=FILE         Write to FILE instead of stdout"
  65 //usage:     "\n        bs=N            Read and write N bytes at a time"
  66 //usage:        IF_FEATURE_DD_IBS_OBS(
  67 //usage:     "\n        ibs=N           Read N bytes at a time"
  68 //usage:        )
  69 //usage:        IF_FEATURE_DD_IBS_OBS(
  70 //usage:     "\n        obs=N           Write N bytes at a time"
  71 //usage:        )
  72 //usage:     "\n        count=N         Copy only N input blocks"
  73 //usage:     "\n        skip=N          Skip N input blocks"
  74 //usage:     "\n        seek=N          Skip N output blocks"
  75 //usage:        IF_FEATURE_DD_IBS_OBS(
  76 //usage:     "\n        conv=notrunc    Don't truncate output file"
  77 //usage:     "\n        conv=noerror    Continue after read errors"
  78 //usage:     "\n        conv=sync       Pad blocks with zeros"
  79 //usage:     "\n        conv=fsync      Physically write data out before finishing"
  80 //usage:     "\n        conv=swab       Swap every pair of bytes"
  81 //usage:     "\n        iflag=skip_bytes        skip=N is in bytes"
  82 //usage:        )
  83 //usage:        IF_FEATURE_DD_STATUS(
  84 //usage:     "\n        status=noxfer   Suppress rate output"
  85 //usage:     "\n        status=none     Suppress all output"
  86 //usage:        )
  87 //usage:     "\n"
  88 //usage:     "\nN may be suffixed by c (1), w (2), b (512), kB (1000), k (1024), MB, M, GB, G"
  89 //usage:
  90 //usage:#define dd_example_usage
  91 //usage:       "$ dd if=/dev/zero of=/dev/ram1 bs=1M count=4\n"
  92 //usage:       "4+0 records in\n"
  93 //usage:       "4+0 records out\n"
  94
  95 #include "libbb.h"
  96 #include "common_bufsiz.h"
  97
  98 /* This is a NOEXEC applet. Be very careful! */
  99
 100
 101 enum {
 102         ifd = STDIN_FILENO,
 103         ofd = STDOUT_FILENO,
 104 };
 105
 106 struct globals {
 107         off_t out_full, out_part, in_full, in_part;
 108 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 109         unsigned long long total_bytes;
 110         unsigned long long begin_time_us;
 111 #endif
 112         int flags;
 113 } FIX_ALIASING;
 114 #define G (*(struct globals*)bb_common_bufsiz1)
 115 #define INIT_G() do { \
 116         setup_common_bufsiz(); \
 117         /* we have to zero it out because of NOEXEC */ \
 118         memset(&G, 0, sizeof(G)); \
 119 } while (0)
 120
 121 enum {
 122         /* Must be in the same order as OP_conv_XXX! */
 123         /* (see "flags |= (1 << what)" below) */
 124         FLAG_NOTRUNC = (1 << 0) * ENABLE_FEATURE_DD_IBS_OBS,
 125         FLAG_SYNC    = (1 << 1) * ENABLE_FEATURE_DD_IBS_OBS,
 126         FLAG_NOERROR = (1 << 2) * ENABLE_FEATURE_DD_IBS_OBS,
 127         FLAG_FSYNC   = (1 << 3) * ENABLE_FEATURE_DD_IBS_OBS,
 128         FLAG_SWAB    = (1 << 4) * ENABLE_FEATURE_DD_IBS_OBS,
 129         /* end of conv flags */
 130         /* start of input flags */
 131         FLAG_IFLAG_SHIFT = 5,
 132         FLAG_SKIP_BYTES = (1 << 5) * ENABLE_FEATURE_DD_IBS_OBS,
 133         /* end of input flags */
 134         FLAG_TWOBUFS = (1 << 6) * ENABLE_FEATURE_DD_IBS_OBS,
 135         FLAG_COUNT   = 1 << 7,
 136         FLAG_STATUS  = 1 << 8,
 137         FLAG_STATUS_NONE = 1 << 9,
 138         FLAG_STATUS_NOXFER = 1 << 10,
 139 };
 140
 141 static void dd_output_status(int UNUSED_PARAM cur_signal)
 142 {
 143 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 144         double seconds;
 145         unsigned long long bytes_sec;
 146         unsigned long long now_us = monotonic_us(); /* before fprintf */
 147 #endif
 148
 149         /* Deliberately using %u, not %d */
 150         fprintf(stderr, "%"OFF_FMT"u+%"OFF_FMT"u records in\n"
 151                         "%"OFF_FMT"u+%"OFF_FMT"u records out\n",
 152                         G.in_full, G.in_part,
 153                         G.out_full, G.out_part);
 154
 155 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 156 # if ENABLE_FEATURE_DD_STATUS
 157         if (G.flags & FLAG_STATUS_NOXFER) /* status=noxfer active? */
 158                 return;
 159         //TODO: should status=none make dd stop reacting to USR1 entirely?
 160         //So far we react to it (we print the stats),
 161         //status=none only suppresses final, non-USR1 generated status message.
 162 # endif
 163         fprintf(stderr, "%llu bytes (%sB) copied, ",
 164                         G.total_bytes,
 165                         /* show fractional digit, use suffixes */
 166                         make_human_readable_str(G.total_bytes, 1, 0)
 167         );
 168         /* Corner cases:
 169          * ./busybox dd </dev/null >/dev/null
 170          * ./busybox dd bs=1M count=2000 </dev/zero >/dev/null
 171          * (echo DONE) | ./busybox dd >/dev/null
 172          * (sleep 1; echo DONE) | ./busybox dd >/dev/null
 173          */
 174         seconds = (now_us - G.begin_time_us) / 1000000.0;
 175         bytes_sec = G.total_bytes / seconds;
 176         fprintf(stderr, "%f seconds, %sB/s\n",
 177                         seconds,
 178                         /* show fractional digit, use suffixes */
 179                         make_human_readable_str(bytes_sec, 1, 0)
 180         );
 181 #endif
 182 }
 183
 184 static ssize_t full_write_or_warn(const void *buf, size_t len,
 185         const char *const filename)
 186 {
 187         ssize_t n = full_write(ofd, buf, len);
 188         if (n < 0)
 189                 bb_perror_msg("writing '%s'", filename);
 190         return n;
 191 }
 192
 193 static bool write_and_stats(const void *buf, size_t len, size_t obs,
 194         const char *filename)
 195 {
 196         ssize_t n = full_write_or_warn(buf, len, filename);
 197         if (n < 0)
 198                 return 1;
 199         if ((size_t)n == obs)
 200                 G.out_full++;
 201         else if (n) /* > 0 */
 202                 G.out_part++;
 203 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 204         G.total_bytes += n;
 205 #endif
 206         return 0;
 207 }
 208
 209 #if ENABLE_LFS
 210 # define XATOU_SFX xatoull_sfx
 211 #else
 212 # define XATOU_SFX xatoul_sfx
 213 #endif
 214
 215 #if ENABLE_FEATURE_DD_IBS_OBS
 216 static int parse_comma_flags(char *val, const char *words, const char *error_in)
 217 {
 218         int flags = 0;
 219         while (1) {
 220                 int n;
 221                 char *arg;
 222                 /* find ',', replace them with NUL so we can use val for
 223                  * index_in_strings() without copying.
 224                  * We rely on val being non-null, else strchr would fault.
 225                  */
 226                 arg = strchr(val, ',');
 227                 if (arg)
 228                         *arg = '\0';
 229                 n = index_in_strings(words, val);
 230                 if (n < 0)
 231                         bb_error_msg_and_die(bb_msg_invalid_arg_to, val, error_in);
 232                 flags |= (1 << n);
 233                 if (!arg) /* no ',' left, so this was the last specifier */
 234                         break;
 235                 *arg = ','; /* to preserve ps listing */
 236                 val = arg + 1; /* skip this keyword and ',' */
 237         }
 238         return flags;
 239 }
 240 #endif
 241
 242 int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 243 int dd_main(int argc UNUSED_PARAM, char **argv)
 244 {
 245         static const char keywords[] ALIGN1 =
 246                 "bs\0""count\0""seek\0""skip\0""if\0""of\0"IF_FEATURE_DD_STATUS("status\0")
 247 #if ENABLE_FEATURE_DD_IBS_OBS
 248                 "ibs\0""obs\0""conv\0""iflag\0"
 249 #endif
 250                 ;
 251 #if ENABLE_FEATURE_DD_IBS_OBS
 252         static const char conv_words[] ALIGN1 =
 253                 "notrunc\0""sync\0""noerror\0""fsync\0""swab\0";
 254         static const char iflag_words[] ALIGN1 =
 255                 "skip_bytes\0";
 256 #endif
 257 #if ENABLE_FEATURE_DD_STATUS
 258         static const char status_words[] ALIGN1 =
 259                 "none\0""noxfer\0";
 260 #endif
 261         enum {
 262                 OP_bs = 0,
 263                 OP_count,
 264                 OP_seek,
 265                 OP_skip,
 266                 OP_if,
 267                 OP_of,
 268                 IF_FEATURE_DD_STATUS(OP_status,)
 269 #if ENABLE_FEATURE_DD_IBS_OBS
 270                 OP_ibs,
 271                 OP_obs,
 272                 OP_conv,
 273                 OP_iflag,
 274                 /* Must be in the same order as FLAG_XXX! */
 275                 OP_conv_notrunc = 0,
 276                 OP_conv_sync,
 277                 OP_conv_noerror,
 278                 OP_conv_fsync,
 279                 OP_conv_swab,
 280         /* Unimplemented conv=XXX: */
 281         //nocreat       do not create the output file
 282         //excl          fail if the output file already exists
 283         //fdatasync     physically write output file data before finishing
 284         //lcase         change upper case to lower case
 285         //ucase         change lower case to upper case
 286         //block         pad newline-terminated records with spaces to cbs-size
 287         //unblock       replace trailing spaces in cbs-size records with newline
 288         //ascii         from EBCDIC to ASCII
 289         //ebcdic        from ASCII to EBCDIC
 290         //ibm           from ASCII to alternate EBCDIC
 291         /* Partially implemented: */
 292         //swab          swap every pair of input bytes: will abort on non-even reads
 293                 OP_iflag_skip_bytes,
 294 #endif
 295         };
 296         smallint exitcode = EXIT_FAILURE;
 297         int i;
 298         size_t ibs = 512;
 299         char *ibuf;
 300 #if ENABLE_FEATURE_DD_IBS_OBS
 301         size_t obs = 512;
 302         char *obuf;
 303 #else
 304 # define obs  ibs
 305 # define obuf ibuf
 306 #endif
 307         /* These are all zeroed at once! */
 308         struct {
 309                 size_t oc;
 310                 ssize_t prev_read_size; /* for detecting swab failure */
 311                 off_t count;
 312                 off_t seek, skip;
 313                 const char *infile, *outfile;
 314         } Z;
 315 #define oc      (Z.oc     )
 316 #define prev_read_size (Z.prev_read_size)
 317 #define count   (Z.count  )
 318 #define seek    (Z.seek   )
 319 #define skip    (Z.skip   )
 320 #define infile  (Z.infile )
 321 #define outfile (Z.outfile)
 322
 323         memset(&Z, 0, sizeof(Z));
 324         INIT_G();
 325         //fflush_all(); - is this needed because of NOEXEC?
 326
 327         for (i = 1; argv[i]; i++) {
 328                 int what;
 329                 char *val;
 330                 char *arg = argv[i];
 331
 332 #if ENABLE_DESKTOP
 333                 /* "dd --". NB: coreutils 6.9 will complain if they see
 334                  * more than one of them. We wouldn't. */
 335                 if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
 336                         continue;
 337 #endif
 338                 val = strchr(arg, '=');
 339                 if (val == NULL)
 340                         bb_show_usage();
 341                 *val = '\0';
 342                 what = index_in_strings(keywords, arg);
 343                 if (what < 0)
 344                         bb_show_usage();
 345                 /* *val = '='; - to preserve ps listing? */
 346                 val++;
 347 #if ENABLE_FEATURE_DD_IBS_OBS
 348                 if (what == OP_ibs) {
 349                         /* Must fit into positive ssize_t */
 350                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 351                         /*continue;*/
 352                 }
 353                 if (what == OP_obs) {
 354                         obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 355                         /*continue;*/
 356                 }
 357                 if (what == OP_conv) {
 358                         G.flags |= parse_comma_flags(val, conv_words, "conv");
 359                         /*continue;*/
 360                 }
 361                 if (what == OP_iflag) {
 362                         G.flags |= parse_comma_flags(val, iflag_words, "iflag") << FLAG_IFLAG_SHIFT;
 363                         /*continue;*/
 364                 }
 365 #endif
 366                 if (what == OP_bs) {
 367                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
 368                         obs = ibs;
 369                         /*continue;*/
 370                 }
 371                 /* These can be large: */
 372                 if (what == OP_count) {
 373                         G.flags |= FLAG_COUNT;
 374                         count = XATOU_SFX(val, cwbkMG_suffixes);
 375                         /*continue;*/
 376                 }
 377                 if (what == OP_seek) {
 378                         seek = XATOU_SFX(val, cwbkMG_suffixes);
 379                         /*continue;*/
 380                 }
 381                 if (what == OP_skip) {
 382                         skip = XATOU_SFX(val, cwbkMG_suffixes);
 383                         /*continue;*/
 384                 }
 385                 if (what == OP_if) {
 386                         infile = val;
 387                         /*continue;*/
 388                 }
 389                 if (what == OP_of) {
 390                         outfile = val;
 391                         /*continue;*/
 392                 }
 393 #if ENABLE_FEATURE_DD_STATUS
 394                 if (what == OP_status) {
 395                         int n;
 396                         n = index_in_strings(status_words, val);
 397                         if (n < 0)
 398                                 bb_error_msg_and_die(bb_msg_invalid_arg_to, val, "status");
 399                         G.flags |= FLAG_STATUS << n;
 400                         /*continue;*/
 401                 }
 402 #endif
 403         } /* end of "for (argv[i])" */
 404
 405 //XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
 406         ibuf = xmalloc(ibs);
 407         obuf = ibuf;
 408 #if ENABLE_FEATURE_DD_IBS_OBS
 409         if (ibs != obs) {
 410                 G.flags |= FLAG_TWOBUFS;
 411                 obuf = xmalloc(obs);
 412         }
 413 #endif
 414
 415 #if ENABLE_FEATURE_DD_SIGNAL_HANDLING
 416         signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
 417 #endif
 418 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 419         G.begin_time_us = monotonic_us();
 420 #endif
 421
 422         if (infile) {
 423                 xmove_fd(xopen(infile, O_RDONLY), ifd);
 424         } else {
 425                 infile = bb_msg_standard_input;
 426         }
 427         if (outfile) {
 428                 int oflag = O_WRONLY | O_CREAT;
 429
 430                 if (!seek && !(G.flags & FLAG_NOTRUNC))
 431                         oflag |= O_TRUNC;
 432
 433                 xmove_fd(xopen(outfile, oflag), ofd);
 434
 435                 if (seek && !(G.flags & FLAG_NOTRUNC)) {
 436                         if (ftruncate(ofd, seek * obs) < 0) {
 437                                 struct stat st;
 438
 439                                 if (fstat(ofd, &st) < 0
 440                                  || S_ISREG(st.st_mode)
 441                                  || S_ISDIR(st.st_mode)
 442                                 ) {
 443                                         goto die_outfile;
 444                                 }
 445                         }
 446                 }
 447         } else {
 448                 outfile = bb_msg_standard_output;
 449         }
 450         if (skip) {
 451                 size_t blocksz = (G.flags & FLAG_SKIP_BYTES) ? 1 : ibs;
 452                 if (lseek(ifd, skip * blocksz, SEEK_CUR) < 0) {
 453                         do {
 454                                 ssize_t n = safe_read(ifd, ibuf, blocksz);
 455                                 if (n < 0)
 456                                         goto die_infile;
 457                                 if (n == 0)
 458                                         break;
 459                         } while (--skip != 0);
 460                 }
 461         }
 462         if (seek) {
 463                 if (lseek(ofd, seek * obs, SEEK_CUR) < 0)
 464                         goto die_outfile;
 465         }
 466
 467         while (!(G.flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
 468                 ssize_t n;
 469
 470                 n = safe_read(ifd, ibuf, ibs);
 471                 if (n == 0)
 472                         break;
 473                 if (n < 0) {
 474                         /* "Bad block" */
 475                         if (!(G.flags & FLAG_NOERROR))
 476                                 goto die_infile;
 477                         bb_simple_perror_msg(infile);
 478                         /* GNU dd with conv=noerror skips over bad blocks */
 479                         xlseek(ifd, ibs, SEEK_CUR);
 480                         /* conv=noerror,sync writes NULs,
 481                          * conv=noerror just ignores input bad blocks */
 482                         n = 0;
 483                 }
 484                 if (G.flags & FLAG_SWAB) {
 485                         uint16_t *p16;
 486                         ssize_t n2;
 487
 488                         /* Our code allows only last read to be odd-sized */
 489                         if (prev_read_size & 1)
 490                                 bb_error_msg_and_die("can't swab %lu byte buffer",
 491                                                 (unsigned long)prev_read_size);
 492                         prev_read_size = n;
 493
 494                         /* If n is odd, last byte is not swapped:
 495                          *  echo -n "qwe" | dd conv=swab
 496                          * prints "wqe".
 497                          */
 498                         p16 = (void*) ibuf;
 499                         n2 = (n >> 1);
 500                         while (--n2 >= 0) {
 501                                 *p16 = bswap_16(*p16);
 502                                 p16++;
 503                         }
 504                 }
 505                 if ((size_t)n == ibs)
 506                         G.in_full++;
 507                 else {
 508                         G.in_part++;
 509                         if (G.flags & FLAG_SYNC) {
 510                                 memset(ibuf + n, 0, ibs - n);
 511                                 n = ibs;
 512                         }
 513                 }
 514                 if (G.flags & FLAG_TWOBUFS) {
 515                         char *tmp = ibuf;
 516                         while (n) {
 517                                 size_t d = obs - oc;
 518
 519                                 if (d > (size_t)n)
 520                                         d = n;
 521                                 memcpy(obuf + oc, tmp, d);
 522                                 n -= d;
 523                                 tmp += d;
 524                                 oc += d;
 525                                 if (oc == obs) {
 526                                         if (write_and_stats(obuf, obs, obs, outfile))
 527                                                 goto out_status;
 528                                         oc = 0;
 529                                 }
 530                         }
 531                 } else {
 532                         if (write_and_stats(ibuf, n, obs, outfile))
 533                                 goto out_status;
 534                 }
 535         }
 536
 537         if (G.flags & FLAG_FSYNC) {
 538                 if (fsync(ofd) < 0)
 539                         goto die_outfile;
 540         }
 541
 542         if (ENABLE_FEATURE_DD_IBS_OBS && oc) {
 543                 if (write_and_stats(obuf, oc, obs, outfile))
 544                         goto out_status;
 545         }
 546         if (close(ifd) < 0) {
 547  die_infile:
 548                 bb_simple_perror_msg_and_die(infile);
 549         }
 550
 551         if (close(ofd) < 0) {
 552  die_outfile:
 553                 bb_simple_perror_msg_and_die(outfile);
 554         }
 555
 556         exitcode = EXIT_SUCCESS;
 557  out_status:
 558         if (!ENABLE_FEATURE_DD_STATUS || !(G.flags & FLAG_STATUS_NONE))
 559                 dd_output_status(0);
 560
 561         if (ENABLE_FEATURE_CLEAN_UP) {
 562                 free(obuf);
 563                 if (G.flags & FLAG_TWOBUFS)
 564                         free(ibuf);
 565         }
 566
 567         return exitcode;
 568 }