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 //usage:#define dd_trivial_usage
  12 //usage:       "[if=FILE] [of=FILE] " IF_FEATURE_DD_IBS_OBS("[ibs=N] [obs=N] ") "[bs=N] [count=N] [skip=N]\n"
  13 //usage:       "        [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync]")
  14 //usage:#define dd_full_usage "\n\n"
  15 //usage:       "Copy a file with converting and formatting\n"
  16 //usage:     "\n        if=FILE         Read from FILE instead of stdin"
  17 //usage:     "\n        of=FILE         Write to FILE instead of stdout"
  18 //usage:     "\n        bs=N            Read and write N bytes at a time"
  19 //usage:        IF_FEATURE_DD_IBS_OBS(
  20 //usage:     "\n        ibs=N           Read N bytes at a time"
  21 //usage:        )
  22 //usage:        IF_FEATURE_DD_IBS_OBS(
  23 //usage:     "\n        obs=N           Write N bytes at a time"
  24 //usage:        )
  25 //usage:     "\n        count=N         Copy only N input blocks"
  26 //usage:     "\n        skip=N          Skip N input blocks"
  27 //usage:     "\n        seek=N          Skip N output blocks"
  28 //usage:        IF_FEATURE_DD_IBS_OBS(
  29 //usage:     "\n        conv=notrunc    Don't truncate output file"
  30 //usage:     "\n        conv=noerror    Continue after read errors"
  31 //usage:     "\n        conv=sync       Pad blocks with zeros"
  32 //usage:     "\n        conv=fsync      Physically write data out before finishing"
  33 //usage:     "\n        conv=swab       Swap every pair of bytes"
  34 //usage:        )
  35 //usage:     "\n"
  36 //usage:     "\nN may be suffixed by c (1), w (2), b (512), kD (1000), k (1024), MD, M, GD, G"
  37 //usage:
  38 //usage:#define dd_example_usage
  39 //usage:       "$ dd if=/dev/zero of=/dev/ram1 bs=1M count=4\n"
  40 //usage:       "4+0 records in\n"
  41 //usage:       "4+0 records out\n"
  42
  43 #include "libbb.h"
  44
  45 /* This is a NOEXEC applet. Be very careful! */
  46
  47
  48 enum {
  49         ifd = STDIN_FILENO,
  50         ofd = STDOUT_FILENO,
  51 };
  52
  53 static const struct suffix_mult dd_suffixes[] = {
  54         { "c", 1 },
  55         { "w", 2 },
  56         { "b", 512 },
  57         { "kD", 1000 },
  58         { "k", 1024 },
  59         { "K", 1024 },  /* compat with coreutils dd */
  60         { "MD", 1000000 },
  61         { "M", 1048576 },
  62         { "GD", 1000000000 },
  63         { "G", 1073741824 },
  64         { "", 0 }
  65 };
  66
  67 struct globals {
  68         off_t out_full, out_part, in_full, in_part;
  69 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
  70         unsigned long long total_bytes;
  71         unsigned long long begin_time_us;
  72 #endif
  73 } FIX_ALIASING;
  74 #define G (*(struct globals*)&bb_common_bufsiz1)
  75 #define INIT_G() do { \
  76         /* we have to zero it out because of NOEXEC */ \
  77         memset(&G, 0, sizeof(G)); \
  78 } while (0)
  79
  80
  81 static void dd_output_status(int UNUSED_PARAM cur_signal)
  82 {
  83 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
  84         double seconds;
  85         unsigned long long bytes_sec;
  86         unsigned long long now_us = monotonic_us(); /* before fprintf */
  87 #endif
  88
  89         /* Deliberately using %u, not %d */
  90         fprintf(stderr, "%"OFF_FMT"u+%"OFF_FMT"u records in\n"
  91                         "%"OFF_FMT"u+%"OFF_FMT"u records out\n",
  92                         G.in_full, G.in_part,
  93                         G.out_full, G.out_part);
  94
  95 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
  96         fprintf(stderr, "%llu bytes (%sB) copied, ",
  97                         G.total_bytes,
  98                         /* show fractional digit, use suffixes */
  99                         make_human_readable_str(G.total_bytes, 1, 0)
 100         );
 101         /* Corner cases:
 102          * ./busybox dd </dev/null >/dev/null
 103          * ./busybox dd bs=1M count=2000 </dev/zero >/dev/null
 104          * (echo DONE) | ./busybox dd >/dev/null
 105          * (sleep 1; echo DONE) | ./busybox dd >/dev/null
 106          */
 107         seconds = (now_us - G.begin_time_us) / 1000000.0;
 108         bytes_sec = G.total_bytes / seconds;
 109         fprintf(stderr, "%f seconds, %sB/s\n",
 110                         seconds,
 111                         /* show fractional digit, use suffixes */
 112                         make_human_readable_str(bytes_sec, 1, 0)
 113         );
 114 #endif
 115 }
 116
 117 static ssize_t full_write_or_warn(const void *buf, size_t len,
 118         const char *const filename)
 119 {
 120         ssize_t n = full_write(ofd, buf, len);
 121         if (n < 0)
 122                 bb_perror_msg("writing '%s'", filename);
 123         return n;
 124 }
 125
 126 static bool write_and_stats(const void *buf, size_t len, size_t obs,
 127         const char *filename)
 128 {
 129         ssize_t n = full_write_or_warn(buf, len, filename);
 130         if (n < 0)
 131                 return 1;
 132         if ((size_t)n == obs)
 133                 G.out_full++;
 134         else if (n) /* > 0 */
 135                 G.out_part++;
 136 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 137         G.total_bytes += n;
 138 #endif
 139         return 0;
 140 }
 141
 142 #if ENABLE_LFS
 143 # define XATOU_SFX xatoull_sfx
 144 #else
 145 # define XATOU_SFX xatoul_sfx
 146 #endif
 147
 148 int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 149 int dd_main(int argc UNUSED_PARAM, char **argv)
 150 {
 151         enum {
 152                 /* Must be in the same order as OP_conv_XXX! */
 153                 /* (see "flags |= (1 << what)" below) */
 154                 FLAG_NOTRUNC = 1 << 0,
 155                 FLAG_SYNC    = 1 << 1,
 156                 FLAG_NOERROR = 1 << 2,
 157                 FLAG_FSYNC   = 1 << 3,
 158                 FLAG_SWAB    = 1 << 4,
 159                 /* end of conv flags */
 160                 FLAG_TWOBUFS = 1 << 5,
 161                 FLAG_COUNT   = 1 << 6,
 162         };
 163         static const char keywords[] ALIGN1 =
 164                 "bs\0""count\0""seek\0""skip\0""if\0""of\0"
 165 #if ENABLE_FEATURE_DD_IBS_OBS
 166                 "ibs\0""obs\0""conv\0"
 167 #endif
 168                 ;
 169 #if ENABLE_FEATURE_DD_IBS_OBS
 170         static const char conv_words[] ALIGN1 =
 171                 "notrunc\0""sync\0""noerror\0""fsync\0""swab\0";
 172 #endif
 173         enum {
 174                 OP_bs = 0,
 175                 OP_count,
 176                 OP_seek,
 177                 OP_skip,
 178                 OP_if,
 179                 OP_of,
 180 #if ENABLE_FEATURE_DD_IBS_OBS
 181                 OP_ibs,
 182                 OP_obs,
 183                 OP_conv,
 184                 /* Must be in the same order as FLAG_XXX! */
 185                 OP_conv_notrunc = 0,
 186                 OP_conv_sync,
 187                 OP_conv_noerror,
 188                 OP_conv_fsync,
 189                 OP_conv_swab,
 190         /* Unimplemented conv=XXX: */
 191         //nocreat       do not create the output file
 192         //excl          fail if the output file already exists
 193         //fdatasync     physically write output file data before finishing
 194         //lcase         change upper case to lower case
 195         //ucase         change lower case to upper case
 196         //block         pad newline-terminated records with spaces to cbs-size
 197         //unblock       replace trailing spaces in cbs-size records with newline
 198         //ascii         from EBCDIC to ASCII
 199         //ebcdic        from ASCII to EBCDIC
 200         //ibm           from ASCII to alternate EBCDIC
 201         /* Partially implemented: */
 202         //swab          swap every pair of input bytes: will abort on non-even reads
 203 #endif
 204         };
 205         int exitcode = EXIT_FAILURE;
 206         size_t ibs = 512, obs = 512;
 207         int i;
 208         char *ibuf, *obuf;
 209         /* And these are all zeroed at once! */
 210         struct {
 211                 int flags;
 212                 size_t oc;
 213                 off_t count;
 214                 off_t seek, skip;
 215                 const char *infile, *outfile;
 216         } Z;
 217 #define flags   (Z.flags  )
 218 #define oc      (Z.oc     )
 219 #define count   (Z.count  )
 220 #define seek    (Z.seek   )
 221 #define skip    (Z.skip   )
 222 #define infile  (Z.infile )
 223 #define outfile (Z.outfile)
 224
 225         memset(&Z, 0, sizeof(Z));
 226         INIT_G();
 227         //fflush_all(); - is this needed because of NOEXEC?
 228
 229         for (i = 1; argv[i]; i++) {
 230                 int what;
 231                 char *val;
 232                 char *arg = argv[i];
 233
 234 #if ENABLE_DESKTOP
 235                 /* "dd --". NB: coreutils 6.9 will complain if they see
 236                  * more than one of them. We wouldn't. */
 237                 if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
 238                         continue;
 239 #endif
 240                 val = strchr(arg, '=');
 241                 if (val == NULL)
 242                         bb_show_usage();
 243                 *val = '\0';
 244                 what = index_in_strings(keywords, arg);
 245                 if (what < 0)
 246                         bb_show_usage();
 247                 /* *val = '='; - to preserve ps listing? */
 248                 val++;
 249 #if ENABLE_FEATURE_DD_IBS_OBS
 250                 if (what == OP_ibs) {
 251                         /* Must fit into positive ssize_t */
 252                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 253                         /*continue;*/
 254                 }
 255                 if (what == OP_obs) {
 256                         obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 257                         /*continue;*/
 258                 }
 259                 if (what == OP_conv) {
 260                         while (1) {
 261                                 /* find ',', replace them with NUL so we can use val for
 262                                  * index_in_strings() without copying.
 263                                  * We rely on val being non-null, else strchr would fault.
 264                                  */
 265                                 arg = strchr(val, ',');
 266                                 if (arg)
 267                                         *arg = '\0';
 268                                 what = index_in_strings(conv_words, val);
 269                                 if (what < 0)
 270                                         bb_error_msg_and_die(bb_msg_invalid_arg, val, "conv");
 271                                 flags |= (1 << what);
 272                                 if (!arg) /* no ',' left, so this was the last specifier */
 273                                         break;
 274                                 /* *arg = ','; - to preserve ps listing? */
 275                                 val = arg + 1; /* skip this keyword and ',' */
 276                         }
 277                         continue; /* we trashed 'what', can't fall through */
 278                 }
 279 #endif
 280                 if (what == OP_bs) {
 281                         ibs = obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 282                         /*continue;*/
 283                 }
 284                 /* These can be large: */
 285                 if (what == OP_count) {
 286                         flags |= FLAG_COUNT;
 287                         count = XATOU_SFX(val, dd_suffixes);
 288                         /*continue;*/
 289                 }
 290                 if (what == OP_seek) {
 291                         seek = XATOU_SFX(val, dd_suffixes);
 292                         /*continue;*/
 293                 }
 294                 if (what == OP_skip) {
 295                         skip = XATOU_SFX(val, dd_suffixes);
 296                         /*continue;*/
 297                 }
 298                 if (what == OP_if) {
 299                         infile = val;
 300                         /*continue;*/
 301                 }
 302                 if (what == OP_of) {
 303                         outfile = val;
 304                         /*continue;*/
 305                 }
 306         } /* end of "for (argv[i])" */
 307
 308 //XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
 309         ibuf = obuf = xmalloc(ibs);
 310         if (ibs != obs) {
 311                 flags |= FLAG_TWOBUFS;
 312                 obuf = xmalloc(obs);
 313         }
 314
 315 #if ENABLE_FEATURE_DD_SIGNAL_HANDLING
 316         signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
 317 #endif
 318 #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
 319         G.begin_time_us = monotonic_us();
 320 #endif
 321
 322         if (infile != NULL)
 323                 xmove_fd(xopen(infile, O_RDONLY), ifd);
 324         else {
 325                 infile = bb_msg_standard_input;
 326         }
 327         if (outfile != NULL) {
 328                 int oflag = O_WRONLY | O_CREAT;
 329
 330                 if (!seek && !(flags & FLAG_NOTRUNC))
 331                         oflag |= O_TRUNC;
 332
 333                 xmove_fd(xopen(outfile, oflag), ofd);
 334
 335                 if (seek && !(flags & FLAG_NOTRUNC)) {
 336                         if (ftruncate(ofd, seek * obs) < 0) {
 337                                 struct stat st;
 338
 339                                 if (fstat(ofd, &st) < 0
 340                                  || S_ISREG(st.st_mode)
 341                                  || S_ISDIR(st.st_mode)
 342                                 ) {
 343                                         goto die_outfile;
 344                                 }
 345                         }
 346                 }
 347         } else {
 348                 outfile = bb_msg_standard_output;
 349         }
 350         if (skip) {
 351                 if (lseek(ifd, skip * ibs, SEEK_CUR) < 0) {
 352                         while (skip-- > 0) {
 353                                 ssize_t n = safe_read(ifd, ibuf, ibs);
 354                                 if (n < 0)
 355                                         goto die_infile;
 356                                 if (n == 0)
 357                                         break;
 358                         }
 359                 }
 360         }
 361         if (seek) {
 362                 if (lseek(ofd, seek * obs, SEEK_CUR) < 0)
 363                         goto die_outfile;
 364         }
 365
 366         while (!(flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
 367                 ssize_t n;
 368
 369                 n = safe_read(ifd, ibuf, ibs);
 370                 if (n == 0)
 371                         break;
 372                 if (n < 0) {
 373                         /* "Bad block" */
 374                         if (!(flags & FLAG_NOERROR))
 375                                 goto die_infile;
 376                         bb_simple_perror_msg(infile);
 377                         /* GNU dd with conv=noerror skips over bad blocks */
 378                         xlseek(ifd, ibs, SEEK_CUR);
 379                         /* conv=noerror,sync writes NULs,
 380                          * conv=noerror just ignores input bad blocks */
 381                         n = 0;
 382                 }
 383                 if (flags & FLAG_SWAB) {
 384                         /* If n is odd, last byte is not swapped:
 385                          *  echo -n "qwe" | dd conv=swab bs=1
 386                          * prints "wqe".
 387                          * The code does not handle correctly odd-sized reads
 388                          * in the *middle* of the input. FIXME.
 389                          */
 390                         uint16_t *p16 = (void*) ibuf;
 391                         uint16_t *end = (void*) (ibuf + (n & ~(ssize_t)1));
 392                         while (p16 < end) {
 393                                 *p16 = bswap_16(*p16);
 394                                 p16++;
 395                         }
 396                 }
 397                 if ((size_t)n == ibs)
 398                         G.in_full++;
 399                 else {
 400                         G.in_part++;
 401                         if (flags & FLAG_SYNC) {
 402                                 memset(ibuf + n, 0, ibs - n);
 403                                 n = ibs;
 404                         }
 405                 }
 406                 if (flags & FLAG_TWOBUFS) {
 407                         char *tmp = ibuf;
 408                         while (n) {
 409                                 size_t d = obs - oc;
 410
 411                                 if (d > (size_t)n)
 412                                         d = n;
 413                                 memcpy(obuf + oc, tmp, d);
 414                                 n -= d;
 415                                 tmp += d;
 416                                 oc += d;
 417                                 if (oc == obs) {
 418                                         if (write_and_stats(obuf, obs, obs, outfile))
 419                                                 goto out_status;
 420                                         oc = 0;
 421                                 }
 422                         }
 423                 } else if (write_and_stats(ibuf, n, obs, outfile))
 424                         goto out_status;
 425
 426                 if (flags & FLAG_FSYNC) {
 427                         if (fsync(ofd) < 0)
 428                                 goto die_outfile;
 429                 }
 430         }
 431
 432         if (ENABLE_FEATURE_DD_IBS_OBS && oc) {
 433                 ssize_t w = full_write_or_warn(obuf, oc, outfile);
 434                 if (w < 0) goto out_status;
 435                 if (w > 0) G.out_part++;
 436         }
 437         if (close(ifd) < 0) {
 438  die_infile:
 439                 bb_simple_perror_msg_and_die(infile);
 440         }
 441
 442         if (close(ofd) < 0) {
 443  die_outfile:
 444                 bb_simple_perror_msg_and_die(outfile);
 445         }
 446
 447         exitcode = EXIT_SUCCESS;
 448  out_status:
 449         dd_output_status(0);
 450
 451         if (ENABLE_FEATURE_CLEAN_UP) {
 452                 free(obuf);
 453                 if (flags & FLAG_TWOBUFS)
 454                         free(ibuf);
 455         }
 456
 457         return exitcode;
 458 }