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 tarball for details.
   9  */
  10
  11 #include <signal.h>  /* For FEATURE_DD_SIGNAL_HANDLING */
  12 #include "libbb.h"
  13
  14 /* This is a NOEXEC applet. Be very careful! */
  15
  16
  17 enum {
  18         ifd = STDIN_FILENO,
  19         ofd = STDOUT_FILENO,
  20 };
  21
  22 static const struct suffix_mult dd_suffixes[] = {
  23         { "c", 1 },
  24         { "w", 2 },
  25         { "b", 512 },
  26         { "kD", 1000 },
  27         { "k", 1024 },
  28         { "K", 1024 },  /* compat with coreutils dd */
  29         { "MD", 1000000 },
  30         { "M", 1048576 },
  31         { "GD", 1000000000 },
  32         { "G", 1073741824 },
  33         { }
  34 };
  35
  36 struct globals {
  37         off_t out_full, out_part, in_full, in_part;
  38 };
  39 #define G (*(struct globals*)&bb_common_bufsiz1)
  40 /* We have to zero it out because of NOEXEC */
  41 #define INIT_G() memset(&G, 0, sizeof(G))
  42
  43
  44 static void dd_output_status(int ATTRIBUTE_UNUSED cur_signal)
  45 {
  46         /* Deliberately using %u, not %d */
  47         fprintf(stderr, "%"OFF_FMT"u+%"OFF_FMT"u records in\n"
  48                         "%"OFF_FMT"u+%"OFF_FMT"u records out\n",
  49                         G.in_full, G.in_part,
  50                         G.out_full, G.out_part);
  51 }
  52
  53 static ssize_t full_write_or_warn(const void *buf, size_t len,
  54         const char *const filename)
  55 {
  56         ssize_t n = full_write(ofd, buf, len);
  57         if (n < 0)
  58                 bb_perror_msg("writing '%s'", filename);
  59         return n;
  60 }
  61
  62 static bool write_and_stats(const void *buf, size_t len, size_t obs,
  63         const char *filename)
  64 {
  65         ssize_t n = full_write_or_warn(buf, len, filename);
  66         if (n < 0)
  67                 return 1;
  68         if (n == obs)
  69                 G.out_full++;
  70         else if (n) /* > 0 */
  71                 G.out_part++;
  72         return 0;
  73 }
  74
  75 #if ENABLE_LFS
  76 #define XATOU_SFX xatoull_sfx
  77 #else
  78 #define XATOU_SFX xatoul_sfx
  79 #endif
  80
  81 int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  82 int dd_main(int argc ATTRIBUTE_UNUSED, char **argv)
  83 {
  84         enum {
  85                 /* Must be in the same order as OP_conv_XXX! */
  86                 /* (see "flags |= (1 << what)" below) */
  87                 FLAG_NOTRUNC = 1 << 0,
  88                 FLAG_SYNC    = 1 << 1,
  89                 FLAG_NOERROR = 1 << 2,
  90                 FLAG_FSYNC   = 1 << 3,
  91                 /* end of conv flags */
  92                 FLAG_TWOBUFS = 1 << 4,
  93                 FLAG_COUNT   = 1 << 5,
  94         };
  95         static const char keywords[] ALIGN1 =
  96                 "bs\0""count\0""seek\0""skip\0""if\0""of\0"
  97 #if ENABLE_FEATURE_DD_IBS_OBS
  98                 "ibs\0""obs\0""conv\0"
  99 #endif
 100                 ;
 101 #if ENABLE_FEATURE_DD_IBS_OBS
 102         static const char conv_words[] ALIGN1 =
 103                 "notrunc\0""sync\0""noerror\0""fsync\0";
 104 #endif
 105         enum {
 106                 OP_bs = 0,
 107                 OP_count,
 108                 OP_seek,
 109                 OP_skip,
 110                 OP_if,
 111                 OP_of,
 112 #if ENABLE_FEATURE_DD_IBS_OBS
 113                 OP_ibs,
 114                 OP_obs,
 115                 OP_conv,
 116                 /* Must be in the same order as FLAG_XXX! */
 117                 OP_conv_notrunc = 0,
 118                 OP_conv_sync,
 119                 OP_conv_noerror,
 120                 OP_conv_fsync,
 121         /* Unimplemented conv=XXX: */
 122         //nocreat       do not create the output file
 123         //excl          fail if the output file already exists
 124         //fdatasync     physically write output file data before finishing
 125         //swab          swap every pair of input bytes
 126         //lcase         change upper case to lower case
 127         //ucase         change lower case to upper case
 128         //block         pad newline-terminated records with spaces to cbs-size
 129         //unblock       replace trailing spaces in cbs-size records with newline
 130         //ascii         from EBCDIC to ASCII
 131         //ebcdic        from ASCII to EBCDIC
 132         //ibm           from ASCII to alternate EBCDIC
 133 #endif
 134         };
 135         int exitcode = EXIT_FAILURE;
 136         size_t ibs = 512, obs = 512;
 137         ssize_t n, w;
 138         char *ibuf, *obuf;
 139         /* And these are all zeroed at once! */
 140         struct {
 141                 int flags;
 142                 size_t oc;
 143                 off_t count;
 144                 off_t seek, skip;
 145                 const char *infile, *outfile;
 146         } Z;
 147 #define flags   (Z.flags  )
 148 #define oc      (Z.oc     )
 149 #define count   (Z.count  )
 150 #define seek    (Z.seek   )
 151 #define skip    (Z.skip   )
 152 #define infile  (Z.infile )
 153 #define outfile (Z.outfile)
 154
 155         memset(&Z, 0, sizeof(Z));
 156         INIT_G();
 157         //fflush(NULL); - is this needed because of NOEXEC?
 158
 159 #if ENABLE_FEATURE_DD_SIGNAL_HANDLING
 160         signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
 161 #endif
 162
 163         for (n = 1; argv[n]; n++) {
 164                 int what;
 165                 char *val;
 166                 char *arg = argv[n];
 167
 168 #if ENABLE_DESKTOP
 169                 /* "dd --". NB: coreutils 6.9 will complain if they see
 170                  * more than one of them. We wouldn't. */
 171                 if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
 172                         continue;
 173 #endif
 174                 val = strchr(arg, '=');
 175                 if (val == NULL)
 176                         bb_show_usage();
 177                 *val = '\0';
 178                 what = index_in_strings(keywords, arg);
 179                 if (what < 0)
 180                         bb_show_usage();
 181                 /* *val = '='; - to preserve ps listing? */
 182                 val++;
 183 #if ENABLE_FEATURE_DD_IBS_OBS
 184                 if (what == OP_ibs) {
 185                         /* Must fit into positive ssize_t */
 186                         ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 187                         /*continue;*/
 188                 }
 189                 if (what == OP_obs) {
 190                         obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 191                         /*continue;*/
 192                 }
 193                 if (what == OP_conv) {
 194                         while (1) {
 195                                 /* find ',', replace them with NUL so we can use val for
 196                                  * index_in_strings() without copying.
 197                                  * We rely on val being non-null, else strchr would fault.
 198                                  */
 199                                 arg = strchr(val, ',');
 200                                 if (arg)
 201                                         *arg = '\0';
 202                                 what = index_in_strings(conv_words, val);
 203                                 if (what < 0)
 204                                         bb_error_msg_and_die(bb_msg_invalid_arg, val, "conv");
 205                                 flags |= (1 << what);
 206                                 if (!arg) /* no ',' left, so this was the last specifier */
 207                                         break;
 208                                 /* *arg = ','; - to preserve ps listing? */
 209                                 val = arg + 1; /* skip this keyword and ',' */
 210                         }
 211                         continue; /* we trashed 'what', can't fall through */
 212                 }
 213 #endif
 214                 if (what == OP_bs) {
 215                         ibs = obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
 216                         /*continue;*/
 217                 }
 218                 /* These can be large: */
 219                 if (what == OP_count) {
 220                         flags |= FLAG_COUNT;
 221                         count = XATOU_SFX(val, dd_suffixes);
 222                         /*continue;*/
 223                 }
 224                 if (what == OP_seek) {
 225                         seek = XATOU_SFX(val, dd_suffixes);
 226                         /*continue;*/
 227                 }
 228                 if (what == OP_skip) {
 229                         skip = XATOU_SFX(val, dd_suffixes);
 230                         /*continue;*/
 231                 }
 232                 if (what == OP_if) {
 233                         infile = val;
 234                         /*continue;*/
 235                 }
 236                 if (what == OP_of) {
 237                         outfile = val;
 238                         /*continue;*/
 239                 }
 240         } /* end of "for (argv[n])" */
 241
 242 //XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
 243         ibuf = obuf = xmalloc(ibs);
 244         if (ibs != obs) {
 245                 flags |= FLAG_TWOBUFS;
 246                 obuf = xmalloc(obs);
 247         }
 248         if (infile != NULL)
 249                 xmove_fd(xopen(infile, O_RDONLY), ifd);
 250         else {
 251                 infile = bb_msg_standard_input;
 252         }
 253         if (outfile != NULL) {
 254                 int oflag = O_WRONLY | O_CREAT;
 255
 256                 if (!seek && !(flags & FLAG_NOTRUNC))
 257                         oflag |= O_TRUNC;
 258
 259                 xmove_fd(xopen(outfile, oflag), ofd);
 260
 261                 if (seek && !(flags & FLAG_NOTRUNC)) {
 262                         if (ftruncate(ofd, seek * obs) < 0) {
 263                                 struct stat st;
 264
 265                                 if (fstat(ofd, &st) < 0 || S_ISREG(st.st_mode) ||
 266                                                 S_ISDIR(st.st_mode))
 267                                         goto die_outfile;
 268                         }
 269                 }
 270         } else {
 271                 outfile = bb_msg_standard_output;
 272         }
 273         if (skip) {
 274                 if (lseek(ifd, skip * ibs, SEEK_CUR) < 0) {
 275                         while (skip-- > 0) {
 276                                 n = safe_read(ifd, ibuf, ibs);
 277                                 if (n < 0)
 278                                         goto die_infile;
 279                                 if (n == 0)
 280                                         break;
 281                         }
 282                 }
 283         }
 284         if (seek) {
 285                 if (lseek(ofd, seek * obs, SEEK_CUR) < 0)
 286                         goto die_outfile;
 287         }
 288
 289         while (!(flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
 290                 if (flags & FLAG_NOERROR) /* Pre-zero the buffer if conv=noerror */
 291                         memset(ibuf, 0, ibs);
 292                 n = safe_read(ifd, ibuf, ibs);
 293                 if (n == 0)
 294                         break;
 295                 if (n < 0) {
 296                         if (!(flags & FLAG_NOERROR))
 297                                 goto die_infile;
 298                         n = ibs;
 299                         bb_simple_perror_msg(infile);
 300                 }
 301                 if ((size_t)n == ibs)
 302                         G.in_full++;
 303                 else {
 304                         G.in_part++;
 305                         if (flags & FLAG_SYNC) {
 306                                 memset(ibuf + n, '\0', ibs - n);
 307                                 n = ibs;
 308                         }
 309                 }
 310                 if (flags & FLAG_TWOBUFS) {
 311                         char *tmp = ibuf;
 312                         while (n) {
 313                                 size_t d = obs - oc;
 314
 315                                 if (d > n)
 316                                         d = n;
 317                                 memcpy(obuf + oc, tmp, d);
 318                                 n -= d;
 319                                 tmp += d;
 320                                 oc += d;
 321                                 if (oc == obs) {
 322                                         if (write_and_stats(obuf, obs, obs, outfile))
 323                                                 goto out_status;
 324                                         oc = 0;
 325                                 }
 326                         }
 327                 } else if (write_and_stats(ibuf, n, obs, outfile))
 328                         goto out_status;
 329
 330                 if (flags & FLAG_FSYNC) {
 331                         if (fsync(ofd) < 0)
 332                                 goto die_outfile;
 333                 }
 334         }
 335
 336         if (ENABLE_FEATURE_DD_IBS_OBS && oc) {
 337                 w = full_write_or_warn(obuf, oc, outfile);
 338                 if (w < 0) goto out_status;
 339                 if (w > 0) G.out_part++;
 340         }
 341         if (close(ifd) < 0) {
 342  die_infile:
 343                 bb_simple_perror_msg_and_die(infile);
 344         }
 345
 346         if (close(ofd) < 0) {
 347  die_outfile:
 348                 bb_simple_perror_msg_and_die(outfile);
 349         }
 350
 351         exitcode = EXIT_SUCCESS;
 352  out_status:
 353         dd_output_status(0);
 354
 355         return exitcode;
 356 }