coreutils/sort.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * SuS3 compliant sort implementation for busybox
   4  *
   5  * Copyright (C) 2004 by Rob Landley <rob@landley.net>
   6  *
   7  * MAINTAINER: Rob Landley <rob@landley.net>
   8  *
   9  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  10  *
  11  * See SuS3 sort standard at:
  12  * http://www.opengroup.org/onlinepubs/007904975/utilities/sort.html
  13  */
  14 //config:config SORT
  15 //config:       bool "sort (7.4 kb)"
  16 //config:       default y
  17 //config:       help
  18 //config:       sort is used to sort lines of text in specified files.
  19 //config:
  20 //config:config FEATURE_SORT_BIG
  21 //config:       bool "Full SuSv3 compliant sort (support -ktcbdfiozgM)"
  22 //config:       default y
  23 //config:       depends on SORT
  24 //config:       help
  25 //config:       Without this, sort only supports -r, -u, -s, and an integer version
  26 //config:       of -n. Selecting this adds sort keys, floating point support, and
  27 //config:       more. This adds a little over 3k to a nonstatic build on x86.
  28 //config:
  29 //config:       The SuSv3 sort standard is available at:
  30 //config:       http://www.opengroup.org/onlinepubs/007904975/utilities/sort.html
  31 //config:
  32 //config:config FEATURE_SORT_OPTIMIZE_MEMORY
  33 //config:       bool "Use less memory (but might be slower)"
  34 //config:       default n   # defaults to N since we are size-paranoid tribe
  35 //config:       depends on SORT
  36 //config:       help
  37 //config:       Attempt to use less memory (by storing only one copy
  38 //config:       of duplicated lines, and such). Useful if you work on huge files.
  39
  40 //applet:IF_SORT(APPLET_NOEXEC(sort, sort, BB_DIR_USR_BIN, BB_SUID_DROP, sort))
  41
  42 //kbuild:lib-$(CONFIG_SORT) += sort.o
  43
  44 //usage:#define sort_trivial_usage
  45 //usage:       "[-nru"
  46 //usage:        IF_FEATURE_SORT_BIG("gMcszbdfiokt] [-o FILE] [-k start[.offset][opts][,end[.offset][opts]] [-t CHAR")
  47 //usage:       "] [FILE]..."
  48 //usage:#define sort_full_usage "\n\n"
  49 //usage:       "Sort lines of text\n"
  50 //usage:        IF_FEATURE_SORT_BIG(
  51 //usage:     "\n        -o FILE Output to FILE"
  52 //usage:     "\n        -c      Check whether input is sorted"
  53 //usage:     "\n        -b      Ignore leading blanks"
  54 //usage:     "\n        -f      Ignore case"
  55 //usage:     "\n        -i      Ignore unprintable characters"
  56 //usage:     "\n        -d      Dictionary order (blank or alphanumeric only)"
  57 //usage:        )
  58 //-h, --human-numeric-sort: compare human readable numbers (e.g., 2K 1G)
  59 //usage:     "\n        -n      Sort numbers"
  60 //usage:        IF_FEATURE_SORT_BIG(
  61 //usage:     "\n        -g      General numerical sort"
  62 //usage:     "\n        -M      Sort month"
  63 //usage:     "\n        -t CHAR Field separator"
  64 //usage:     "\n        -k N[,M] Sort by Nth field"
  65 //usage:        )
  66 //usage:     "\n        -r      Reverse sort order"
  67 //usage:     "\n        -s      Stable (don't sort ties alphabetically)"
  68 //usage:     "\n        -u      Suppress duplicate lines"
  69 //usage:        IF_FEATURE_SORT_BIG(
  70 //usage:     "\n        -z      Lines are terminated by NUL, not newline"
  71 ///////:     "\n        -m      Ignored for GNU compatibility"
  72 ///////:     "\n        -S BUFSZ Ignored for GNU compatibility"
  73 ///////:     "\n        -T TMPDIR Ignored for GNU compatibility"
  74 //usage:        )
  75 //usage:
  76 //usage:#define sort_example_usage
  77 //usage:       "$ echo -e \"e\\nf\\nb\\nd\\nc\\na\" | sort\n"
  78 //usage:       "a\n"
  79 //usage:       "b\n"
  80 //usage:       "c\n"
  81 //usage:       "d\n"
  82 //usage:       "e\n"
  83 //usage:       "f\n"
  84 //usage:        IF_FEATURE_SORT_BIG(
  85 //usage:                "$ echo -e \"c 3\\nb 2\\nd 2\" | $SORT -k 2,2n -k 1,1r\n"
  86 //usage:                "d 2\n"
  87 //usage:                "b 2\n"
  88 //usage:                "c 3\n"
  89 //usage:        )
  90 //usage:       ""
  91
  92 #include "libbb.h"
  93
  94 /* These are sort types */
  95 enum {
  96         FLAG_n  = 1,            /* Numeric sort */
  97         FLAG_g  = 2,            /* Sort using strtod() */
  98         FLAG_M  = 4,            /* Sort date */
  99 /* ucsz apply to root level only, not keys.  b at root level implies bb */
 100         FLAG_u  = 8,            /* Unique */
 101         FLAG_c  = 0x10,         /* Check: no output, exit(!ordered) */
 102         FLAG_s  = 0x20,         /* Stable sort, no ascii fallback at end */
 103         FLAG_z  = 0x40,         /* Input and output is NUL terminated, not \n */
 104 /* These can be applied to search keys, the previous four can't */
 105         FLAG_b  = 0x80,         /* Ignore leading blanks */
 106         FLAG_r  = 0x100,        /* Reverse */
 107         FLAG_d  = 0x200,        /* Ignore !(isalnum()|isspace()) */
 108         FLAG_f  = 0x400,        /* Force uppercase */
 109         FLAG_i  = 0x800,        /* Ignore !isprint() */
 110         FLAG_m  = 0x1000,       /* ignored: merge already sorted files; do not sort */
 111         FLAG_S  = 0x2000,       /* ignored: -S, --buffer-size=SIZE */
 112         FLAG_T  = 0x4000,       /* ignored: -T, --temporary-directory=DIR */
 113         FLAG_o  = 0x8000,
 114         FLAG_k  = 0x10000,
 115         FLAG_t  = 0x20000,
 116         FLAG_bb = 0x80000000,   /* Ignore trailing blanks  */
 117         FLAG_no_tie_break = 0x40000000,
 118 };
 119
 120 static const char sort_opt_str[] ALIGN1 = "^"
 121                         "ngMucszbrdfimS:T:o:k:*t:"
 122                         "\0" "o--o:t--t"/*-t, -o: at most one of each*/;
 123 /*
 124  * OPT_STR must not be string literal, needs to have stable address:
 125  * code uses "strchr(OPT_STR,c) - OPT_STR" idiom.
 126  */
 127 #define OPT_STR (sort_opt_str + 1)
 128
 129 #if ENABLE_FEATURE_SORT_BIG
 130 static char key_separator;
 131
 132 static struct sort_key {
 133         struct sort_key *next_key;  /* linked list */
 134         unsigned range[4];          /* start word, start char, end word, end char */
 135         unsigned flags;
 136 } *key_list;
 137
 138
 139 /* This is a NOEXEC applet. Be very careful! */
 140
 141
 142 static char *get_key(char *str, struct sort_key *key, int flags)
 143 {
 144         int start = start; /* for compiler */
 145         int end;
 146         int len, j;
 147         unsigned i;
 148
 149         /* Special case whole string, so we don't have to make a copy */
 150         if (key->range[0] == 1 && !key->range[1] && !key->range[2] && !key->range[3]
 151          && !(flags & (FLAG_b | FLAG_d | FLAG_f | FLAG_i | FLAG_bb))
 152         ) {
 153                 return str;
 154         }
 155
 156         /* Find start of key on first pass, end on second pass */
 157         len = strlen(str);
 158         for (j = 0; j < 2; j++) {
 159                 if (!key->range[2*j])
 160                         end = len;
 161                 /* Loop through fields */
 162                 else {
 163                         unsigned char ch = 0;
 164
 165                         end = 0;
 166                         for (i = 1; i < key->range[2*j] + j; i++) {
 167                                 if (key_separator) {
 168                                         /* Skip body of key and separator */
 169                                         while ((ch = str[end]) != '\0') {
 170                                                         end++;
 171                                                 if (ch == key_separator)
 172                                                         break;
 173                                         }
 174                                 } else {
 175                                         /* Skip leading blanks */
 176                                         while (isspace(str[end]))
 177                                                 end++;
 178                                         /* Skip body of key */
 179                                         while (str[end] != '\0') {
 180                                                 if (isspace(str[end]))
 181                                                         break;
 182                                                 end++;
 183                                         }
 184                                 }
 185                         }
 186                         /* Remove last delim: "abc:def:" => "abc:def" */
 187                         if (j && ch) {
 188                                 //if (str[end-1] != key_separator)
 189                                 //  bb_error_msg(_and_die("BUG! "
 190                                 //  "str[start:%d,end:%d]:'%.*s'",
 191                                 //  start, end, (int)(end-start), &str[start]);
 192                                 end--;
 193                         }
 194                 }
 195                 if (!j) start = end;
 196         }
 197         /* Strip leading whitespace if necessary */
 198         if (flags & FLAG_b)
 199                 /* not using skip_whitespace() for speed */
 200                 while (isspace(str[start])) start++;
 201         /* Strip trailing whitespace if necessary */
 202         if (flags & FLAG_bb)
 203                 while (end > start && isspace(str[end-1])) end--;
 204         /* -kSTART,N.ENDCHAR: honor ENDCHAR (1-based) */
 205         if (key->range[3]) {
 206                 end = key->range[3];
 207                 if (end > len) end = len;
 208         }
 209         /* -kN.STARTCHAR[,...]: honor STARTCHAR (1-based) */
 210         if (key->range[1]) {
 211                 start += key->range[1] - 1;
 212                 if (start > len) start = len;
 213         }
 214         /* Make the copy */
 215         if (end < start)
 216                 end = start;
 217         str = xstrndup(str+start, end-start);
 218         /* Handle -d */
 219         if (flags & FLAG_d) {
 220                 for (start = end = 0; str[end]; end++)
 221                         if (isspace(str[end]) || isalnum(str[end]))
 222                                 str[start++] = str[end];
 223                 str[start] = '\0';
 224         }
 225         /* Handle -i */
 226         if (flags & FLAG_i) {
 227                 for (start = end = 0; str[end]; end++)
 228                         if (isprint_asciionly(str[end]))
 229                                 str[start++] = str[end];
 230                 str[start] = '\0';
 231         }
 232         /* Handle -f */
 233         if (flags & FLAG_f)
 234                 for (i = 0; str[i]; i++)
 235                         str[i] = toupper(str[i]);
 236
 237         return str;
 238 }
 239
 240 static struct sort_key *add_key(void)
 241 {
 242         struct sort_key **pkey = &key_list;
 243         while (*pkey)
 244                 pkey = &((*pkey)->next_key);
 245         return *pkey = xzalloc(sizeof(struct sort_key));
 246 }
 247
 248 #define GET_LINE(fp) \
 249         ((option_mask32 & FLAG_z) \
 250         ? bb_get_chunk_from_file(fp, NULL) \
 251         : xmalloc_fgetline(fp))
 252 #else
 253 #define GET_LINE(fp) xmalloc_fgetline(fp)
 254 #endif
 255
 256 /* Iterate through keys list and perform comparisons */
 257 static int compare_keys(const void *xarg, const void *yarg)
 258 {
 259         int flags = option_mask32, retval = 0;
 260         char *x, *y;
 261
 262 #if ENABLE_FEATURE_SORT_BIG
 263         struct sort_key *key;
 264
 265         for (key = key_list; !retval && key; key = key->next_key) {
 266                 flags = key->flags ? key->flags : option_mask32;
 267                 /* Chop out and modify key chunks, handling -dfib */
 268                 x = get_key(*(char **)xarg, key, flags);
 269                 y = get_key(*(char **)yarg, key, flags);
 270 #else
 271         /* This curly bracket serves no purpose but to match the nesting
 272          * level of the for () loop we're not using */
 273         {
 274                 x = *(char **)xarg;
 275                 y = *(char **)yarg;
 276 #endif
 277                 /* Perform actual comparison */
 278                 switch (flags & (FLAG_n | FLAG_M | FLAG_g)) {
 279                 default:
 280                         bb_error_msg_and_die("unknown sort type");
 281                         break;
 282                 /* Ascii sort */
 283                 case 0:
 284 #if ENABLE_LOCALE_SUPPORT
 285                         retval = strcoll(x, y);
 286 #else
 287                         retval = strcmp(x, y);
 288 #endif
 289                         break;
 290 #if ENABLE_FEATURE_SORT_BIG
 291                 case FLAG_g: {
 292                         char *xx, *yy;
 293                         double dx = strtod(x, &xx);
 294                         double dy = strtod(y, &yy);
 295                         /* not numbers < NaN < -infinity < numbers < +infinity) */
 296                         if (x == xx)
 297                                 retval = (y == yy ? 0 : -1);
 298                         else if (y == yy)
 299                                 retval = 1;
 300                         /* Check for isnan */
 301                         else if (dx != dx)
 302                                 retval = (dy != dy) ? 0 : -1;
 303                         else if (dy != dy)
 304                                 retval = 1;
 305                         /* Check for infinity.  Could underflow, but it avoids libm. */
 306                         else if (1.0 / dx == 0.0) {
 307                                 if (dx < 0)
 308                                         retval = (1.0 / dy == 0.0 && dy < 0) ? 0 : -1;
 309                                 else
 310                                         retval = (1.0 / dy == 0.0 && dy > 0) ? 0 : 1;
 311                         } else if (1.0 / dy == 0.0)
 312                                 retval = (dy < 0) ? 1 : -1;
 313                         else
 314                                 retval = (dx > dy) ? 1 : ((dx < dy) ? -1 : 0);
 315                         break;
 316                 }
 317                 case FLAG_M: {
 318                         struct tm thyme;
 319                         int dx;
 320                         char *xx, *yy;
 321
 322                         xx = strptime(x, "%b", &thyme);
 323                         dx = thyme.tm_mon;
 324                         yy = strptime(y, "%b", &thyme);
 325                         if (!xx)
 326                                 retval = (!yy) ? 0 : -1;
 327                         else if (!yy)
 328                                 retval = 1;
 329                         else
 330                                 retval = dx - thyme.tm_mon;
 331                         break;
 332                 }
 333                 /* Full floating point version of -n */
 334                 case FLAG_n: {
 335                         double dx = atof(x);
 336                         double dy = atof(y);
 337                         retval = (dx > dy) ? 1 : ((dx < dy) ? -1 : 0);
 338                         break;
 339                 }
 340                 } /* switch */
 341                 /* Free key copies. */
 342                 if (x != *(char **)xarg) free(x);
 343                 if (y != *(char **)yarg) free(y);
 344                 /* if (retval) break; - done by for () anyway */
 345 #else
 346                 /* Integer version of -n for tiny systems */
 347                 case FLAG_n:
 348                         retval = atoi(x) - atoi(y);
 349                         break;
 350                 } /* switch */
 351 #endif
 352         } /* for */
 353
 354         if (retval == 0) {
 355                 /* So far lines are "the same" */
 356
 357                 if (option_mask32 & FLAG_s) {
 358                         /* "Stable sort": later line is "greater than",
 359                          * IOW: do not allow qsort() to swap equal lines.
 360                          */
 361                         uint32_t *p32;
 362                         uint32_t x32, y32;
 363                         char *line;
 364                         unsigned len;
 365
 366                         line = *(char**)xarg;
 367                         len = (strlen(line) + 4) & (~3u);
 368                         p32 = (void*)(line + len);
 369                         x32 = *p32;
 370                         line = *(char**)yarg;
 371                         len = (strlen(line) + 4) & (~3u);
 372                         p32 = (void*)(line + len);
 373                         y32 = *p32;
 374
 375                         /* If x > y, 1, else -1 */
 376                         retval = (x32 > y32) * 2 - 1;
 377                 } else
 378                 if (!(option_mask32 & FLAG_no_tie_break)) {
 379                         /* fallback sort */
 380                         flags = option_mask32;
 381                         retval = strcmp(*(char **)xarg, *(char **)yarg);
 382                 }
 383         }
 384
 385         if (flags & FLAG_r)
 386                 return -retval;
 387
 388         return retval;
 389 }
 390
 391 #if ENABLE_FEATURE_SORT_BIG
 392 static unsigned str2u(char **str)
 393 {
 394         unsigned long lu;
 395         if (!isdigit((*str)[0]))
 396                 bb_error_msg_and_die("bad field specification");
 397         lu = strtoul(*str, str, 10);
 398         if ((sizeof(long) > sizeof(int) && lu > INT_MAX) || !lu)
 399                 bb_error_msg_and_die("bad field specification");
 400         return lu;
 401 }
 402 #endif
 403
 404 int sort_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 405 int sort_main(int argc UNUSED_PARAM, char **argv)
 406 {
 407         char **lines;
 408         char *str_ignored, *str_o, *str_t;
 409         llist_t *lst_k = NULL;
 410         int i;
 411         int linecount;
 412         unsigned opts;
 413 #if ENABLE_FEATURE_SORT_OPTIMIZE_MEMORY
 414         bool can_drop_dups;
 415         size_t prev_len = 0;
 416         /* Postpone optimizing if the input is small, < 16k lines:
 417          * even just free()ing duplicate lines takes time.
 418          */
 419         size_t count_to_optimize_dups = 0x3fff;
 420 #endif
 421
 422         xfunc_error_retval = 2;
 423
 424         /* Parse command line options */
 425         opts = getopt32(argv,
 426                         sort_opt_str,
 427                         &str_ignored, &str_ignored, &str_o, &lst_k, &str_t
 428         );
 429 #if ENABLE_FEATURE_SORT_OPTIMIZE_MEMORY
 430         /* Can drop dups only if -u but no "complicating" options,
 431          * IOW: if we do a full line compares. Safe options:
 432          * -o FILE Output to FILE
 433          * -z      Lines are terminated by NUL, not newline
 434          * -r      Reverse sort order
 435          * -s      Stable (don't sort ties alphabetically)
 436          * Not sure about these:
 437          * -b      Ignore leading blanks
 438          * -f      Ignore case
 439          * -i      Ignore unprintable characters
 440          * -d      Dictionary order (blank or alphanumeric only)
 441          * -n      Sort numbers
 442          * -g      General numerical sort
 443          * -M      Sort month
 444          */
 445         can_drop_dups = ((opts & ~(FLAG_o|FLAG_z|FLAG_r|FLAG_s)) == FLAG_u);
 446         /* Stable sort needs every line to be uniquely allocated,
 447          * disable optimization to reuse strings:
 448          */
 449         if (opts & FLAG_s)
 450                 count_to_optimize_dups = (size_t)-1L;
 451 #endif
 452         /* global b strips leading and trailing spaces */
 453         if (opts & FLAG_b)
 454                 option_mask32 |= FLAG_bb;
 455 #if ENABLE_FEATURE_SORT_BIG
 456         if (opts & FLAG_t) {
 457                 if (!str_t[0] || str_t[1])
 458                         bb_error_msg_and_die("bad -t parameter");
 459                 key_separator = str_t[0];
 460         }
 461         /* note: below this point we use option_mask32, not opts,
 462          * since that reduces register pressure and makes code smaller */
 463
 464         /* Parse sort key */
 465         while (lst_k) {
 466                 enum {
 467                         FLAG_allowed_for_k =
 468                                 FLAG_n | /* Numeric sort */
 469                                 FLAG_g | /* Sort using strtod() */
 470                                 FLAG_M | /* Sort date */
 471                                 FLAG_b | /* Ignore leading blanks */
 472                                 FLAG_r | /* Reverse */
 473                                 FLAG_d | /* Ignore !(isalnum()|isspace()) */
 474                                 FLAG_f | /* Force uppercase */
 475                                 FLAG_i | /* Ignore !isprint() */
 476                         0
 477                 };
 478                 struct sort_key *key = add_key();
 479                 char *str_k = llist_pop(&lst_k);
 480
 481                 i = 0; /* i==0 before comma, 1 after (-k3,6) */
 482                 while (*str_k) {
 483                         /* Start of range */
 484                         /* Cannot use bb_strtou - suffix can be a letter */
 485                         key->range[2*i] = str2u(&str_k);
 486                         if (*str_k == '.') {
 487                                 str_k++;
 488                                 key->range[2*i+1] = str2u(&str_k);
 489                         }
 490                         while (*str_k) {
 491                                 int flag;
 492                                 const char *idx;
 493
 494                                 if (*str_k == ',' && !i++) {
 495                                         str_k++;
 496                                         break;
 497                                 } /* no else needed: fall through to syntax error
 498                                         because comma isn't in OPT_STR */
 499                                 idx = strchr(OPT_STR, *str_k);
 500                                 if (!idx)
 501                                         bb_error_msg_and_die("unknown key option");
 502                                 flag = 1 << (idx - OPT_STR);
 503                                 if (flag & ~FLAG_allowed_for_k)
 504                                         bb_error_msg_and_die("unknown sort type");
 505                                 /* b after ',' means strip _trailing_ space */
 506                                 if (i && flag == FLAG_b)
 507                                         flag = FLAG_bb;
 508                                 key->flags |= flag;
 509                                 str_k++;
 510                         }
 511                 }
 512         }
 513 #endif
 514
 515         /* Open input files and read data */
 516         argv += optind;
 517         if (!*argv)
 518                 *--argv = (char*)"-";
 519         linecount = 0;
 520         lines = NULL;
 521         do {
 522                 /* coreutils 6.9 compat: abort on first open error,
 523                  * do not continue to next file: */
 524                 FILE *fp = xfopen_stdin(*argv);
 525                 for (;;) {
 526                         char *line = GET_LINE(fp);
 527                         if (!line)
 528                                 break;
 529
 530 #if ENABLE_FEATURE_SORT_OPTIMIZE_MEMORY
 531                         if (count_to_optimize_dups != 0)
 532                                 count_to_optimize_dups--;
 533                         if (count_to_optimize_dups == 0) {
 534                                 size_t len;
 535                                 char *new_line;
 536                                 char first = *line;
 537
 538                                 /* On kernel/linux/arch/ *.[ch] files,
 539                                  * this reduces memory usage by 6%.
 540                                  *  yes | head -99999999 | sort
 541                                  * goes down from 1900Mb to 380 Mb.
 542                                  */
 543                                 if (first == '\0' || first == '\n') {
 544                                         len = !(first == '\0');
 545                                         new_line = (char*)"\n" + 1 - len;
 546                                         goto replace;
 547                                 }
 548                                 len = strlen(line);
 549                                 if (len <= prev_len) {
 550                                         new_line = lines[linecount-1] + (prev_len - len);
 551                                         if (strcmp(line, new_line) == 0) {
 552                                                 if (can_drop_dups && prev_len == len) {
 553                                                         free(line);
 554                                                         continue;
 555                                                 }
 556  replace:
 557                                                 free(line);
 558                                                 line = new_line;
 559                                         }
 560                                 }
 561                                 prev_len = len;
 562                         }
 563 #endif
 564                         lines = xrealloc_vector(lines, 6, linecount);
 565                         lines[linecount++] = line;
 566                 }
 567                 fclose_if_not_stdin(fp);
 568         } while (*++argv);
 569
 570 #if ENABLE_FEATURE_SORT_BIG
 571         /* If no key, perform alphabetic sort */
 572         if (!key_list)
 573                 add_key()->range[0] = 1;
 574         /* Handle -c */
 575         if (option_mask32 & FLAG_c) {
 576                 int j = (option_mask32 & FLAG_u) ? -1 : 0;
 577                 for (i = 1; i < linecount; i++) {
 578                         if (compare_keys(&lines[i-1], &lines[i]) > j) {
 579                                 fprintf(stderr, "Check line %u\n", i);
 580                                 return EXIT_FAILURE;
 581                         }
 582                 }
 583                 return EXIT_SUCCESS;
 584         }
 585 #else
 586 //TODO: lighter version which only drops total dups if can_drop_dups == true
 587 #endif
 588
 589         /* For stable sort, store original line position beyond terminating NUL */
 590         if (option_mask32 & FLAG_s) {
 591                 for (i = 0; i < linecount; i++) {
 592                         uint32_t *p32;
 593                         char *line;
 594                         unsigned len;
 595
 596                         line = lines[i];
 597                         len = (strlen(line) + 4) & (~3u);
 598                         lines[i] = line = xrealloc(line, len + 4);
 599                         p32 = (void*)(line + len);
 600                         *p32 = i;
 601                 }
 602                 /*option_mask32 |= FLAG_no_tie_break;*/
 603                 /* ^^^redundant: if FLAG_s, compare_keys() does no tie break */
 604         }
 605
 606         /* Perform the actual sort */
 607         qsort(lines, linecount, sizeof(lines[0]), compare_keys);
 608
 609         /* Handle -u */
 610         if (option_mask32 & FLAG_u) {
 611                 int j = 0;
 612                 /* coreutils 6.3 drop lines for which only key is the same
 613                  * -- disabling last-resort compare, or else compare_keys()
 614                  * will be the same only for completely identical lines.
 615                  */
 616                 option_mask32 |= FLAG_no_tie_break;
 617                 for (i = 1; i < linecount; i++) {
 618                         if (compare_keys(&lines[j], &lines[i]) == 0)
 619                                 free(lines[i]);
 620                         else
 621                                 lines[++j] = lines[i];
 622                 }
 623                 if (linecount)
 624                         linecount = j+1;
 625         }
 626
 627         /* Print it */
 628 #if ENABLE_FEATURE_SORT_BIG
 629         /* Open output file _after_ we read all input ones */
 630         if (option_mask32 & FLAG_o)
 631                 xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), STDOUT_FILENO);
 632 #endif
 633         {
 634                 int ch = (option_mask32 & FLAG_z) ? '\0' : '\n';
 635                 for (i = 0; i < linecount; i++)
 636                         printf("%s%c", lines[i], ch);
 637         }
 638
 639         fflush_stdout_and_exit(EXIT_SUCCESS);
 640 }