usr.bin/sed/process.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1992 Diomidis Spinellis.
   5  * Copyright (c) 1992, 1993, 1994
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * This code is derived from software contributed to Berkeley by
   9  * Diomidis Spinellis of Imperial College, University of London.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD$");
  38
  39 #ifndef lint
  40 static const char sccsid[] = "@(#)process.c     8.6 (Berkeley) 4/20/94";
  41 #endif
  42
  43 #include <sys/types.h>
  44 #include <sys/stat.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/uio.h>
  47
  48 #include <ctype.h>
  49 #include <err.h>
  50 #include <errno.h>
  51 #include <fcntl.h>
  52 #include <limits.h>
  53 #include <regex.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <unistd.h>
  58 #include <wchar.h>
  59 #include <wctype.h>
  60
  61 #include "defs.h"
  62 #include "extern.h"
  63
  64 static SPACE HS, PS, SS, YS;
  65 #define pd              PS.deleted
  66 #define ps              PS.space
  67 #define psl             PS.len
  68 #define psanl           PS.append_newline
  69 #define hs              HS.space
  70 #define hsl             HS.len
  71
  72 static inline int        applies(struct s_command *);
  73 static void              do_tr(struct s_tr *);
  74 static void              flush_appends(void);
  75 static void              lputs(char *, size_t);
  76 static int               regexec_e(regex_t *, const char *, int, int, size_t,
  77                              size_t);
  78 static void              regsub(SPACE *, char *, char *);
  79 static int               substitute(struct s_command *);
  80
  81 struct s_appends *appends;      /* Array of pointers to strings to append. */
  82 static unsigned int appendx;    /* Index into appends array. */
  83 unsigned int appendnum;         /* Size of appends array. */
  84
  85 static int lastaddr;            /* Set by applies if last address of a range. */
  86 static int sdone;               /* If any substitutes since last line input. */
  87                                 /* Iov structure for 'w' commands. */
  88 static regex_t *defpreg;
  89 size_t maxnsub;
  90 regmatch_t *match;
  91
  92 #define OUT() do {                                                      \
  93         fwrite(ps, 1, psl, outfile);                                    \
  94         if (psanl) fputc('\n', outfile);                                \
  95 } while (0)
  96
  97 void
  98 process(void)
  99 {
 100         struct s_command *cp;
 101         SPACE tspace;
 102         size_t oldpsl;
 103         char *p;
 104         int oldpsanl;
 105
 106         p = NULL;
 107         oldpsanl = oldpsl = 0;
 108
 109         for (linenum = 0; mf_fgets(&PS, REPLACE);) {
 110                 pd = 0;
 111 top:
 112                 cp = prog;
 113 redirect:
 114                 while (cp != NULL) {
 115                         if (!applies(cp)) {
 116                                 cp = cp->next;
 117                                 continue;
 118                         }
 119                         switch (cp->code) {
 120                         case '{':
 121                                 cp = cp->u.c;
 122                                 goto redirect;
 123                         case 'a':
 124                                 if (appendx >= appendnum)
 125                                         if ((appends = realloc(appends,
 126                                             sizeof(struct s_appends) *
 127                                             (appendnum *= 2))) == NULL)
 128                                                 err(1, "realloc");
 129                                 appends[appendx].type = AP_STRING;
 130                                 appends[appendx].s = cp->t;
 131                                 appends[appendx].len = strlen(cp->t);
 132                                 appendx++;
 133                                 break;
 134                         case 'b':
 135                                 cp = cp->u.c;
 136                                 goto redirect;
 137                         case 'c':
 138                                 pd = 1;
 139                                 psl = 0;
 140                                 if (cp->a2 == NULL || lastaddr || lastline())
 141                                         (void)fprintf(outfile, "%s", cp->t);
 142                                 break;
 143                         case 'd':
 144                                 pd = 1;
 145                                 goto new;
 146                         case 'D':
 147                                 if (pd)
 148                                         goto new;
 149                                 if (psl == 0 ||
 150                                     (p = memchr(ps, '\n', psl)) == NULL) {
 151                                         pd = 1;
 152                                         goto new;
 153                                 } else {
 154                                         psl -= (p + 1) - ps;
 155                                         memmove(ps, p + 1, psl);
 156                                         goto top;
 157                                 }
 158                         case 'g':
 159                                 cspace(&PS, hs, hsl, REPLACE);
 160                                 break;
 161                         case 'G':
 162                                 cspace(&PS, "\n", 1, APPEND);
 163                                 cspace(&PS, hs, hsl, APPEND);
 164                                 break;
 165                         case 'h':
 166                                 cspace(&HS, ps, psl, REPLACE);
 167                                 break;
 168                         case 'H':
 169                                 cspace(&HS, "\n", 1, APPEND);
 170                                 cspace(&HS, ps, psl, APPEND);
 171                                 break;
 172                         case 'i':
 173                                 (void)fprintf(outfile, "%s", cp->t);
 174                                 break;
 175                         case 'l':
 176                                 lputs(ps, psl);
 177                                 break;
 178                         case 'n':
 179                                 if (!nflag && !pd)
 180                                         OUT();
 181                                 flush_appends();
 182                                 if (!mf_fgets(&PS, REPLACE))
 183                                         exit(0);
 184                                 pd = 0;
 185                                 break;
 186                         case 'N':
 187                                 flush_appends();
 188                                 cspace(&PS, "\n", 1, APPEND);
 189                                 if (!mf_fgets(&PS, APPEND))
 190                                         exit(0);
 191                                 break;
 192                         case 'p':
 193                                 if (pd)
 194                                         break;
 195                                 OUT();
 196                                 break;
 197                         case 'P':
 198                                 if (pd)
 199                                         break;
 200                                 if ((p = memchr(ps, '\n', psl)) != NULL) {
 201                                         oldpsl = psl;
 202                                         oldpsanl = psanl;
 203                                         psl = p - ps;
 204                                         psanl = 1;
 205                                 }
 206                                 OUT();
 207                                 if (p != NULL) {
 208                                         psl = oldpsl;
 209                                         psanl = oldpsanl;
 210                                 }
 211                                 break;
 212                         case 'q':
 213                                 if (inplace == NULL) {
 214                                         if (!nflag && !pd)
 215                                                 OUT();
 216                                         flush_appends();
 217                                         exit(0);
 218                                 }
 219                                 quit = 1;
 220                                 break;
 221                         case 'r':
 222                                 if (appendx >= appendnum)
 223                                         if ((appends = realloc(appends,
 224                                             sizeof(struct s_appends) *
 225                                             (appendnum *= 2))) == NULL)
 226                                                 err(1, "realloc");
 227                                 appends[appendx].type = AP_FILE;
 228                                 appends[appendx].s = cp->t;
 229                                 appends[appendx].len = strlen(cp->t);
 230                                 appendx++;
 231                                 break;
 232                         case 's':
 233                                 sdone |= substitute(cp);
 234                                 break;
 235                         case 't':
 236                                 if (sdone) {
 237                                         sdone = 0;
 238                                         cp = cp->u.c;
 239                                         goto redirect;
 240                                 }
 241                                 break;
 242                         case 'w':
 243                                 if (pd)
 244                                         break;
 245                                 if (cp->u.fd == -1 && (cp->u.fd = open(cp->t,
 246                                     O_WRONLY|O_APPEND|O_CREAT|O_TRUNC,
 247                                     DEFFILEMODE)) == -1)
 248                                         err(1, "%s", cp->t);
 249                                 if (write(cp->u.fd, ps, psl) != (ssize_t)psl ||
 250                                     write(cp->u.fd, "\n", 1) != 1)
 251                                         err(1, "%s", cp->t);
 252                                 break;
 253                         case 'x':
 254                                 /*
 255                                  * If the hold space is null, make it empty
 256                                  * but not null.  Otherwise the pattern space
 257                                  * will become null after the swap, which is
 258                                  * an abnormal condition.
 259                                  */
 260                                 if (hs == NULL)
 261                                         cspace(&HS, "", 0, REPLACE);
 262                                 tspace = PS;
 263                                 PS = HS;
 264                                 psanl = tspace.append_newline;
 265                                 HS = tspace;
 266                                 break;
 267                         case 'y':
 268                                 if (pd || psl == 0)
 269                                         break;
 270                                 do_tr(cp->u.y);
 271                                 break;
 272                         case ':':
 273                         case '}':
 274                                 break;
 275                         case '=':
 276                                 (void)fprintf(outfile, "%lu\n", linenum);
 277                         }
 278                         cp = cp->next;
 279                 } /* for all cp */
 280
 281 new:            if (!nflag && !pd)
 282                         OUT();
 283                 flush_appends();
 284         } /* for all lines */
 285 }
 286
 287 /*
 288  * TRUE if the address passed matches the current program state
 289  * (lastline, linenumber, ps).
 290  */
 291 #define MATCH(a)                                                        \
 292         ((a)->type == AT_RE ? regexec_e((a)->u.r, ps, 0, 1, 0, psl) :   \
 293             (a)->type == AT_LINE ? linenum == (a)->u.l : lastline())
 294
 295 /*
 296  * Return TRUE if the command applies to the current line.  Sets the start
 297  * line for process ranges.  Interprets the non-select (``!'') flag.
 298  */
 299 static inline int
 300 applies(struct s_command *cp)
 301 {
 302         int r;
 303
 304         lastaddr = 0;
 305         if (cp->a1 == NULL && cp->a2 == NULL)
 306                 r = 1;
 307         else if (cp->a2)
 308                 if (cp->startline > 0) {
 309                         switch (cp->a2->type) {
 310                         case AT_RELLINE:
 311                                 if (linenum - cp->startline <= cp->a2->u.l)
 312                                         r = 1;
 313                                 else {
 314                                         cp->startline = 0;
 315                                         r = 0;
 316                                 }
 317                                 break;
 318                         default:
 319                                 if (MATCH(cp->a2)) {
 320                                         cp->startline = 0;
 321                                         lastaddr = 1;
 322                                         r = 1;
 323                                 } else if (cp->a2->type == AT_LINE &&
 324                                             linenum > cp->a2->u.l) {
 325                                         /*
 326                                          * We missed the 2nd address due to a
 327                                          * branch, so just close the range and
 328                                          * return false.
 329                                          */
 330                                         cp->startline = 0;
 331                                         r = 0;
 332                                 } else
 333                                         r = 1;
 334                         }
 335                 } else if (cp->a1 && MATCH(cp->a1)) {
 336                         /*
 337                          * If the second address is a number less than or
 338                          * equal to the line number first selected, only
 339                          * one line shall be selected.
 340                          *      -- POSIX 1003.2
 341                          * Likewise if the relative second line address is zero.
 342                          */
 343                         if ((cp->a2->type == AT_LINE &&
 344                             linenum >= cp->a2->u.l) ||
 345                             (cp->a2->type == AT_RELLINE && cp->a2->u.l == 0))
 346                                 lastaddr = 1;
 347                         else {
 348                                 cp->startline = linenum;
 349                         }
 350                         r = 1;
 351                 } else
 352                         r = 0;
 353         else
 354                 r = MATCH(cp->a1);
 355         return (cp->nonsel ? ! r : r);
 356 }
 357
 358 /*
 359  * Reset the sed processor to its initial state.
 360  */
 361 void
 362 resetstate(void)
 363 {
 364         struct s_command *cp;
 365
 366         /*
 367          * Reset all in-range markers.
 368          */
 369         for (cp = prog; cp; cp = cp->code == '{' ? cp->u.c : cp->next)
 370                 if (cp->a2)
 371                         cp->startline = 0;
 372
 373         /*
 374          * Clear out the hold space.
 375          */
 376         cspace(&HS, "", 0, REPLACE);
 377 }
 378
 379 /*
 380  * substitute --
 381  *      Do substitutions in the pattern space.  Currently, we build a
 382  *      copy of the new pattern space in the substitute space structure
 383  *      and then swap them.
 384  */
 385 static int
 386 substitute(struct s_command *cp)
 387 {
 388         SPACE tspace;
 389         regex_t *re;
 390         regoff_t slen;
 391         int lastempty, n;
 392         regoff_t le = 0;
 393         char *s;
 394
 395         s = ps;
 396         re = cp->u.s->re;
 397         if (re == NULL) {
 398                 if (defpreg != NULL && cp->u.s->maxbref > defpreg->re_nsub) {
 399                         linenum = cp->u.s->linenum;
 400                         errx(1, "%lu: %s: \\%u not defined in the RE",
 401                                         linenum, fname, cp->u.s->maxbref);
 402                 }
 403         }
 404         if (!regexec_e(re, ps, 0, 0, 0, psl))
 405                 return (0);
 406
 407         SS.len = 0;                             /* Clean substitute space. */
 408         slen = psl;
 409         n = cp->u.s->n;
 410         lastempty = 1;
 411
 412         do {
 413                 /* Copy the leading retained string. */
 414                 if (n <= 1 && (match[0].rm_so > le))
 415                         cspace(&SS, s, match[0].rm_so - le, APPEND);
 416
 417                 /* Skip zero-length matches right after other matches. */
 418                 if (lastempty || (match[0].rm_so - le) ||
 419                     match[0].rm_so != match[0].rm_eo) {
 420                         if (n <= 1) {
 421                                 /* Want this match: append replacement. */
 422                                 regsub(&SS, ps, cp->u.s->new);
 423                                 if (n == 1)
 424                                         n = -1;
 425                         } else {
 426                                 /* Want a later match: append original. */
 427                                 if (match[0].rm_eo - le)
 428                                         cspace(&SS, s, match[0].rm_eo - le,
 429                                             APPEND);
 430                                 n--;
 431                         }
 432                 }
 433
 434                 /* Move past this match. */
 435                 s = ps + match[0].rm_eo;
 436                 slen = psl - match[0].rm_eo;
 437                 le = match[0].rm_eo;
 438
 439                 /*
 440                  * After a zero-length match, advance one byte,
 441                  * and at the end of the line, terminate.
 442                  */
 443                 if (match[0].rm_so == match[0].rm_eo) {
 444                         if (*s == '\0' || *s == '\n')
 445                                 slen = -1;
 446                         else
 447                                 slen--;
 448                         if (*s != '\0') {
 449                                 cspace(&SS, s++, 1, APPEND);
 450                                 le++;
 451                         }
 452                         lastempty = 1;
 453                 } else
 454                         lastempty = 0;
 455
 456         } while (n >= 0 && slen >= 0 &&
 457             regexec_e(re, ps, REG_NOTBOL, 0, le, psl));
 458
 459         /* Did not find the requested number of matches. */
 460         if (n > 0)
 461                 return (0);
 462
 463         /* Copy the trailing retained string. */
 464         if (slen > 0)
 465                 cspace(&SS, s, slen, APPEND);
 466
 467         /*
 468          * Swap the substitute space and the pattern space, and make sure
 469          * that any leftover pointers into stdio memory get lost.
 470          */
 471         tspace = PS;
 472         PS = SS;
 473         psanl = tspace.append_newline;
 474         SS = tspace;
 475         SS.space = SS.back;
 476
 477         /* Handle the 'p' flag. */
 478         if (cp->u.s->p)
 479                 OUT();
 480
 481         /* Handle the 'w' flag. */
 482         if (cp->u.s->wfile && !pd) {
 483                 if (cp->u.s->wfd == -1 && (cp->u.s->wfd = open(cp->u.s->wfile,
 484                     O_WRONLY|O_APPEND|O_CREAT|O_TRUNC, DEFFILEMODE)) == -1)
 485                         err(1, "%s", cp->u.s->wfile);
 486                 if (write(cp->u.s->wfd, ps, psl) != (ssize_t)psl ||
 487                     write(cp->u.s->wfd, "\n", 1) != 1)
 488                         err(1, "%s", cp->u.s->wfile);
 489         }
 490         return (1);
 491 }
 492
 493 /*
 494  * do_tr --
 495  *      Perform translation ('y' command) in the pattern space.
 496  */
 497 static void
 498 do_tr(struct s_tr *y)
 499 {
 500         SPACE tmp;
 501         char c, *p;
 502         size_t clen, left;
 503         int i;
 504
 505         if (MB_CUR_MAX == 1) {
 506                 /*
 507                  * Single-byte encoding: perform in-place translation
 508                  * of the pattern space.
 509                  */
 510                 for (p = ps; p < &ps[psl]; p++)
 511                         *p = y->bytetab[(u_char)*p];
 512         } else {
 513                 /*
 514                  * Multi-byte encoding: perform translation into the
 515                  * translation space, then swap the translation and
 516                  * pattern spaces.
 517                  */
 518                 /* Clean translation space. */
 519                 YS.len = 0;
 520                 for (p = ps, left = psl; left > 0; p += clen, left -= clen) {
 521                         if ((c = y->bytetab[(u_char)*p]) != '\0') {
 522                                 cspace(&YS, &c, 1, APPEND);
 523                                 clen = 1;
 524                                 continue;
 525                         }
 526                         for (i = 0; i < y->nmultis; i++)
 527                                 if (left >= y->multis[i].fromlen &&
 528                                     memcmp(p, y->multis[i].from,
 529                                     y->multis[i].fromlen) == 0)
 530                                         break;
 531                         if (i < y->nmultis) {
 532                                 cspace(&YS, y->multis[i].to,
 533                                     y->multis[i].tolen, APPEND);
 534                                 clen = y->multis[i].fromlen;
 535                         } else {
 536                                 cspace(&YS, p, 1, APPEND);
 537                                 clen = 1;
 538                         }
 539                 }
 540                 /* Swap the translation space and the pattern space. */
 541                 tmp = PS;
 542                 PS = YS;
 543                 psanl = tmp.append_newline;
 544                 YS = tmp;
 545                 YS.space = YS.back;
 546         }
 547 }
 548
 549 /*
 550  * Flush append requests.  Always called before reading a line,
 551  * therefore it also resets the substitution done (sdone) flag.
 552  */
 553 static void
 554 flush_appends(void)
 555 {
 556         FILE *f;
 557         unsigned int count, idx;
 558         char buf[8 * 1024];
 559
 560         for (idx = 0; idx < appendx; idx++)
 561                 switch (appends[idx].type) {
 562                 case AP_STRING:
 563                         fwrite(appends[idx].s, sizeof(char), appends[idx].len,
 564                             outfile);
 565                         break;
 566                 case AP_FILE:
 567                         /*
 568                          * Read files probably shouldn't be cached.  Since
 569                          * it's not an error to read a non-existent file,
 570                          * it's possible that another program is interacting
 571                          * with the sed script through the filesystem.  It
 572                          * would be truly bizarre, but possible.  It's probably
 573                          * not that big a performance win, anyhow.
 574                          */
 575                         if ((f = fopen(appends[idx].s, "r")) == NULL)
 576                                 break;
 577                         while ((count = fread(buf, sizeof(char), sizeof(buf), f)))
 578                                 (void)fwrite(buf, sizeof(char), count, outfile);
 579                         (void)fclose(f);
 580                         break;
 581                 }
 582         if (ferror(outfile))
 583                 errx(1, "%s: %s", outfname, strerror(errno ? errno : EIO));
 584         appendx = sdone = 0;
 585 }
 586
 587 static void
 588 lputs(char *s, size_t len)
 589 {
 590         static const char escapes[] = "\\\a\b\f\r\t\v";
 591         int c, col, width;
 592         const char *p;
 593         struct winsize win;
 594         static int termwidth = -1;
 595         size_t clen, i;
 596         wchar_t wc;
 597         mbstate_t mbs;
 598
 599         if (outfile != stdout)
 600                 termwidth = 60;
 601         if (termwidth == -1) {
 602                 if ((p = getenv("COLUMNS")) && *p != '\0')
 603                         termwidth = atoi(p);
 604                 else if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) == 0 &&
 605                     win.ws_col > 0)
 606                         termwidth = win.ws_col;
 607                 else
 608                         termwidth = 60;
 609         }
 610         if (termwidth <= 0)
 611                 termwidth = 1;
 612
 613         memset(&mbs, 0, sizeof(mbs));
 614         col = 0;
 615         while (len != 0) {
 616                 clen = mbrtowc(&wc, s, len, &mbs);
 617                 if (clen == 0)
 618                         clen = 1;
 619                 if (clen == (size_t)-1 || clen == (size_t)-2) {
 620                         wc = (unsigned char)*s;
 621                         clen = 1;
 622                         memset(&mbs, 0, sizeof(mbs));
 623                 }
 624                 if (wc == '\n') {
 625                         if (col + 1 >= termwidth)
 626                                 fprintf(outfile, "\\\n");
 627                         fputc('$', outfile);
 628                         fputc('\n', outfile);
 629                         col = 0;
 630                 } else if (iswprint(wc)) {
 631                         width = wcwidth(wc);
 632                         if (col + width >= termwidth) {
 633                                 fprintf(outfile, "\\\n");
 634                                 col = 0;
 635                         }
 636                         fwrite(s, 1, clen, outfile);
 637                         col += width;
 638                 } else if (wc != L'\0' && (c = wctob(wc)) != EOF &&
 639                     (p = strchr(escapes, c)) != NULL) {
 640                         if (col + 2 >= termwidth) {
 641                                 fprintf(outfile, "\\\n");
 642                                 col = 0;
 643                         }
 644                         fprintf(outfile, "\\%c", "\\abfrtv"[p - escapes]);
 645                         col += 2;
 646                 } else {
 647                         if (col + 4 * clen >= (unsigned)termwidth) {
 648                                 fprintf(outfile, "\\\n");
 649                                 col = 0;
 650                         }
 651                         for (i = 0; i < clen; i++)
 652                                 fprintf(outfile, "\\%03o",
 653                                     (int)(unsigned char)s[i]);
 654                         col += 4 * clen;
 655                 }
 656                 s += clen;
 657                 len -= clen;
 658         }
 659         if (col + 1 >= termwidth)
 660                 fprintf(outfile, "\\\n");
 661         (void)fputc('$', outfile);
 662         (void)fputc('\n', outfile);
 663         if (ferror(outfile))
 664                 errx(1, "%s: %s", outfname, strerror(errno ? errno : EIO));
 665 }
 666
 667 static int
 668 regexec_e(regex_t *preg, const char *string, int eflags, int nomatch,
 669         size_t start, size_t stop)
 670 {
 671         int eval;
 672
 673         if (preg == NULL) {
 674                 if (defpreg == NULL)
 675                         errx(1, "first RE may not be empty");
 676         } else
 677                 defpreg = preg;
 678
 679         /* Set anchors */
 680         match[0].rm_so = start;
 681         match[0].rm_eo = stop;
 682
 683         eval = regexec(defpreg, string,
 684             nomatch ? 0 : maxnsub + 1, match, eflags | REG_STARTEND);
 685         switch(eval) {
 686         case 0:
 687                 return (1);
 688         case REG_NOMATCH:
 689                 return (0);
 690         }
 691         errx(1, "RE error: %s", strregerror(eval, defpreg));
 692         /* NOTREACHED */
 693 }
 694
 695 /*
 696  * regsub - perform substitutions after a regexp match
 697  * Based on a routine by Henry Spencer
 698  */
 699 static void
 700 regsub(SPACE *sp, char *string, char *src)
 701 {
 702         int len, no;
 703         char c, *dst;
 704
 705 #define NEEDSP(reqlen)                                                  \
 706         /* XXX What is the +1 for? */                                   \
 707         if (sp->len + (reqlen) + 1 >= sp->blen) {                       \
 708                 sp->blen += (reqlen) + 1024;                            \
 709                 if ((sp->space = sp->back = realloc(sp->back, sp->blen)) \
 710                     == NULL)                                            \
 711                         err(1, "realloc");                              \
 712                 dst = sp->space + sp->len;                              \
 713         }
 714
 715         dst = sp->space + sp->len;
 716         while ((c = *src++) != '\0') {
 717                 if (c == '&')
 718                         no = 0;
 719                 else if (c == '\\' && isdigit((unsigned char)*src))
 720                         no = *src++ - '0';
 721                 else
 722                         no = -1;
 723                 if (no < 0) {           /* Ordinary character. */
 724                         if (c == '\\' && (*src == '\\' || *src == '&'))
 725                                 c = *src++;
 726                         NEEDSP(1);
 727                         *dst++ = c;
 728                         ++sp->len;
 729                 } else if (match[no].rm_so != -1 && match[no].rm_eo != -1) {
 730                         len = match[no].rm_eo - match[no].rm_so;
 731                         NEEDSP(len);
 732                         memmove(dst, string + match[no].rm_so, len);
 733                         dst += len;
 734                         sp->len += len;
 735                 }
 736         }
 737         NEEDSP(1);
 738         *dst = '\0';
 739 }
 740
 741 /*
 742  * cspace --
 743  *      Concatenate space: append the source space to the destination space,
 744  *      allocating new space as necessary.
 745  */
 746 void
 747 cspace(SPACE *sp, const char *p, size_t len, enum e_spflag spflag)
 748 {
 749         size_t tlen;
 750
 751         /* Make sure SPACE has enough memory and ramp up quickly. */
 752         tlen = sp->len + len + 1;
 753         if (tlen > sp->blen) {
 754                 sp->blen = tlen + 1024;
 755                 if ((sp->space = sp->back = realloc(sp->back, sp->blen)) ==
 756                     NULL)
 757                         err(1, "realloc");
 758         }
 759
 760         if (spflag == REPLACE)
 761                 sp->len = 0;
 762
 763         memmove(sp->space + sp->len, p, len);
 764
 765         sp->space[sp->len += len] = '\0';
 766 }
 767
 768 /*
 769  * Close all cached opened files and report any errors
 770  */
 771 void
 772 cfclose(struct s_command *cp, struct s_command *end)
 773 {
 774
 775         for (; cp != end; cp = cp->next)
 776                 switch(cp->code) {
 777                 case 's':
 778                         if (cp->u.s->wfd != -1 && close(cp->u.s->wfd))
 779                                 err(1, "%s", cp->u.s->wfile);
 780                         cp->u.s->wfd = -1;
 781                         break;
 782                 case 'w':
 783                         if (cp->u.fd != -1 && close(cp->u.fd))
 784                                 err(1, "%s", cp->t);
 785                         cp->u.fd = -1;
 786                         break;
 787                 case '{':
 788                         cfclose(cp->u.c, cp->next);
 789                         break;
 790                 }
 791 }