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  * @(#)process.c        8.6 (Berkeley) 4/20/94
  36  * $FreeBSD: head/usr.bin/sed/process.c 338375 2018-08-29 17:09:03Z markj $
  37  */
  38
  39 #include <sys/cdefs.h>
  40
  41 #include <sys/types.h>
  42 #include <sys/stat.h>
  43 #include <sys/ioctl.h>
  44 #include <sys/uio.h>
  45
  46 #include <ctype.h>
  47 #include <err.h>
  48 #include <errno.h>
  49 #include <fcntl.h>
  50 #include <limits.h>
  51 #include <regex.h>
  52 #include <stdio.h>
  53 #include <stdlib.h>
  54 #include <string.h>
  55 #include <unistd.h>
  56 #include <wchar.h>
  57 #include <wctype.h>
  58
  59 #include "defs.h"
  60 #include "extern.h"
  61
  62 static SPACE HS, PS, SS, YS;
  63 #define pd              PS.deleted
  64 #define ps              PS.space
  65 #define psl             PS.len
  66 #define psanl           PS.append_newline
  67 #define hs              HS.space
  68 #define hsl             HS.len
  69
  70 static inline int        applies(struct s_command *);
  71 static void              do_tr(struct s_tr *);
  72 static void              flush_appends(void);
  73 static void              lputs(char *, size_t);
  74 static int               regexec_e(regex_t *, const char *, int, int, size_t,
  75                              size_t);
  76 static void              regsub(SPACE *, char *, char *);
  77 static int               substitute(struct s_command *);
  78
  79 struct s_appends *appends;      /* Array of pointers to strings to append. */
  80 static unsigned int appendx;    /* Index into appends array. */
  81 unsigned int appendnum;         /* Size of appends array. */
  82
  83 static int lastaddr;            /* Set by applies if last address of a range. */
  84 static int sdone;               /* If any substitutes since last line input. */
  85                                 /* Iov structure for 'w' commands. */
  86 static regex_t *defpreg;
  87 size_t maxnsub;
  88 regmatch_t *match;
  89
  90 #define OUT() do {                                                      \
  91         fwrite(ps, 1, psl, outfile);                                    \
  92         if (psanl) fputc('\n', outfile);                                \
  93 } while (0)
  94
  95 void
  96 process(void)
  97 {
  98         struct s_command *cp;
  99         SPACE tspace;
 100         size_t oldpsl;
 101         char *p;
 102         int oldpsanl;
 103
 104         p = NULL;
 105         oldpsanl = oldpsl = 0;
 106
 107         for (linenum = 0; mf_fgets(&PS, REPLACE);) {
 108                 pd = 0;
 109 top:
 110                 cp = prog;
 111 redirect:
 112                 while (cp != NULL) {
 113                         if (!applies(cp)) {
 114                                 cp = cp->next;
 115                                 continue;
 116                         }
 117                         switch (cp->code) {
 118                         case '{':
 119                                 cp = cp->u.c;
 120                                 goto redirect;
 121                         case 'a':
 122                                 if (appendx >= appendnum)
 123                                         if ((appends = realloc(appends,
 124                                             sizeof(struct s_appends) *
 125                                             (appendnum *= 2))) == NULL)
 126                                                 err(1, "realloc");
 127                                 appends[appendx].type = AP_STRING;
 128                                 appends[appendx].s = cp->t;
 129                                 appends[appendx].len = strlen(cp->t);
 130                                 appendx++;
 131                                 break;
 132                         case 'b':
 133                                 cp = cp->u.c;
 134                                 goto redirect;
 135                         case 'c':
 136                                 pd = 1;
 137                                 psl = 0;
 138                                 if (cp->a2 == NULL || lastaddr || lastline())
 139                                         (void)fprintf(outfile, "%s", cp->t);
 140                                 break;
 141                         case 'd':
 142                                 pd = 1;
 143                                 goto new;
 144                         case 'D':
 145                                 if (pd)
 146                                         goto new;
 147                                 if (psl == 0 ||
 148                                     (p = memchr(ps, '\n', psl)) == NULL) {
 149                                         pd = 1;
 150                                         goto new;
 151                                 } else {
 152                                         psl -= (p + 1) - ps;
 153                                         memmove(ps, p + 1, psl);
 154                                         goto top;
 155                                 }
 156                         case 'g':
 157                                 cspace(&PS, hs, hsl, REPLACE);
 158                                 break;
 159                         case 'G':
 160                                 cspace(&PS, "\n", 1, APPEND);
 161                                 cspace(&PS, hs, hsl, APPEND);
 162                                 break;
 163                         case 'h':
 164                                 cspace(&HS, ps, psl, REPLACE);
 165                                 break;
 166                         case 'H':
 167                                 cspace(&HS, "\n", 1, APPEND);
 168                                 cspace(&HS, ps, psl, APPEND);
 169                                 break;
 170                         case 'i':
 171                                 (void)fprintf(outfile, "%s", cp->t);
 172                                 break;
 173                         case 'l':
 174                                 lputs(ps, psl);
 175                                 break;
 176                         case 'n':
 177                                 if (!nflag && !pd)
 178                                         OUT();
 179                                 flush_appends();
 180                                 if (!mf_fgets(&PS, REPLACE))
 181                                         exit(0);
 182                                 pd = 0;
 183                                 break;
 184                         case 'N':
 185                                 flush_appends();
 186                                 cspace(&PS, "\n", 1, APPEND);
 187                                 if (!mf_fgets(&PS, APPEND))
 188                                         exit(0);
 189                                 break;
 190                         case 'p':
 191                                 if (pd)
 192                                         break;
 193                                 OUT();
 194                                 break;
 195                         case 'P':
 196                                 if (pd)
 197                                         break;
 198                                 if ((p = memchr(ps, '\n', psl)) != NULL) {
 199                                         oldpsl = psl;
 200                                         oldpsanl = psanl;
 201                                         psl = p - ps;
 202                                         psanl = 1;
 203                                 }
 204                                 OUT();
 205                                 if (p != NULL) {
 206                                         psl = oldpsl;
 207                                         psanl = oldpsanl;
 208                                 }
 209                                 break;
 210                         case 'q':
 211                                 if (inplace == NULL) {
 212                                         if (!nflag && !pd)
 213                                                 OUT();
 214                                         flush_appends();
 215                                         exit(0);
 216                                 }
 217                                 quit = 1;
 218                                 break;
 219                         case 'r':
 220                                 if (appendx >= appendnum)
 221                                         if ((appends = realloc(appends,
 222                                             sizeof(struct s_appends) *
 223                                             (appendnum *= 2))) == NULL)
 224                                                 err(1, "realloc");
 225                                 appends[appendx].type = AP_FILE;
 226                                 appends[appendx].s = cp->t;
 227                                 appends[appendx].len = strlen(cp->t);
 228                                 appendx++;
 229                                 break;
 230                         case 's':
 231                                 sdone |= substitute(cp);
 232                                 break;
 233                         case 't':
 234                                 if (sdone) {
 235                                         sdone = 0;
 236                                         cp = cp->u.c;
 237                                         goto redirect;
 238                                 }
 239                                 break;
 240                         case 'w':
 241                                 if (pd)
 242                                         break;
 243                                 if (cp->u.fd == -1 && (cp->u.fd = open(cp->t,
 244                                     O_WRONLY|O_APPEND|O_CREAT|O_TRUNC,
 245                                     DEFFILEMODE)) == -1)
 246                                         err(1, "%s", cp->t);
 247                                 if (write(cp->u.fd, ps, psl) != (ssize_t)psl ||
 248                                     write(cp->u.fd, "\n", 1) != 1)
 249                                         err(1, "%s", cp->t);
 250                                 break;
 251                         case 'x':
 252                                 /*
 253                                  * If the hold space is null, make it empty
 254                                  * but not null.  Otherwise the pattern space
 255                                  * will become null after the swap, which is
 256                                  * an abnormal condition.
 257                                  */
 258                                 if (hs == NULL)
 259                                         cspace(&HS, "", 0, REPLACE);
 260                                 tspace = PS;
 261                                 PS = HS;
 262                                 psanl = tspace.append_newline;
 263                                 HS = tspace;
 264                                 break;
 265                         case 'y':
 266                                 if (pd || psl == 0)
 267                                         break;
 268                                 do_tr(cp->u.y);
 269                                 break;
 270                         case ':':
 271                         case '}':
 272                                 break;
 273                         case '=':
 274                                 (void)fprintf(outfile, "%lu\n", linenum);
 275                         }
 276                         cp = cp->next;
 277                 } /* for all cp */
 278
 279 new:            if (!nflag && !pd)
 280                         OUT();
 281                 flush_appends();
 282         } /* for all lines */
 283 }
 284
 285 /*
 286  * TRUE if the address passed matches the current program state
 287  * (lastline, linenumber, ps).
 288  */
 289 #define MATCH(a)                                                        \
 290         ((a)->type == AT_RE ? regexec_e((a)->u.r, ps, 0, 1, 0, psl) :   \
 291             (a)->type == AT_LINE ? linenum == (a)->u.l : lastline())
 292
 293 /*
 294  * Return TRUE if the command applies to the current line.  Sets the start
 295  * line for process ranges.  Interprets the non-select (``!'') flag.
 296  */
 297 static inline int
 298 applies(struct s_command *cp)
 299 {
 300         int r;
 301
 302         lastaddr = 0;
 303         if (cp->a1 == NULL && cp->a2 == NULL)
 304                 r = 1;
 305         else if (cp->a2)
 306                 if (cp->startline > 0) {
 307                         switch (cp->a2->type) {
 308                         case AT_RELLINE:
 309                                 if (linenum - cp->startline <= cp->a2->u.l)
 310                                         r = 1;
 311                                 else {
 312                                         cp->startline = 0;
 313                                         r = 0;
 314                                 }
 315                                 break;
 316                         default:
 317                                 if (MATCH(cp->a2)) {
 318                                         cp->startline = 0;
 319                                         lastaddr = 1;
 320                                         r = 1;
 321                                 } else if (cp->a2->type == AT_LINE &&
 322                                             linenum > cp->a2->u.l) {
 323                                         /*
 324                                          * We missed the 2nd address due to a
 325                                          * branch, so just close the range and
 326                                          * return false.
 327                                          */
 328                                         cp->startline = 0;
 329                                         r = 0;
 330                                 } else
 331                                         r = 1;
 332                         }
 333                 } else if (cp->a1 && MATCH(cp->a1)) {
 334                         /*
 335                          * If the second address is a number less than or
 336                          * equal to the line number first selected, only
 337                          * one line shall be selected.
 338                          *      -- POSIX 1003.2
 339                          * Likewise if the relative second line address is zero.
 340                          */
 341                         if ((cp->a2->type == AT_LINE &&
 342                             linenum >= cp->a2->u.l) ||
 343                             (cp->a2->type == AT_RELLINE && cp->a2->u.l == 0))
 344                                 lastaddr = 1;
 345                         else {
 346                                 cp->startline = linenum;
 347                         }
 348                         r = 1;
 349                 } else
 350                         r = 0;
 351         else
 352                 r = MATCH(cp->a1);
 353         return (cp->nonsel ? ! r : r);
 354 }
 355
 356 /*
 357  * Reset the sed processor to its initial state.
 358  */
 359 void
 360 resetstate(void)
 361 {
 362         struct s_command *cp;
 363
 364         /*
 365          * Reset all in-range markers.
 366          */
 367         for (cp = prog; cp; cp = cp->code == '{' ? cp->u.c : cp->next)
 368                 if (cp->a2)
 369                         cp->startline = 0;
 370
 371         /*
 372          * Clear out the hold space.
 373          */
 374         cspace(&HS, "", 0, REPLACE);
 375 }
 376
 377 /*
 378  * substitute --
 379  *      Do substitutions in the pattern space.  Currently, we build a
 380  *      copy of the new pattern space in the substitute space structure
 381  *      and then swap them.
 382  */
 383 static int
 384 substitute(struct s_command *cp)
 385 {
 386         SPACE tspace;
 387         regex_t *re;
 388         regoff_t slen;
 389         int lastempty, n;
 390         regoff_t le = 0;
 391         char *s;
 392
 393         s = ps;
 394         re = cp->u.s->re;
 395         if (re == NULL) {
 396                 if (defpreg != NULL && cp->u.s->maxbref > defpreg->re_nsub) {
 397                         linenum = cp->u.s->linenum;
 398                         errx(1, "%lu: %s: \\%u not defined in the RE",
 399                                         linenum, fname, cp->u.s->maxbref);
 400                 }
 401         }
 402         if (!regexec_e(re, ps, 0, 0, 0, psl))
 403                 return (0);
 404
 405         SS.len = 0;                             /* Clean substitute space. */
 406         slen = psl;
 407         n = cp->u.s->n;
 408         lastempty = 1;
 409
 410         do {
 411                 /* Copy the leading retained string. */
 412                 if (n <= 1 && (match[0].rm_so > le))
 413                         cspace(&SS, s, match[0].rm_so - le, APPEND);
 414
 415                 /* Skip zero-length matches right after other matches. */
 416                 if (lastempty || (match[0].rm_so - le) ||
 417                     match[0].rm_so != match[0].rm_eo) {
 418                         if (n <= 1) {
 419                                 /* Want this match: append replacement. */
 420                                 regsub(&SS, ps, cp->u.s->new);
 421                                 if (n == 1)
 422                                         n = -1;
 423                         } else {
 424                                 /* Want a later match: append original. */
 425                                 if (match[0].rm_eo - le)
 426                                         cspace(&SS, s, match[0].rm_eo - le,
 427                                             APPEND);
 428                                 n--;
 429                         }
 430                 }
 431
 432                 /* Move past this match. */
 433                 s = ps + match[0].rm_eo;
 434                 slen = psl - match[0].rm_eo;
 435                 le = match[0].rm_eo;
 436
 437                 /*
 438                  * After a zero-length match, advance one byte,
 439                  * and at the end of the line, terminate.
 440                  */
 441                 if (match[0].rm_so == match[0].rm_eo) {
 442                         if (*s == '\0' || *s == '\n')
 443                                 slen = -1;
 444                         else
 445                                 slen--;
 446                         if (*s != '\0') {
 447                                 cspace(&SS, s++, 1, APPEND);
 448                                 le++;
 449                         }
 450                         lastempty = 1;
 451                 } else
 452                         lastempty = 0;
 453
 454         } while (n >= 0 && slen >= 0 &&
 455             regexec_e(re, ps, REG_NOTBOL, 0, le, psl));
 456
 457         /* Did not find the requested number of matches. */
 458         if (n > 0)
 459                 return (0);
 460
 461         /* Copy the trailing retained string. */
 462         if (slen > 0)
 463                 cspace(&SS, s, slen, APPEND);
 464
 465         /*
 466          * Swap the substitute space and the pattern space, and make sure
 467          * that any leftover pointers into stdio memory get lost.
 468          */
 469         tspace = PS;
 470         PS = SS;
 471         psanl = tspace.append_newline;
 472         SS = tspace;
 473         SS.space = SS.back;
 474
 475         /* Handle the 'p' flag. */
 476         if (cp->u.s->p)
 477                 OUT();
 478
 479         /* Handle the 'w' flag. */
 480         if (cp->u.s->wfile && !pd) {
 481                 if (cp->u.s->wfd == -1 && (cp->u.s->wfd = open(cp->u.s->wfile,
 482                     O_WRONLY|O_APPEND|O_CREAT|O_TRUNC, DEFFILEMODE)) == -1)
 483                         err(1, "%s", cp->u.s->wfile);
 484                 if (write(cp->u.s->wfd, ps, psl) != (ssize_t)psl ||
 485                     write(cp->u.s->wfd, "\n", 1) != 1)
 486                         err(1, "%s", cp->u.s->wfile);
 487         }
 488         return (1);
 489 }
 490
 491 /*
 492  * do_tr --
 493  *      Perform translation ('y' command) in the pattern space.
 494  */
 495 static void
 496 do_tr(struct s_tr *y)
 497 {
 498         SPACE tmp;
 499         char c, *p;
 500         size_t clen, left;
 501         int i;
 502
 503         if (MB_CUR_MAX == 1) {
 504                 /*
 505                  * Single-byte encoding: perform in-place translation
 506                  * of the pattern space.
 507                  */
 508                 for (p = ps; p < &ps[psl]; p++)
 509                         *p = y->bytetab[(u_char)*p];
 510         } else {
 511                 /*
 512                  * Multi-byte encoding: perform translation into the
 513                  * translation space, then swap the translation and
 514                  * pattern spaces.
 515                  */
 516                 /* Clean translation space. */
 517                 YS.len = 0;
 518                 for (p = ps, left = psl; left > 0; p += clen, left -= clen) {
 519                         if ((c = y->bytetab[(u_char)*p]) != '\0') {
 520                                 cspace(&YS, &c, 1, APPEND);
 521                                 clen = 1;
 522                                 continue;
 523                         }
 524                         for (i = 0; i < y->nmultis; i++)
 525                                 if (left >= y->multis[i].fromlen &&
 526                                     memcmp(p, y->multis[i].from,
 527                                     y->multis[i].fromlen) == 0)
 528                                         break;
 529                         if (i < y->nmultis) {
 530                                 cspace(&YS, y->multis[i].to,
 531                                     y->multis[i].tolen, APPEND);
 532                                 clen = y->multis[i].fromlen;
 533                         } else {
 534                                 cspace(&YS, p, 1, APPEND);
 535                                 clen = 1;
 536                         }
 537                 }
 538                 /* Swap the translation space and the pattern space. */
 539                 tmp = PS;
 540                 PS = YS;
 541                 psanl = tmp.append_newline;
 542                 YS = tmp;
 543                 YS.space = YS.back;
 544         }
 545 }
 546
 547 /*
 548  * Flush append requests.  Always called before reading a line,
 549  * therefore it also resets the substitution done (sdone) flag.
 550  */
 551 static void
 552 flush_appends(void)
 553 {
 554         FILE *f;
 555         unsigned int count, idx;
 556         char buf[8 * 1024];
 557
 558         for (idx = 0; idx < appendx; idx++)
 559                 switch (appends[idx].type) {
 560                 case AP_STRING:
 561                         fwrite(appends[idx].s, sizeof(char), appends[idx].len,
 562                             outfile);
 563                         break;
 564                 case AP_FILE:
 565                         /*
 566                          * Read files probably shouldn't be cached.  Since
 567                          * it's not an error to read a non-existent file,
 568                          * it's possible that another program is interacting
 569                          * with the sed script through the filesystem.  It
 570                          * would be truly bizarre, but possible.  It's probably
 571                          * not that big a performance win, anyhow.
 572                          */
 573                         if ((f = fopen(appends[idx].s, "r")) == NULL)
 574                                 break;
 575                         while ((count = fread(buf, sizeof(char), sizeof(buf), f)))
 576                                 (void)fwrite(buf, sizeof(char), count, outfile);
 577                         (void)fclose(f);
 578                         break;
 579                 }
 580         if (ferror(outfile))
 581                 errx(1, "%s: %s", outfname, strerror(errno ? errno : EIO));
 582         appendx = sdone = 0;
 583 }
 584
 585 static void
 586 lputs(char *s, size_t len)
 587 {
 588         static const char escapes[] = "\\\a\b\f\r\t\v";
 589         int c, col, width;
 590         const char *p;
 591         struct winsize win;
 592         static int termwidth = -1;
 593         size_t clen, i;
 594         wchar_t wc;
 595         mbstate_t mbs;
 596
 597         if (outfile != stdout)
 598                 termwidth = 60;
 599         if (termwidth == -1) {
 600                 if ((p = getenv("COLUMNS")) && *p != '\0')
 601                         termwidth = atoi(p);
 602                 else if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) == 0 &&
 603                     win.ws_col > 0)
 604                         termwidth = win.ws_col;
 605                 else
 606                         termwidth = 60;
 607         }
 608         if (termwidth <= 0)
 609                 termwidth = 1;
 610
 611         memset(&mbs, 0, sizeof(mbs));
 612         col = 0;
 613         while (len != 0) {
 614                 clen = mbrtowc(&wc, s, len, &mbs);
 615                 if (clen == 0)
 616                         clen = 1;
 617                 if (clen == (size_t)-1 || clen == (size_t)-2) {
 618                         wc = (unsigned char)*s;
 619                         clen = 1;
 620                         memset(&mbs, 0, sizeof(mbs));
 621                 }
 622                 if (wc == '\n') {
 623                         if (col + 1 >= termwidth)
 624                                 fprintf(outfile, "\\\n");
 625                         fputc('$', outfile);
 626                         fputc('\n', outfile);
 627                         col = 0;
 628                 } else if (iswprint(wc)) {
 629                         width = wcwidth(wc);
 630                         if (col + width >= termwidth) {
 631                                 fprintf(outfile, "\\\n");
 632                                 col = 0;
 633                         }
 634                         fwrite(s, 1, clen, outfile);
 635                         col += width;
 636                 } else if (wc != L'\0' && (c = wctob(wc)) != EOF &&
 637                     (p = strchr(escapes, c)) != NULL) {
 638                         if (col + 2 >= termwidth) {
 639                                 fprintf(outfile, "\\\n");
 640                                 col = 0;
 641                         }
 642                         fprintf(outfile, "\\%c", "\\abfrtv"[p - escapes]);
 643                         col += 2;
 644                 } else {
 645                         if (col + 4 * clen >= (unsigned)termwidth) {
 646                                 fprintf(outfile, "\\\n");
 647                                 col = 0;
 648                         }
 649                         for (i = 0; i < clen; i++)
 650                                 fprintf(outfile, "\\%03o",
 651                                     (int)(unsigned char)s[i]);
 652                         col += 4 * clen;
 653                 }
 654                 s += clen;
 655                 len -= clen;
 656         }
 657         if (col + 1 >= termwidth)
 658                 fprintf(outfile, "\\\n");
 659         (void)fputc('$', outfile);
 660         (void)fputc('\n', outfile);
 661         if (ferror(outfile))
 662                 errx(1, "%s: %s", outfname, strerror(errno ? errno : EIO));
 663 }
 664
 665 static int
 666 regexec_e(regex_t *preg, const char *string, int eflags, int nomatch,
 667         size_t start, size_t stop)
 668 {
 669         int eval;
 670
 671         if (preg == NULL) {
 672                 if (defpreg == NULL)
 673                         errx(1, "first RE may not be empty");
 674         } else
 675                 defpreg = preg;
 676
 677         /* Set anchors */
 678         match[0].rm_so = start;
 679         match[0].rm_eo = stop;
 680
 681         eval = regexec(defpreg, string,
 682             nomatch ? 0 : maxnsub + 1, match, eflags | REG_STARTEND);
 683         switch(eval) {
 684         case 0:
 685                 return (1);
 686         case REG_NOMATCH:
 687                 return (0);
 688         }
 689         errx(1, "RE error: %s", strregerror(eval, defpreg));
 690         /* NOTREACHED */
 691 }
 692
 693 /*
 694  * regsub - perform substitutions after a regexp match
 695  * Based on a routine by Henry Spencer
 696  */
 697 static void
 698 regsub(SPACE *sp, char *string, char *src)
 699 {
 700         int len, no;
 701         char c, *dst;
 702
 703 #define NEEDSP(reqlen)                                                  \
 704         /* XXX What is the +1 for? */                                   \
 705         if (sp->len + (reqlen) + 1 >= sp->blen) {                       \
 706                 sp->blen += (reqlen) + 1024;                            \
 707                 if ((sp->space = sp->back = realloc(sp->back, sp->blen)) \
 708                     == NULL)                                            \
 709                         err(1, "realloc");                              \
 710                 dst = sp->space + sp->len;                              \
 711         }
 712
 713         dst = sp->space + sp->len;
 714         while ((c = *src++) != '\0') {
 715                 if (c == '&')
 716                         no = 0;
 717                 else if (c == '\\' && isdigit((unsigned char)*src))
 718                         no = *src++ - '0';
 719                 else
 720                         no = -1;
 721                 if (no < 0) {           /* Ordinary character. */
 722                         if (c == '\\' && (*src == '\\' || *src == '&'))
 723                                 c = *src++;
 724                         NEEDSP(1);
 725                         *dst++ = c;
 726                         ++sp->len;
 727                 } else if (match[no].rm_so != -1 && match[no].rm_eo != -1) {
 728                         len = match[no].rm_eo - match[no].rm_so;
 729                         NEEDSP(len);
 730                         memmove(dst, string + match[no].rm_so, len);
 731                         dst += len;
 732                         sp->len += len;
 733                 }
 734         }
 735         NEEDSP(1);
 736         *dst = '\0';
 737 }
 738
 739 /*
 740  * cspace --
 741  *      Concatenate space: append the source space to the destination space,
 742  *      allocating new space as necessary.
 743  */
 744 void
 745 cspace(SPACE *sp, const char *p, size_t len, enum e_spflag spflag)
 746 {
 747         size_t tlen;
 748
 749         /* Make sure SPACE has enough memory and ramp up quickly. */
 750         tlen = sp->len + len + 1;
 751         if (tlen > sp->blen) {
 752                 sp->blen = tlen + 1024;
 753                 if ((sp->space = sp->back = realloc(sp->back, sp->blen)) ==
 754                     NULL)
 755                         err(1, "realloc");
 756         }
 757
 758         if (spflag == REPLACE)
 759                 sp->len = 0;
 760
 761         memmove(sp->space + sp->len, p, len);
 762
 763         sp->space[sp->len += len] = '\0';
 764 }
 765
 766 /*
 767  * Close all cached opened files and report any errors
 768  */
 769 void
 770 cfclose(struct s_command *cp, struct s_command *end)
 771 {
 772
 773         for (; cp != end; cp = cp->next)
 774                 switch(cp->code) {
 775                 case 's':
 776                         if (cp->u.s->wfd != -1 && close(cp->u.s->wfd))
 777                                 err(1, "%s", cp->u.s->wfile);
 778                         cp->u.s->wfd = -1;
 779                         break;
 780                 case 'w':
 781                         if (cp->u.fd != -1 && close(cp->u.fd))
 782                                 err(1, "%s", cp->t);
 783                         cp->u.fd = -1;
 784                         break;
 785                 case '{':
 786                         cfclose(cp->u.c, cp->next);
 787                         break;
 788                 }
 789 }