usr.bin/sed/process.c

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