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