482 lines
11 KiB
C
482 lines
11 KiB
C
/* search.c - searching subroutines using dfa, kwset and regex for grep.
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Copyright (C) 1992 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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Written August 1992 by Mike Haertel. */
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#include <ctype.h>
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#ifdef STDC_HEADERS
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#include <limits.h>
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#include <stdlib.h>
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#else
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#define UCHAR_MAX 255
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#include <sys/types.h>
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extern char *malloc();
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#endif
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#ifdef HAVE_MEMCHR
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#include <string.h>
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#ifdef NEED_MEMORY_H
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#include <memory.h>
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#endif
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#else
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#ifdef __STDC__
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extern void *memchr();
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#else
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extern char *memchr();
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#endif
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#endif
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#if defined(HAVE_STRING_H) || defined(STDC_HEADERS)
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#undef bcopy
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#define bcopy(s, d, n) memcpy((d), (s), (n))
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#endif
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#ifdef isascii
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#define ISALNUM(C) (isascii(C) && isalnum(C))
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#define ISUPPER(C) (isascii(C) && isupper(C))
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#else
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#define ISALNUM(C) isalnum(C)
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#define ISUPPER(C) isupper(C)
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#endif
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#define TOLOWER(C) (ISUPPER(C) ? tolower(C) : (C))
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#include "grep.h"
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#include "dfa.h"
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#include "kwset.h"
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#include "gnuregex.h"
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#define NCHAR (UCHAR_MAX + 1)
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#if __STDC__
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static void Gcompile(char *, size_t);
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static void Ecompile(char *, size_t);
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static char *EGexecute(char *, size_t, char **);
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static void Fcompile(char *, size_t);
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static char *Fexecute(char *, size_t, char **);
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#else
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static void Gcompile();
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static void Ecompile();
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static char *EGexecute();
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static void Fcompile();
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static char *Fexecute();
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#endif
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/* Here is the matchers vector for the main program. */
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struct matcher matchers[] = {
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{ "default", Gcompile, EGexecute },
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{ "grep", Gcompile, EGexecute },
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{ "ggrep", Gcompile, EGexecute },
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{ "egrep", Ecompile, EGexecute },
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{ "posix-egrep", Ecompile, EGexecute },
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{ "gegrep", Ecompile, EGexecute },
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{ "fgrep", Fcompile, Fexecute },
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{ "gfgrep", Fcompile, Fexecute },
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{ 0, 0, 0 },
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};
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/* For -w, we also consider _ to be word constituent. */
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#define WCHAR(C) (ISALNUM(C) || (C) == '_')
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/* DFA compiled regexp. */
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static struct dfa dfa;
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/* Regex compiled regexp. */
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static struct re_pattern_buffer regex;
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/* KWset compiled pattern. For Ecompile and Gcompile, we compile
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a list of strings, at least one of which is known to occur in
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any string matching the regexp. */
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static kwset_t kwset;
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/* Last compiled fixed string known to exactly match the regexp.
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If kwsexec() returns < lastexact, then we don't need to
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call the regexp matcher at all. */
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static int lastexact;
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void
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dfaerror(mesg)
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char *mesg;
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{
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fatal(mesg, 0);
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}
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static void
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kwsinit()
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{
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static char trans[NCHAR];
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int i;
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if (match_icase)
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for (i = 0; i < NCHAR; ++i)
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trans[i] = TOLOWER(i);
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if (!(kwset = kwsalloc(match_icase ? trans : (char *) 0)))
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fatal("memory exhausted", 0);
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}
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/* If the DFA turns out to have some set of fixed strings one of
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which must occur in the match, then we build a kwset matcher
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to find those strings, and thus quickly filter out impossible
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matches. */
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static void
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kwsmusts()
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{
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struct dfamust *dm;
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char *err;
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if (dfa.musts)
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{
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kwsinit();
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/* First, we compile in the substrings known to be exact
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matches. The kwset matcher will return the index
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of the matching string that it chooses. */
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for (dm = dfa.musts; dm; dm = dm->next)
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{
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if (!dm->exact)
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continue;
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++lastexact;
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if ((err = kwsincr(kwset, dm->must, strlen(dm->must))) != 0)
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fatal(err, 0);
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}
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/* Now, we compile the substrings that will require
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the use of the regexp matcher. */
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for (dm = dfa.musts; dm; dm = dm->next)
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{
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if (dm->exact)
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continue;
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if ((err = kwsincr(kwset, dm->must, strlen(dm->must))) != 0)
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fatal(err, 0);
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}
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if ((err = kwsprep(kwset)) != 0)
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fatal(err, 0);
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}
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}
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static void
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Gcompile(pattern, size)
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char *pattern;
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size_t size;
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{
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#ifdef __STDC__
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const
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#endif
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char *err;
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re_set_syntax(RE_SYNTAX_GREP | RE_HAT_LISTS_NOT_NEWLINE);
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dfasyntax(RE_SYNTAX_GREP | RE_HAT_LISTS_NOT_NEWLINE, match_icase);
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if ((err = re_compile_pattern(pattern, size, ®ex)) != 0)
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fatal(err, 0);
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dfainit(&dfa);
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/* In the match_words and match_lines cases, we use a different pattern
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for the DFA matcher that will quickly throw out cases that won't work.
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Then if DFA succeeds we do some hairy stuff using the regex matcher
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to decide whether the match should really count. */
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if (match_words || match_lines)
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{
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/* In the whole-word case, we use the pattern:
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(^|[^A-Za-z_])(userpattern)([^A-Za-z_]|$).
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In the whole-line case, we use the pattern:
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^(userpattern)$.
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BUG: Using [A-Za-z_] is locale-dependent! */
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char *n = malloc(size + 50);
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int i = 0;
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strcpy(n, "");
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if (match_lines)
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strcpy(n, "^\\(");
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if (match_words)
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strcpy(n, "\\(^\\|[^0-9A-Za-z_]\\)\\(");
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i = strlen(n);
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bcopy(pattern, n + i, size);
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i += size;
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if (match_words)
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strcpy(n + i, "\\)\\([^0-9A-Za-z_]\\|$\\)");
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if (match_lines)
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strcpy(n + i, "\\)$");
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i += strlen(n + i);
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dfacomp(n, i, &dfa, 1);
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}
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else
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dfacomp(pattern, size, &dfa, 1);
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kwsmusts();
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}
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static void
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Ecompile(pattern, size)
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char *pattern;
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size_t size;
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{
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#ifdef __STDC__
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const
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#endif
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char *err;
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if (strcmp(matcher, "posix-egrep") == 0)
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{
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re_set_syntax(RE_SYNTAX_POSIX_EGREP);
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dfasyntax(RE_SYNTAX_POSIX_EGREP, match_icase);
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}
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else
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{
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re_set_syntax(RE_SYNTAX_EGREP);
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dfasyntax(RE_SYNTAX_EGREP, match_icase);
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}
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if ((err = re_compile_pattern(pattern, size, ®ex)) != 0)
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fatal(err, 0);
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dfainit(&dfa);
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/* In the match_words and match_lines cases, we use a different pattern
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for the DFA matcher that will quickly throw out cases that won't work.
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Then if DFA succeeds we do some hairy stuff using the regex matcher
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to decide whether the match should really count. */
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if (match_words || match_lines)
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{
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/* In the whole-word case, we use the pattern:
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(^|[^A-Za-z_])(userpattern)([^A-Za-z_]|$).
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In the whole-line case, we use the pattern:
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^(userpattern)$.
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BUG: Using [A-Za-z_] is locale-dependent! */
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char *n = malloc(size + 50);
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int i = 0;
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strcpy(n, "");
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if (match_lines)
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strcpy(n, "^(");
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if (match_words)
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strcpy(n, "(^|[^0-9A-Za-z_])(");
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i = strlen(n);
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bcopy(pattern, n + i, size);
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i += size;
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if (match_words)
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strcpy(n + i, ")([^0-9A-Za-z_]|$)");
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if (match_lines)
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strcpy(n + i, ")$");
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i += strlen(n + i);
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dfacomp(n, i, &dfa, 1);
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}
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else
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dfacomp(pattern, size, &dfa, 1);
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kwsmusts();
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}
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static char *
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EGexecute(buf, size, endp)
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char *buf;
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size_t size;
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char **endp;
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{
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register char *buflim, *beg, *end, save;
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int backref, start, len;
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struct kwsmatch kwsm;
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static struct re_registers regs; /* This is static on account of a BRAIN-DEAD
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Q@#%!# library interface in regex.c. */
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buflim = buf + size;
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for (beg = end = buf; end < buflim; beg = end + 1)
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{
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if (kwset)
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{
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/* Find a possible match using the KWset matcher. */
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beg = kwsexec(kwset, beg, buflim - beg, &kwsm);
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if (!beg)
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goto failure;
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/* Narrow down to the line containing the candidate, and
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run it through DFA. */
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end = memchr(beg, '\n', buflim - beg);
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if (!end)
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end = buflim;
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while (beg > buf && beg[-1] != '\n')
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--beg;
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save = *end;
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if (kwsm.index < lastexact)
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goto success;
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if (!dfaexec(&dfa, beg, end, 0, (int *) 0, &backref))
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{
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*end = save;
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continue;
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}
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*end = save;
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/* Successful, no backreferences encountered. */
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if (!backref)
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goto success;
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}
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else
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{
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/* No good fixed strings; start with DFA. */
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save = *buflim;
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beg = dfaexec(&dfa, beg, buflim, 0, (int *) 0, &backref);
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*buflim = save;
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if (!beg)
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goto failure;
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/* Narrow down to the line we've found. */
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end = memchr(beg, '\n', buflim - beg);
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if (!end)
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end = buflim;
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while (beg > buf && beg[-1] != '\n')
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--beg;
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/* Successful, no backreferences encountered! */
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if (!backref)
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goto success;
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}
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/* If we've made it to this point, this means DFA has seen
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a probable match, and we need to run it through Regex. */
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regex.not_eol = 0;
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if ((start = re_search(®ex, beg, end - beg, 0, end - beg, ®s)) >= 0)
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{
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len = regs.end[0] - start;
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if (!match_lines && !match_words || match_lines && len == end - beg)
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goto success;
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/* If -w, check if the match aligns with word boundaries.
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We do this iteratively because:
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(a) the line may contain more than one occurence of the pattern, and
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(b) Several alternatives in the pattern might be valid at a given
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point, and we may need to consider a shorter one to find a word
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boundary. */
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if (match_words)
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while (start >= 0)
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{
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if ((start == 0 || !WCHAR(beg[start - 1]))
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&& (len == end - beg || !WCHAR(beg[start + len])))
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goto success;
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if (len > 0)
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{
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/* Try a shorter length anchored at the same place. */
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--len;
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regex.not_eol = 1;
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len = re_match(®ex, beg, start + len, start, ®s);
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}
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if (len <= 0)
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{
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/* Try looking further on. */
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if (start == end - beg)
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break;
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++start;
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regex.not_eol = 0;
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start = re_search(®ex, beg, end - beg,
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start, end - beg - start, ®s);
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len = regs.end[0] - start;
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}
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}
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}
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}
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failure:
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return 0;
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success:
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*endp = end < buflim ? end + 1 : end;
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return beg;
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}
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static void
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Fcompile(pattern, size)
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char *pattern;
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size_t size;
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{
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char *beg, *lim, *err;
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kwsinit();
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beg = pattern;
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do
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{
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for (lim = beg; lim < pattern + size && *lim != '\n'; ++lim)
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;
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if ((err = kwsincr(kwset, beg, lim - beg)) != 0)
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fatal(err, 0);
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if (lim < pattern + size)
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++lim;
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beg = lim;
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}
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while (beg < pattern + size);
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if ((err = kwsprep(kwset)) != 0)
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fatal(err, 0);
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}
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static char *
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Fexecute(buf, size, endp)
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char *buf;
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size_t size;
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char **endp;
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{
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register char *beg, *try, *end;
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register size_t len;
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struct kwsmatch kwsmatch;
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for (beg = buf; beg <= buf + size; ++beg)
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{
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if (!(beg = kwsexec(kwset, beg, buf + size - beg, &kwsmatch)))
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return 0;
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len = kwsmatch.size[0];
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if (match_lines)
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{
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if (beg > buf && beg[-1] != '\n')
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continue;
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if (beg + len < buf + size && beg[len] != '\n')
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continue;
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goto success;
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}
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else if (match_words)
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for (try = beg; len && try;)
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{
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if (try > buf && WCHAR((unsigned char) try[-1]))
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break;
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if (try + len < buf + size && WCHAR((unsigned char) try[len]))
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{
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try = kwsexec(kwset, beg, --len, &kwsmatch);
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len = kwsmatch.size[0];
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}
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else
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goto success;
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}
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else
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goto success;
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}
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return 0;
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success:
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if ((end = memchr(beg + len, '\n', (buf + size) - (beg + len))) != 0)
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++end;
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else
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end = buf + size;
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*endp = end;
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while (beg > buf && beg[-1] != '\n')
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--beg;
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return beg;
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}
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