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Diffstat (limited to 'rubbos/app/httpd-2.0.64/srclib/pcre/study.c')
| -rw-r--r-- | rubbos/app/httpd-2.0.64/srclib/pcre/study.c | 401 |
1 files changed, 401 insertions, 0 deletions
diff --git a/rubbos/app/httpd-2.0.64/srclib/pcre/study.c b/rubbos/app/httpd-2.0.64/srclib/pcre/study.c new file mode 100644 index 00000000..f924543d --- /dev/null +++ b/rubbos/app/httpd-2.0.64/srclib/pcre/study.c @@ -0,0 +1,401 @@ +/************************************************* +* Perl-Compatible Regular Expressions * +*************************************************/ + +/* +This is a library of functions to support regular expressions whose syntax +and semantics are as close as possible to those of the Perl 5 language. See +the file Tech.Notes for some information on the internals. + +Written by: Philip Hazel <ph10@cam.ac.uk> + + Copyright (c) 1997-2001 University of Cambridge + +----------------------------------------------------------------------------- +Permission is granted to anyone to use this software for any purpose on any +computer system, and to redistribute it freely, subject to the following +restrictions: + +1. This software is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + +2. The origin of this software must not be misrepresented, either by + explicit claim or by omission. + +3. Altered versions must be plainly marked as such, and must not be + misrepresented as being the original software. + +4. If PCRE is embedded in any software that is released under the GNU + General Purpose Licence (GPL), then the terms of that licence shall + supersede any condition above with which it is incompatible. +----------------------------------------------------------------------------- +*/ + + +/* Include the internals header, which itself includes Standard C headers plus +the external pcre header. */ + +#include "internal.h" + + + +/************************************************* +* Set a bit and maybe its alternate case * +*************************************************/ + +/* Given a character, set its bit in the table, and also the bit for the other +version of a letter if we are caseless. + +Arguments: + start_bits points to the bit map + c is the character + caseless the caseless flag + cd the block with char table pointers + +Returns: nothing +*/ + +static void +set_bit(uschar *start_bits, int c, BOOL caseless, compile_data *cd) +{ +start_bits[c/8] |= (1 << (c&7)); +if (caseless && (cd->ctypes[c] & ctype_letter) != 0) + start_bits[cd->fcc[c]/8] |= (1 << (cd->fcc[c]&7)); +} + + + +/************************************************* +* Create bitmap of starting chars * +*************************************************/ + +/* This function scans a compiled unanchored expression and attempts to build a +bitmap of the set of initial characters. If it can't, it returns FALSE. As time +goes by, we may be able to get more clever at doing this. + +Arguments: + code points to an expression + start_bits points to a 32-byte table, initialized to 0 + caseless the current state of the caseless flag + cd the block with char table pointers + +Returns: TRUE if table built, FALSE otherwise +*/ + +static BOOL +set_start_bits(const uschar *code, uschar *start_bits, BOOL caseless, + compile_data *cd) +{ +register int c; + +/* This next statement and the later reference to dummy are here in order to +trick the optimizer of the IBM C compiler for OS/2 into generating correct +code. Apparently IBM isn't going to fix the problem, and we would rather not +disable optimization (in this module it actually makes a big difference, and +the pcre module can use all the optimization it can get). */ + +volatile int dummy; + +do + { + const uschar *tcode = code + 3; + BOOL try_next = TRUE; + + while (try_next) + { + /* If a branch starts with a bracket or a positive lookahead assertion, + recurse to set bits from within them. That's all for this branch. */ + + if ((int)*tcode >= OP_BRA || *tcode == OP_ASSERT) + { + if (!set_start_bits(tcode, start_bits, caseless, cd)) + return FALSE; + try_next = FALSE; + } + + else switch(*tcode) + { + default: + return FALSE; + + /* Skip over extended extraction bracket number */ + + case OP_BRANUMBER: + tcode += 3; + break; + + /* Skip over lookbehind and negative lookahead assertions */ + + case OP_ASSERT_NOT: + case OP_ASSERTBACK: + case OP_ASSERTBACK_NOT: + do tcode += (tcode[1] << 8) + tcode[2]; while (*tcode == OP_ALT); + tcode += 3; + break; + + /* Skip over an option setting, changing the caseless flag */ + + case OP_OPT: + caseless = (tcode[1] & PCRE_CASELESS) != 0; + tcode += 2; + break; + + /* BRAZERO does the bracket, but carries on. */ + + case OP_BRAZERO: + case OP_BRAMINZERO: + if (!set_start_bits(++tcode, start_bits, caseless, cd)) + return FALSE; + dummy = 1; + do tcode += (tcode[1] << 8) + tcode[2]; while (*tcode == OP_ALT); + tcode += 3; + break; + + /* Single-char * or ? sets the bit and tries the next item */ + + case OP_STAR: + case OP_MINSTAR: + case OP_QUERY: + case OP_MINQUERY: + set_bit(start_bits, tcode[1], caseless, cd); + tcode += 2; + break; + + /* Single-char upto sets the bit and tries the next */ + + case OP_UPTO: + case OP_MINUPTO: + set_bit(start_bits, tcode[3], caseless, cd); + tcode += 4; + break; + + /* At least one single char sets the bit and stops */ + + case OP_EXACT: /* Fall through */ + tcode++; + + case OP_CHARS: /* Fall through */ + tcode++; + + case OP_PLUS: + case OP_MINPLUS: + set_bit(start_bits, tcode[1], caseless, cd); + try_next = FALSE; + break; + + /* Single character type sets the bits and stops */ + + case OP_NOT_DIGIT: + for (c = 0; c < 32; c++) + start_bits[c] |= ~cd->cbits[c+cbit_digit]; + try_next = FALSE; + break; + + case OP_DIGIT: + for (c = 0; c < 32; c++) + start_bits[c] |= cd->cbits[c+cbit_digit]; + try_next = FALSE; + break; + + case OP_NOT_WHITESPACE: + for (c = 0; c < 32; c++) + start_bits[c] |= ~cd->cbits[c+cbit_space]; + try_next = FALSE; + break; + + case OP_WHITESPACE: + for (c = 0; c < 32; c++) + start_bits[c] |= cd->cbits[c+cbit_space]; + try_next = FALSE; + break; + + case OP_NOT_WORDCHAR: + for (c = 0; c < 32; c++) + start_bits[c] |= ~cd->cbits[c+cbit_word]; + try_next = FALSE; + break; + + case OP_WORDCHAR: + for (c = 0; c < 32; c++) + start_bits[c] |= cd->cbits[c+cbit_word]; + try_next = FALSE; + break; + + /* One or more character type fudges the pointer and restarts, knowing + it will hit a single character type and stop there. */ + + case OP_TYPEPLUS: + case OP_TYPEMINPLUS: + tcode++; + break; + + case OP_TYPEEXACT: + tcode += 3; + break; + + /* Zero or more repeats of character types set the bits and then + try again. */ + + case OP_TYPEUPTO: + case OP_TYPEMINUPTO: + tcode += 2; /* Fall through */ + + case OP_TYPESTAR: + case OP_TYPEMINSTAR: + case OP_TYPEQUERY: + case OP_TYPEMINQUERY: + switch(tcode[1]) + { + case OP_NOT_DIGIT: + for (c = 0; c < 32; c++) + start_bits[c] |= ~cd->cbits[c+cbit_digit]; + break; + + case OP_DIGIT: + for (c = 0; c < 32; c++) + start_bits[c] |= cd->cbits[c+cbit_digit]; + break; + + case OP_NOT_WHITESPACE: + for (c = 0; c < 32; c++) + start_bits[c] |= ~cd->cbits[c+cbit_space]; + break; + + case OP_WHITESPACE: + for (c = 0; c < 32; c++) + start_bits[c] |= cd->cbits[c+cbit_space]; + break; + + case OP_NOT_WORDCHAR: + for (c = 0; c < 32; c++) + start_bits[c] |= ~cd->cbits[c+cbit_word]; + break; + + case OP_WORDCHAR: + for (c = 0; c < 32; c++) + start_bits[c] |= cd->cbits[c+cbit_word]; + break; + } + + tcode += 2; + break; + + /* Character class: set the bits and either carry on or not, + according to the repeat count. */ + + case OP_CLASS: + { + tcode++; + for (c = 0; c < 32; c++) start_bits[c] |= tcode[c]; + tcode += 32; + switch (*tcode) + { + case OP_CRSTAR: + case OP_CRMINSTAR: + case OP_CRQUERY: + case OP_CRMINQUERY: + tcode++; + break; + + case OP_CRRANGE: + case OP_CRMINRANGE: + if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5; + else try_next = FALSE; + break; + + default: + try_next = FALSE; + break; + } + } + break; /* End of class handling */ + + } /* End of switch */ + } /* End of try_next loop */ + + code += (code[1] << 8) + code[2]; /* Advance to next branch */ + } +while (*code == OP_ALT); +return TRUE; +} + + + +/************************************************* +* Study a compiled expression * +*************************************************/ + +/* This function is handed a compiled expression that it must study to produce +information that will speed up the matching. It returns a pcre_extra block +which then gets handed back to pcre_exec(). + +Arguments: + re points to the compiled expression + options contains option bits + errorptr points to where to place error messages; + set NULL unless error + +Returns: pointer to a pcre_extra block, + NULL on error or if no optimization possible +*/ + +pcre_extra * +pcre_study(const pcre *external_re, int options, const char **errorptr) +{ +uschar start_bits[32]; +real_pcre_extra *extra; +const real_pcre *re = (const real_pcre *)external_re; +compile_data compile_block; + +*errorptr = NULL; + +if (re == NULL || re->magic_number != MAGIC_NUMBER) + { + *errorptr = "argument is not a compiled regular expression"; + return NULL; + } + +if ((options & ~PUBLIC_STUDY_OPTIONS) != 0) + { + *errorptr = "unknown or incorrect option bit(s) set"; + return NULL; + } + +/* For an anchored pattern, or an unchored pattern that has a first char, or a +multiline pattern that matches only at "line starts", no further processing at +present. */ + +if ((re->options & (PCRE_ANCHORED|PCRE_FIRSTSET|PCRE_STARTLINE)) != 0) + return NULL; + +/* Set the character tables in the block which is passed around */ + +compile_block.lcc = re->tables + lcc_offset; +compile_block.fcc = re->tables + fcc_offset; +compile_block.cbits = re->tables + cbits_offset; +compile_block.ctypes = re->tables + ctypes_offset; + +/* See if we can find a fixed set of initial characters for the pattern. */ + +memset(start_bits, 0, 32 * sizeof(uschar)); +if (!set_start_bits(re->code, start_bits, (re->options & PCRE_CASELESS) != 0, + &compile_block)) return NULL; + +/* Get an "extra" block and put the information therein. */ + +extra = (real_pcre_extra *)(pcre_malloc)(sizeof(real_pcre_extra)); + +if (extra == NULL) + { + *errorptr = "failed to get memory"; + return NULL; + } + +extra->options = PCRE_STUDY_MAPPED; +memcpy(extra->start_bits, start_bits, sizeof(start_bits)); + +return (pcre_extra *)extra; +} + +/* End of study.c */ |