/************************************************* * 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 Copyright (c) 1997-2003 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 utf8 TRUE if in UTF-8 mode 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, BOOL utf8, 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 + 1 + LINK_SIZE; 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, utf8, cd)) return FALSE; try_next = FALSE; } else switch(*tcode) { default: return FALSE; /* Skip over callout */ case OP_CALLOUT: tcode += 2; break; /* 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 += GET(tcode, 1); while (*tcode == OP_ALT); tcode += 1+LINK_SIZE; 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, utf8, cd)) return FALSE; dummy = 1; do tcode += GET(tcode,1); while (*tcode == OP_ALT); tcode += 1+LINK_SIZE; 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; #ifdef SUPPORT_UTF8 if (utf8) while ((*tcode & 0xc0) == 0x80) tcode++; #endif 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; #ifdef SUPPORT_UTF8 if (utf8) while ((*tcode & 0xc0) == 0x80) tcode++; #endif 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_ANY: return FALSE; 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 where all the information is in a bit map: set the bits and either carry on or not, according to the repeat count. If it was a negative class, and we are operating with UTF-8 characters, any byte with a value >= 0xc4 is a potentially valid starter because it starts a character with a value > 255. */ case OP_NCLASS: if (utf8) { start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */ memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */ } /* Fall through */ case OP_CLASS: { tcode++; /* In UTF-8 mode, the bits in a bit map correspond to character values, not to byte values. However, the bit map we are constructing is for byte values. So we have to do a conversion for characters whose value is > 127. In fact, there are only two possible starting bytes for characters in the range 128 - 255. */ if (utf8) { for (c = 0; c < 16; c++) start_bits[c] |= tcode[c]; for (c = 128; c < 256; c++) { if ((tcode[c/8] && (1 << (c&7))) != 0) { int d = (c >> 6) | 0xc0; /* Set bit for this starter */ start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */ c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */ } } } /* In non-UTF-8 mode, the two bit maps are completely compatible. */ else { for (c = 0; c < 32; c++) start_bits[c] |= tcode[c]; } /* Advance past the bit map, and act on what follows */ 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 bitmap class handling */ } /* End of switch */ } /* End of try_next loop */ code += GET(code, 1); /* 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, with study_data filled in and the appropriate flag set; NULL on error or if no optimization possible */ EXPORT pcre_extra * _pcre_study(const pcre *external_re, int options, const char **errorptr) { uschar start_bits[32]; pcre_extra *extra; pcre_study_data *study; const real_pcre *re = (const real_pcre *)external_re; uschar *code = (uschar *)re + sizeof(real_pcre) + (re->name_count * re->name_entry_size); 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 unanchored 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(code, start_bits, (re->options & PCRE_CASELESS) != 0, (re->options & PCRE_UTF8) != 0, &compile_block)) return NULL; /* Get a pcre_extra block and a pcre_study_data block. The study data is put in the latter, which is pointed to by the former, which may also get additional data set later by the calling program. At the moment, the size of pcre_study_data is fixed. We nevertheless save it in a field for returning via the pcre_fullinfo() function so that if it becomes variable in the future, we don't have to change that code. */ extra = (pcre_extra *)(g_malloc) (sizeof(pcre_extra) + sizeof(pcre_study_data)); if (extra == NULL) { *errorptr = "failed to get memory"; return NULL; } study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra)); extra->flags = PCRE_EXTRA_STUDY_DATA; extra->study_data = study; study->size = sizeof(pcre_study_data); study->options = PCRE_STUDY_MAPPED; memcpy(study->start_bits, start_bits, sizeof(start_bits)); return extra; } /* End of study.c */