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Diffstat (limited to 'erts/emulator/pcre/pcre_study.c')
| -rw-r--r-- | erts/emulator/pcre/pcre_study.c | 580 |
1 files changed, 580 insertions, 0 deletions
diff --git a/erts/emulator/pcre/pcre_study.c b/erts/emulator/pcre/pcre_study.c new file mode 100644 index 0000000000..25bd6bde07 --- /dev/null +++ b/erts/emulator/pcre/pcre_study.c @@ -0,0 +1,580 @@ +/************************************************* +* Perl-Compatible Regular Expressions * +*************************************************/ + +/* PCRE 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. + + Written by Philip Hazel + Copyright (c) 1997-2008 University of Cambridge + +----------------------------------------------------------------------------- +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + * Redistributions of source code must retain the above copyright notice, + this list of conditions and the following disclaimer. + + * Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in the + documentation and/or other materials provided with the distribution. + + * Neither the name of the University of Cambridge nor the names of its + contributors may be used to endorse or promote products derived from + this software without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +POSSIBILITY OF SUCH DAMAGE. +----------------------------------------------------------------------------- +*/ + + +/* This module contains the external function erts_pcre_study(), along with local +supporting functions. */ + +/* %ExternalCopyright% */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "pcre_internal.h" + + +/* Returns from set_start_bits() */ + +enum { SSB_FAIL, SSB_DONE, SSB_CONTINUE }; + + +/************************************************* +* 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, unsigned 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 bytes * +*************************************************/ + +/* This function scans a compiled unanchored expression recursively and +attempts to build a bitmap of the set of possible starting bytes. As time goes +by, we may be able to get more clever at doing this. The SSB_CONTINUE return is +useful for parenthesized groups in patterns such as (a*)b where the group +provides some optional starting bytes but scanning must continue at the outer +level to find at least one mandatory byte. At the outermost level, this +function fails unless the result is SSB_DONE. + +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: SSB_FAIL => Failed to find any starting bytes + SSB_DONE => Found mandatory starting bytes + SSB_CONTINUE => Found optional starting bytes +*/ + +static int +set_start_bits(const uschar *code, uschar *start_bits, BOOL caseless, + BOOL utf8, compile_data *cd) +{ +register int c; +int yield = SSB_DONE; + +#if 0 +/* ========================================================================= */ +/* The following comment and code was inserted in January 1999. In May 2006, +when it was observed to cause compiler warnings about unused values, I took it +out again. If anybody is still using OS/2, they will have to put it back +manually. */ + +/* 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; +/* ========================================================================= */ +#endif + +do + { + const uschar *tcode = code + (((int)*code == OP_CBRA)? 3:1) + LINK_SIZE; + BOOL try_next = TRUE; + + while (try_next) /* Loop for items in this branch */ + { + int rc; + switch(*tcode) + { + /* Fail if we reach something we don't understand */ + + default: + return SSB_FAIL; + + /* If we hit a bracket or a positive lookahead assertion, recurse to set + bits from within the subpattern. If it can't find anything, we have to + give up. If it finds some mandatory character(s), we are done for this + branch. Otherwise, carry on scanning after the subpattern. */ + + case OP_BRA: + case OP_SBRA: + case OP_CBRA: + case OP_SCBRA: + case OP_ONCE: + case OP_ASSERT: + rc = set_start_bits(tcode, start_bits, caseless, utf8, cd); + if (rc == SSB_FAIL) return SSB_FAIL; + if (rc == SSB_DONE) try_next = FALSE; else + { + do tcode += GET(tcode, 1); while (*tcode == OP_ALT); + tcode += 1 + LINK_SIZE; + } + break; + + /* If we hit ALT or KET, it means we haven't found anything mandatory in + this branch, though we might have found something optional. For ALT, we + continue with the next alternative, but we have to arrange that the final + result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET, + return SSB_CONTINUE: if this is the top level, that indicates failure, + but after a nested subpattern, it causes scanning to continue. */ + + case OP_ALT: + yield = SSB_CONTINUE; + try_next = FALSE; + break; + + case OP_KET: + case OP_KETRMAX: + case OP_KETRMIN: + return SSB_CONTINUE; + + /* Skip over callout */ + + case OP_CALLOUT: + tcode += 2 + 2*LINK_SIZE; + 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) == SSB_FAIL) + return SSB_FAIL; +/* ========================================================================= + See the comment at the head of this function concerning the next line, + which was an old fudge for the benefit of OS/2. + 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_POSSTAR: + case OP_QUERY: + case OP_MINQUERY: + case OP_POSQUERY: + set_bit(start_bits, tcode[1], caseless, cd); + tcode += 2; +#ifdef SUPPORT_UTF8 + if (utf8 && tcode[-1] >= 0xc0) + tcode += _erts_pcre_utf8_table4[tcode[-1] & 0x3f]; +#endif + break; + + /* Single-char upto sets the bit and tries the next */ + + case OP_UPTO: + case OP_MINUPTO: + case OP_POSUPTO: + set_bit(start_bits, tcode[3], caseless, cd); + tcode += 4; +#ifdef SUPPORT_UTF8 + if (utf8 && tcode[-1] >= 0xc0) + tcode += _erts_pcre_utf8_table4[tcode[-1] & 0x3f]; +#endif + break; + + /* At least one single char sets the bit and stops */ + + case OP_EXACT: /* Fall through */ + tcode += 2; + + case OP_CHAR: + case OP_CHARNC: + case OP_PLUS: + case OP_MINPLUS: + case OP_POSPLUS: + 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; + + /* The cbit_space table has vertical tab as whitespace; we have to + discard it. */ + + case OP_NOT_WHITESPACE: + for (c = 0; c < 32; c++) + { + int d = cd->cbits[c+cbit_space]; + if (c == 1) d &= ~0x08; + start_bits[c] |= ~d; + } + try_next = FALSE; + break; + + /* The cbit_space table has vertical tab as whitespace; we have to + discard it. */ + + case OP_WHITESPACE: + for (c = 0; c < 32; c++) + { + int d = cd->cbits[c+cbit_space]; + if (c == 1) d &= ~0x08; + start_bits[c] |= d; + } + 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: + case OP_TYPEPOSUPTO: + tcode += 2; /* Fall through */ + + case OP_TYPESTAR: + case OP_TYPEMINSTAR: + case OP_TYPEPOSSTAR: + case OP_TYPEQUERY: + case OP_TYPEMINQUERY: + case OP_TYPEPOSQUERY: + switch(tcode[1]) + { + case OP_ANY: + return SSB_FAIL; + + 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; + + /* The cbit_space table has vertical tab as whitespace; we have to + discard it. */ + + case OP_NOT_WHITESPACE: + for (c = 0; c < 32; c++) + { + int d = cd->cbits[c+cbit_space]; + if (c == 1) d &= ~0x08; + start_bits[c] |= ~d; + } + break; + + /* The cbit_space table has vertical tab as whitespace; we have to + discard it. */ + + case OP_WHITESPACE: + for (c = 0; c < 32; c++) + { + int d = cd->cbits[c+cbit_space]; + if (c == 1) d &= ~0x08; + start_bits[c] |= d; + } + 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: +#ifdef SUPPORT_UTF8 + if (utf8) + { + start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */ + memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */ + } +#endif + /* 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. */ + +#ifdef SUPPORT_UTF8 + 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 +#endif + { + 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 yield; +} + + + +/************************************************* +* 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 +*/ + +PCRE_EXP_DEFN pcre_extra * +erts_pcre_study(const pcre *external_re, int options, const char **errorptr) +{ +uschar start_bits[32]; +pcre_extra *extra; +pcre_study_data *study; +const uschar *tables; +uschar *code; +compile_data compile_block; +const real_pcre *re = (const real_pcre *)external_re; + +*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; + } + +code = (uschar *)re + re->name_table_offset + + (re->name_count * re->name_entry_size); + +/* 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) != 0 || + (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) != 0) + return NULL; + +/* Set the character tables in the block that is passed around */ + +tables = re->tables; +if (tables == NULL) + (void)erts_pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES, + (void *)(&tables)); + +compile_block.lcc = tables + lcc_offset; +compile_block.fcc = tables + fcc_offset; +compile_block.cbits = tables + cbits_offset; +compile_block.ctypes = 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) != SSB_DONE) 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 erts_pcre_fullinfo() function so that if it becomes variable in the future, we +don't have to change that code. */ + +extra = (pcre_extra *)(erts_pcre_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 pcre_study.c */ |