src/pcre2posix.c

/*************************************************
*      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
     Original API code Copyright (c) 1997-2012 University of Cambridge
          New API code Copyright (c) 2016-2021 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 is a wrapper that provides a POSIX API to the underlying PCRE2
functions. The operative functions are called pcre2_regcomp(), etc., with
wrappers that use the plain POSIX names. In addition, pcre2posix.h defines the
POSIX names as macros for the pcre2_xxx functions, so any program that includes
it and uses the POSIX names will call the base functions directly. This makes
it easier for an application to be sure it gets the PCRE2 versions in the
presence of other POSIX regex libraries. */


#ifdef HAVE_CONFIG_H
#include "config.h"
#endif


/* Ensure that the PCRE2POSIX_EXP_xxx macros are set appropriately for
compiling these functions. This must come before including pcre2posix.h, where
they are set for an application (using these functions) if they have not
previously been set. */

#if defined(_WIN32) && !defined(PCRE2_STATIC)
#  define PCRE2POSIX_EXP_DECL extern __declspec(dllexport)
#  define PCRE2POSIX_EXP_DEFN __declspec(dllexport)
#endif

/* Older versions of MSVC lack snprintf(). This define allows for
warning/error-free compilation and testing with MSVC compilers back to at least
MSVC 10/2010. Except for VC6 (which is missing some fundamentals and fails). */

#if defined(_MSC_VER) && (_MSC_VER < 1900)
#define snprintf _snprintf
#endif


/* Compile-time error numbers start at this value. It should probably never be
changed. This #define is a copy of the one in pcre2_internal.h. */

#define COMPILE_ERROR_BASE 100


/* Standard C headers */

#include <ctype.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* PCRE2 headers */

#include "pcre2.h"
#include "pcre2posix.h"

/* When compiling with the MSVC compiler, it is sometimes necessary to include
a "calling convention" before exported function names. (This is secondhand
information; I know nothing about MSVC myself). For example, something like

  void __cdecl function(....)

might be needed. In order to make this easy, all the exported functions have
PCRE2_CALL_CONVENTION just before their names. It is rarely needed; if not
set, we ensure here that it has no effect. */

#ifndef PCRE2_CALL_CONVENTION
#define PCRE2_CALL_CONVENTION
#endif

/* Table to translate PCRE2 compile time error codes into POSIX error codes.
Only a few PCRE2 errors with a value greater than 23 turn into special POSIX
codes: most go to REG_BADPAT. The second table lists, in pairs, those that
don't. */

static const int eint1[] = {
  0,           /* No error */
  REG_EESCAPE, /* \ at end of pattern */
  REG_EESCAPE, /* \c at end of pattern */
  REG_EESCAPE, /* unrecognized character follows \ */
  REG_BADBR,   /* numbers out of order in {} quantifier */
  /* 5 */
  REG_BADBR,   /* number too big in {} quantifier */
  REG_EBRACK,  /* missing terminating ] for character class */
  REG_ECTYPE,  /* invalid escape sequence in character class */
  REG_ERANGE,  /* range out of order in character class */
  REG_BADRPT,  /* nothing to repeat */
  /* 10 */
  REG_ASSERT,  /* internal error: unexpected repeat */
  REG_BADPAT,  /* unrecognized character after (? or (?- */
  REG_BADPAT,  /* POSIX named classes are supported only within a class */
  REG_BADPAT,  /* POSIX collating elements are not supported */
  REG_EPAREN,  /* missing ) */
  /* 15 */
  REG_ESUBREG, /* reference to non-existent subpattern */
  REG_INVARG,  /* pattern passed as NULL */
  REG_INVARG,  /* unknown compile-time option bit(s) */
  REG_EPAREN,  /* missing ) after (?# comment */
  REG_ESIZE,   /* parentheses nested too deeply */
  /* 20 */
  REG_ESIZE,   /* regular expression too large */
  REG_ESPACE,  /* failed to get memory */
  REG_EPAREN,  /* unmatched closing parenthesis */
  REG_ASSERT   /* internal error: code overflow */
  };

static const int eint2[] = {
  30, REG_ECTYPE,  /* unknown POSIX class name */
  32, REG_INVARG,  /* this version of PCRE2 does not have Unicode support */
  37, REG_EESCAPE, /* PCRE2 does not support \L, \l, \N{name}, \U, or \u */
  56, REG_INVARG,  /* internal error: unknown newline setting */
  92, REG_INVARG,  /* invalid option bits with PCRE2_LITERAL */
  99, REG_EESCAPE  /* \K in lookaround */
};

/* Table of texts corresponding to POSIX error codes */

static const char *const pstring[] = {
  "",                                /* Dummy for value 0 */
  "internal error",                  /* REG_ASSERT */
  "invalid repeat counts in {}",     /* BADBR      */
  "pattern error",                   /* BADPAT     */
  "? * + invalid",                   /* BADRPT     */
  "unbalanced {}",                   /* EBRACE     */
  "unbalanced []",                   /* EBRACK     */
  "collation error - not relevant",  /* ECOLLATE   */
  "bad class",                       /* ECTYPE     */
  "bad escape sequence",             /* EESCAPE    */
  "empty expression",                /* EMPTY      */
  "unbalanced ()",                   /* EPAREN     */
  "bad range inside []",             /* ERANGE     */
  "expression too big",              /* ESIZE      */
  "failed to get memory",            /* ESPACE     */
  "bad back reference",              /* ESUBREG    */
  "bad argument",                    /* INVARG     */
  "match failed"                     /* NOMATCH    */
};



#if 0  /* REMOVE THIS CODE */

The code below was created for 10.33 (see ChangeLog 10.33 #4) when the
POSIX functions were given pcre2_... names instead of the traditional POSIX
names. However, it has proved to be more troublesome than useful. There have
been at least two cases where a program links with two others, one of which
uses the POSIX library and the other uses the PCRE2 POSIX functions, thus
causing two instances of the POSIX runctions to exist, leading to trouble. For
10.37 this code is commented out. In due course it can be removed if there are
no issues. The only small worry is the comment below about languages that do
not include pcre2posix.h. If there are any such cases, they will have to use
the PCRE2 names.


/*************************************************
*      Wrappers with traditional POSIX names     *
*************************************************/

/* Keep defining them to preseve the ABI for applications linked to the pcre2
POSIX library before these names were changed into macros in pcre2posix.h.
This also ensures that the POSIX names are callable from languages that do not
include pcre2posix.h. It is vital to #undef the macro definitions from
pcre2posix.h! */

#undef regerror
PCRE2POSIX_EXP_DECL size_t regerror(int, const regex_t *, char *, size_t);
PCRE2POSIX_EXP_DEFN size_t PCRE2_CALL_CONVENTION
regerror(int errcode, const regex_t *preg, char *errbuf, size_t errbuf_size)
{
return pcre2_regerror(errcode, preg, errbuf, errbuf_size);
}

#undef regfree
PCRE2POSIX_EXP_DECL void regfree(regex_t *);
PCRE2POSIX_EXP_DEFN void PCRE2_CALL_CONVENTION
regfree(regex_t *preg)
{
pcre2_regfree(preg);
}

#undef regcomp
PCRE2POSIX_EXP_DECL int regcomp(regex_t *, const char *, int);
PCRE2POSIX_EXP_DEFN int PCRE2_CALL_CONVENTION
regcomp(regex_t *preg, const char *pattern, int cflags)
{
return pcre2_regcomp(preg, pattern, cflags);
}

#undef regexec
PCRE2POSIX_EXP_DECL int regexec(const regex_t *, const char *, size_t,
  regmatch_t *, int);
PCRE2POSIX_EXP_DEFN int PCRE2_CALL_CONVENTION
regexec(const regex_t *preg, const char *string, size_t nmatch,
  regmatch_t pmatch[], int eflags)
{
return pcre2_regexec(preg, string, nmatch, pmatch, eflags);
}
#endif


/*************************************************
*          Translate error code to string        *
*************************************************/

PCRE2POSIX_EXP_DEFN size_t PCRE2_CALL_CONVENTION
pcre2_regerror(int errcode, const regex_t *preg, char *errbuf,
  size_t errbuf_size)
{
int used;
const char *message;

message = (errcode <= 0 || errcode >= (int)(sizeof(pstring)/sizeof(char *)))?
  "unknown error code" : pstring[errcode];

if (preg != NULL && (int)preg->re_erroffset != -1)
  {
  used = snprintf(errbuf, errbuf_size, "%s at offset %-6d", message,
    (int)preg->re_erroffset);
  }
else
  {
  used = snprintf(errbuf, errbuf_size, "%s", message);
  }

return used + 1;
}



/*************************************************
*           Free store held by a regex           *
*************************************************/

PCRE2POSIX_EXP_DEFN void PCRE2_CALL_CONVENTION
pcre2_regfree(regex_t *preg)
{
pcre2_match_data_free(preg->re_match_data);
pcre2_code_free(preg->re_pcre2_code);
}



/*************************************************
*            Compile a regular expression        *
*************************************************/

/*
Arguments:
  preg        points to a structure for recording the compiled expression
  pattern     the pattern to compile
  cflags      compilation flags

Returns:      0 on success
              various non-zero codes on failure
*/

PCRE2POSIX_EXP_DEFN int PCRE2_CALL_CONVENTION
pcre2_regcomp(regex_t *preg, const char *pattern, int cflags)
{
PCRE2_SIZE erroffset;
PCRE2_SIZE patlen;
int errorcode;
int options = 0;
int re_nsub = 0;

patlen = ((cflags & REG_PEND) != 0)? (PCRE2_SIZE)(preg->re_endp - pattern) :
  PCRE2_ZERO_TERMINATED;

if ((cflags & REG_ICASE) != 0)    options |= PCRE2_CASELESS;
if ((cflags & REG_NEWLINE) != 0)  options |= PCRE2_MULTILINE;
if ((cflags & REG_DOTALL) != 0)   options |= PCRE2_DOTALL;
if ((cflags & REG_NOSPEC) != 0)   options |= PCRE2_LITERAL;
if ((cflags & REG_UTF) != 0)      options |= PCRE2_UTF;
if ((cflags & REG_UCP) != 0)      options |= PCRE2_UCP;
if ((cflags & REG_UNGREEDY) != 0) options |= PCRE2_UNGREEDY;

preg->re_cflags = cflags;
preg->re_pcre2_code = pcre2_compile((PCRE2_SPTR)pattern, patlen, options,
  &errorcode, &erroffset, NULL);
preg->re_erroffset = erroffset;

if (preg->re_pcre2_code == NULL)
  {
  unsigned int i;

  /* A negative value is a UTF error; otherwise all error codes are greater
  than COMPILE_ERROR_BASE, but check, just in case. */

  if (errorcode < COMPILE_ERROR_BASE) return REG_BADPAT;
  errorcode -= COMPILE_ERROR_BASE;

  if (errorcode < (int)(sizeof(eint1)/sizeof(const int)))
    return eint1[errorcode];
  for (i = 0; i < sizeof(eint2)/sizeof(const int); i += 2)
    if (errorcode == eint2[i]) return eint2[i+1];
  return REG_BADPAT;
  }

(void)pcre2_pattern_info((const pcre2_code *)preg->re_pcre2_code,
  PCRE2_INFO_CAPTURECOUNT, &re_nsub);
preg->re_nsub = (size_t)re_nsub;
preg->re_match_data = pcre2_match_data_create(re_nsub + 1, NULL);
preg->re_erroffset = (size_t)(-1);  /* No meaning after successful compile */

if (preg->re_match_data == NULL)
  {
  pcre2_code_free(preg->re_pcre2_code);
  return REG_ESPACE;
  }

return 0;
}



/*************************************************
*              Match a regular expression        *
*************************************************/

/* A suitable match_data block, large enough to hold all possible captures, was
obtained when the pattern was compiled, to save having to allocate and free it
for each match. If REG_NOSUB was specified at compile time, the nmatch and
pmatch arguments are ignored, and the only result is yes/no/error. */

PCRE2POSIX_EXP_DEFN int PCRE2_CALL_CONVENTION
pcre2_regexec(const regex_t *preg, const char *string, size_t nmatch,
  regmatch_t pmatch[], int eflags)
{
int rc, so, eo;
int options = 0;
pcre2_match_data *md = (pcre2_match_data *)preg->re_match_data;

if (string == NULL) return REG_INVARG;

if ((eflags & REG_NOTBOL) != 0) options |= PCRE2_NOTBOL;
if ((eflags & REG_NOTEOL) != 0) options |= PCRE2_NOTEOL;
if ((eflags & REG_NOTEMPTY) != 0) options |= PCRE2_NOTEMPTY;

/* When REG_NOSUB was specified, or if no vector has been passed in which to
put captured strings, ensure that nmatch is zero. This will stop any attempt to
write to pmatch. */

if ((preg->re_cflags & REG_NOSUB) != 0 || pmatch == NULL) nmatch = 0;

/* REG_STARTEND is a BSD extension, to allow for non-NUL-terminated strings.
The man page from OS X says "REG_STARTEND affects only the location of the
string, not how it is matched". That is why the "so" value is used to bump the
start location rather than being passed as a PCRE2 "starting offset". */

if ((eflags & REG_STARTEND) != 0)
  {
  if (pmatch == NULL) return REG_INVARG;
  so = pmatch[0].rm_so;
  eo = pmatch[0].rm_eo;
  }
else
  {
  so = 0;
  eo = (int)strlen(string);
  }

rc = pcre2_match((const pcre2_code *)preg->re_pcre2_code,
  (PCRE2_SPTR)string + so, (eo - so), 0, options, md, NULL);

/* Successful match */

if (rc >= 0)
  {
  size_t i;
  PCRE2_SIZE *ovector = pcre2_get_ovector_pointer(md);
  if ((size_t)rc > nmatch) rc = (int)nmatch;
  for (i = 0; i < (size_t)rc; i++)
    {
    pmatch[i].rm_so = (ovector[i*2] == PCRE2_UNSET)? -1 :
      (int)(ovector[i*2] + so);
    pmatch[i].rm_eo = (ovector[i*2+1] == PCRE2_UNSET)? -1 :
      (int)(ovector[i*2+1] + so);
    }
  for (; i < nmatch; i++) pmatch[i].rm_so = pmatch[i].rm_eo = -1;
  return 0;
  }

/* Unsuccessful match */

if (rc <= PCRE2_ERROR_UTF8_ERR1 && rc >= PCRE2_ERROR_UTF8_ERR21)
  return REG_INVARG;

switch(rc)
  {
  default: return REG_ASSERT;
  case PCRE2_ERROR_BADMODE: return REG_INVARG;
  case PCRE2_ERROR_BADMAGIC: return REG_INVARG;
  case PCRE2_ERROR_BADOPTION: return REG_INVARG;
  case PCRE2_ERROR_BADUTFOFFSET: return REG_INVARG;
  case PCRE2_ERROR_MATCHLIMIT: return REG_ESPACE;
  case PCRE2_ERROR_NOMATCH: return REG_NOMATCH;
  case PCRE2_ERROR_NOMEMORY: return REG_ESPACE;
  case PCRE2_ERROR_NULL: return REG_INVARG;
  }
}

/* End of pcre2posix.c */