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revision 553 by ph10, Fri Oct 22 15:57:50 2010 UTC revision 691 by ph10, Sun Sep 11 14:31:21 2011 UTC
# Line 1  Line 1 
1  .TH PCREAPI 3  .TH PCREAPI 3
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .SH "PCRE NATIVE API"  .SH "PCRE NATIVE API BASIC FUNCTIONS"
5  .rs  .rs
6  .sp  .sp
7  .B #include <pcre.h>  .B #include <pcre.h>
# Line 25  PCRE - Perl-compatible regular expressio Line 25  PCRE - Perl-compatible regular expressio
25  .ti +5n  .ti +5n
26  .B const char **\fIerrptr\fP);  .B const char **\fIerrptr\fP);
27  .PP  .PP
28    .B void pcre_free_study(pcre_extra *\fIextra\fP);
29    .PP
30  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
31  .ti +5n  .ti +5n
32  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
33  .ti +5n  .ti +5n
34  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
35    .
36    .
37    .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
38    .rs
39    .sp
40    .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
41    .PP
42    .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
43    .PP
44    .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
45    .ti +5n
46    .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
47  .PP  .PP
48  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
49  .ti +5n  .ti +5n
# Line 97  PCRE - Perl-compatible regular expressio Line 111  PCRE - Perl-compatible regular expressio
111  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
112  .PP  .PP
113  .B char *pcre_version(void);  .B char *pcre_version(void);
114  .PP  .
115    .
116    .SH "PCRE NATIVE API INDIRECTED FUNCTIONS"
117    .rs
118    .sp
119  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
120  .PP  .PP
121  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
# Line 114  PCRE - Perl-compatible regular expressio Line 132  PCRE - Perl-compatible regular expressio
132  .sp  .sp
133  PCRE has its own native API, which is described in this document. There are  PCRE has its own native API, which is described in this document. There are
134  also some wrapper functions that correspond to the POSIX regular expression  also some wrapper functions that correspond to the POSIX regular expression
135  API. These are described in the  API, but they do not give access to all the functionality. They are described
136    in the
137  .\" HREF  .\" HREF
138  \fBpcreposix\fP  \fBpcreposix\fP
139  .\"  .\"
140  documentation. Both of these APIs define a set of C function calls. A C++  documentation. Both of these APIs define a set of C function calls. A C++
141  wrapper is distributed with PCRE. It is documented in the  wrapper is also distributed with PCRE. It is documented in the
142  .\" HREF  .\" HREF
143  \fBpcrecpp\fP  \fBpcrecpp\fP
144  .\"  .\"
# Line 152  documentation, and the Line 171  documentation, and the
171  .\"  .\"
172  documentation describes how to compile and run it.  documentation describes how to compile and run it.
173  .P  .P
174    Just-in-time compiler support is an optional feature of PCRE that can be built
175    in appropriate hardware environments. It greatly speeds up the matching
176    performance of many patterns. Simple programs can easily request that it be
177    used if available, by setting an option that is ignored when it is not
178    relevant. More complicated programs might need to make use of the functions
179    \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
180    \fBpcre_assign_jit_stack()\fP in order to control the JIT code's memory usage.
181    These functions are discussed in the
182    .\" HREF
183    \fBpcrejit\fP
184    .\"
185    documentation.
186    .P
187  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
188  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
189  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
# Line 282  callout function pointed to by \fBpcre_c Line 314  callout function pointed to by \fBpcre_c
314  .P  .P
315  The compiled form of a regular expression is not altered during matching, so  The compiled form of a regular expression is not altered during matching, so
316  the same compiled pattern can safely be used by several threads at once.  the same compiled pattern can safely be used by several threads at once.
317    .P
318    If the just-in-time optimization feature is being used, it needs separate
319    memory stack areas for each thread. See the
320    .\" HREF
321    \fBpcrejit\fP
322    .\"
323    documentation for more details.
324  .  .
325  .  .
326  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
# Line 324  otherwise it is set to zero. Line 363  otherwise it is set to zero.
363  The output is an integer that is set to one if support for Unicode character  The output is an integer that is set to one if support for Unicode character
364  properties is available; otherwise it is set to zero.  properties is available; otherwise it is set to zero.
365  .sp  .sp
366      PCRE_CONFIG_JIT
367    .sp
368    The output is an integer that is set to one if support for just-in-time
369    compiling is available; otherwise it is set to zero.
370    .sp
371    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
372  .sp  .sp
373  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
# Line 428  within the pattern (see the detailed des Line 472  within the pattern (see the detailed des
472  documentation). For those options that can be different in different parts of  documentation). For those options that can be different in different parts of
473  the pattern, the contents of the \fIoptions\fP argument specifies their  the pattern, the contents of the \fIoptions\fP argument specifies their
474  settings at the start of compilation and execution. The PCRE_ANCHORED,  settings at the start of compilation and execution. The PCRE_ANCHORED,
475  PCRE_BSR_\fIxxx\fP, and PCRE_NEWLINE_\fIxxx\fP options can be set at the time  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
476  of matching as well as at compile time.  PCRE_NO_START_OPT options can be set at the time of matching as well as at
477    compile time.
478  .P  .P
479  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
480  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
481  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
482  error message. This is a static string that is part of the library. You must  error message. This is a static string that is part of the library. You must
483  not try to free it. The byte offset from the start of the pattern to the  not try to free it. Normally, the offset from the start of the pattern to the
484  character that was being processed when the error was discovered is placed in  byte that was being processed when the error was discovered is placed in the
485  the variable pointed to by \fIerroffset\fP, which must not be NULL. If it is,  variable pointed to by \fIerroffset\fP, which must not be NULL (if it is, an
486  an immediate error is given. Some errors are not detected until checks are  immediate error is given). However, for an invalid UTF-8 string, the offset is
487  carried out when the whole pattern has been scanned; in this case the offset is  that of the first byte of the failing character. Also, some errors are not
488  set to the end of the pattern.  detected until checks are carried out when the whole pattern has been scanned;
489    in these cases the offset passed back is the length of the pattern.
490    .P
491    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
492    sometimes point into the middle of a UTF-8 character.
493  .P  .P
494  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
495  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
# Line 519  pattern. Line 568  pattern.
568  .sp  .sp
569    PCRE_DOTALL    PCRE_DOTALL
570  .sp  .sp
571  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharacter in the pattern matches a character of
572  including those that indicate newline. Without it, a dot does not match when  any value, including one that indicates a newline. However, it only ever
573  the current position is at a newline. This option is equivalent to Perl's /s  matches one character, even if newlines are coded as CRLF. Without this option,
574  option, and it can be changed within a pattern by a (?s) option setting. A  a dot does not match when the current position is at a newline. This option is
575  negative class such as [^a] always matches newline characters, independent of  equivalent to Perl's /s option, and it can be changed within a pattern by a
576  the setting of this option.  (?s) option setting. A negative class such as [^a] always matches newline
577    characters, independent of the setting of this option.
578  .sp  .sp
579    PCRE_DUPNAMES    PCRE_DUPNAMES
580  .sp  .sp
# Line 546  unescaped # outside a character class an Line 596  unescaped # outside a character class an
596  ignored. This is equivalent to Perl's /x option, and it can be changed within a  ignored. This is equivalent to Perl's /x option, and it can be changed within a
597  pattern by a (?x) option setting.  pattern by a (?x) option setting.
598  .P  .P
599    Which characters are interpreted as newlines is controlled by the options
600    passed to \fBpcre_compile()\fP or by a special sequence at the start of the
601    pattern, as described in the section entitled
602    .\" HTML <a href="pcrepattern.html#newlines">
603    .\" </a>
604    "Newline conventions"
605    .\"
606    in the \fBpcrepattern\fP documentation. Note that the end of this type of
607    comment is a literal newline sequence in the pattern; escape sequences that
608    happen to represent a newline do not count.
609    .P
610  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
611  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
612  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
613  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
614  .sp  .sp
615    PCRE_EXTRA    PCRE_EXTRA
616  .sp  .sp
# Line 624  option, the combination may or may not b Line 685  option, the combination may or may not b
685  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
686  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
687  .P  .P
688  The only time that a line break is specially recognized when compiling a  The only time that a line break in a pattern is specially recognized when
689  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character  compiling is when PCRE_EXTENDED is set. CR and LF are whitespace characters,
690  class is encountered. This indicates a comment that lasts until after the next  and so are ignored in this mode. Also, an unescaped # outside a character class
691  line break sequence. In other circumstances, line break sequences are treated  indicates a comment that lasts until after the next line break sequence. In
692  as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated  other circumstances, line break sequences in patterns are treated as literal
693  as whitespace characters and are therefore ignored.  data.
694  .P  .P
695  The newline option that is set at compile time becomes the default that is used  The newline option that is set at compile time becomes the default that is used
696  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
# Line 642  were followed by ?: but named parenthese Line 703  were followed by ?: but named parenthese
703  they acquire numbers in the usual way). There is no equivalent of this option  they acquire numbers in the usual way). There is no equivalent of this option
704  in Perl.  in Perl.
705  .sp  .sp
706      NO_START_OPTIMIZE
707    .sp
708    This is an option that acts at matching time; that is, it is really an option
709    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
710    it is remembered with the compiled pattern and assumed at matching time. For
711    details see the discussion of PCRE_NO_START_OPTIMIZE
712    .\" HTML <a href="#execoptions">
713    .\" </a>
714    below.
715    .\"
716    .sp
717    PCRE_UCP    PCRE_UCP
718  .sp  .sp
719  This option changes the way PCRE processes \eb, \ed, \es, \ew, and some of the  This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
720  POSIX character classes. By default, only ASCII characters are recognized, but  \ew, and some of the POSIX character classes. By default, only ASCII characters
721  if PCRE_UCP is set, Unicode properties are used instead to classify characters.  are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
722  More details are given in the section on  classify characters. More details are given in the section on
723  .\" HTML <a href="pcre.html#genericchartypes">  .\" HTML <a href="pcre.html#genericchartypes">
724  .\" </a>  .\" </a>
725  generic character types  generic character types
# Line 673  of UTF-8 characters instead of single-by Line 745  of UTF-8 characters instead of single-by
745  available only when PCRE is built to include UTF-8 support. If not, the use  available only when PCRE is built to include UTF-8 support. If not, the use
746  of this option provokes an error. Details of how this option changes the  of this option provokes an error. Details of how this option changes the
747  behaviour of PCRE are given in the  behaviour of PCRE are given in the
 .\" HTML <a href="pcre.html#utf8support">  
 .\" </a>  
 section on UTF-8 support  
 .\"  
 in the main  
748  .\" HREF  .\" HREF
749  \fBpcre\fP  \fBpcreunicode\fP
750  .\"  .\"
751  page.  page.
752  .sp  .sp
# Line 749  out of use. To avoid confusion, they hav Line 816  out of use. To avoid confusion, they hav
816    34  character value in \ex{...} sequence is too large    34  character value in \ex{...} sequence is too large
817    35  invalid condition (?(0)    35  invalid condition (?(0)
818    36  \eC not allowed in lookbehind assertion    36  \eC not allowed in lookbehind assertion
819    37  PCRE does not support \eL, \el, \eN, \eU, or \eu    37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
820    38  number after (?C is > 255    38  number after (?C is > 255
821    39  closing ) for (?C expected    39  closing ) for (?C expected
822    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
# Line 783  out of use. To avoid confusion, they hav Line 850  out of use. To avoid confusion, they hav
850          not allowed          not allowed
851    66  (*MARK) must have an argument    66  (*MARK) must have an argument
852    67  this version of PCRE is not compiled with PCRE_UCP support    67  this version of PCRE is not compiled with PCRE_UCP support
853      68  \ec must be followed by an ASCII character
854      69  \ek is not followed by a braced, angle-bracketed, or quoted name
855  .sp  .sp
856  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
857  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
858  .  .
859  .  .
860    .\" HTML <a name="studyingapattern"></a>
861  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
862  .rs  .rs
863  .sp  .sp
# Line 818  If studying the pattern does not produce Line 888  If studying the pattern does not produce
888  wants to pass any of the other fields to \fBpcre_exec()\fP or  wants to pass any of the other fields to \fBpcre_exec()\fP or
889  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
890  .P  .P
891  The second argument of \fBpcre_study()\fP contains option bits. At present, no  The second argument of \fBpcre_study()\fP contains option bits. There is only
892  options are defined, and this argument should always be zero.  one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in-time
893    compiler is available, the pattern is further compiled into machine code that
894    executes much faster than the \fBpcre_exec()\fP matching function. If
895    the just-in-time compiler is not available, this option is ignored. All other
896    bits in the \fIoptions\fP argument must be zero.
897    .P
898    JIT compilation is a heavyweight optimization. It can take some time for
899    patterns to be analyzed, and for one-off matches and simple patterns the
900    benefit of faster execution might be offset by a much slower study time.
901    Not all patterns can be optimized by the JIT compiler. For those that cannot be
902    handled, matching automatically falls back to the \fBpcre_exec()\fP
903    interpreter. For more details, see the
904    .\" HREF
905    \fBpcrejit\fP
906    .\"
907    documentation.
908  .P  .P
909  The third argument for \fBpcre_study()\fP is a pointer for an error message. If  The third argument for \fBpcre_study()\fP is a pointer for an error message. If
910  studying succeeds (even if no data is returned), the variable it points to is  studying succeeds (even if no data is returned), the variable it points to is
# Line 828  static string that is part of the librar Line 913  static string that is part of the librar
913  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
914  sure that it has run successfully.  sure that it has run successfully.
915  .P  .P
916  This is a typical call to \fBpcre_study\fP():  When you are finished with a pattern, you can free the memory used for the
917    study data by calling \fBpcre_free_study()\fP. This function was added to the
918    API for release 8.20. For earlier versions, the memory could be freed with
919    \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
920    where PCRE_STUDY_JIT_COMPILE is not used, but it is advisable to change to the
921    new function when convenient.
922    .P
923    This is a typical way in which \fBpcre_study\fP() is used (except that in a
924    real application there should be tests for errors):
925  .sp  .sp
926    pcre_extra *pe;    int rc;
927    pe = pcre_study(    pcre *re;
928      pcre_extra *sd;
929      re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
930      sd = pcre_study(
931      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
932      0,              /* no options exist */      0,              /* no options */
933      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
934      rc = pcre_exec(   /* see below for details of pcre_exec() options */
935        re, sd, "subject", 7, 0, 0, ovector, 30);
936      ...
937      pcre_free_study(sd);
938      pcre_free(re);
939  .sp  .sp
940  Studying a pattern does two things: first, a lower bound for the length of  Studying a pattern does two things: first, a lower bound for the length of
941  subject string that is needed to match the pattern is computed. This does not  subject string that is needed to match the pattern is computed. This does not
# Line 849  single fixed starting character. A bitma Line 950  single fixed starting character. A bitma
950  created. This speeds up finding a position in the subject at which to start  created. This speeds up finding a position in the subject at which to start
951  matching.  matching.
952  .P  .P
953  The two optimizations just described can be disabled by setting the  These two optimizations apply to both \fBpcre_exec()\fP and
954  PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or  \fBpcre_dfa_exec()\fP. However, they are not used by \fBpcre_exec()\fP if
955    \fBpcre_study()\fP is called with the PCRE_STUDY_JIT_COMPILE option, and
956    just-in-time compiling is successful. The optimizations can be disabled by
957    setting the PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
958  \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains  \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
959  callouts, or make use of (*MARK), and you make use of these in cases where  callouts or (*MARK) (which cannot be handled by the JIT compiler), and you want
960  matching fails. See the discussion of PCRE_NO_START_OPTIMIZE  to make use of these facilities in cases where matching fails. See the
961    discussion of PCRE_NO_START_OPTIMIZE
962  .\" HTML <a href="#execoptions">  .\" HTML <a href="#execoptions">
963  .\" </a>  .\" </a>
964  below.  below.
# Line 918  one in which it was compiled. Passing ta Line 1023  one in which it was compiled. Passing ta
1023  below in the section on matching a pattern.  below in the section on matching a pattern.
1024  .  .
1025  .  .
1026    .\" HTML <a name="infoaboutpattern"></a>
1027  .SH "INFORMATION ABOUT A PATTERN"  .SH "INFORMATION ABOUT A PATTERN"
1028  .rs  .rs
1029  .sp  .sp
# Line 949  check against passing an arbitrary memor Line 1055  check against passing an arbitrary memor
1055    size_t length;    size_t length;
1056    rc = pcre_fullinfo(    rc = pcre_fullinfo(
1057      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
1058      pe,               /* result of pcre_study(), or NULL */      sd,               /* result of pcre_study(), or NULL */
1059      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
1060      &length);         /* where to put the data */      &length);         /* where to put the data */
1061  .sp  .sp
# Line 1014  Return 1 if the (?J) or (?-J) option set Line 1120  Return 1 if the (?J) or (?-J) option set
1120  0. The fourth argument should point to an \fBint\fP variable. (?J) and  0. The fourth argument should point to an \fBint\fP variable. (?J) and
1121  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1122  .sp  .sp
1123      PCRE_INFO_JIT
1124    .sp
1125    Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE option, and
1126    just-in-time compiling was successful. The fourth argument should point to an
1127    \fBint\fP variable. A return value of 0 means that JIT support is not available
1128    in this version of PCRE, or that the pattern was not studied with the
1129    PCRE_STUDY_JIT_COMPILE option, or that the JIT compiler could not handle this
1130    particular pattern. See the
1131    .\" HREF
1132    \fBpcrejit\fP
1133    .\"
1134    documentation for details of what can and cannot be handled.
1135    .sp
1136    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1137  .sp  .sp
1138  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal byte that must exist in any matched
# Line 1136  variable. Line 1255  variable.
1255  .sp  .sp
1256    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1257  .sp  .sp
1258  Return the size of the data block pointed to by the \fIstudy_data\fP field in  Return the size of the data block pointed to by the \fIstudy_data\fP field in a
1259  a \fBpcre_extra\fP block. That is, it is the value that was passed to  \fBpcre_extra\fP block. If \fBpcre_extra\fP is NULL, or there is no study data,
1260  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  zero is returned. The fourth argument should point to a \fBsize_t\fP variable.
1261  created by \fBpcre_study()\fP. If \fBpcre_extra\fP is NULL, or there is no  The \fIstudy_data\fP field is set by \fBpcre_study()\fP to record information
1262  study data, zero is returned. The fourth argument should point to a  that will speed up matching (see the section entitled
1263  \fBsize_t\fP variable.  .\" HTML <a href="#studyingapattern">
1264    .\" </a>
1265    "Studying a pattern"
1266    .\"
1267    above). The format of the \fIstudy_data\fP block is private, but its length
1268    is made available via this option so that it can be saved and restored (see the
1269    .\" HREF
1270    \fBpcreprecompile\fP
1271    .\"
1272    documentation for details).
1273  .  .
1274  .  .
1275  .SH "OBSOLETE INFO FUNCTION"  .SH "OBSOLETE INFO FUNCTION"
# Line 1236  Here is an example of a simple call to \ Line 1364  Here is an example of a simple call to \
1364      ovector,        /* vector of integers for substring information */      ovector,        /* vector of integers for substring information */
1365      30);            /* number of elements (NOT size in bytes) */      30);            /* number of elements (NOT size in bytes) */
1366  .  .
1367    .
1368  .\" HTML <a name="extradata"></a>  .\" HTML <a name="extradata"></a>
1369  .SS "Extra data for \fBpcre_exec()\fR"  .SS "Extra data for \fBpcre_exec()\fR"
1370  .rs  .rs
# Line 1248  fields (not necessarily in this order): Line 1377  fields (not necessarily in this order):
1377  .sp  .sp
1378    unsigned long int \fIflags\fP;    unsigned long int \fIflags\fP;
1379    void *\fIstudy_data\fP;    void *\fIstudy_data\fP;
1380      void *\fIexecutable_jit\fP;
1381    unsigned long int \fImatch_limit\fP;    unsigned long int \fImatch_limit\fP;
1382    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1383    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
# Line 1258  The \fIflags\fP field is a bitmap that s Line 1388  The \fIflags\fP field is a bitmap that s
1388  are set. The flag bits are:  are set. The flag bits are:
1389  .sp  .sp
1390    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1391      PCRE_EXTRA_EXECUTABLE_JIT
1392    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1393    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1394    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1395    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1396    PCRE_EXTRA_MARK    PCRE_EXTRA_MARK
1397  .sp  .sp
1398  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the  Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes
1399  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
1400  the appropriate flag bit. You should not set this yourself, but you may add to  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1401  the block by setting the other fields and their corresponding flag bits.  should not set these yourself, but you may add to the block by setting the
1402    other fields and their corresponding flag bits.
1403  .P  .P
1404  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1405  vast amount of resources when running patterns that are not going to match,  vast amount of resources when running patterns that are not going to match,
1406  but which have a very large number of possibilities in their search trees. The  but which have a very large number of possibilities in their search trees. The
1407  classic example is a pattern that uses nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1408  .P  .P
1409  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
1410  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the  calls repeatedly (sometimes recursively). The limit set by \fImatch_limit\fP is
1411  number of times this function is called during a match, which has the effect of  imposed on the number of times this function is called during a match, which
1412  limiting the amount of backtracking that can take place. For patterns that are  has the effect of limiting the amount of backtracking that can take place. For
1413  not anchored, the count restarts from zero for each position in the subject  patterns that are not anchored, the count restarts from zero for each position
1414  string.  in the subject string.
1415    .P
1416    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1417    with the PCRE_STUDY_JIT_COMPILE option, the way that the matching is executed
1418    is entirely different. However, there is still the possibility of runaway
1419    matching that goes on for a very long time, and so the \fImatch_limit\fP value
1420    is also used in this case (but in a different way) to limit how long the
1421    matching can continue.
1422  .P  .P
1423  The default value for the limit can be set when PCRE is built; the default  The default value for the limit can be set when PCRE is built; the default
1424  default is 10 million, which handles all but the most extreme cases. You can  default is 10 million, which handles all but the most extreme cases. You can
# Line 1294  limits the depth of recursion. The recur Line 1433  limits the depth of recursion. The recur
1433  total number of calls, because not all calls to \fBmatch()\fP are recursive.  total number of calls, because not all calls to \fBmatch()\fP are recursive.
1434  This limit is of use only if it is set smaller than \fImatch_limit\fP.  This limit is of use only if it is set smaller than \fImatch_limit\fP.
1435  .P  .P
1436  Limiting the recursion depth limits the amount of stack that can be used, or,  Limiting the recursion depth limits the amount of machine stack that can be
1437  when PCRE has been compiled to use memory on the heap instead of the stack, the  used, or, when PCRE has been compiled to use memory on the heap instead of the
1438  amount of heap memory that can be used.  stack, the amount of heap memory that can be used. This limit is not relevant,
1439    and is ignored, if the pattern was successfully studied with
1440    PCRE_STUDY_JIT_COMPILE.
1441  .P  .P
1442  The default value for \fImatch_limit_recursion\fP can be set when PCRE is  The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1443  built; the default default is the same value as the default for  built; the default default is the same value as the default for
# Line 1355  zero. The only bits that may be set are Line 1496  zero. The only bits that may be set are
1496  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1497  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1498  PCRE_PARTIAL_HARD.  PCRE_PARTIAL_HARD.
1499    .P
1500    If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,
1501    the only supported options for JIT execution are PCRE_NO_UTF8_CHECK,
1502    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NOTEMPTY_ATSTART. Note in
1503    particular that partial matching is not supported. If an unsupported option is
1504    used, JIT execution is disabled and the normal interpretive code in
1505    \fBpcre_exec()\fP is run.
1506  .sp  .sp
1507    PCRE_ANCHORED    PCRE_ANCHORED
1508  .sp  .sp
# Line 1450  the Line 1598  the
1598  .\" HREF  .\" HREF
1599  \fBpcredemo\fP  \fBpcredemo\fP
1600  .\"  .\"
1601  sample program.  sample program. In the most general case, you have to check to see if the
1602    newline convention recognizes CRLF as a newline, and if so, and the current
1603    character is CR followed by LF, advance the starting offset by two characters
1604    instead of one.
1605  .sp  .sp
1606    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1607  .sp  .sp
# Line 1468  a pre-scan of the subject that takes pla Line 1619  a pre-scan of the subject that takes pla
1619  The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly  The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1620  causing performance to suffer, but ensuring that in cases where the result is  causing performance to suffer, but ensuring that in cases where the result is
1621  "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)  "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1622  are considered at every possible starting position in the subject string.  are considered at every possible starting position in the subject string. If
1623    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1624    time.
1625    .P
1626  Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.  Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1627  Consider the pattern  Consider the pattern
1628  .sp  .sp
# Line 1512  in the main Line 1666  in the main
1666  \fBpcre\fP  \fBpcre\fP
1667  .\"  .\"
1668  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1669  the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,  the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is
1670  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
1671    both cases, information about the precise nature of the error may also be
1672    returned (see the descriptions of these errors in the section entitled \fIError
1673    return values from\fP \fBpcre_exec()\fP
1674    .\" HTML <a href="#errorlist">
1675    .\" </a>
1676    below).
1677    .\"
1678    If \fIstartoffset\fP contains a value that does not point to the start of a
1679    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1680    returned.
1681  .P  .P
1682  If you already know that your subject is valid, and you want to skip these  If you already know that your subject is valid, and you want to skip these
1683  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1684  calling \fBpcre_exec()\fP. You might want to do this for the second and  calling \fBpcre_exec()\fP. You might want to do this for the second and
1685  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1686  all the matches in a single subject string. However, you should be sure that  all the matches in a single subject string. However, you should be sure that
1687  the value of \fIstartoffset\fP points to the start of a UTF-8 character. When  the value of \fIstartoffset\fP points to the start of a UTF-8 character (or the
1688  PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a  end of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1689  subject, or a value of \fIstartoffset\fP that does not point to the start of a  invalid UTF-8 string as a subject or an invalid value of \fIstartoffset\fP is
1690  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1691  .sp  .sp
1692    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1693    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1541  but only if no complete match can be fou Line 1705  but only if no complete match can be fou
1705  If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a  If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1706  partial match is found, \fBpcre_exec()\fP immediately returns  partial match is found, \fBpcre_exec()\fP immediately returns
1707  PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,  PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1708  when PCRE_PARTIAL_HARD is set, a partial match is considered to be more  when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1709  important that an alternative complete match.  important that an alternative complete match.
1710  .P  .P
1711  In both cases, the portion of the string that was inspected when the partial  In both cases, the portion of the string that was inspected when the partial
# Line 1552  discussion of partial and multi-segment Line 1716  discussion of partial and multi-segment
1716  .\"  .\"
1717  documentation.  documentation.
1718  .  .
1719    .
1720  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1721  .rs  .rs
1722  .sp  .sp
1723  The subject string is passed to \fBpcre_exec()\fP as a pointer in  The subject string is passed to \fBpcre_exec()\fP as a pointer in
1724  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset
1725  in \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of  in \fIstartoffset\fP. If this is negative or greater than the length of the
1726  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1727  zero bytes. When the starting offset is zero, the search for a match starts at  offset is zero, the search for a match starts at the beginning of the subject,
1728  the beginning of the subject, and this is by far the most common case.  and this is by far the most common case. In UTF-8 mode, the byte offset must
1729    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1730    pattern string, the subject may contain binary zero bytes.
1731  .P  .P
1732  A non-zero starting offset is useful when searching for another match in the  A non-zero starting offset is useful when searching for another match in the
1733  same subject by calling \fBpcre_exec()\fP again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
# Line 1580  start of the subject, which is deemed to Line 1747  start of the subject, which is deemed to
1747  set to 4, it finds the second occurrence of "iss" because it is able to look  set to 4, it finds the second occurrence of "iss" because it is able to look
1748  behind the starting point to discover that it is preceded by a letter.  behind the starting point to discover that it is preceded by a letter.
1749  .P  .P
1750    Finding all the matches in a subject is tricky when the pattern can match an
1751    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1752    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1753    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1754    and trying an ordinary match again. There is some code that demonstrates how to
1755    do this in the
1756    .\" HREF
1757    \fBpcredemo\fP
1758    .\"
1759    sample program. In the most general case, you have to check to see if the
1760    newline convention recognizes CRLF as a newline, and if so, and the current
1761    character is CR followed by LF, advance the starting offset by two characters
1762    instead of one.
1763    .P
1764  If a non-zero starting offset is passed when the pattern is anchored, one  If a non-zero starting offset is passed when the pattern is anchored, one
1765  attempt to match at the given offset is made. This can only succeed if the  attempt to match at the given offset is made. This can only succeed if the
1766  pattern does not require the match to be at the start of the subject.  pattern does not require the match to be at the start of the subject.
1767  .  .
1768    .
1769  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1770  .rs  .rs
1771  .sp  .sp
# Line 1627  string that it matched that is returned. Line 1809  string that it matched that is returned.
1809  .P  .P
1810  If the vector is too small to hold all the captured substring offsets, it is  If the vector is too small to hold all the captured substring offsets, it is
1811  used as far as possible (up to two-thirds of its length), and the function  used as far as possible (up to two-thirds of its length), and the function
1812  returns a value of zero. If the substring offsets are not of interest,  returns a value of zero. If neither the actual string matched not any captured
1813  \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and  substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
1814  \fIovecsize\fP as zero. However, if the pattern contains back references and  passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
1815  the \fIovector\fP is not big enough to remember the related substrings, PCRE  back references and the \fIovector\fP is not big enough to remember the related
1816  has to get additional memory for use during matching. Thus it is usually  substrings, PCRE has to get additional memory for use during matching. Thus it
1817  advisable to supply an \fIovector\fP.  is usually advisable to supply an \fIovector\fP of reasonable size.
1818    .P
1819    There are some cases where zero is returned (indicating vector overflow) when
1820    in fact the vector is exactly the right size for the final match. For example,
1821    consider the pattern
1822    .sp
1823      (a)(?:(b)c|bd)
1824    .sp
1825    If a vector of 6 elements (allowing for only 1 captured substring) is given
1826    with subject string "abd", \fBpcre_exec()\fP will try to set the second
1827    captured string, thereby recording a vector overflow, before failing to match
1828    "c" and backing up to try the second alternative. The zero return, however,
1829    does correctly indicate that the maximum number of slots (namely 2) have been
1830    filled. In similar cases where there is temporary overflow, but the final
1831    number of used slots is actually less than the maximum, a non-zero value is
1832    returned.
1833  .P  .P
1834  The \fBpcre_fullinfo()\fP function can be used to find out how many capturing  The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
1835  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
# Line 1650  Offset values that correspond to unused Line 1847  Offset values that correspond to unused
1847  expression are also set to -1. For example, if the string "abc" is matched  expression are also set to -1. For example, if the string "abc" is matched
1848  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1849  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1850  number is 1. However, you can refer to the offsets for the second and third  number is 1, and the offsets for for the second and third capturing subpatterns
1851  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1852  course).  .P
1853    \fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
1854    correspond to capturing parentheses in the pattern are never changed. That is,
1855    if a pattern contains \fIn\fP capturing parentheses, no more than
1856    \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
1857    elements (in the first two-thirds) retain whatever values they previously had.
1858  .P  .P
1859  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1860  as separate strings. These are described below.  as separate strings. These are described below.
1861  .  .
1862    .
1863  .\" HTML <a name="errorlist"></a>  .\" HTML <a name="errorlist"></a>
1864  .SS "Error return values from \fBpcre_exec()\fP"  .SS "Error return values from \fBpcre_exec()\fP"
1865  .rs  .rs
# Line 1726  documentation for details. Line 1929  documentation for details.
1929  .sp  .sp
1930    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1931  .sp  .sp
1932  A string that contains an invalid UTF-8 byte sequence was passed as a subject.  A string that contains an invalid UTF-8 byte sequence was passed as a subject,
1933    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
1934    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
1935    UTF-8 character is placed in the first element, and a reason code is placed in
1936    the second element. The reason codes are listed in the
1937    .\" HTML <a href="#badutf8reasons">
1938    .\" </a>
1939    following section.
1940    .\"
1941    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
1942    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
1943    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
1944  .sp  .sp
1945    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1946  .sp  .sp
1947  The UTF-8 byte sequence that was passed as a subject was valid, but the value  The UTF-8 byte sequence that was passed as a subject was checked and found to
1948  of \fIstartoffset\fP did not point to the beginning of a UTF-8 character.  be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
1949    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1950    end of the subject.
1951  .sp  .sp
1952    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1953  .sp  .sp
# Line 1766  description above. Line 1982  description above.
1982    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1983  .sp  .sp
1984  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1985    .sp
1986      PCRE_ERROR_BADOFFSET      (-24)
1987    .sp
1988    The value of \fIstartoffset\fP was negative or greater than the length of the
1989    subject, that is, the value in \fIlength\fP.
1990    .sp
1991      PCRE_ERROR_SHORTUTF8      (-25)
1992    .sp
1993    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
1994    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
1995    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
1996    fact sufficient to detect this case, but this special error code for
1997    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
1998    retained for backwards compatibility.
1999    .sp
2000      PCRE_ERROR_RECURSELOOP    (-26)
2001    .sp
2002    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
2003    the pattern. Specifically, it means that either the whole pattern or a
2004    subpattern has been called recursively for the second time at the same position
2005    in the subject string. Some simple patterns that might do this are detected and
2006    faulted at compile time, but more complicated cases, in particular mutual
2007    recursions between two different subpatterns, cannot be detected until run
2008    time.
2009    .sp
2010      PCRE_ERROR_JIT_STACKLIMIT (-27)
2011    .sp
2012    This error is returned when a pattern that was successfully studied using the
2013    PCRE_STUDY_JIT_COMPILE option is being matched, but the memory available for
2014    the just-in-time processing stack is not large enough. See the
2015    .\" HREF
2016    \fBpcrejit\fP
2017    .\"
2018    documentation for more details.
2019  .P  .P
2020  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
2021  .  .
2022  .  .
2023    .\" HTML <a name="badutf8reasons"></a>
2024    .SS "Reason codes for invalid UTF-8 strings"
2025    .rs
2026    .sp
2027    When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
2028    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
2029    least 2, the offset of the start of the invalid UTF-8 character is placed in
2030    the first output vector element (\fIovector[0]\fP) and a reason code is placed
2031    in the second element (\fIovector[1]\fP). The reason codes are given names in
2032    the \fBpcre.h\fP header file:
2033    .sp
2034      PCRE_UTF8_ERR1
2035      PCRE_UTF8_ERR2
2036      PCRE_UTF8_ERR3
2037      PCRE_UTF8_ERR4
2038      PCRE_UTF8_ERR5
2039    .sp
2040    The string ends with a truncated UTF-8 character; the code specifies how many
2041    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
2042    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
2043    allows for up to 6 bytes, and this is checked first; hence the possibility of
2044    4 or 5 missing bytes.
2045    .sp
2046      PCRE_UTF8_ERR6
2047      PCRE_UTF8_ERR7
2048      PCRE_UTF8_ERR8
2049      PCRE_UTF8_ERR9
2050      PCRE_UTF8_ERR10
2051    .sp
2052    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
2053    character do not have the binary value 0b10 (that is, either the most
2054    significant bit is 0, or the next bit is 1).
2055    .sp
2056      PCRE_UTF8_ERR11
2057      PCRE_UTF8_ERR12
2058    .sp
2059    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
2060    these code points are excluded by RFC 3629.
2061    .sp
2062      PCRE_UTF8_ERR13
2063    .sp
2064    A 4-byte character has a value greater than 0x10fff; these code points are
2065    excluded by RFC 3629.
2066    .sp
2067      PCRE_UTF8_ERR14
2068    .sp
2069    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
2070    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
2071    from UTF-8.
2072    .sp
2073      PCRE_UTF8_ERR15
2074      PCRE_UTF8_ERR16
2075      PCRE_UTF8_ERR17
2076      PCRE_UTF8_ERR18
2077      PCRE_UTF8_ERR19
2078    .sp
2079    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
2080    value that can be represented by fewer bytes, which is invalid. For example,
2081    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
2082    one byte.
2083    .sp
2084      PCRE_UTF8_ERR20
2085    .sp
2086    The two most significant bits of the first byte of a character have the binary
2087    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
2088    byte can only validly occur as the second or subsequent byte of a multi-byte
2089    character.
2090    .sp
2091      PCRE_UTF8_ERR21
2092    .sp
2093    The first byte of a character has the value 0xfe or 0xff. These values can
2094    never occur in a valid UTF-8 string.
2095    .
2096    .
2097  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
2098  .rs  .rs
2099  .sp  .sp
# Line 1932  names are not included in the compiled c Line 2256  names are not included in the compiled c
2256  numbers. For this reason, the use of different names for subpatterns of the  numbers. For this reason, the use of different names for subpatterns of the
2257  same number causes an error at compile time.  same number causes an error at compile time.
2258  .  .
2259    .
2260  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
2261  .rs  .rs
2262  .sp  .sp
# Line 1965  fourth are pointers to variables which a Line 2290  fourth are pointers to variables which a
2290  has run, they point to the first and last entries in the name-to-number table  has run, they point to the first and last entries in the name-to-number table
2291  for the given name. The function itself returns the length of each entry, or  for the given name. The function itself returns the length of each entry, or
2292  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
2293  described above in the section entitled \fIInformation about a pattern\fP.  described above in the section entitled \fIInformation about a pattern\fP
2294    .\" HTML <a href="#infoaboutpattern">
2295    .\" </a>
2296    above.
2297    .\"
2298  Given all the relevant entries for the name, you can extract each of their  Given all the relevant entries for the name, you can extract each of their
2299  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2300  .  .
# Line 2095  match. There is more discussion of this Line 2424  match. There is more discussion of this
2424  .\"  .\"
2425  documentation.  documentation.
2426  .  .
2427    .
2428  .SS "Successful returns from \fBpcre_dfa_exec()\fP"  .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2429  .rs  .rs
2430  .sp  .sp
# Line 2126  returns data, even though the meaning of Line 2456  returns data, even though the meaning of
2456  The strings are returned in reverse order of length; that is, the longest  The strings are returned in reverse order of length; that is, the longest
2457  matching string is given first. If there were too many matches to fit into  matching string is given first. If there were too many matches to fit into
2458  \fIovector\fP, the yield of the function is zero, and the vector is filled with  \fIovector\fP, the yield of the function is zero, and the vector is filled with
2459  the longest matches.  the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
2460    the entire \fIovector\fP for returning matched strings.
2461    .
2462  .  .
2463  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
2464  .rs  .rs
# Line 2155  group. These are not supported. Line 2487  group. These are not supported.
2487    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
2488  .sp  .sp
2489  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
2490  block that contains a setting of the \fImatch_limit\fP field. This is not  block that contains a setting of the \fImatch_limit\fP or
2491  supported (it is meaningless).  \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2492    meaningless for DFA matching).
2493  .sp  .sp
2494    PCRE_ERROR_DFA_WSSIZE     (-19)    PCRE_ERROR_DFA_WSSIZE     (-19)
2495  .sp  .sp
# Line 2193  Cambridge CB2 3QH, England. Line 2526  Cambridge CB2 3QH, England.
2526  .rs  .rs
2527  .sp  .sp
2528  .nf  .nf
2529  Last updated: 22 October 2010  Last updated: 06 September 2011
2530  Copyright (c) 1997-2010 University of Cambridge.  Copyright (c) 1997-2011 University of Cambridge.
2531  .fi  .fi

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