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pcre_exec.c
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/*************************************************
* 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 pcre_exec(), the externally visible function that does
pattern matching using an NFA algorithm, trying to mimic Perl as closely as
possible. There are also some static supporting functions. */
#ifdef WIN32
#include "pcre_winconfig.h"
#else
#include "config.h"
#endif
#define NLBLOCK md /* Block containing newline information */
#define PSSTART start_subject /* Field containing processed string start */
#define PSEND end_subject /* Field containing processed string end */
#include "pcre_internal.h"
/* Undefine some potentially clashing cpp symbols */
#undef min
#undef max
/* Flag bits for the match() function */
#define match_condassert 0x01 /* Called to check a condition assertion */
#define match_cbegroup 0x02 /* Could-be-empty unlimited repeat group */
/* Non-error returns from the match() function. Error returns are externally
defined PCRE_ERROR_xxx codes, which are all negative. */
#define MATCH_MATCH 1
#define MATCH_NOMATCH 0
/* Special internal returns from the match() function. Make them sufficiently
negative to avoid the external error codes. */
#define MATCH_COMMIT (-999)
#define MATCH_PRUNE (-998)
#define MATCH_SKIP (-997)
#define MATCH_THEN (-996)
/* Maximum number of ints of offset to save on the stack for recursive calls.
If the offset vector is bigger, malloc is used. This should be a multiple of 3,
because the offset vector is always a multiple of 3 long. */
#define REC_STACK_SAVE_MAX 30
/* Min and max values for the common repeats; for the maxima, 0 => infinity */
static const char rep_min[] = { 0, 0, 1, 1, 0, 0 };
static const char rep_max[] = { 0, 0, 0, 0, 1, 1 };
#ifdef DEBUG
/*************************************************
* Debugging function to print chars *
*************************************************/
/* Print a sequence of chars in printable format, stopping at the end of the
subject if the requested.
Arguments:
p points to characters
length number to print
is_subject TRUE if printing from within md->start_subject
md pointer to matching data block, if is_subject is TRUE
Returns: nothing
*/
static void
pchars(const uschar *p, int length, BOOL is_subject, match_data *md)
{
unsigned int c;
if (is_subject && length > md->end_subject - p) length = md->end_subject - p;
while (length-- > 0)
if (isprint(c = *(p++))) printf("%c", c); else printf("\\x%02x", c);
}
#endif
/*************************************************
* Match a back-reference *
*************************************************/
/* If a back reference hasn't been set, the length that is passed is greater
than the number of characters left in the string, so the match fails.
Arguments:
offset index into the offset vector
eptr points into the subject
length length to be matched
md points to match data block
ims the ims flags
Returns: TRUE if matched
*/
static BOOL
match_ref(int offset, register USPTR eptr, int length, match_data *md,
unsigned long int ims)
{
USPTR p = md->start_subject + md->offset_vector[offset];
#ifdef DEBUG
if (eptr >= md->end_subject)
printf("matching subject <null>");
else
{
printf("matching subject ");
pchars(eptr, length, TRUE, md);
}
printf(" against backref ");
pchars(p, length, FALSE, md);
printf("\n");
#endif
/* Always fail if not enough characters left */
if (length > md->end_subject - eptr) return FALSE;
/* Separate the caselesss case for speed */
if ((ims & PCRE_CASELESS) != 0)
{
while (length-- > 0)
if (md->lcc[*p++] != md->lcc[*eptr++]) return FALSE;
}
else
{ while (length-- > 0) if (*p++ != *eptr++) return FALSE; }
return TRUE;
}
/***************************************************************************
****************************************************************************
RECURSION IN THE match() FUNCTION
The match() function is highly recursive, though not every recursive call
increases the recursive depth. Nevertheless, some regular expressions can cause
it to recurse to a great depth. I was writing for Unix, so I just let it call
itself recursively. This uses the stack for saving everything that has to be
saved for a recursive call. On Unix, the stack can be large, and this works
fine.
It turns out that on some non-Unix-like systems there are problems with
programs that use a lot of stack. (This despite the fact that every last chip
has oodles of memory these days, and techniques for extending the stack have
been known for decades.) So....
There is a fudge, triggered by defining NO_RECURSE, which avoids recursive
calls by keeping local variables that need to be preserved in blocks of memory
obtained from malloc() instead instead of on the stack. Macros are used to
achieve this so that the actual code doesn't look very different to what it
always used to.
The original heap-recursive code used longjmp(). However, it seems that this
can be very slow on some operating systems. Following a suggestion from Stan
Switzer, the use of longjmp() has been abolished, at the cost of having to
provide a unique number for each call to RMATCH. There is no way of generating
a sequence of numbers at compile time in C. I have given them names, to make
them stand out more clearly.
Crude tests on x86 Linux show a small speedup of around 5-8%. However, on
FreeBSD, avoiding longjmp() more than halves the time taken to run the standard
tests. Furthermore, not using longjmp() means that local dynamic variables
don't have indeterminate values; this has meant that the frame size can be
reduced because the result can be "passed back" by straight setting of the
variable instead of being passed in the frame.
****************************************************************************
***************************************************************************/
/* Numbers for RMATCH calls. When this list is changed, the code at HEAP_RETURN
below must be updated in sync. */
enum { RM1=1, RM2, RM3, RM4, RM5, RM6, RM7, RM8, RM9, RM10,
RM11, RM12, RM13, RM14, RM15, RM16, RM17, RM18, RM19, RM20,
RM21, RM22, RM23, RM24, RM25, RM26, RM27, RM28, RM29, RM30,
RM31, RM32, RM33, RM34, RM35, RM36, RM37, RM38, RM39, RM40,
RM41, RM42, RM43, RM44, RM45, RM46, RM47, RM48, RM49, RM50,
RM51, RM52, RM53, RM54 };
/* These versions of the macros use the stack, as normal. There are debugging
versions and production versions. Note that the "rw" argument of RMATCH isn't
actuall used in this definition. */
#ifndef NO_RECURSE
#define REGISTER register
#ifdef DEBUG
#define RMATCH(ra,rb,rc,rd,re,rf,rg,rw) \
{ \
printf("match() called in line %d\n", __LINE__); \
rrc = match(ra,rb,mstart,rc,rd,re,rf,rg,rdepth+1); \
printf("to line %d\n", __LINE__); \
}
#define RRETURN(ra) \
{ \
printf("match() returned %d from line %d ", ra, __LINE__); \
return ra; \
}
#else
#define RMATCH(ra,rb,rc,rd,re,rf,rg,rw) \
rrc = match(ra,rb,mstart,rc,rd,re,rf,rg,rdepth+1)
#define RRETURN(ra) return ra
#endif
#else
/* These versions of the macros manage a private stack on the heap. Note that
the "rd" argument of RMATCH isn't actually used in this definition. It's the md
argument of match(), which never changes. */
#define REGISTER
#define RMATCH(ra,rb,rc,rd,re,rf,rg,rw)\
{\
heapframe *newframe = (pcre_stack_malloc)(sizeof(heapframe));\
frame->Xwhere = rw; \
newframe->Xeptr = ra;\
newframe->Xecode = rb;\
newframe->Xmstart = mstart;\
newframe->Xoffset_top = rc;\
newframe->Xims = re;\
newframe->Xeptrb = rf;\
newframe->Xflags = rg;\
newframe->Xrdepth = frame->Xrdepth + 1;\
newframe->Xprevframe = frame;\
frame = newframe;\
DPRINTF(("restarting from line %d\n", __LINE__));\
goto HEAP_RECURSE;\
L_##rw:\
DPRINTF(("jumped back to line %d\n", __LINE__));\
}
#define RRETURN(ra)\
{\
heapframe *newframe = frame;\
frame = newframe->Xprevframe;\
(pcre_stack_free)(newframe);\
if (frame != NULL)\
{\
rrc = ra;\
goto HEAP_RETURN;\
}\
return ra;\
}
/* Structure for remembering the local variables in a private frame */
typedef struct heapframe {
struct heapframe *Xprevframe;
/* Function arguments that may change */
const uschar *Xeptr;
const uschar *Xecode;
const uschar *Xmstart;
int Xoffset_top;
long int Xims;
eptrblock *Xeptrb;
int Xflags;
unsigned int Xrdepth;
/* Function local variables */
const uschar *Xcallpat;
const uschar *Xcharptr;
const uschar *Xdata;
const uschar *Xnext;
const uschar *Xpp;
const uschar *Xprev;
const uschar *Xsaved_eptr;
recursion_info Xnew_recursive;
BOOL Xcur_is_word;
BOOL Xcondition;
BOOL Xprev_is_word;
unsigned long int Xoriginal_ims;
#ifdef SUPPORT_UCP
int Xprop_type;
int Xprop_value;
int Xprop_fail_result;
int Xprop_category;
int Xprop_chartype;
int Xprop_script;
int Xoclength;
uschar Xocchars[8];
#endif
int Xctype;
unsigned int Xfc;
int Xfi;
int Xlength;
int Xmax;
int Xmin;
int Xnumber;
int Xoffset;
int Xop;
int Xsave_capture_last;
int Xsave_offset1, Xsave_offset2, Xsave_offset3;
int Xstacksave[REC_STACK_SAVE_MAX];
eptrblock Xnewptrb;
/* Where to jump back to */
int Xwhere;
} heapframe;
#endif
/***************************************************************************
***************************************************************************/
/*************************************************
* Match from current position *
*************************************************/
/* This function is called recursively in many circumstances. Whenever it
returns a negative (error) response, the outer incarnation must also return the
same response.
Performance note: It might be tempting to extract commonly used fields from the
md structure (e.g. utf8, end_subject) into individual variables to improve
performance. Tests using gcc on a SPARC disproved this; in the first case, it
made performance worse.
Arguments:
eptr pointer to current character in subject
ecode pointer to current position in compiled code
mstart pointer to the current match start position (can be modified
by encountering \K)
offset_top current top pointer
md pointer to "static" info for the match
ims current /i, /m, and /s options
eptrb pointer to chain of blocks containing eptr at start of
brackets - for testing for empty matches
flags can contain
match_condassert - this is an assertion condition
match_cbegroup - this is the start of an unlimited repeat
group that can match an empty string
rdepth the recursion depth
Returns: MATCH_MATCH if matched ) these values are >= 0
MATCH_NOMATCH if failed to match )
a negative PCRE_ERROR_xxx value if aborted by an error condition
(e.g. stopped by repeated call or recursion limit)
*/
static int
match(REGISTER USPTR eptr, REGISTER const uschar *ecode, const uschar *mstart,
int offset_top, match_data *md, unsigned long int ims, eptrblock *eptrb,
int flags, unsigned int rdepth)
{
/* These variables do not need to be preserved over recursion in this function,
so they can be ordinary variables in all cases. Mark some of them with
"register" because they are used a lot in loops. */
register int rrc; /* Returns from recursive calls */
register int i; /* Used for loops not involving calls to RMATCH() */
register unsigned int c; /* Character values not kept over RMATCH() calls */
register BOOL utf8; /* Local copy of UTF-8 flag for speed */
BOOL minimize, possessive; /* Quantifier options */
/* When recursion is not being used, all "local" variables that have to be
preserved over calls to RMATCH() are part of a "frame" which is obtained from
heap storage. Set up the top-level frame here; others are obtained from the
heap whenever RMATCH() does a "recursion". See the macro definitions above. */
#ifdef NO_RECURSE
heapframe *frame = (pcre_stack_malloc)(sizeof(heapframe));
frame->Xprevframe = NULL; /* Marks the top level */
/* Copy in the original argument variables */
frame->Xeptr = eptr;
frame->Xecode = ecode;
frame->Xmstart = mstart;
frame->Xoffset_top = offset_top;
frame->Xims = ims;
frame->Xeptrb = eptrb;
frame->Xflags = flags;
frame->Xrdepth = rdepth;
/* This is where control jumps back to to effect "recursion" */
HEAP_RECURSE:
/* Macros make the argument variables come from the current frame */
#define eptr frame->Xeptr
#define ecode frame->Xecode
#define mstart frame->Xmstart
#define offset_top frame->Xoffset_top
#define ims frame->Xims
#define eptrb frame->Xeptrb
#define flags frame->Xflags
#define rdepth frame->Xrdepth
/* Ditto for the local variables */
#ifdef SUPPORT_UTF8
#define charptr frame->Xcharptr
#endif
#define callpat frame->Xcallpat
#define data frame->Xdata
#define next frame->Xnext
#define pp frame->Xpp
#define prev frame->Xprev
#define saved_eptr frame->Xsaved_eptr
#define new_recursive frame->Xnew_recursive
#define cur_is_word frame->Xcur_is_word
#define condition frame->Xcondition
#define prev_is_word frame->Xprev_is_word
#define original_ims frame->Xoriginal_ims
#ifdef SUPPORT_UCP
#define prop_type frame->Xprop_type
#define prop_value frame->Xprop_value
#define prop_fail_result frame->Xprop_fail_result
#define prop_category frame->Xprop_category
#define prop_chartype frame->Xprop_chartype
#define prop_script frame->Xprop_script
#define oclength frame->Xoclength
#define occhars frame->Xocchars
#endif
#define ctype frame->Xctype
#define fc frame->Xfc
#define fi frame->Xfi
#define length frame->Xlength
#define max frame->Xmax
#define min frame->Xmin
#define number frame->Xnumber
#define offset frame->Xoffset
#define op frame->Xop
#define save_capture_last frame->Xsave_capture_last
#define save_offset1 frame->Xsave_offset1
#define save_offset2 frame->Xsave_offset2
#define save_offset3 frame->Xsave_offset3
#define stacksave frame->Xstacksave
#define newptrb frame->Xnewptrb
/* When recursion is being used, local variables are allocated on the stack and
get preserved during recursion in the normal way. In this environment, fi and
i, and fc and c, can be the same variables. */
#else /* NO_RECURSE not defined */
#define fi i
#define fc c
#ifdef SUPPORT_UTF8 /* Many of these variables are used only */
const uschar *charptr; /* in small blocks of the code. My normal */
#endif /* style of coding would have declared */
const uschar *callpat; /* them within each of those blocks. */
const uschar *data; /* However, in order to accommodate the */
const uschar *next; /* version of this code that uses an */
USPTR pp; /* external "stack" implemented on the */
const uschar *prev; /* heap, it is easier to declare them all */
USPTR saved_eptr; /* here, so the declarations can be cut */
/* out in a block. The only declarations */
recursion_info new_recursive; /* within blocks below are for variables */
/* that do not have to be preserved over */
BOOL cur_is_word; /* a recursive call to RMATCH(). */
BOOL condition;
BOOL prev_is_word;
unsigned long int original_ims;
#ifdef SUPPORT_UCP
int prop_type;
int prop_value;
int prop_fail_result;
int prop_category;
int prop_chartype;
int prop_script;
int oclength;
uschar occhars[8];
#endif
int ctype;
int length;
int max;
int min;
int number;
int offset;
int op;
int save_capture_last;
int save_offset1, save_offset2, save_offset3;
int stacksave[REC_STACK_SAVE_MAX];
eptrblock newptrb;
#endif /* NO_RECURSE */
/* These statements are here to stop the compiler complaining about unitialized
variables. */
#ifdef SUPPORT_UCP
prop_value = 0;
prop_fail_result = 0;
#endif
/* This label is used for tail recursion, which is used in a few cases even
when NO_RECURSE is not defined, in order to reduce the amount of stack that is
used. Thanks to Ian Taylor for noticing this possibility and sending the
original patch. */
TAIL_RECURSE:
/* OK, now we can get on with the real code of the function. Recursive calls
are specified by the macro RMATCH and RRETURN is used to return. When
NO_RECURSE is *not* defined, these just turn into a recursive call to match()
and a "return", respectively (possibly with some debugging if DEBUG is
defined). However, RMATCH isn't like a function call because it's quite a
complicated macro. It has to be used in one particular way. This shouldn't,
however, impact performance when true recursion is being used. */
#ifdef SUPPORT_UTF8
utf8 = md->utf8; /* Local copy of the flag */
#else
utf8 = FALSE;
#endif
/* First check that we haven't called match() too many times, or that we
haven't exceeded the recursive call limit. */
if (md->match_call_count++ >= md->match_limit) RRETURN(PCRE_ERROR_MATCHLIMIT);
if (rdepth >= md->match_limit_recursion) RRETURN(PCRE_ERROR_RECURSIONLIMIT);
original_ims = ims; /* Save for resetting on ')' */
/* At the start of a group with an unlimited repeat that may match an empty
string, the match_cbegroup flag is set. When this is the case, add the current
subject pointer to the chain of such remembered pointers, to be checked when we
hit the closing ket, in order to break infinite loops that match no characters.
When match() is called in other circumstances, don't add to the chain. The
match_cbegroup flag must NOT be used with tail recursion, because the memory
block that is used is on the stack, so a new one may be required for each
match(). */
if ((flags & match_cbegroup) != 0)
{
newptrb.epb_saved_eptr = eptr;
newptrb.epb_prev = eptrb;
eptrb = &newptrb;
}
/* Now start processing the opcodes. */
for (;;)
{
minimize = possessive = FALSE;
op = *ecode;
/* For partial matching, remember if we ever hit the end of the subject after
matching at least one subject character. */
if (md->partial &&
eptr >= md->end_subject &&
eptr > mstart)
md->hitend = TRUE;
switch(op)
{
case OP_FAIL:
RRETURN(MATCH_NOMATCH);
case OP_PRUNE:
RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,
ims, eptrb, flags, RM51);
if (rrc != MATCH_NOMATCH) RRETURN(rrc);
RRETURN(MATCH_PRUNE);
case OP_COMMIT:
RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,
ims, eptrb, flags, RM52);
if (rrc != MATCH_NOMATCH) RRETURN(rrc);
RRETURN(MATCH_COMMIT);
case OP_SKIP:
RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,
ims, eptrb, flags, RM53);
if (rrc != MATCH_NOMATCH) RRETURN(rrc);
md->start_match_ptr = eptr; /* Pass back current position */
RRETURN(MATCH_SKIP);
case OP_THEN:
RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,
ims, eptrb, flags, RM54);
if (rrc != MATCH_NOMATCH) RRETURN(rrc);
RRETURN(MATCH_THEN);
/* Handle a capturing bracket. If there is space in the offset vector, save
the current subject position in the working slot at the top of the vector.
We mustn't change the current values of the data slot, because they may be
set from a previous iteration of this group, and be referred to by a
reference inside the group.
If the bracket fails to match, we need to restore this value and also the
values of the final offsets, in case they were set by a previous iteration
of the same bracket.
If there isn't enough space in the offset vector, treat this as if it were
a non-capturing bracket. Don't worry about setting the flag for the error
case here; that is handled in the code for KET. */
case OP_CBRA:
case OP_SCBRA:
number = GET2(ecode, 1+LINK_SIZE);
offset = number << 1;
#ifdef DEBUG
printf("start bracket %d\n", number);
printf("subject=");
pchars(eptr, 16, TRUE, md);
printf("\n");
#endif
if (offset < md->offset_max)
{
save_offset1 = md->offset_vector[offset];
save_offset2 = md->offset_vector[offset+1];
save_offset3 = md->offset_vector[md->offset_end - number];
save_capture_last = md->capture_last;
DPRINTF(("saving %d %d %d\n", save_offset1, save_offset2, save_offset3));
md->offset_vector[md->offset_end - number] = eptr - md->start_subject;
flags = (op == OP_SCBRA)? match_cbegroup : 0;
do
{
RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md,
ims, eptrb, flags, RM1);
if (rrc != MATCH_NOMATCH && rrc != MATCH_THEN) RRETURN(rrc);
md->capture_last = save_capture_last;
ecode += GET(ecode, 1);
}
while (*ecode == OP_ALT);
DPRINTF(("bracket %d failed\n", number));
md->offset_vector[offset] = save_offset1;
md->offset_vector[offset+1] = save_offset2;
md->offset_vector[md->offset_end - number] = save_offset3;
RRETURN(MATCH_NOMATCH);
}
/* FALL THROUGH ... Insufficient room for saving captured contents. Treat
as a non-capturing bracket. */
/* VVVVVVVVVVVVVVVVVVVVVVVVV */
/* VVVVVVVVVVVVVVVVVVVVVVVVV */
DPRINTF(("insufficient capture room: treat as non-capturing\n"));
/* VVVVVVVVVVVVVVVVVVVVVVVVV */
/* VVVVVVVVVVVVVVVVVVVVVVVVV */
/* Non-capturing bracket. Loop for all the alternatives. When we get to the
final alternative within the brackets, we would return the result of a
recursive call to match() whatever happened. We can reduce stack usage by
turning this into a tail recursion, except in the case when match_cbegroup
is set.*/
case OP_BRA:
case OP_SBRA:
DPRINTF(("start non-capturing bracket\n"));
flags = (op >= OP_SBRA)? match_cbegroup : 0;
for (;;)
{
if (ecode[GET(ecode, 1)] != OP_ALT) /* Final alternative */
{
if (flags == 0) /* Not a possibly empty group */
{
ecode += _pcre_OP_lengths[*ecode];
DPRINTF(("bracket 0 tail recursion\n"));
goto TAIL_RECURSE;
}
/* Possibly empty group; can't use tail recursion. */
RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md, ims,
eptrb, flags, RM48);
RRETURN(rrc);
}
/* For non-final alternatives, continue the loop for a NOMATCH result;
otherwise return. */
RMATCH(eptr, ecode + _pcre_OP_lengths[*ecode], offset_top, md, ims,
eptrb, flags, RM2);
if (rrc != MATCH_NOMATCH && rrc != MATCH_THEN) RRETURN(rrc);
ecode += GET(ecode, 1);
}
/* Control never reaches here. */
/* Conditional group: compilation checked that there are no more than
two branches. If the condition is false, skipping the first branch takes us
past the end if there is only one branch, but that's OK because that is
exactly what going to the ket would do. As there is only one branch to be
obeyed, we can use tail recursion to avoid using another stack frame. */
case OP_COND:
case OP_SCOND:
if (ecode[LINK_SIZE+1] == OP_RREF) /* Recursion test */
{
offset = GET2(ecode, LINK_SIZE + 2); /* Recursion group number*/
condition = md->recursive != NULL &&
(offset == RREF_ANY || offset == md->recursive->group_num);
ecode += condition? 3 : GET(ecode, 1);
}
else if (ecode[LINK_SIZE+1] == OP_CREF) /* Group used test */
{
offset = GET2(ecode, LINK_SIZE+2) << 1; /* Doubled ref number */
condition = offset < offset_top && md->offset_vector[offset] >= 0;
ecode += condition? 3 : GET(ecode, 1);
}
else if (ecode[LINK_SIZE+1] == OP_DEF) /* DEFINE - always false */
{
condition = FALSE;
ecode += GET(ecode, 1);
}
/* The condition is an assertion. Call match() to evaluate it - setting
the final argument match_condassert causes it to stop at the end of an
assertion. */
else
{
RMATCH(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
match_condassert, RM3);
if (rrc == MATCH_MATCH)
{
condition = TRUE;
ecode += 1 + LINK_SIZE + GET(ecode, LINK_SIZE + 2);
while (*ecode == OP_ALT) ecode += GET(ecode, 1);
}
else if (rrc != MATCH_NOMATCH && rrc != MATCH_THEN)
{
RRETURN(rrc); /* Need braces because of following else */
}
else
{
condition = FALSE;
ecode += GET(ecode, 1);
}
}
/* We are now at the branch that is to be obeyed. As there is only one,
we can use tail recursion to avoid using another stack frame, except when
match_cbegroup is required for an unlimited repeat of a possibly empty
group. If the second alternative doesn't exist, we can just plough on. */
if (condition || *ecode == OP_ALT)
{
ecode += 1 + LINK_SIZE;
if (op == OP_SCOND) /* Possibly empty group */
{
RMATCH(eptr, ecode, offset_top, md, ims, eptrb, match_cbegroup, RM49);
RRETURN(rrc);
}
else /* Group must match something */
{
flags = 0;
goto TAIL_RECURSE;
}
}
else /* Condition false & no 2nd alternative */
{
ecode += 1 + LINK_SIZE;
}
break;
/* End of the pattern, either real or forced. If we are in a top-level
recursion, we should restore the offsets appropriately and continue from
after the call. */
case OP_ACCEPT:
case OP_END:
if (md->recursive != NULL && md->recursive->group_num == 0)
{
recursion_info *rec = md->recursive;
DPRINTF(("End of pattern in a (?0) recursion\n"));
md->recursive = rec->prevrec;
memmove(md->offset_vector, rec->offset_save,
rec->saved_max * sizeof(int));
mstart = rec->save_start;
ims = original_ims;
ecode = rec->after_call;
break;
}
/* Otherwise, if PCRE_NOTEMPTY is set, fail if we have matched an empty
string - backtracking will then try other alternatives, if any. */
if (md->notempty && eptr == mstart) RRETURN(MATCH_NOMATCH);
md->end_match_ptr = eptr; /* Record where we ended */
md->end_offset_top = offset_top; /* and how many extracts were taken */
md->start_match_ptr = mstart; /* and the start (\K can modify) */
RRETURN(MATCH_MATCH);
/* Change option settings */
case OP_OPT:
ims = ecode[1];
ecode += 2;
DPRINTF(("ims set to %02lx\n", ims));
break;
/* Assertion brackets. Check the alternative branches in turn - the
matching won't pass the KET for an assertion. If any one branch matches,
the assertion is true. Lookbehind assertions have an OP_REVERSE item at the
start of each branch to move the current point backwards, so the code at
this level is identical to the lookahead case. */
case OP_ASSERT:
case OP_ASSERTBACK:
do
{
RMATCH(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL, 0,
RM4);
if (rrc == MATCH_MATCH) break;
if (rrc != MATCH_NOMATCH && rrc != MATCH_THEN) RRETURN(rrc);
ecode += GET(ecode, 1);
}
while (*ecode == OP_ALT);
if (*ecode == OP_KET) RRETURN(MATCH_NOMATCH);
/* If checking an assertion for a condition, return MATCH_MATCH. */
if ((flags & match_condassert) != 0) RRETURN(MATCH_MATCH);
/* Continue from after the assertion, updating the offsets high water
mark, since extracts may have been taken during the assertion. */
do ecode += GET(ecode,1); while (*ecode == OP_ALT);
ecode += 1 + LINK_SIZE;
offset_top = md->end_offset_top;
continue;
/* Negative assertion: all branches must fail to match */
case OP_ASSERT_NOT:
case OP_ASSERTBACK_NOT:
do
{
RMATCH(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL, 0,
RM5);
if (rrc == MATCH_MATCH) RRETURN(MATCH_NOMATCH);
if (rrc != MATCH_NOMATCH && rrc != MATCH_THEN) RRETURN(rrc);
ecode += GET(ecode,1);
}
while (*ecode == OP_ALT);
if ((flags & match_condassert) != 0) RRETURN(MATCH_MATCH);
ecode += 1 + LINK_SIZE;
continue;
/* Move the subject pointer back. This occurs only at the start of
each branch of a lookbehind assertion. If we are too close to the start to
move back, this match function fails. When working with UTF-8 we move
back a number of characters, not bytes. */
case OP_REVERSE:
#ifdef SUPPORT_UTF8
if (utf8)
{
i = GET(ecode, 1);
while (i-- > 0)
{
eptr--;
if (eptr < md->start_subject) RRETURN(MATCH_NOMATCH);
BACKCHAR(eptr);
}
}
else
#endif
/* No UTF-8 support, or not in UTF-8 mode: count is byte count */
{
eptr -= GET(ecode, 1);
if (eptr < md->start_subject) RRETURN(MATCH_NOMATCH);
}
/* Skip to next op code */
ecode += 1 + LINK_SIZE;
break;
/* The callout item calls an external function, if one is provided, passing
details of the match so far. This is mainly for debugging, though the
function is able to force a failure. */
case OP_CALLOUT:
if (pcre_callout != NULL)
{
pcre_callout_block cb;
cb.version = 1; /* Version 1 of the callout block */
cb.callout_number = ecode[1];
cb.offset_vector = md->offset_vector;
cb.subject = (PCRE_SPTR)md->start_subject;
cb.subject_length = md->end_subject - md->start_subject;
cb.start_match = mstart - md->start_subject;
cb.current_position = eptr - md->start_subject;
cb.pattern_position = GET(ecode, 2);
cb.next_item_length = GET(ecode, 2 + LINK_SIZE);
cb.capture_top = offset_top/2;
cb.capture_last = md->capture_last;
cb.callout_data = md->callout_data;
if ((rrc = (*pcre_callout)(&cb)) > 0) RRETURN(MATCH_NOMATCH);
if (rrc < 0) RRETURN(rrc);
}
ecode += 2 + 2*LINK_SIZE;
break;
/* Recursion either matches the current regex, or some subexpression. The
offset data is the offset to the starting bracket from the start of the
whole pattern. (This is so that it works from duplicated subpatterns.)
If there are any capturing brackets started but not finished, we have to
save their starting points and reinstate them after the recursion. However,
we don't know how many such there are (offset_top records the completed
total) so we just have to save all the potential data. There may be up to
65535 such values, which is too large to put on the stack, but using malloc
for small numbers seems expensive. As a compromise, the stack is used when
there are no more than REC_STACK_SAVE_MAX values to store; otherwise malloc
is used. A problem is what to do if the malloc fails ... there is no way of
returning to the top level with an error. Save the top REC_STACK_SAVE_MAX
values on the stack, and accept that the rest may be wrong.
There are also other values that have to be saved. We use a chained
sequence of blocks that actually live on the stack. Thanks to Robin Houston
for the original version of this logic. */