Ensure ovector[0,1] are both PCRE2_UNSET during callouts.
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.TH PCRE2CALLOUT 3 "29 March 2017" "PCRE2 10.30"
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.TH PCRE2CALLOUT 3 "14 April 2017" "PCRE2 10.30"
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.SH NAME
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.SH NAME
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PCRE2 - Perl-compatible regular expressions (revised API)
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PCRE2 - Perl-compatible regular expressions (revised API)
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.SH SYNOPSIS
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.SH SYNOPSIS
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@ -191,8 +191,8 @@ callouts such as the example above are obeyed.
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.rs
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.rs
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.sp
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.sp
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During matching, when PCRE2 reaches a callout point, if an external function is
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During matching, when PCRE2 reaches a callout point, if an external function is
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set in the match context, it is called. This applies to both normal and DFA
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provided in the match context, it is called. This applies to both normal and
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matching. The first argument to the callout function is a pointer to a
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DFA matching. The first argument to the callout function is a pointer to a
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\fBpcre2_callout\fP block. The second argument is the void * callout data that
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\fBpcre2_callout\fP block. The second argument is the void * callout data that
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was supplied when the callout was set up by calling \fBpcre2_set_callout()\fP
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was supplied when the callout was set up by calling \fBpcre2_set_callout()\fP
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(see the
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(see the
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@ -261,7 +261,7 @@ The remaining fields in the callout block are the same for both kinds of
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callout.
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callout.
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.P
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.P
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The \fIoffset_vector\fP field is a pointer to a vector of capturing offsets
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The \fIoffset_vector\fP field is a pointer to a vector of capturing offsets
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(the "ovector"). You may read certain elements in this vector, but you must not
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(the "ovector"). You may read the elements in this vector, but you must not
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change any of them.
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change any of them.
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.P
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.P
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For calls to \fBpcre2_match()\fP, the \fIoffset_vector\fP field is not (since
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For calls to \fBpcre2_match()\fP, the \fIoffset_vector\fP field is not (since
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@ -282,9 +282,10 @@ for example, when the callout in the pattern ((a)(b))(?C2) is taken,
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The contents of ovector[2] to ovector[<capture_top>*2-1] can be inspected in
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The contents of ovector[2] to ovector[<capture_top>*2-1] can be inspected in
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order to extract substrings that have been matched so far, in the same way as
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order to extract substrings that have been matched so far, in the same way as
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extracting substrings after a match has completed. The values in ovector[0] and
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extracting substrings after a match has completed. The values in ovector[0] and
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ovector[1] are undefined and should not be used in any way. Substrings that
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ovector[1] are always PCRE2_UNSET because the match is by definition not
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have not been captured (but whose numbers are less than \fIcapture_top\fP) have
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complete. Substrings that have not been captured but whose numbers are less
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both of their ovector slots set to PCRE2_UNSET.
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than \fIcapture_top\fP also have both of their ovector slots set to
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PCRE2_UNSET.
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.P
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.P
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For DFA matching, the \fIoffset_vector\fP field points to the ovector that was
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For DFA matching, the \fIoffset_vector\fP field points to the ovector that was
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passed to the matching function in the match data block, but it holds no useful
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passed to the matching function in the match data block, but it holds no useful
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@ -410,6 +411,6 @@ Cambridge, England.
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.rs
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.rs
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.sp
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.sp
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.nf
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.nf
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Last updated: 29 March 2017
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Last updated: 14 April 2017
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Copyright (c) 1997-2017 University of Cambridge.
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Copyright (c) 1997-2017 University of Cambridge.
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.fi
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.fi
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@ -263,20 +263,14 @@ Returns: the return from the callout
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static int
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static int
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do_callout(heapframe *F, match_block *mb, PCRE2_SIZE *lengthptr)
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do_callout(heapframe *F, match_block *mb, PCRE2_SIZE *lengthptr)
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{
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{
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PCRE2_SIZE save0, save1;
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pcre2_callout_block cb;
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pcre2_callout_block cb;
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int rc;
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*lengthptr = (*Fecode == OP_CALLOUT)?
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*lengthptr = (*Fecode == OP_CALLOUT)?
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PRIV(OP_lengths)[OP_CALLOUT] : GET(Fecode, 1 + 2*LINK_SIZE);
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PRIV(OP_lengths)[OP_CALLOUT] : GET(Fecode, 1 + 2*LINK_SIZE);
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if (mb->callout == NULL) return 0; /* No callout function provided */
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if (mb->callout == NULL) return 0; /* No callout function provided */
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/* The original matching code (pre 10.40) worked directly with the ovector
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passed by the user, and this was passed to callouts. Now that the working
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ovector is in the backtracking frame, it no longer needs to reserve space for
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the overall match offsets (which would waste space in the frame). For backward
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compatibility, however, we pass capture_top and offset_vector to the callout as
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if for the extended ovector. */
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cb.version = 1;
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cb.version = 1;
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cb.capture_top = (uint32_t)Foffset_top/2 + 1;
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cb.capture_top = (uint32_t)Foffset_top/2 + 1;
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cb.capture_last = Fcapture_last;
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cb.capture_last = Fcapture_last;
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@ -305,7 +299,21 @@ else /* String callout */
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*lengthptr - (1 + 4*LINK_SIZE) - 2;
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*lengthptr - (1 + 4*LINK_SIZE) - 2;
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}
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}
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return mb->callout(&cb, mb->callout_data);
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/* The original matching code (pre 10.30) worked directly with the ovector
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passed by the user, and this was passed to callouts. Now that the working
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ovector is in the backtracking frame, it no longer needs to reserve space for
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the overall match offsets (which would waste space in the frame). For backward
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compatibility, however, we pass capture_top and offset_vector to the callout as
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if for the extended ovector, and we ensure that the first two slots are unset
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by preserving and restoring their current contents. */
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save0 = Fovector[-2];
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save1 = Fovector[-1];
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Fovector[-2] = Fovector[-1] = PCRE2_UNSET;
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rc = mb->callout(&cb, mb->callout_data);
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Fovector[-2] = save0;
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Fovector[-1] = save1;
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return rc;
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}
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}
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