libc: regexec(3) adjustment.
Change the behavior of when REG_STARTEND is combined with REG_NOTBOL. From the original posting[1]: "Enable the assumption that pmatch[0].rm_so is a continuation offset to a string and allows us to do a proper assessment of the character in regards to it's word position ('^' or '\<'), without risking going into unallocated memory." This change makes us similar to how glibc handles REG_STARTEND | REG_NOTBOL, and is closely related to a soon-to-land fix to sed. Special thanks to Martijn van Duren and Ingo Schwarze for working out some consistent behaviour. Differential Revision: https://reviews.freebsd.org/D6257 Taken from: openbsd-tech 2016-05-24 [1] (Martijn van Duren) Relnotes: yes MFC after: 1 month
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=300683
@ -786,7 +786,7 @@ fast( struct match *m,
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ASSIGN(fresh, st);
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SP("start", st, *p);
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coldp = NULL;
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if (start == m->beginp)
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if (start == m->offp || (start == m->beginp && !(m->eflags®_NOTBOL)))
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c = OUT;
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else {
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/*
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@ -891,7 +891,7 @@ slow( struct match *m,
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SP("sstart", st, *p);
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st = step(m->g, startst, stopst, st, NOTHING, st);
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matchp = NULL;
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if (start == m->beginp)
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if (start == m->offp || (start == m->beginp && !(m->eflags®_NOTBOL)))
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c = OUT;
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else {
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/*
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@ -32,7 +32,7 @@
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.\" @(#)regex.3 8.4 (Berkeley) 3/20/94
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.\" $FreeBSD$
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.\"
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.Dd August 17, 2005
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.Dd May 25, 2016
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.Dt REGEX 3
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.Os
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.Sh NAME
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@ -235,11 +235,16 @@ The
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argument is the bitwise OR of zero or more of the following flags:
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.Bl -tag -width REG_STARTEND
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.It Dv REG_NOTBOL
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The first character of
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the string
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is not the beginning of a line, so the
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.Ql ^\&
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anchor should not match before it.
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The first character of the string is treated as the continuation
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of a line.
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This means that the anchors
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.Ql ^\& ,
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.Ql [[:<:]] ,
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and
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.Ql \e<
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do not match before it; but see
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.Dv REG_STARTEND
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below.
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This does not affect the behavior of newlines under
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.Dv REG_NEWLINE .
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.It Dv REG_NOTEOL
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@ -247,19 +252,16 @@ The NUL terminating
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the string
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does not end a line, so the
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.Ql $\&
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anchor should not match before it.
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anchor does not match before it.
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This does not affect the behavior of newlines under
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.Dv REG_NEWLINE .
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.It Dv REG_STARTEND
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The string is considered to start at
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.Fa string
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+
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.Fa pmatch Ns [0]. Ns Va rm_so
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and to have a terminating NUL located at
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.Fa string
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+
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.Fa pmatch Ns [0]. Ns Va rm_eo
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(there need not actually be a NUL at that location),
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.Fa string No +
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.Fa pmatch Ns [0]. Ns Fa rm_so
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and to end before the byte located at
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.Fa string No +
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.Fa pmatch Ns [0]. Ns Fa rm_eo ,
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regardless of the value of
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.Fa nmatch .
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See below for the definition of
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@ -271,13 +273,37 @@ compatible with but not specified by
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.St -p1003.2 ,
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and should be used with
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caution in software intended to be portable to other systems.
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Note that a non-zero
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.Va rm_so
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does not imply
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.Dv REG_NOTBOL ;
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.Dv REG_STARTEND
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affects only the location of the string,
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not how it is matched.
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.Pp
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Without
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.Dv REG_NOTBOL ,
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the position
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.Fa rm_so
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is considered the beginning of a line, such that
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.Ql ^
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matches before it, and the beginning of a word if there is a word
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character at this position, such that
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.Ql [[:<:]]
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and
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.Ql \e<
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match before it.
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.Pp
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With
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.Dv REG_NOTBOL ,
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the character at position
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.Fa rm_so
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is treated as the continuation of a line, and if
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.Fa rm_so
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is greater than 0, the preceding character is taken into consideration.
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If the preceding character is a newline and the regular expression was compiled
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with
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.Dv REG_NEWLINE ,
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.Ql ^
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matches before the string; if the preceding character is not a word character
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but the string starts with a word character,
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.Ql [[:<:]]
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and
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.Ql \e<
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match before the string.
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.El
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.Pp
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See
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