* [PATCH] expand: Recognize '^' as a negation character in BE
@ 2021-07-16 9:42 Dimitar Yurukov
2021-07-16 10:00 ` Harald van Dijk
2021-07-16 12:50 ` [PATCH v2] " Dimitar Yurukov
0 siblings, 2 replies; 5+ messages in thread
From: Dimitar Yurukov @ 2021-07-16 9:42 UTC (permalink / raw)
To: dash; +Cc: Dimitar Yurukov
While parsing bracket expression ('[...]'), DASH recognizes only '!' as
a special character for negation/inversion, but POSIX specifies '^'.
The POSIX specification (2018 edition) states:
^ The <circumflex> shall signify a non-matching list expression when
it occurs first in a list, immediately following a
<left-square-bracket> (see RE Bracket Expression).
DASH:
$ i='123 asd' && printf "%s\n" "${i##*[!a-z]}"
asd
$ i='123 asd' && printf "%s\n" "${i##*[^a-z]}"
<empty expansion>
BASH (with --posix):
$ i='123 asd' && printf "%s\n" "${i##*[!a-z]}"
asd
$ i='123 asd' && printf "%s\n" "${i##*[^a-z]}"
asd
Make <circumflex> ('^') a special character used to specify
negation/inversion in bracket expressions:
$ i='123 asd' && printf "%s\n" "${i##*[^a-z]}"
asd
Signed-off-by: Dimitar Yurukov <mscalindt@gmail.com>
---
src/expand.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/expand.c b/src/expand.c
index 1730670..06392ff 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -1565,7 +1565,7 @@ pmatch(const char *pattern, const char *string)
startp = p;
invert = 0;
- if (*p == '!') {
+ if (*p == '!' || *p == '^') {
invert++;
p++;
}
--
2.32.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] expand: Recognize '^' as a negation character in BE
2021-07-16 9:42 [PATCH] expand: Recognize '^' as a negation character in BE Dimitar Yurukov
@ 2021-07-16 10:00 ` Harald van Dijk
2021-07-16 12:46 ` Dimitar Yurukov
2021-07-16 12:50 ` [PATCH v2] " Dimitar Yurukov
1 sibling, 1 reply; 5+ messages in thread
From: Harald van Dijk @ 2021-07-16 10:00 UTC (permalink / raw)
To: Dimitar Yurukov, dash
On 16/07/2021 10:42, Dimitar Yurukov wrote:
> While parsing bracket expression ('[...]'), DASH recognizes only '!' as
> a special character for negation/inversion, but POSIX specifies '^'.
>
> The POSIX specification (2018 edition) states:
>
> ^ The <circumflex> shall signify a non-matching list expression when
> it occurs first in a list, immediately following a
> <left-square-bracket> (see RE Bracket Expression).
It also states:
the <exclamation-mark> character ( '!' ) shall replace the
<circumflex> character ( '^' ) in its role in a non-matching list in the
regular expression notation
and
A bracket expression starting with an unquoted <circumflex> character
produces unspecified results.
See 2.13.1 Patterns Matching a Single Character.
So both the dash and the bash behaviour are permitted and this patch
does not address a correctness issue. Scripts that rely on ^ for
negation should be modified to use !.
The patch may still be worthwhile to increase compatibility, but in that
case the same change also needs to be made to expmeta().
Cheers,
Harald van Dijk
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] expand: Recognize '^' as a negation character in BE
2021-07-16 10:00 ` Harald van Dijk
@ 2021-07-16 12:46 ` Dimitar Yurukov
0 siblings, 0 replies; 5+ messages in thread
From: Dimitar Yurukov @ 2021-07-16 12:46 UTC (permalink / raw)
To: harald; +Cc: dash, mscalindt
On 16/07/2021 11:00, Harald van Dijk wrote:
> On 16/07/2021 10:42, Dimitar Yurukov wrote:
> > While parsing bracket expression ('[...]'), DASH recognizes only '!' as
> > a special character for negation/inversion, but POSIX specifies '^'.
> >
> > The POSIX specification (2018 edition) states:
> >
> > ^ The <circumflex> shall signify a non-matching list expression when
> > it occurs first in a list, immediately following a
> > <left-square-bracket> (see RE Bracket Expression).
>
> It also states:
>
> the <exclamation-mark> character ( '!' ) shall replace the
> <circumflex> character ( '^' ) in its role in a non-matching list in the
> regular expression notation
>
> and
>
> A bracket expression starting with an unquoted <circumflex> character
> produces unspecified results.
>
> See 2.13.1 Patterns Matching a Single Character.
Oh, my bad, sorry for the noise.
> The patch may still be worthwhile to increase compatibility, but in that
> case the same change also needs to be made to expmeta().
Oops, you are right. Will attach v2.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] expand: Recognize '^' as a negation character in BE
2021-07-16 9:42 [PATCH] expand: Recognize '^' as a negation character in BE Dimitar Yurukov
2021-07-16 10:00 ` Harald van Dijk
@ 2021-07-16 12:50 ` Dimitar Yurukov
2021-07-19 5:13 ` Herbert Xu
1 sibling, 1 reply; 5+ messages in thread
From: Dimitar Yurukov @ 2021-07-16 12:50 UTC (permalink / raw)
To: mscalindt; +Cc: dash, harald
While performing bracket expression ('[...]'), DASH recognizes only '!'
as a special character for negation/inversion, but POSIX specifies '^'.
The specification (2018 edition):
"
9.3.3 BRE Special Characters
^ The <circumflex> shall signify a non-matching list expression when it
occurs first in a list, immediately following a <left-square-bracket>
(see RE Bracket Expression).
"
DASH:
$ i='123 asd' && printf "%s\n" "${i##*[!a-z]}"
asd
$ i='123 asd' && printf "%s\n" "${i##*[^a-z]}"
$
BASH (with --posix):
$ i='123 asd' && printf "%s\n" "${i##*[!a-z]}"
asd
$ i='123 asd' && printf "%s\n" "${i##*[^a-z]}"
asd
$
This patch makes <circumflex> ('^') a special character used to specify
negation/inversion.
Signed-off-by: Dimitar Yurukov <mscalindt@gmail.com>
---
Changes in v2:
- Fixed the patch (patched expmeta())
src/expand.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/expand.c b/src/expand.c
index 1730670..32a1b5a 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -1296,7 +1296,7 @@ expmeta(char *name, unsigned name_len, unsigned expdir_len)
metaflag = 1;
else if (*p == '[') {
char *q = p + 1;
- if (*q == '!')
+ if (*q == '!' || *q == '^')
q++;
for (;;) {
if (*q == '\\')
@@ -1565,7 +1565,7 @@ pmatch(const char *pattern, const char *string)
startp = p;
invert = 0;
- if (*p == '!') {
+ if (*p == '!' || *p == '^') {
invert++;
p++;
}
--
2.32.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v2] expand: Recognize '^' as a negation character in BE
2021-07-16 12:50 ` [PATCH v2] " Dimitar Yurukov
@ 2021-07-19 5:13 ` Herbert Xu
0 siblings, 0 replies; 5+ messages in thread
From: Herbert Xu @ 2021-07-19 5:13 UTC (permalink / raw)
To: Dimitar Yurukov; +Cc: mscalindt, dash, harald
Dimitar Yurukov <mscalindt@gmail.com> wrote:
> While performing bracket expression ('[...]'), DASH recognizes only '!'
> as a special character for negation/inversion, but POSIX specifies '^'.
>
> The specification (2018 edition):
> "
> 9.3.3 BRE Special Characters
>
> ^ The <circumflex> shall signify a non-matching list expression when it
> occurs first in a list, immediately following a <left-square-bracket>
> (see RE Bracket Expression).
> "
This is incorrect and ^ cannot be used in a portable script.
Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-07-16 9:42 [PATCH] expand: Recognize '^' as a negation character in BE Dimitar Yurukov
2021-07-16 10:00 ` Harald van Dijk
2021-07-16 12:46 ` Dimitar Yurukov
2021-07-16 12:50 ` [PATCH v2] " Dimitar Yurukov
2021-07-19 5:13 ` Herbert Xu
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