[bug] locale ctype not always honoured properly in pcre matching

[bug] locale ctype not always honoured properly in pcre matching

[Stephane Chazelas]

$ locale charmap
UTF-8
$ set -o rematchpcre
$ LC_ALL=C [ $'\xc3\xa9' '=~' '^..\z' ] && echo yes
yes

OK, in C locale, those two bytes are considered as two characters.

$ [ $'\xc3\xa9' '=~' '^..\z' ] && echo yes
$

OK, in UTF-8, those two bytes form one é character

$ LC_ALL=C [ $'\xc3\xa9' '=~' '^..\z' ] && echo yes
$

Same command as above, but now it doesn't match (?!) and instead:

$ LC_ALL=C [ $'\xc3\xa9' '=~' '^.\z' ] && echo yes
yes

Behaves  as if doing a match in UTF-8.

Same goes with:

$ PS1='$ ' zsh -f
$ set -o rematchpcre
$ (LC_ALL=C; [[ $'\xc3\xa9' =~ '^..\z' ]] && echo yes )
yes
$ [[ $'\xc3\xa9' =~ '^..\z' ]] && echo yes
$ (LC_ALL=C; [[ $'\xc3\xa9' =~ '^..\z' ]] && echo yes )
$

-- 
Stephane

Re: [bug] locale ctype not always honoured properly in pcre matching

[Bart Schaefer]

I'm not 100% sure, but I think this is because in Src/Modules/pcre.c
the state of UTF-8 parsing is cached and only changes when the
MULTIBYTE option is different upon re-entry.  Changing the locale
doesn't have that effect.

Re: [bug] locale ctype not always honoured properly in pcre matching

[Jun. T]

> 2022/09/21 8:08, Bart Schaefer <schaefer@brasslantern.com> wrote:
> 
> I'm not 100% sure, but I think this is because in Src/Modules/pcre.c
> the state of UTF-8 parsing is cached and only changes when the
> MULTIBYTE option is different upon re-entry.  Changing the locale
> doesn't have that effect.

Yes.
The following patch seems to solve the problem.
With this patch strcmp(nl_langinfo(CODESET),..) is called every time
pcre matching is used, but I think the overhead is negligible.
For example, I tried

time (repeat 1000000; do [[ 'a' =~ '^.\z' ]]; done)

before and after the patch, but the time difference was negligible
at least on my Mac (both are about 3 seconds).



diff --git a/Src/Modules/pcre.c b/Src/Modules/pcre.c
index 6289e003e..46875a59b 100644
--- a/Src/Modules/pcre.c
+++ b/Src/Modules/pcre.c
@@ -47,8 +47,6 @@ zpcre_utf8_enabled(void)
 #if defined(MULTIBYTE_SUPPORT) && defined(HAVE_NL_LANGINFO) && defined(CODESET)
     static int have_utf8_pcre = -1;
 
-    /* value can toggle based on MULTIBYTE, so don't
-     * be too eager with caching */
     if (have_utf8_pcre < -1)
 	return 0;
 
@@ -56,15 +54,11 @@ zpcre_utf8_enabled(void)
 	return 0;
 
     if ((have_utf8_pcre == -1) &&
-        (!strcmp(nl_langinfo(CODESET), "UTF-8"))) {
-
-	if (pcre_config(PCRE_CONFIG_UTF8, &have_utf8_pcre))
+	(pcre_config(PCRE_CONFIG_UTF8, &have_utf8_pcre))) {
 	    have_utf8_pcre = -2; /* erk, failed to ask */
     }
 
-    if (have_utf8_pcre < 0)
-	return 0;
-    return have_utf8_pcre;
+    return (have_utf8_pcre == 1) && (!strcmp(nl_langinfo(CODESET), "UTF-8"));
 
 #else
     return 0;