[PATCH v2] expand: Recognize '^' as a negation character in BE

[Dimitar Yurukov <mscalindt@gmail.com>]

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