On 4/21/22 00:57, Arnold Robbins wrote:
As far as my testing indicates, dfa.c doesn't need a patch, it seems to accept "---" inside brackets for a single minus.
Yes, a brief perusal of the dfa.c source code suggests you're right. Thanks for looking into this. I tend to agree with you that POSIX is not likely to outlaw this extension.
If there are no objections, can we get this into Gnulib?
Although the basic idea looks good, I see a few places where the patch can be improved.
* The two calls to re_string_peek_byte might go past the end of the pattern (a subscript violation). This is possible because the pattern is not necessarily null-terminated.
* The two calls to re_string_fetch_byte can be simplified into a single call to re_string_skip_bytes.
* No need to assign to token->opr.c, as it already has the correct value. * Can fall through to the default case to save a bit of duplicate code.* glibc still uses comments /* like this */ for style reasons, and we should stick to that.
I wrote a patch with these improvements in mind and installed it into Gnulib (see attached); hope it works for Gawk too.
From dd83dfb3f2d2e5139ea7d00240b5441daa0b3a56 Mon Sep 17 00:00:00 2001 From: Paul Eggert <egg...@cs.ucla.edu> Date: Thu, 21 Apr 2022 18:56:12 -0700 Subject: [PATCH] regex: match [...---...] like V7 grep Problem reported by Arnold Robbins in: https://bugs.gnu.org/20657 https://lists.gnu.org/r/bug-gnulib/2022-04/msg00053.html * lib/regcomp.c (peek_token_bracket): Let [...---...] match '-'. This is an extension to POSIX, and matches V7 Unix grep. --- ChangeLog | 9 +++++++++ lib/regcomp.c | 16 +++++++++++++--- 2 files changed, 22 insertions(+), 3 deletions(-) diff --git a/ChangeLog b/ChangeLog index cd16bbe0cd..ddd4826bcf 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,12 @@ +2022-04-21 Paul Eggert <egg...@cs.ucla.edu> + + regex: match [...---...] like V7 grep + Problem reported by Arnold Robbins in: + https://bugs.gnu.org/20657 + https://lists.gnu.org/r/bug-gnulib/2022-04/msg00053.html + * lib/regcomp.c (peek_token_bracket): Let [...---...] match '-'. + This is an extension to POSIX, and matches V7 Unix grep. + 2022-04-20 Paul Eggert <egg...@cs.ucla.edu> backupfile: fix bug when renaming simple backups diff --git a/lib/regcomp.c b/lib/regcomp.c index b607c85320..122c3de58c 100644 --- a/lib/regcomp.c +++ b/lib/regcomp.c @@ -2038,15 +2038,25 @@ peek_token_bracket (re_token_t *token, re_string_t *input, reg_syntax_t syntax) } switch (c) { - case '-': - token->type = OP_CHARSET_RANGE; - break; case ']': token->type = OP_CLOSE_BRACKET; break; case '^': token->type = OP_NON_MATCH_LIST; break; + case '-': + /* In V7 Unix grep and Unix awk and mawk, [...---...] + (3 adjacent minus signs) stands for a single minus sign. + Support that without breaking anything else. */ + if (! (re_string_cur_idx (input) + 2 < re_string_length (input) + && re_string_peek_byte (input, 1) == '-' + && re_string_peek_byte (input, 2) == '-')) + { + token->type = OP_CHARSET_RANGE; + break; + } + re_string_skip_bytes (input, 2); + FALLTHROUGH; default: token->type = CHARACTER; } -- 2.35.1
