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Date: Wed, 5 Oct 2016 12:23:05 -0400
From: Rich Felker <dalias@...c.org>
To: Julien Ramseier <j.ramseier@...il.com>
Cc: musl@...ts.openwall.com, Johannes.Schindelin@....de
Subject: Re: [PATCH] regex: REG_STARTEND support
On Wed, Oct 05, 2016 at 02:19:35PM +0200, Julien Ramseier wrote:
> Here's my REG_STARTEND patch, mostly copied from the original tre[1]
> implementation.
> It's only lightly tested.
> [...]
> diff --git a/src/regex/regexec.c b/src/regex/regexec.c
> index 16c5d0a..ae65726 100644
> --- a/src/regex/regexec.c
> +++ b/src/regex/regexec.c
> @@ -29,6 +29,7 @@
>
> */
>
> +#include <sys/types.h>
> #include <stdlib.h>
> #include <string.h>
> #include <wchar.h>
> @@ -51,11 +52,15 @@ tre_fill_pmatch(size_t nmatch, regmatch_t pmatch[], int cflags,
>
> #define GET_NEXT_WCHAR() do { \
> prev_c = next_c; pos += pos_add_next; \
> - if ((pos_add_next = mbtowc(&next_c, str_byte, MB_LEN_MAX)) <= 0) { \
> - if (pos_add_next < 0) { ret = REG_NOMATCH; goto error_exit; } \
> - else pos_add_next++; \
> + if (len >= 0 && pos >= len) \
> + next_c = L'\0'; \
As caught discussing this on #musl yesterday, pos (int) here has the
wrong type, int, which is a big problem. I'm going to work on a test
case to show it and confirm that changing the type fixes it.
> + else { \
> + if ((pos_add_next = mbtowc(&next_c, str_byte, MB_LEN_MAX)) <= 0) { \
> + if (pos_add_next < 0) { ret = REG_NOMATCH; goto error_exit; } \
> + else pos_add_next++; \
> + } \
> + str_byte += pos_add_next; \
> } \
> - str_byte += pos_add_next; \
There also seems to be a bug, which was also present in the original
TRE I think, whereby read past len can happen if the buffer up to len
ends with a partial multibyte character. Avoiding this seems rather
costly.
Otherwise this doesn't look too bad. I'll see if we can get some
figures for how it affects performance.
Rich
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