Re: Parameter expansion, patterns and fnmatch

[Harald van Dijk <harald@gigawatt.nl>]

On 03/09/16 15:58, Herbert Xu wrote:
> On Sat, Sep 03, 2016 at 03:19:57PM +0200, Harald van Dijk wrote:
>>
>> But yeah, sure, if the bug has been there for over 10 years, and I'm
>> unable to find older versions of dash to check, I would have guessed
>> that dash indeed has never worked this way.
>
> OK it looks like this actually wasn't the original behaviour.
> It was introduced along with the character class support.  So
> with that in mind, I feel a lot happier in changing the behaviour
> of the case statement.
>
> I've changed your patch slightly and will commit it if there are
> no other issues.

None that I can see. Agreed that avoiding increment-decrement-increment 
to just do a single increment instead is an improvement, and I don't 
spot any issues in it.

> ---8<---
> Subject: expand - Fix dangling left square brackets in patterns
>
> When there is an unmatched left square bracket in patterns, pmatch
> will behave strangely and exhibit undefined behaviour.  This patch
> (based on Harld van Dijk's original) fixes this by treating it as
> a literal left square bracket.
>
> Reported-by: Olof Johansson <olof@ethup.se>
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>
> diff --git a/src/expand.c b/src/expand.c
> index 36bea76..2a50830 100644
> --- a/src/expand.c
> +++ b/src/expand.c
> @@ -1584,14 +1584,14 @@ pmatch(const char *pattern, const char *string)
>  				p++;
>  			}
>  			found = 0;
> -			chr = *q++;
> +			chr = *q;
>  			if (chr == '\0')
>  				return 0;
>  			c = *p++;
>  			do {
>  				if (!c) {
>  					p = startp;
> -					c = *p;
> +					c = '[';
>  					goto dft;
>  				}
>  				if (c == '[') {
> @@ -1618,6 +1618,7 @@ pmatch(const char *pattern, const char *string)
>  			} while ((c = *p++) != ']');
>  			if (found == invert)
>  				return 0;
> +			q++;
>  			break;
>  		}
>  dft:	        default:
>