Re: Parameter expansion stopped working in recent ash/dash

[Brian Inglis <Brian.Inglis@Shaw.ca>]

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On 2023-02-07 12:01, Brian Inglis via Cygwin wrote:
> On 2023-02-07 10:19, Brian Inglis via Cygwin wrote:
>> On 2023-02-07 05:07, Andrey Repin via Cygwin wrote:
>>> In the attached script, that I always run using dash, the expansion is
>>> supposed to strip leading/trailing spaces from provided parameter.
>>> The upgrade that took place after which the expansion stopped working is
>>> libsolv:   - dash-0.5.11.5-1.any -> dash-0.5.12-1.any
>>> Downgrading to 0.5.11.5 restored the expected behavior.
>>> I failed to find anything relevant in the dash 0.5.12 patch notes, but perhaps
>>> community could help?

>> Looks like something in dash broke space trimming of any sort: see attached 
>> script and logs.
>> I will see what upstream has to say for themselves, or about Cygwin.

> Stupid errors in test script, didn't actually run trim3 anyway, redone, and that 
> and updated logs attached.
> It appears the locale dependent [[:space:]] regexp no longer works but using 
> escapes generated by echo still does, see corrected trim3, so perhaps use those 
> for now, if you can, while I follow this upstream.
> You may need to add escape sequences for any locale dependent spacing characters 
> to the space string, so please let us know if there are.

Hi Andrey,

A new test release 0.5.12-2 has been uploaded so please install and test that 
behaves as expected in past releases.

The issue was caused as glibc fnmatch and glob now support locale dependent 
named character classes, equivalents, etc. as in grep, so the build now defaults 
to using the local libc fnmatch and glob, without any config test for which libc 
or supported features.

Cygwin winsup and newlib libc fnmatch and glob do not support those locale 
dependent named character classes, equivalents, etc. as in grep, so those 
features are no longer provided in dash by default.

The new test release disables the build from using libc fnmatch and glob and use 
those provided by dash (possibly by or from gnulib), so those classes again 
appear to work as expected: see attached log.

If there are no further negative reports by this weekend, I will replace the 
current stable release with this latest test release.

-- 
Take care. Thanks, Brian Inglis			Calgary, Alberta, Canada

La perfection est atteinte			Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter	not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer	but when there is no more to cut
			-- Antoine de Saint-Exupéry

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#!/bin/dash -vx

trim() {
  # remove leading whitespace characters
  __trim="${*#${*%%[![:space:]]*}}"
  # remove trailing whitespace characters
  printf "%s" "${__trim%${__trim##*[![:space:]]}}"
}

trim " alpha" | od -t x1a
+ trim  alpha
+ __trim=alpha
+ printf %s alpha
+ od -t x1a
0000000  61  6c  70  68  61
          a   l   p   h   a
0000005
trim "beta " | od -t x1a
+ trim beta 
+ __trim=beta 
+ printf %s beta
+ od -t x1a
0000000  62  65  74  61
          b   e   t   a
0000004
trim "\rgamma	" | od -t x1a
+ trim \rgamma	
+ __trim=gamma	
+ printf %s gamma
+ od -t x1a
0000000  67  61  6d  6d  61
          g   a   m   m   a
0000005

trim2() {
  # remove leading whitespace characters
  __trim="${*##[[:space:]]}"
  # remove trailing whitespace characters
  printf "%s" "${__trim%%[[:space:]]}"
}

trim2 " alpha" | od -t x1a
+ trim2  alpha
+ __trim=alpha
+ printf %s alpha
+ od -t x1a
0000000  61  6c  70  68  61
          a   l   p   h   a
0000005
trim2 "beta " | od -t x1a
+ trim2 beta 
+ __trim=beta 
+ printf %s beta
+ od -t x1a
0000000  62  65  74  61
          b   e   t   a
0000004
trim2 "\rgamma	" | od -t x1a
+ trim2 \rgamma	
+ __trim=gamma	
+ printf %s gamma
+ od -t x1a
0000000  67  61  6d  6d  61
          g   a   m   m   a
0000005

trim3() {
  _space="$(echo -n '[\b\t\n\v\f\r ]')"
  # remove leading whitespace characters
  __trim="${*##$_space}"
  # remove trailing whitespace characters
  printf "%s" "${__trim%%$_space}"
}

trim3 " alpha" | od -t x1a
+ trim3  alpha
+ od -t x1a
+ echo -n [\b\t\n\v\f\r ]
+ _space=[\b	
\v\f\r ]
+ __trim=alpha
+ printf %s alpha
0000000  61  6c  70  68  61
          a   l   p   h   a
0000005
trim3 "beta " | od -t x1a
+ trim3 beta 
+ od -t x1a
+ echo -n [\b\t\n\v\f\r ]
+ _space=[\b	
\v\f\r ]
+ __trim=beta 
+ printf %s beta
0000000  62  65  74  61
          b   e   t   a
0000004
trim3 "\rgamma	" | od -t x1a
+ trim3 \rgamma	
+ od -t x1a
+ echo -n [\b\t\n\v\f\r ]
+ _space=[\b	
\v\f\r ]
+ __trim=gamma	
+ printf %s gamma
0000000  67  61  6d  6d  61
          g   a   m   m   a
0000005