FYI: [PATCH] libtool: make fork minimisation compatible with dash and zsh.
* build-aub/general.m4sh (lt_HAVE_PLUSEQ_OP): Instead of using
$((..)) arithmetic, which causes an error on dash, use a case
based bash version check.
(lt_HAVE_ARITH_OP, lt_HAVE_XSI_OPS): Also short circuit the
feature probing forks and set these automatically when zsh is
detected.
Reported by Stefano Lattarini.
Signed-off-by: Gary V. Vaughan
---
build-aux/general.m4sh | 12 +++-
1 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/build-aux/general.m4sh b/build-aux/general.m4sh
index e96c0e4..3cfecee 100644
--- a/build-aux/general.m4sh
+++ b/build-aux/general.m4sh
@@ -75,14 +75,16 @@ basename='s|^.*/||'
# We should try to minimise forks, especially on Windows where they are
-# unreasonably slow, so skip the feature probes when bash is being used:
-if test set = "${BASH_VERSION+set}"; then
+# unreasonably slow, so skip the feature probes when bash or zsh are
+# being used:
+if test set = "${BASH_VERSION+set}${ZSH_VERSION}"; then
: ${lt_HAVE_ARITH_OP="yes"}
: ${lt_HAVE_XSI_OPS="yes"}
# The += operator was introduced in bash 3.1
-test -z "$lt_HAVE_PLUSEQ_OP" \
- && test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
- && lt_HAVE_PLUSEQ_OP=yes
+case $BASH_VERSION in
+ [12].* | 3.0 | 3.0.*) ;;
+ *)lt_HAVE_PLUSEQ_OP=yes ;;
+esac
fi
--
1.7.8
Cheers,
--
Gary V. Vaughan (gary AT gnu DOT org)
Re: FYI [PATCH] libtool: minimise forks per invocation under bash.
Hi Stefano,
On 18 Dec 2011, at 17:19, Stefano Lattarini wrote:
> On 12/18/2011 11:07 AM, Gary V. Vaughan wrote:
>> On 18 Dec 2011, at 17:02, Stefano Lattarini wrote:
>>> On 12/18/2011 10:52 AM, Stefano Lattarini wrote:
On 12/18/2011 06:15 AM, Gary V. Vaughan wrote:
> +# We should try to minimise forks, especially on Windows where they are
> +# unreasonably slow, so skip the feature probes when bash is being used:
> +if test set = "${BASH_VERSION+set}"; then
> +: ${lt_HAVE_ARITH_OP="yes"}
> +: ${lt_HAVE_XSI_OPS="yes"}
> +# The += operator was introduced in bash 3.1
> +test -z "$lt_HAVE_PLUSEQ_OP" \
> +&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))"
> \
> +&& lt_HAVE_PLUSEQ_OP=yes
> +fi
This will likely break with dash 0.5.2:
$ cat foo.sh
#!/bin/sh
if test set = "${BASH_VERSION+set}"; then
: ${lt_HAVE_ARITH_OP="yes"}
: ${lt_HAVE_XSI_OPS="yes"}
# The += operator was introduced in bash 3.1
test -z "$lt_HAVE_PLUSEQ_OP" \
&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
&& lt_HAVE_PLUSEQ_OP=yes
fi
$ dash foo.sh
foo.sh: 7: Syntax error: Bad substitution
>>> Update: the same happens with NetBSD 5.1 /bin/sh (which is probably
>>> an ash-derivative).
>> Thanks for the report.
>>
>> Unfortunately, I'm out of ideas on how to portably detect the bash version
>> without
>> spending a fork, in which case it seems easiest to spend that fork actually
>> testing
>> for += support rather than poking at the bash version.
>>
>> Can anyone think of something better than just removing the whole
>> lt_HAVE_PLUSEQ_OP
>> clause from the patch quoted above, and letting the shell figure it by
>> itself later
>> on?
> Adding an extra eval seems to do the trick:
>
> eval 'test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))"'
>
> Of course, a comment about why this eval is needed would be definitely
> warranted.
Not that I've looked at the implementation, but isn't eval as bad as a fork on
Windows? (which is the only reason to avoid forks, since they are extremely
cheap on
Unix.)
> Or, to be even safer, you could directly poke at $BASH_VERSION instead:
>
> case $BASH_VERSION in
>[12].*|3.0.*) ;;
>*) lt_HAVE_PLUSEQ_OP=yes;;
> esac
Ah, true... I guess I was too focussed on a straight forward one liner, and
missed
the obvious one. D'oh! I'll switch to that and push presently.
Cheers,
--
Gary V. Vaughan (gary AT gnu DOT org)
Re: FYI [PATCH] libtool: minimise forks per invocation under bash.
On 12/18/2011 11:07 AM, Gary V. Vaughan wrote:
Hi Stefano,
On 18 Dec 2011, at 17:02, Stefano Lattarini wrote:
On 12/18/2011 10:52 AM, Stefano Lattarini wrote:
On 12/18/2011 06:15 AM, Gary V. Vaughan wrote:
+# We should try to minimise forks, especially on Windows where they are
+# unreasonably slow, so skip the feature probes when bash is being used:
+if test set = "${BASH_VERSION+set}"; then
+: ${lt_HAVE_ARITH_OP="yes"}
+: ${lt_HAVE_XSI_OPS="yes"}
+# The += operator was introduced in bash 3.1
+test -z "$lt_HAVE_PLUSEQ_OP" \
+&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
+&& lt_HAVE_PLUSEQ_OP=yes
+fi
This will likely break with dash 0.5.2:
$ cat foo.sh
#!/bin/sh
if test set = "${BASH_VERSION+set}"; then
: ${lt_HAVE_ARITH_OP="yes"}
: ${lt_HAVE_XSI_OPS="yes"}
# The += operator was introduced in bash 3.1
test -z "$lt_HAVE_PLUSEQ_OP" \
&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
&& lt_HAVE_PLUSEQ_OP=yes
fi
$ dash foo.sh
foo.sh: 7: Syntax error: Bad substitution
Update: the same happens with NetBSD 5.1 /bin/sh (which is probably
an ash-derivative).
Thanks for the report.
Unfortunately, I'm out of ideas on how to portably detect the bash version
without
spending a fork, in which case it seems easiest to spend that fork actually
testing
for += support rather than poking at the bash version.
Can anyone think of something better than just removing the whole
lt_HAVE_PLUSEQ_OP
clause from the patch quoted above, and letting the shell figure it by itself
later
on?
Adding an extra eval seems to do the trick:
eval 'test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 +
${BASH_VERSINFO[1]}))"'
Of course, a comment about why this eval is needed would be definitely
warranted.
Or, to be even safer, you could directly poke at $BASH_VERSION instead:
case $BASH_VERSION in
[12].*|3.0.*) ;;
*) lt_HAVE_PLUSEQ_OP=yes;;
esac
Regards,
Stefano
Re: FYI [PATCH] libtool: minimise forks per invocation under bash.
Hi Stefano,
On 18 Dec 2011, at 17:02, Stefano Lattarini wrote:
> On 12/18/2011 10:52 AM, Stefano Lattarini wrote:
>> On 12/18/2011 06:15 AM, Gary V. Vaughan wrote:
>>> +# We should try to minimise forks, especially on Windows where they are
>>> +# unreasonably slow, so skip the feature probes when bash is being used:
>>> +if test set = "${BASH_VERSION+set}"; then
>>> +: ${lt_HAVE_ARITH_OP="yes"}
>>> +: ${lt_HAVE_XSI_OPS="yes"}
>>> +# The += operator was introduced in bash 3.1
>>> +test -z "$lt_HAVE_PLUSEQ_OP" \
>>> +&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
>>> +&& lt_HAVE_PLUSEQ_OP=yes
>>> +fi
>> This will likely break with dash 0.5.2:
>>
>> $ cat foo.sh
>> #!/bin/sh
>> if test set = "${BASH_VERSION+set}"; then
>>: ${lt_HAVE_ARITH_OP="yes"}
>>: ${lt_HAVE_XSI_OPS="yes"}
>># The += operator was introduced in bash 3.1
>>test -z "$lt_HAVE_PLUSEQ_OP" \
>> && test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
>> && lt_HAVE_PLUSEQ_OP=yes
>> fi
>> $ dash foo.sh
>> foo.sh: 7: Syntax error: Bad substitution
>>
> Update: the same happens with NetBSD 5.1 /bin/sh (which is probably
> an ash-derivative).
Thanks for the report.
Unfortunately, I'm out of ideas on how to portably detect the bash version
without
spending a fork, in which case it seems easiest to spend that fork actually
testing
for += support rather than poking at the bash version.
Can anyone think of something better than just removing the whole
lt_HAVE_PLUSEQ_OP
clause from the patch quoted above, and letting the shell figure it by itself
later
on?
Cheers,
--
Gary V. Vaughan (gary AT gnu DOT org)
Re: FYI [PATCH] libtool: minimise forks per invocation under bash.
On 12/18/2011 10:52 AM, Stefano Lattarini wrote:
On 12/18/2011 06:15 AM, Gary V. Vaughan wrote:
+# We should try to minimise forks, especially on Windows where they are
+# unreasonably slow, so skip the feature probes when bash is being
used:
+if test set = "${BASH_VERSION+set}"; then
+: ${lt_HAVE_ARITH_OP="yes"}
+: ${lt_HAVE_XSI_OPS="yes"}
+# The += operator was introduced in bash 3.1
+test -z "$lt_HAVE_PLUSEQ_OP" \
+&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 +
${BASH_VERSINFO[1]}))" \
+&& lt_HAVE_PLUSEQ_OP=yes
+fi
This will likely break with dash 0.5.2:
$ cat foo.sh
#!/bin/sh
if test set = "${BASH_VERSION+set}"; then
: ${lt_HAVE_ARITH_OP="yes"}
: ${lt_HAVE_XSI_OPS="yes"}
# The += operator was introduced in bash 3.1
test -z "$lt_HAVE_PLUSEQ_OP" \
&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
&& lt_HAVE_PLUSEQ_OP=yes
fi
$ dash foo.sh
foo.sh: 7: Syntax error: Bad substitution
Update: the same happens with NetBSD 5.1 /bin/sh (which is probably
an ash-derivative).
Regards,
Stefano
Re: FYI [PATCH] libtool: minimise forks per invocation under bash.
On 12/18/2011 06:15 AM, Gary V. Vaughan wrote:
+# We should try to minimise forks, especially on Windows where they are
+# unreasonably slow, so skip the feature probes when bash is being used:
+if test set = "${BASH_VERSION+set}"; then
+: ${lt_HAVE_ARITH_OP="yes"}
+: ${lt_HAVE_XSI_OPS="yes"}
+# The += operator was introduced in bash 3.1
+test -z "$lt_HAVE_PLUSEQ_OP" \
+&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
+&& lt_HAVE_PLUSEQ_OP=yes
+fi
This will likely break with dash 0.5.2:
$ cat foo.sh
#!/bin/sh
if test set = "${BASH_VERSION+set}"; then
: ${lt_HAVE_ARITH_OP="yes"}
: ${lt_HAVE_XSI_OPS="yes"}
# The += operator was introduced in bash 3.1
test -z "$lt_HAVE_PLUSEQ_OP" \
&& test 3000 -lt "$((${BASH_VERSINFO[0]}*1000 + ${BASH_VERSINFO[1]}))" \
&& lt_HAVE_PLUSEQ_OP=yes
fi
$ dash foo.sh
foo.sh: 7: Syntax error: Bad substitution
Regards,
Stefano
