[PATCH] test-lib: don't use ulimit in test prerequisites on cygwin

[PATCH] test-lib: don't use ulimit in test prerequisites on cygwin

[Ramsay Jones]

On cygwin (and MinGW), the 'ulimit' built-in bash command does not have
the desired effect of limiting the resources of new processes, at least
for the stack and file descriptors. However, it always returns success
and leads to several test prerequisites being erroneously set to true.

Add a check for cygwin and MinGW to the prerequisite expressions, using
'uname -s', and return false instead of (indirectly) using 'ulimit'.
This affects the prerequisite expressions for the ULIMIT_STACK_SIZE,
CMDLINE_LIMIT and ULIMIT_FILE_DESCRIPTORS prerequisites.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
---

Hi Michael,

So, I finally got around to testing ulimit with open files and
found that it does not limit them on cygwin (it actually fails
on the hard limit of 3200). Having seen Johannes email earlier,
I took a chance and added MinGW to this patch as well. (Hopefully
this won't cause any screams!) ;-)

So, this patch was developed on top of the 'pu' branch, but it
also applies cleanly to your 'mg/name-rev-tests-with-short-stack'
branch (ie. on top of commit 31625b34c0).

If you are going to re-roll your branch, could you please add this
on top (after squashing the two comment deletions into your earlier
patches, maybe).

Thanks!

ATB,
Ramsay Jones

 t/t1400-update-ref.sh | 11 ++++++++++-
 t/t6120-describe.sh   |  1 -
 t/t7004-tag.sh        |  1 -
 t/test-lib.sh         | 22 ++++++++++++++++++++--
 4 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index dc98b4bc6..49415074f 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -1253,7 +1253,16 @@ run_with_limited_open_files () {
 	(ulimit -n 32 && "$@")
 }
 
-test_lazy_prereq ULIMIT_FILE_DESCRIPTORS 'run_with_limited_open_files true'
+test_lazy_prereq ULIMIT_FILE_DESCRIPTORS '
+	case $(uname -s) in
+	CYGWIN*|MINGW*)
+		false
+		;;
+	*)
+		run_with_limited_open_files true
+		;;
+	esac
+'
 
 test_expect_success ULIMIT_FILE_DESCRIPTORS 'large transaction creating branches does not burst open file limit' '
 (
diff --git a/t/t6120-describe.sh b/t/t6120-describe.sh
index dd6dd9df9..3d45dc295 100755
--- a/t/t6120-describe.sh
+++ b/t/t6120-describe.sh
@@ -279,7 +279,6 @@ test_expect_success 'describe ignoring a borken submodule' '
 	grep broken out
 '
 
-# we require ulimit, this excludes Windows
 test_expect_failure ULIMIT_STACK_SIZE 'name-rev works in a deep repo' '
 	i=1 &&
 	while test $i -lt 8000
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index 5bf5ace56..b545c33f8 100755
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -1863,7 +1863,6 @@ test_expect_success 'version sort with very long prerelease suffix' '
 	git tag -l --sort=version:refname
 '
 
-# we require ulimit, this excludes Windows
 test_expect_success ULIMIT_STACK_SIZE '--contains and --no-contains work in a deep repo' '
 	>expect &&
 	i=1 &&
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 83f5d3dd2..250ba5e9b 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1170,13 +1170,31 @@ run_with_limited_cmdline () {
 	(ulimit -s 128 && "$@")
 }
 
-test_lazy_prereq CMDLINE_LIMIT 'run_with_limited_cmdline true'
+test_lazy_prereq CMDLINE_LIMIT '
+	case $(uname -s) in
+	CYGWIN*|MINGW*)
+		false
+		;;
+	*)
+		run_with_limited_cmdline true
+		;;
+	esac
+'
 
 run_with_limited_stack () {
 	(ulimit -s 128 && "$@")
 }
 
-test_lazy_prereq ULIMIT_STACK_SIZE 'run_with_limited_stack true'
+test_lazy_prereq ULIMIT_STACK_SIZE '
+	case $(uname -s) in
+	CYGWIN*|MINGW*)
+		false
+		;;
+	*)
+		run_with_limited_stack true
+		;;
+	esac
+'
 
 build_option () {
 	git version --build-options |
-- 
2.14.0

Re: [PATCH] test-lib: don't use ulimit in test prerequisites on cygwin

[Jonathan Nieder]

Ramsay Jones wrote:

> On cygwin (and MinGW), the 'ulimit' built-in bash command does not have
> the desired effect of limiting the resources of new processes, at least
> for the stack and file descriptors. However, it always returns success
> and leads to several test prerequisites being erroneously set to true.
>
> Add a check for cygwin and MinGW to the prerequisite expressions, using
> 'uname -s', and return false instead of (indirectly) using 'ulimit'.
> This affects the prerequisite expressions for the ULIMIT_STACK_SIZE,
> CMDLINE_LIMIT and ULIMIT_FILE_DESCRIPTORS prerequisites.
>
> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
> ---
>  t/t1400-update-ref.sh | 11 ++++++++++-
>  t/t6120-describe.sh   |  1 -
>  t/t7004-tag.sh        |  1 -
>  t/test-lib.sh         | 22 ++++++++++++++++++++--
>  4 files changed, 30 insertions(+), 5 deletions(-)

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>

Thanks.

An alternative would be to do some more explicit feature-based test
like using "ulimit" to set a limit and then reading back the limit in
a separate process, but that feels like overkill.

Sincerely,
Jonathan

Re: [PATCH] test-lib: don't use ulimit in test prerequisites on cygwin

[Michael J Gruber]

Jonathan Nieder venit, vidit, dixit 13.09.2017 21:20:
> Ramsay Jones wrote:
> 
>> On cygwin (and MinGW), the 'ulimit' built-in bash command does not have
>> the desired effect of limiting the resources of new processes, at least
>> for the stack and file descriptors. However, it always returns success
>> and leads to several test prerequisites being erroneously set to true.
>>
>> Add a check for cygwin and MinGW to the prerequisite expressions, using
>> 'uname -s', and return false instead of (indirectly) using 'ulimit'.
>> This affects the prerequisite expressions for the ULIMIT_STACK_SIZE,
>> CMDLINE_LIMIT and ULIMIT_FILE_DESCRIPTORS prerequisites.
>>
>> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
>> ---
>>  t/t1400-update-ref.sh | 11 ++++++++++-
>>  t/t6120-describe.sh   |  1 -
>>  t/t7004-tag.sh        |  1 -
>>  t/test-lib.sh         | 22 ++++++++++++++++++++--
>>  4 files changed, 30 insertions(+), 5 deletions(-)
> 
> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
> 
> Thanks.
> 
> An alternative would be to do some more explicit feature-based test
> like using "ulimit" to set a limit and then reading back the limit in
> a separate process, but that feels like overkill.

It's still not clear whether these limits would be in effect or just
reported.

Rather than checking uname -s in several places, I think we should just
define ulimit to be false in one place, or rather set the prerequisite
there.

Michael

Re: [PATCH] test-lib: don't use ulimit in test prerequisites on cygwin

[Johannes Schindelin]

Hi Ramsay,

On Wed, 13 Sep 2017, Ramsay Jones wrote:

> So, I finally got around to testing ulimit with open files and
> found that it does not limit them on cygwin (it actually fails
> on the hard limit of 3200).

Thank you!

> Having seen Johannes email earlier, I took a chance and added MinGW to
> this patch as well. (Hopefully this won't cause any screams!) ;-)

It earns you my gratitude instead.

If you want to see the difference between the MSYS2 runtime (Git for
Windows flavor) and the Cygwin runtime, the patches applied on top of the
Cygwin runtime's source code can be seen here:

https://github.com/git-for-windows/MSYS2-packages/tree/master/msys2-runtime

The current overall diff can be inspected here:

https://github.com/git-for-windows/msys2-runtime/compare/aca9144e65ba...874e2c8efeed

The changes are not *all* that extensive, revolving more around the
Windows <-> POSIX path conversion (I am actually no longer certain that
the characterisation of "POSIX path" is correct, think about VMS still
being considered POSIX...).

There is also some stuff about environment variables, but that's about it.

Most importantly, the core code (such as ulimit functionality) seems not
to be changed at all IIAC.

Meaning: I agree with your assessment to enable the workaround also for
`uname -s` starting with MINGW.

One suggestion:

> diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
> index dc98b4bc6..49415074f 100755
> --- a/t/t1400-update-ref.sh
> +++ b/t/t1400-update-ref.sh
> @@ -1253,7 +1253,16 @@ run_with_limited_open_files () {
>  	(ulimit -n 32 && "$@")
>  }
>  
> -test_lazy_prereq ULIMIT_FILE_DESCRIPTORS 'run_with_limited_open_files true'
> +test_lazy_prereq ULIMIT_FILE_DESCRIPTORS '
> +	case $(uname -s) in
> +	CYGWIN*|MINGW*)
> +		false
> +		;;
> +	*)
> +		run_with_limited_open_files true
> +		;;
> +	esac
> +'

It would be more semantically meanginful to do this instead:

-test_lazy_prereq ULIMIT_FILE_DESCRIPTORS 'run_with_limited_open_files true'
+test_lazy_prereq ULIMIT_FILE_DESCRIPTORS '
+	test_have_prereq !MINGW,!CYGWIN && run_with_limited_open_files true
+'

In other words, *spell out* that we want neither MINGW nor CYGWIN as
prerequisites before testing ulimit with that shell function.

It would also be a little more succinct.

Ciao,
Dscho

[PATCH 1/2] test-lib: group system specific FIFO tests by system

[Michael J Gruber]

test-lib determines whether a file-system supports FIFOs and needs to do
special casing for CYGWIN and MINGW. This separates those system
specific settings from those at more central place.

Set mkfifo()  to false in the central system specific place so that the
same test works everywhere.

Signed-off-by: Michael J Gruber <git@grubix.eu>
---
 t/test-lib.sh | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 5fbd8d4a90..b8a0b05102 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -994,6 +994,10 @@ case $uname_s in
 	pwd () {
 		builtin pwd -W
 	}
+	# no FIFOs
+	mkfifo () {
+		false
+	}
 	# no POSIX permissions
 	# backslashes in pathspec are converted to '/'
 	# exec does not inherit the PID
@@ -1004,6 +1008,10 @@ case $uname_s in
 	GIT_TEST_CMP=mingw_test_cmp
 	;;
 *CYGWIN*)
+	# no FIFOs
+	mkfifo () {
+		false
+	}
 	test_set_prereq POSIXPERM
 	test_set_prereq EXECKEEPSPID
 	test_set_prereq CYGWIN
@@ -1062,14 +1070,7 @@ test_i18ngrep () {
 
 test_lazy_prereq PIPE '
 	# test whether the filesystem supports FIFOs
-	case $(uname -s) in
-	CYGWIN*|MINGW*)
-		false
-		;;
-	*)
-		rm -f testfifo && mkfifo testfifo
-		;;
-	esac
+	rm -f testfifo && mkfifo testfifo
 '
 
 test_lazy_prereq SYMLINKS '
-- 
2.14.1.712.gda4591c8a2

[PATCH 2/2] test-lib: ulimit does not limit on CYGWIN and MINGW

[Michael J Gruber]

ulimit succeeds (by return value) but does not limit on some systems.

Set ulimit() to false on these systems so that we do not rely on its
output nor effect. As an intended side-effect, ulimit based
prerequisites are set correctly (to "not-have") on these systems.

Reported-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Reported-by: Adam Dinwoodie <adam@dinwoodie.org>
Reported-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Michael J Gruber <git@grubix.eu>
---
This is independent of my series, but should best go before so that no
ulimit based test is run on CYGWIN and MINGW.

It follows the basic assumption that a tool like ulimit is either
present and functional or not present; and that we work around by
defines or such when that assumption is broken.
(Alternatively, we could set ULIMT_LIMITS or so and depend on that.)

 t/test-lib.sh | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/t/test-lib.sh b/t/test-lib.sh
index b8a0b05102..f6ac60d487 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -998,6 +998,10 @@ case $uname_s in
 	mkfifo () {
 		false
 	}
+	# ulimit succeeds but does not limit
+	ulimit () {
+		false
+	}
 	# no POSIX permissions
 	# backslashes in pathspec are converted to '/'
 	# exec does not inherit the PID
@@ -1012,6 +1016,10 @@ case $uname_s in
 	mkfifo () {
 		false
 	}
+	# ulimit succeeds but does not limit
+	ulimit () {
+		false
+	}
 	test_set_prereq POSIXPERM
 	test_set_prereq EXECKEEPSPID
 	test_set_prereq CYGWIN
-- 
2.14.1.712.gda4591c8a2

Re: [PATCH 2/2] test-lib: ulimit does not limit on CYGWIN and MINGW

[Ramsay Jones]

On 14/09/17 15:52, Michael J Gruber wrote:
> ulimit succeeds (by return value) but does not limit on some systems.
> 
> Set ulimit() to false on these systems so that we do not rely on its
> output nor effect. As an intended side-effect, ulimit based
> prerequisites are set correctly (to "not-have") on these systems.
> 
> Reported-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
> Reported-by: Adam Dinwoodie <adam@dinwoodie.org>
> Reported-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
> Signed-off-by: Michael J Gruber <git@grubix.eu>
> ---
> This is independent of my series, but should best go before so that no
> ulimit based test is run on CYGWIN and MINGW.
> 
> It follows the basic assumption that a tool like ulimit is either
> present and functional or not present; and that we work around by
> defines or such when that assumption is broken.
> (Alternatively, we could set ULIMT_LIMITS or so and depend on that.)

Heh, this was my first suggestion, if you recall, but I decided to
go a different way ... ;-)

Also, Johannes made a good suggestion, which lead to a new version
of my patch (which could easily be extended to cover the FIFO).

I don't have a strong preference for either approach (but I would
have to test your patches, which I haven't done yet), so I would
be happy to see either applied.

ATB,
Ramsay Jones

Re: [PATCH 1/2] test-lib: group system specific FIFO tests by system

[Johannes Schindelin]

Hi Michael,

On Thu, 14 Sep 2017, Michael J Gruber wrote:

> test-lib determines whether a file-system supports FIFOs and needs to do
> special casing for CYGWIN and MINGW. This separates those system
> specific settings from those at more central place.
> 
> Set mkfifo()  to false in the central system specific place so that the
> same test works everywhere.

The mkfifo() emulation of Cygwin seems to work, no? I think it works even
in MSYS2, but not in MINGW.

So maybe this patch should affect only the MINGW arm?

Ciao,
Dscho

Re: [PATCH 1/2] test-lib: group system specific FIFO tests by system

[Michael J Gruber]

Johannes Schindelin venit, vidit, dixit 15.09.2017 00:21:
> Hi Michael,
> 
> On Thu, 14 Sep 2017, Michael J Gruber wrote:
> 
>> test-lib determines whether a file-system supports FIFOs and needs to do
>> special casing for CYGWIN and MINGW. This separates those system
>> specific settings from those at more central place.
>>
>> Set mkfifo()  to false in the central system specific place so that the
>> same test works everywhere.
> 
> The mkfifo() emulation of Cygwin seems to work, no? I think it works even
> in MSYS2, but not in MINGW.
> 
> So maybe this patch should affect only the MINGW arm?

I only reorganised the code, so in that sense the patch does not affect
any system ;)

If indeed mkfifo works on CYGWIN than a separate patch should remove the
exclusion of CYGWIN; alas, I can't confirm (I wish MS still had the old
academic alliance programme).

Michael

Re: [PATCH 1/2] test-lib: group system specific FIFO tests by system

[Ramsay Jones]

On 15/09/17 11:31, Michael J Gruber wrote:
> Johannes Schindelin venit, vidit, dixit 15.09.2017 00:21:
>> Hi Michael,
>>
>> On Thu, 14 Sep 2017, Michael J Gruber wrote:
>>
>>> test-lib determines whether a file-system supports FIFOs and needs to do
>>> special casing for CYGWIN and MINGW. This separates those system
>>> specific settings from those at more central place.
>>>
>>> Set mkfifo()  to false in the central system specific place so that the
>>> same test works everywhere.
>>
>> The mkfifo() emulation of Cygwin seems to work, no? I think it works even
>> in MSYS2, but not in MINGW.
>>
>> So maybe this patch should affect only the MINGW arm?
> 
> I only reorganised the code, so in that sense the patch does not affect
> any system ;)
> 
> If indeed mkfifo works on CYGWIN than a separate patch should remove the
> exclusion of CYGWIN; alas, I can't confirm (I wish MS still had the old
> academic alliance programme).

I haven't tried recently, but back in 2013 Mark Levedahl wrote
in his commit message that mkfifo was known not to work on the cygwin
mailing list. (see commit 9443605b5d, "test-lib.sh - cygwin does
not have usable FIFOs", 04-07-2013) In fact, you can see that this
was disabled on cygwin before MinGW!

It is possible, of course, that fifos now work on cygwin. (I will
put it on my TODO list).

In any event, this is indeed a separate issue.

ATB,
Ramsay Jones

Re: [PATCH 1/2] test-lib: group system specific FIFO tests by system

[Johannes Schindelin]

Hi Michael,

On Fri, 15 Sep 2017, Michael J Gruber wrote:

> Johannes Schindelin venit, vidit, dixit 15.09.2017 00:21:
> > 
> > On Thu, 14 Sep 2017, Michael J Gruber wrote:
> > 
> >> test-lib determines whether a file-system supports FIFOs and needs to do
> >> special casing for CYGWIN and MINGW. This separates those system
> >> specific settings from those at more central place.
> >>
> >> Set mkfifo()  to false in the central system specific place so that the
> >> same test works everywhere.
> > 
> > The mkfifo() emulation of Cygwin seems to work, no? I think it works even
> > in MSYS2, but not in MINGW.
> > 
> > So maybe this patch should affect only the MINGW arm?
> 
> I only reorganised the code, so in that sense the patch does not affect
> any system ;)
> 
> If indeed mkfifo works on CYGWIN than a separate patch should remove the
> exclusion of CYGWIN; alas, I can't confirm (I wish MS still had the old
> academic alliance programme).

You don't need an academic license, as there are free VMs available (they
expire after a while, though):

https://developer.microsoft.com/en-us/windows/downloads/virtual-machines

It seems that the current free VM will expire in 4 days. After that,
probably a new one will be available that expires some time later (not
sure about the exact time frame of those VMs).

Alternatively, you can download VMs meant for web testing at
https://developer.microsoft.com/en-us/microsoft-edge/tools/vms/ which
expire after 90 days.

Ciao,
Dscho