[PATCH] t: use portable wrapper for readlink(1)

Not all systems have a readlink program available for use by the shell.
This causes t3210 to fail on at least AIX. Let's provide a perl
one-liner to do the same thing, and use it there.

I also updated calls in t9802. Nobody reported failure there, but it's
the same issue. Presumably nobody actually tests with p4 on AIX in the
first place (if it is even available there).

I left the use of readlink in the "--valgrind" setup in test-lib.sh, as
valgrind isn't available on exotic platforms anyway (and I didn't want
to increase dependencies between test-lib.sh and test-lib-functions.sh).

There's one other curious case. Commit d2addc3b96 (t7800: readlink may
not be available, 2016-05-31) fixed a similar case. We can't use our
wrapper function there, though, as it's inside a sub-script triggered by
Git. It uses a slightly different technique ("ls" piped to "sed"). I
chose not to use that here as it gives confusing "ls -l" output if the
file is unexpectedly not a symlink (which is OK for its limited use, but
potentially confusing for general use within the test suite). The perl
version emits the empty string.

Reported-by: Ævar Arnfjörð Bjarmason <redacted>
Signed-off-by: Jeff King <redacted>
---
This is a re-post that doesn't seem to have made it into "seen"; the
original[1] was buried in a thread, but Ævar reported there that it
fixes t3210 on his AIX build.

[1] https://lore.kernel.org/git/YLk0Zm2J6VOA%2Flks@coredump.intra.peff.net/

 t/t3210-pack-refs.sh       | 2 +-
 t/t9802-git-p4-filetype.sh | 4 ++--
 t/test-lib-functions.sh    | 6 ++++++
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/t/t3210-pack-refs.sh b/t/t3210-pack-refs.sh
index 3b7cdc56ec..577f32dc71 100755
--- a/t/t3210-pack-refs.sh
+++ b/t/t3210-pack-refs.sh

@@ -253,7 +253,7 @@ test_expect_success SYMLINKS 'pack symlinked packed-refs' '
 	git for-each-ref >all-refs-packed &&
 	test_cmp all-refs-before all-refs-packed &&
 	test -h .git/packed-refs &&
-	test "$(readlink .git/packed-refs)" = "my-deviant-packed-refs"
+	test "$(test_readlink .git/packed-refs)" = "my-deviant-packed-refs"
 '
 
 test_done

diff --git a/t/t9802-git-p4-filetype.sh b/t/t9802-git-p4-filetype.sh
index 94edebe272..19073c6e9f 100755
--- a/t/t9802-git-p4-filetype.sh
+++ b/t/t9802-git-p4-filetype.sh

@@ -263,7 +263,7 @@ test_expect_success SYMLINKS 'ensure p4 symlink parsed correctly' '
 	(
 		cd "$git" &&
 		test -L symlink &&
-		test $(readlink symlink) = symlink-target
+		test $(test_readlink symlink) = symlink-target
 	)
 '
 

@@ -329,7 +329,7 @@ test_expect_success SYMLINKS 'empty symlink target' '
 	git p4 clone --dest="$git" //depot@all &&
 	(
 		cd "$git" &&
-		test $(readlink empty-symlink) = target2
+		test $(test_readlink empty-symlink) = target2
 	)
 '
 

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index f0448daa74..b2810478a2 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh

@@ -1708,3 +1708,9 @@ test_region () {
 
 	return 0
 }
+
+# Print the destination of symlink(s) provided as arguments. Basically
+# the same as the readlink command, but it's not available everywhere.
+test_readlink () {
+	perl -le 'print readlink($_) for @ARGV' "$@"
+}

-- 
2.32.0.352.gff02c21e72

On 2021-06-18 at 16:32:22, Jeff King wrote:

Not all systems have a readlink program available for use by the shell.
This causes t3210 to fail on at least AIX. Let's provide a perl
one-liner to do the same thing, and use it there.

I also updated calls in t9802. Nobody reported failure there, but it's
the same issue. Presumably nobody actually tests with p4 on AIX in the
first place (if it is even available there).

I left the use of readlink in the "--valgrind" setup in test-lib.sh, as
valgrind isn't available on exotic platforms anyway (and I didn't want
to increase dependencies between test-lib.sh and test-lib-functions.sh).

There's one other curious case. Commit d2addc3b96 (t7800: readlink may
not be available, 2016-05-31) fixed a similar case. We can't use our
wrapper function there, though, as it's inside a sub-script triggered by
Git. It uses a slightly different technique ("ls" piped to "sed"). I
chose not to use that here as it gives confusing "ls -l" output if the
file is unexpectedly not a symlink (which is OK for its limited use, but
potentially confusing for general use within the test suite). The perl
version emits the empty string.

Reported-by: Ævar Arnfjörð Bjarmason <redacted>
Signed-off-by: Jeff King <redacted>
---
This is a re-post that doesn't seem to have made it into "seen"; the
original[1] was buried in a thread, but Ævar reported there that it
fixes t3210 on his AIX build.

[1] https://lore.kernel.org/git/YLk0Zm2J6VOA%2Flks@coredump.intra.peff.net/

In case I didn't say it up in the previous post, this looks fine to me.
Using Perl here seems like a fine solution.  If we needed to in the
future, we could add this to test-tool and use the real readlink(2), but
we can hold off until we decide we need to.
-- 
brian m. carlson (he/him or they/them)
Toronto, Ontario, CA

On Fri, Jun 18, 2021 at 07:13:31PM +0000, brian m. carlson wrote:

quoted

This is a re-post that doesn't seem to have made it into "seen"; the
original[1] was buried in a thread, but Ævar reported there that it
fixes t3210 on his AIX build.

[1] https://lore.kernel.org/git/YLk0Zm2J6VOA%2Flks@coredump.intra.peff.net/

In case I didn't say it up in the previous post, this looks fine to me.
Using Perl here seems like a fine solution.  If we needed to in the
future, we could add this to test-tool and use the real readlink(2), but
we can hold off until we decide we need to.

Agreed on all counts (if we do want to drop perl from the test suite,
there are a lot of these little one-liners that would need converting).

Thanks.

-Peff