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[net] selftests: openvswitch: Use bash as interpreter

Message ID 20240617-ovs-selftest-bash-v1-1-7ae6ccd3617b@kernel.org
State Accepted
Commit e2b447c9a1bba718f9c07513a1e8958209e862a1
Headers show
Series [net] selftests: openvswitch: Use bash as interpreter | expand

Commit Message

Simon Horman June 17, 2024, 8:28 a.m. UTC
openvswitch.sh makes use of substitutions of the form ${ns:0:1}, to
obtain the first character of $ns. Empirically, this is works with bash
but not dash. When run with dash these evaluate to an empty string and
printing an error to stdout.

 # dash -c 'ns=client; echo "${ns:0:1}"' 2>error
 # cat error
 dash: 1: Bad substitution
 # bash -c 'ns=client; echo "${ns:0:1}"' 2>error
 c
 # cat error

This leads to tests that neither pass nor fail.
F.e.

 TEST: arp_ping                                                      [START]
 adding sandbox 'test_arp_ping'
 Adding DP/Bridge IF: sbx:test_arp_ping dp:arpping {, , }
 create namespaces
 ./openvswitch.sh: 282: eval: Bad substitution
 TEST: ct_connect_v4                                                 [START]
 adding sandbox 'test_ct_connect_v4'
 Adding DP/Bridge IF: sbx:test_ct_connect_v4 dp:ct4 {, , }
 ./openvswitch.sh: 322: eval: Bad substitution
 create namespaces

Resolve this by making openvswitch.sh a bash script.

Fixes: 918423fda910 ("selftests: openvswitch: add an initial flow programming case")
Signed-off-by: Simon Horman <horms@kernel.org>
---
 tools/testing/selftests/net/openvswitch/openvswitch.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

David Laight June 19, 2024, 9:21 a.m. UTC | #1
From: Simon Horman
> Sent: 17 June 2024 11:34
...
> > sidenote: I like very much the idea to use the least powerful tool, like
> > sh vs bash, awk vs gawk, but it breaks when we forget what is outside of
> > the scope of the former/standard.
> > Perhaps for shell, we could convert all the selftests at once?
> 
> Thanks,
> 
> Now that you mention it, I have the same feelings.
> 
> Do we ever expect to use the minimal tools, when other
> parts of the test suite depend on the enhanced ones?

Certainly trying to avoid bash-isms seems like a good idea.
Especially in scripts where it isn't really that hard.
OTOH avoiding posix features (so the script will run on a traditional SYSV /bin/sh)
is probably excessive.

I'd use "${foo%"${foo#?}"}" to get the first character without bash-isms.
But, IIRC, one version of ash/dash made a 'pig's breakfast' of the nested
pattern match.
(Most syntax highlighters don't get the quoting right either...)

	David

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Patch

diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
index 5cae53543849..15bca0708717 100755
--- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
+++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
@@ -1,4 +1,4 @@ 
-#!/bin/sh
+#!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 #
 # OVS kernel module self tests