[PATCH V2] tools/perf/tests: Fix string substitutions in build id test

[Athira Rajeev]

The perf test named “build id cache operations” skips with below
error on some distros:

<<>>
 78: build id cache operations                                       :
test child forked, pid 111101
WARNING: wine not found. PE binaries will not be run.
test binaries: /tmp/perf.ex.SHA1.PKz /tmp/perf.ex.MD5.Gt3 ./tests/shell/../pe-file.exe
DEBUGINFOD_URLS=
Adding 4abd406f041feb4f10ecde3fc30fd0639e1a91cb /tmp/perf.ex.SHA1.PKz: Ok
build id: 4abd406f041feb4f10ecde3fc30fd0639e1a91cb
./tests/shell/buildid.sh: 69: ./tests/shell/buildid.sh: Bad substitution
test child finished with -2
build id cache operations: Skip
<<>>

The test script "tests/shell/buildid.sh" uses some of the
string substitution ways which are supported in bash, but not in
"sh" or other shells. Above error on line number 69 that reports
"Bad substitution" is:

<<>>
link=${build_id_dir}/.build-id/${id:0:2}/${id:2}
<<>>

Here the way of getting first two characters from id ie,
${id:0:2} and similarly expressions like ${id:2} is not
recognised in "sh". So the line errors and instead of
hitting failure, the test gets skipped as shown in logs.
So the syntax issue causes test not to be executed in
such cases. Similarly usage : "${@: -1}" [ to pick last
argument passed to a function] in “test_record” doesn’t
work in all distros.

Fix this by using alternative way with "cut" command
to pick "n" characters from the string. Also fix the usage
of “${@: -1}” to work in all cases.

Another usage in “test_record” is:
<<>>
${perf} record --buildid-all -o ${data} $@ &> ${log}
<<>>

This causes the perf record to start in background and
Results in the data file not being created by the time
"check" function is invoked. Below log shows perf record
result getting displayed after the call to "check" function.

<<>>
running: perf record /tmp/perf.ex.SHA1.EAU
build id: 4abd406f041feb4f10ecde3fc30fd0639e1a91cb
link: /tmp/perf.debug.mLT/.build-id/4a/bd406f041feb4f10ecde3fc30fd0639e1a91cb
failed: link /tmp/perf.debug.mLT/.build-id/4a/bd406f041feb4f10ecde3fc30fd0639e1a91cb does not exist
test child finished with -1
build id cache operations: FAILED!
root at machine:~/athira/linux/tools/perf# Couldn't synthesize bpf events.
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.010 MB /tmp/perf.data.bFF ]
<<>>

Fix this by redirecting output instead of using “&” which
starts the command in background.

Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
Acked-by: Ian Rogers <irogers at google.com>
---
Changelog:
- Added Acked-by from Ian.
- Rebased to tmp.perf/urgent of:
  git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git

 tools/perf/tests/shell/buildid.sh | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/tools/perf/tests/shell/buildid.sh b/tools/perf/tests/shell/buildid.sh
index aaf851108ca3..43e43e131be7 100755
--- a/tools/perf/tests/shell/buildid.sh
+++ b/tools/perf/tests/shell/buildid.sh
@@ -66,7 +66,7 @@ check()
 	esac
 	echo "build id: ${id}"
 
-	link=${build_id_dir}/.build-id/${id:0:2}/${id:2}
+	link=${build_id_dir}/.build-id/$(echo ${id}|cut -c 1-2)/$(echo ${id}|cut -c 3-)
 	echo "link: ${link}"
 
 	if [ ! -h $link ]; then
@@ -74,7 +74,7 @@ check()
 		exit 1
 	fi
 
-	file=${build_id_dir}/.build-id/${id:0:2}/`readlink ${link}`/elf
+	file=${build_id_dir}/.build-id/$(echo ${id}|cut -c 1-2)/`readlink ${link}`/elf
 	echo "file: ${file}"
 
 	# Check for file permission of original file
@@ -130,20 +130,22 @@ test_record()
 {
 	data=$(mktemp /tmp/perf.data.XXX)
 	build_id_dir=$(mktemp -d /tmp/perf.debug.XXX)
-	log=$(mktemp /tmp/perf.log.XXX)
+	log_out=$(mktemp /tmp/perf.log.out.XXX)
+	log_err=$(mktemp /tmp/perf.log.err.XXX)
 	perf="perf --buildid-dir ${build_id_dir}"
+	eval last=\${$#}
 
 	echo "running: perf record $@"
-	${perf} record --buildid-all -o ${data} $@ &> ${log}
+	${perf} record --buildid-all -o ${data} $@ 1>${log_out} 2>${log_err}
 	if [ $? -ne 0 ]; then
 		echo "failed: record $@"
-		echo "see log: ${log}"
+		echo "see log: ${log_err}"
 		exit 1
 	fi
 
-	check ${@: -1}
+	check $last
 
-	rm -f ${log}
+	rm -f ${log_out} ${log_err}
 	rm -rf ${build_id_dir}
 	rm -rf ${data}
 }
-- 
2.31.1