[PATCH v2 1/3] tst: Extend cross-test-ssh.sh to specify if target date can be altered

[Lukasz Majewski <lukma@denx.de>]

This code adds new flag - '--allow-time-setting' to cross-test-ssh.sh
script to indicate if it is allowed to alter the date on the system
on which tests are executed. This change is supposed to be used with
test systems, which use virtual machines for testing.

The GLIBC_TEST_ALLOW_TIME_SETTING env variable is exported to the
remote environment on which the eligible test is run and brings no
functional change when it is not.

Changes for v2:
- Utilize flock to provide serialization of cross-test-ssh.sh script
  execution.
- Add entry to manual/install.texi about --allow-time-setting flag
  usage.
---
 manual/install.texi       |  2 ++
 scripts/cross-test-ssh.sh | 22 +++++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/manual/install.texi b/manual/install.texi
index 419576f49c..2c8e49d31e 100644
--- a/manual/install.texi
+++ b/manual/install.texi
@@ -379,6 +379,8 @@ directory and @var{hostname} is the host name of a system that can run
 the newly built binaries of @theglibc{}.  The source and build
 directories must be visible at the same locations on both the build
 system and @var{hostname}.
+It is also possible to execute tests on the target machine, when passing
+@option{--allow-time-setting} flag, which would require setting date.
 
 In general, when testing @theglibc{}, @samp{test-wrapper} may be set
 to the name and arguments of any program to run newly built binaries.
diff --git a/scripts/cross-test-ssh.sh b/scripts/cross-test-ssh.sh
index 6d8fbcdfd2..c4b112aa1d 100755
--- a/scripts/cross-test-ssh.sh
+++ b/scripts/cross-test-ssh.sh
@@ -22,7 +22,7 @@
 
 progname="$(basename $0)"
 
-usage="usage: ${progname} [--ssh SSH] HOST COMMAND ..."
+usage="usage: ${progname} [--ssh SSH][--allow-time-setting] HOST COMMAND ..."
 help="Run a glibc test COMMAND on the remote machine HOST, via ssh,
 preserving the current working directory, and respecting quoting.
 
@@ -32,6 +32,11 @@ instead of ordinary 'ssh'.
 If the '--timeoutfactor FACTOR' flag is present, set TIMEOUTFACTOR on
 the remote machine to the specified FACTOR.
 
+If the '--allow-time-setting' flag is present, set
+GLIBC_TEST_ALLOW_TIME_SETTING on the remote machine to inform that
+time can be safely adjusted when e.g. tests are run in a virtual
+machine.
+
 To use this to run glibc tests, invoke the tests as follows:
 
   $ make test-wrapper='ABSPATH/cross-test-ssh.sh HOST' tests
@@ -81,6 +86,10 @@ while [ $# -gt 0 ]; do
       timeoutfactor="$1"
       ;;
 
+    "--allow-time-setting")
+      settimeallowed="1"
+      ;;
+
     "--help")
       echo "$usage"
       echo "$help"
@@ -127,6 +136,17 @@ if [ "$timeoutfactor" ]; then
 ${command}"
 fi
 
+# Add command to set the info that time on target can be adjusted,
+# if required.
+# Serialize execution of this script on host to prevent from unintended
+# change of target time.
+FLOCK_PATH="/var/lock/clock_settime"
+if [ "$settimeallowed" ]; then
+  exec 99<>${FLOCK_PATH}
+  flock 99 || { echo "Cannot lock ${FLOCK_PATH}"; exit 1; }
+  command="export GLIBC_TEST_ALLOW_TIME_SETTING=1 ${command}"
+fi
+
 # HOST's sshd simply concatenates its arguments with spaces and
 # passes them to some shell.  We want to force the use of /bin/sh,
 # so we need to re-quote the whole command to ensure it appears as
-- 
2.20.1