[OE-core] [PATCH] QemuRunner: avoid tainting os.environ

[Patrick Ohly]

That a utility function permanently changes the process environment is
bad style and leads to subtle, hard to debug problems.

For example, we had one oe-selftest which used runqemu() with an
override for DEPLOY_DIR_IMAGE. Another test then just called runCmd()
and ended up passing the wrong DEPLOY_DIR_IMAGE set earlier in
os.environ.

The approach used here is to extend the launch command such that 'env'
sets the environment variables. The specific values here should be
safe to use this way, even without extra quoting. This approach is
simple and has the advantage that the existing log.info('launchcmd=')
output includes the environment variables.

A more complex approach would be to pass a modified environment hash
to the subprocess module.

[YOCTO #11443]

Signed-off-by: Patrick Ohly <patrick.ohly at intel.com>
---
 meta/lib/oeqa/utils/qemurunner.py | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/meta/lib/oeqa/utils/qemurunner.py b/meta/lib/oeqa/utils/qemurunner.py
index ba44b96..c543797 100644
--- a/meta/lib/oeqa/utils/qemurunner.py
+++ b/meta/lib/oeqa/utils/qemurunner.py
@@ -98,11 +98,12 @@ class QemuRunner:
                 raise SystemExit
 
     def start(self, qemuparams = None, get_ip = True, extra_bootparams = None, runqemuparams='', launch_cmd=None, discard_writes=True):
+        env = []
         if self.display:
-            os.environ["DISPLAY"] = self.display
+            env.append("DISPLAY=" + self.display)
             # Set this flag so that Qemu doesn't do any grabs as SDL grabs
             # interact badly with screensavers.
-            os.environ["QEMU_DONT_GRAB"] = "1"
+            env.append("QEMU_DONT_GRAB=1")
         if not os.path.exists(self.rootfs):
             logger.error("Invalid rootfs %s" % self.rootfs)
             return False
@@ -110,12 +111,12 @@ class QemuRunner:
             logger.error("Invalid TMPDIR path %s" % self.tmpdir)
             return False
         else:
-            os.environ["OE_TMPDIR"] = self.tmpdir
+            env.append("OE_TMPDIR=" + self.tmpdir)
         if not os.path.exists(self.deploy_dir_image):
             logger.error("Invalid DEPLOY_DIR_IMAGE path %s" % self.deploy_dir_image)
             return False
         else:
-            os.environ["DEPLOY_DIR_IMAGE"] = self.deploy_dir_image
+            env.append("DEPLOY_DIR_IMAGE=" + self.deploy_dir_image)
 
         if not launch_cmd:
             launch_cmd = 'runqemu %s %s ' % ('snapshot' if discard_writes else '', runqemuparams)
@@ -128,6 +129,9 @@ class QemuRunner:
                 launch_cmd += ' nographic'
             launch_cmd += ' %s %s' % (self.machine, self.rootfs)
 
+        if env:
+            launch_cmd = 'env %s %s' % (' '.join(env), launch_cmd)
+
         return self.launch(launch_cmd, qemuparams=qemuparams, get_ip=get_ip, extra_bootparams=extra_bootparams)
 
     def launch(self, launch_cmd, get_ip = True, qemuparams = None, extra_bootparams = None):

base-commit: ba2884f6ad3a4e746fc80cbd707f83fa8abd4210
-- 
git-series 0.9.1