[PATCH 2/2] Configure custom layers via environment variables

[Amir Goldstein <amir73il@gmail.com>]

The following environment variables are supported:

 UNIONMOUNT_BASEDIR  - base dir for --samefs (default: /base)
 UNIONMOUNT_UPPERDIR - upper layer root path (default: /upper)
 UNIONMOUNT_LOWERDIR - lower layer root path (default: /lower)
 UNIONMOUNT_MNTPOINT - mount point for tests (default: /mnt)

User provided paths for base/lower/upper should point at a pre-mounted
filesystem, whereas tmpfs instances will be created on default paths.

This is going to be used for running unionmount tests from xfstests.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 README      | 11 +++++++++++
 run         |  3 ++-
 settings.py | 51 ++++++++++++++++++++++++++++++---------------------
 3 files changed, 43 insertions(+), 22 deletions(-)

diff --git a/README b/README
index c352878..616135f 100644
--- a/README
+++ b/README
@@ -47,5 +47,16 @@ To run these tests:
 	./run --ov --fuse=<subfs-type>
 
 
+The following environment variables are supported:
+
+     UNIONMOUNT_BASEDIR  - base dir for --samefs (default: /base)
+     UNIONMOUNT_UPPERDIR - upper layer root path (default: /upper)
+     UNIONMOUNT_LOWERDIR - lower layer root path (default: /lower)
+     UNIONMOUNT_MNTPOINT - mount point for tests (default: /mnt)
+
+     User provided paths for base/lower/upper should point at a pre-mounted
+     filesystem, whereas tmpfs instances will be created on default paths.
+
+
 For more advanced overlayfs test options and more examples, see:
      https://github.com/amir73il/overlayfs/wiki/Overlayfs-testing
diff --git a/run b/run
index e6262b8..60d5d0d 100755
--- a/run
+++ b/run
@@ -20,10 +20,11 @@ def show_format(why):
     print("\t", sys.argv[0], "--<fsop> <file> [<args>*] [-aLlv] [-R <content>] [-B] [-E <err>]")
     sys.exit(2)
 
+cfg = config(sys.argv[0])
+
 if len(sys.argv) < 2:
     show_format("Insufficient arguments")
 
-cfg = config(sys.argv[0])
 args = sys.argv[1:]
 
 ###############################################################################
diff --git a/settings.py b/settings.py
index ced9cae..f065494 100644
--- a/settings.py
+++ b/settings.py
@@ -20,15 +20,27 @@ along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 """
 
+import os
+
 class config:
     def __init__(self, progname):
         self.__progname = progname
         self.__testing_overlayfs = False
         self.__testing_none = False
-        self.__base_mntroot = None
-        self.__lower_mntroot = None
-        self.__upper_mntroot = None
-        self.__union_mntroot = None
+        self.__base_mntroot = os.getenv('UNIONMOUNT_BASEDIR')
+        self.__lower_mntroot = os.getenv('UNIONMOUNT_LOWERDIR')
+        self.__upper_mntroot = os.getenv('UNIONMOUNT_UPPERDIR')
+        self.__union_mntroot = os.getenv('UNIONMOUNT_MNTPOINT')
+        print("Environment variables:")
+        if self.__base_mntroot:
+            print("UNIONMOUNT_BASEDIR=" + self.__base_mntroot)
+        if self.__lower_mntroot:
+            print("UNIONMOUNT_LOWERDIR=" + self.__lower_mntroot)
+        if self.__upper_mntroot:
+            print("UNIONMOUNT_UPPERDIR=" + self.__upper_mntroot)
+        if self.__union_mntroot:
+            print("UNIONMOUNT_MNTPOINT=" + self.__union_mntroot)
+        print()
         self.__verbose = False
         self.__verify = False
         self.__maxfs = 0
@@ -50,49 +62,46 @@ class config:
         return self.__testing_overlayfs
 
     def set_testing_none(self):
-        self.__lower_mntroot = "/lower"
-        self.__union_mntroot = "/mnt"
         self.__testing_none = True
 
     def set_testing_overlayfs(self):
-        self.__base_mntroot = "/base"
-        self.__lower_mntroot = "/lower"
-        self.__upper_mntroot = "/upper"
-        self.__union_mntroot = "/mnt"
         self.__testing_overlayfs = True
 
     # base dir is mounted only for --ov --samefs
+    # A user provided base dir should already be mounted
     def should_mount_base(self):
-        return self.testing_overlayfs() and self.is_samefs()
+        return self.__base_mntroot is None and self.testing_overlayfs() and self.is_samefs()
     def base_mntroot(self):
-        return self.__base_mntroot
+        return self.__base_mntroot or "/base"
     # lower dir is mounted ro for --ov (without --samefs) ...
     def should_mount_lower_ro(self):
-        return self.testing_overlayfs() and not self.is_samefs()
+        return self.__lower_mntroot is None and self.testing_overlayfs() and not self.is_samefs()
     # ... and mounted rw for --no
+    # A user provided lower dir should already be mounted
     def should_mount_lower_rw(self):
-        return self.testing_none()
+        return self.__lower_mntroot is None and self.testing_none()
     def should_mount_lower(self):
         return self.should_mount_lower_ro() or self.should_mount_lower_rw()
     def set_lower_mntroot(self, path):
         self.__lower_mntroot = path
     def lower_mntroot(self):
-        return self.__lower_mntroot
+        return self.__lower_mntroot or "/lower"
     # upper dir is mounted for --ov (without --samefs)
+    # A user provided upper dir should already be mounted
     def should_mount_upper(self):
-        return self.testing_overlayfs() and not self.is_samefs()
+        return self.__upper_mntroot is None and self.testing_overlayfs() and not self.is_samefs()
     def set_upper_mntroot(self, path):
         self.__upper_mntroot = path
     def upper_mntroot(self):
-        return self.__upper_mntroot
+        return self.__upper_mntroot or "/upper"
     def union_mntroot(self):
-        return self.__union_mntroot
+        return self.__union_mntroot or "/mnt"
     def lowerdir(self):
-        return self.__lower_mntroot + "/a"
+        return self.lower_mntroot() + "/a"
     def lowerimg(self):
-        return self.__lower_mntroot + "/a.img"
+        return self.lower_mntroot() + "/a.img"
     def testdir(self):
-        return self.__union_mntroot + "/a"
+        return self.union_mntroot() + "/a"
 
     def set_verbose(self, to=True):
         self.__verbose = to
-- 
2.17.1