Move bwrap checks in platform/linux.py

Remove the bwraps checks from _site.py and put them in platform.linux
which is the only place where they are run.

This allows the removal of a double level of caching, making
reasoning about tests easier

2 files changed, 30 insertions, 48 deletions

diff --git a/buildstream/_platform/linux.py b/buildstream/_platform/linux.py
index 6e488472f..afdf81c79 100644
--- a/buildstream/_platform/linux.py
+++ b/buildstream/_platform/linux.py
@@ -18,9 +18,9 @@
 #        Tristan Maat <tristan.maat@codethink.co.uk>
 
 import os
+import shutil
 import subprocess
 
-from .. import _site
 from .. import utils
 from ..sandbox import SandboxDummy
 
@@ -37,12 +37,19 @@ class Linux(Platform):
         self._gid = os.getegid()
 
         self._have_fuse = os.path.exists("/dev/fuse")
-        self._bwrap_exists = _site.check_bwrap_version(0, 0, 0)
-        self._have_good_bwrap = _site.check_bwrap_version(0, 1, 2)
 
-        self._local_sandbox_available = self._have_fuse and self._have_good_bwrap
+        bwrap_version = self._get_bwrap_version()
 
-        self._die_with_parent_available = _site.check_bwrap_version(0, 1, 8)
+        if bwrap_version is None:
+            self._bwrap_exists = False
+            self._have_good_bwrap = False
+            self._die_with_parent_available = False
+        else:
+            self._bwrap_exists = True
+            self._have_good_bwrap = (0, 1, 2) <= bwrap_version
+            self._die_with_parent_available = (0, 1, 8) <= bwrap_version
+
+        self._local_sandbox_available = self._have_fuse and self._have_good_bwrap
 
         if self._local_sandbox_available:
             self._user_ns_available = self._check_user_ns_available()
@@ -112,3 +119,21 @@ class Linux(Platform):
             output = ''
 
         return output == 'root'
+
+    def _get_bwrap_version(self):
+        # Get the current bwrap version
+        #
+        # returns None if no bwrap was found
+        # otherwise returns a tuple of 3 int: major, minor, patch
+        bwrap_path = shutil.which('bwrap')
+
+        if not bwrap_path:
+            return None
+
+        cmd = [bwrap_path, "--version"]
+        try:
+            version = str(subprocess.check_output(cmd).split()[1], "utf-8")
+        except subprocess.CalledProcessError:
+            return None
+
+        return tuple(int(x) for x in version.split("."))
diff --git a/buildstream/_site.py b/buildstream/_site.py
index 30e1000d4..d64390b5d 100644
--- a/buildstream/_site.py
+++ b/buildstream/_site.py
@@ -18,8 +18,6 @@
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 
 import os
-import shutil
-import subprocess
 
 #
 # Private module declaring some info about where the buildstream
@@ -46,44 +44,3 @@ build_all_template = os.path.join(root, 'data', 'build-all.sh.in')
 
 # Module building script template
 build_module_template = os.path.join(root, 'data', 'build-module.sh.in')
-
-# Cached bwrap version
-_bwrap_major = None
-_bwrap_minor = None
-_bwrap_patch = None
-
-
-# check_bwrap_version()
-#
-# Checks the version of installed bwrap against the requested version
-#
-# Args:
-#    major (int): The required major version
-#    minor (int): The required minor version
-#    patch (int): The required patch level
-#
-# Returns:
-#    (bool): Whether installed bwrap meets the requirements
-#
-def check_bwrap_version(major, minor, patch):
-    # pylint: disable=global-statement
-
-    global _bwrap_major
-    global _bwrap_minor
-    global _bwrap_patch
-
-    # Parse bwrap version and save into cache, if not already cached
-    if _bwrap_major is None:
-        bwrap_path = shutil.which('bwrap')
-        if not bwrap_path:
-            return False
-        cmd = [bwrap_path, "--version"]
-        try:
-            version = str(subprocess.check_output(cmd).split()[1], "utf-8")
-        except subprocess.CalledProcessError:
-            # Failure trying to run bubblewrap
-            return False
-        _bwrap_major, _bwrap_minor, _bwrap_patch = map(int, version.split("."))
-
-    # Check whether the installed version meets the requirements
-    return (_bwrap_major, _bwrap_minor, _bwrap_patch) >= (major, minor, patch)