[gentoo-portage-dev] [PATCH] portage.data: add build user (bug 600804)

[Zac Medico]

Add attributes and override variables for a separate build
user, with defaults corresponding to the status quo. This
reuses the existing PORTAGE_BUILD_USER and PORTAGE_BUILD_GROUP
variables that were already exported to the ebuild environment.

When PORTAGE_BUILD_USER and PORTAGE_BUILD_GROUP are unset,
the build user can still be overridden by the existing
PORTAGE_USERNAME and PORTAGE_GRPNAME variables.

This sets the stage for migration of internal code to use
a separate build user, as required to solve bug 600804 in a
manner that complies with PMS.

Bug: https://bugs.gentoo.org/600804
---
 pym/portage/data.py                    | 54 +++++++++++++++++++++++++++++-----
 pym/portage/package/ebuild/doebuild.py | 12 ++++----
 2 files changed, 52 insertions(+), 14 deletions(-)

diff --git a/pym/portage/data.py b/pym/portage/data.py
index 28d6eb79db..7b2db21c6b 100644
--- a/pym/portage/data.py
+++ b/pym/portage/data.py
@@ -105,6 +105,15 @@ try:
 except KeyError:
 	pass
 
+_attr_env_vars = {
+	# TODO: Migrate all internals to use the build user/group
+	# instead of the "portage" user/group where appropriate.
+	'_build_group': 'PORTAGE_BUILD_GROUP',
+	'_build_user': 'PORTAGE_BUILD_USER',
+	'_portage_grpname': 'PORTAGE_GRPNAME',
+	'_portage_username': 'PORTAGE_USERNAME',
+}
+
 # The portage_uid and portage_gid global constants, and others that
 # depend on them are initialized lazily, in order to allow configuration
 # via make.conf. Eventually, these constants may be deprecated in favor
@@ -142,6 +151,32 @@ def _get_global(k):
 		elif _get_global('portage_gid') in os.getgroups():
 			v = 1
 
+	elif k in ('_build_gid', '_build_uid'):
+		keyerror = False
+		try:
+			build_uid = pwd.getpwnam(_get_global('_build_user')).pw_uid
+		except KeyError:
+			writemsg('!!! PORTAGE_BUILD_USER refers to non-existant user "%s"\n'
+				% _get_global('_build_user'), noiselevel=-1)
+			build_uid = 0
+
+		try:
+			build_gid = grp.getgrnam(_get_global('_build_group')).gr_gid
+		except KeyError:
+			writemsg('!!! PORTAGE_BUILD_GROUP refers to non-existant user "%s"\n'
+				% _get_global('_build_group'), noiselevel=-1)
+			build_gid = 0
+
+		globals()['_build_gid'] = build_gid
+		_initialized_globals.add('_build_gid')
+		globals()['_build_uid'] = build_uid
+		_initialized_globals.add('_build_uid')
+
+		if k == '_build_gid':
+			return build_gid
+		else:
+			return build_uid
+
 	elif k in ('portage_gid', 'portage_uid'):
 
 		#Discover the uid and gid of the portage user/group
@@ -193,7 +228,7 @@ def _get_global(k):
 			# Get a list of group IDs for the portage user. Do not use
 			# grp.getgrall() since it is known to trigger spurious
 			# SIGPIPE problems with nss_ldap.
-			cmd = ["id", "-G", _portage_username]
+			cmd = ["id", "-G", _get_global('_build_user')]
 
 			if sys.hexversion < 0x3020000 and sys.hexversion >= 0x3000000:
 				# Python 3.1 _execvp throws TypeError for non-absolute executable
@@ -223,12 +258,9 @@ def _get_global(k):
 
 	# Avoid instantiating portage.settings when the desired
 	# variable is set in os.environ.
-	elif k in ('_portage_grpname', '_portage_username'):
+	elif k in _attr_env_vars:
 		v = None
-		if k == '_portage_grpname':
-			env_key = 'PORTAGE_GRPNAME'
-		else:
-			env_key = 'PORTAGE_USERNAME'
+		env_key = _attr_env_vars[k]
 
 		if env_key in os.environ:
 			v = os.environ[env_key]
@@ -245,7 +277,7 @@ def _get_global(k):
 				pass
 			else:
 				if _unprivileged_mode(eroot_or_parent, eroot_st):
-					if k == '_portage_grpname':
+					if k in ('_build_group', '_portage_grpname'):
 						try:
 							grp_struct = grp.getgrgid(eroot_st.st_gid)
 						except KeyError:
@@ -261,7 +293,12 @@ def _get_global(k):
 							v = pwd_struct.pw_name
 
 		if v is None:
-			v = 'portage'
+			if k == '_build_group':
+				v = _get_global('_portage_grpname')
+			elif k == '_build_user':
+				v = _get_global('_portage_username')
+			else:
+				v = 'portage'
 	else:
 		raise AssertionError('unknown name: %s' % k)
 
@@ -281,6 +318,7 @@ class _GlobalProxy(portage.proxy.objectproxy.ObjectProxy):
 		return _get_global(object.__getattribute__(self, '_name'))
 
 for k in ('portage_gid', 'portage_uid', 'secpass', 'userpriv_groups',
+	'_build_gid', '_build_group', '_build_uid', '_build_user',
 	'_portage_grpname', '_portage_username'):
 	globals()[k] = _GlobalProxy(k)
 del k
diff --git a/pym/portage/package/ebuild/doebuild.py b/pym/portage/package/ebuild/doebuild.py
index 97a9199a31..3981a7d7ae 100644
--- a/pym/portage/package/ebuild/doebuild.py
+++ b/pym/portage/package/ebuild/doebuild.py
@@ -1592,8 +1592,8 @@ def spawn(mystring, mysettings, debug=False, free=False, droppriv=False,
 		if "userpriv" in features and "userpriv" not in mysettings["PORTAGE_RESTRICT"].split() and secpass >= 2:
 			# Since Python 3.4, getpwuid and getgrgid
 			# require int type (no proxies).
-			portage_build_uid = int(portage_uid)
-			portage_build_gid = int(portage_gid)
+			portage_build_uid = int(portage.data._build_uid)
+			portage_build_gid = int(portage.data._build_gid)
 
 	if "PORTAGE_BUILD_USER" not in mysettings:
 		user = None
@@ -1602,8 +1602,8 @@ def spawn(mystring, mysettings, debug=False, free=False, droppriv=False,
 		except KeyError:
 			if portage_build_uid == 0:
 				user = "root"
-			elif portage_build_uid == portage_uid:
-				user = portage.data._portage_username
+			elif portage_build_uid == portage.data._build_uid:
+				user = portage.data._build_user
 		if user is not None:
 			mysettings["PORTAGE_BUILD_USER"] = user
 
@@ -1614,8 +1614,8 @@ def spawn(mystring, mysettings, debug=False, free=False, droppriv=False,
 		except KeyError:
 			if portage_build_gid == 0:
 				group = "root"
-			elif portage_build_gid == portage_gid:
-				group = portage.data._portage_grpname
+			elif portage_build_gid == portage.data._build_gid:
+				group = portage.data._build_group
 		if group is not None:
 			mysettings["PORTAGE_BUILD_GROUP"] = group
 
-- 
2.13.6