From f1d0edfcfa19ad7b14201be299fe2fe33d737eb0 Mon Sep 17 00:00:00 2001
From: Zac Medico <zmedico@gentoo.org>
Date: Thu, 31 Jul 2008 03:46:10 +0000
Subject: Fixes in portage.fetch() for bugs #233303 and #94133:

* Totally skip $DISTDIR creation if the fetch_to_ro feature is enabled.
* Don't touch $DISTDIR permissions unless unless usepriv and/or userfetch
  are enabled.
* When usepriv and/or userfetch are enabled, test whether or not a process
  that has dropped privileges is able to create a file in the directory,
  and only adjust permissions if the test fails.

* Completely

svn path=/main/trunk/; revision=11290
---
 pym/portage/__init__.py | 50 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 48 insertions(+), 2 deletions(-)

(limited to 'pym')

diff --git a/pym/portage/__init__.py b/pym/portage/__init__.py
index 5dae685d..94f818af 100644
--- a/pym/portage/__init__.py
+++ b/pym/portage/__init__.py
@@ -3184,7 +3184,8 @@ def _spawn_fetch(settings, args, **kwargs):
 			con = con.replace(settings["PORTAGE_T"], settings["PORTAGE_FETCH_T"])
 			selinux.setexec(con)
 			# bash is an allowed entrypoint, while most binaries are not
-			args = [BASH_BINARY, "-c", "exec \"$@\"", args[0]] + args
+			if args[0] != BASH_BINARY:
+				args = [BASH_BINARY, "-c", "exec \"$@\"", args[0]] + args
 
 		rval = portage.process.spawn(args,
 			env=dict(settings.iteritems()), **kwargs)
@@ -3195,6 +3196,35 @@ def _spawn_fetch(settings, args, **kwargs):
 
 	return rval
 
+_userpriv_test_write_file_cache = {}
+_userpriv_test_write_cmd_script = "> %(file_path)s ; rval=$? ; " + \
+	"rm -f  %(file_path)s ; exit $rval"
+
+def _userpriv_test_write_file(settings, file_path):
+	"""
+	Drop privileges and try to open a file for writing. The file may or
+	may not exist, and the parent directory is assumed to exist. The file
+	is removed before returning.
+
+	@param settings: A config instance which is passed to _spawn_fetch()
+	@param file_path: A file path to open and write.
+	@return: True if write succeeds, False otherwise.
+	"""
+
+	global _userpriv_test_write_file_cache, _userpriv_test_write_cmd_script
+	rval = _userpriv_test_write_file_cache.get(file_path)
+	if rval is not None:
+		return rval
+
+	args = [BASH_BINARY, "-c", _userpriv_test_write_cmd_script % \
+		{"file_path" : _shell_quote(file_path)}]
+
+	returncode = _spawn_fetch(settings, args)
+
+	rval = returncode == os.EX_OK
+	_userpriv_test_write_file_cache[file_path] = rval
+	return rval
+
 def _checksum_failure_temp_file(distdir, basename):
 	"""
 	First try to find a duplicate temp file with the same checksum and return
@@ -3302,6 +3332,11 @@ def fetch(myuris, mysettings, listonly=0, fetchonly=0, locks_in_subdir=".locks",
 
 	features = mysettings.features
 	restrict = mysettings.get("PORTAGE_RESTRICT","").split()
+
+	from portage.data import secpass
+	userfetch = secpass >= 2 and "userfetch" in features
+	userpriv = secpass >= 2 and "userpriv" in features
+
 	# 'nomirror' is bad/negative logic. You Restrict mirroring, not no-mirroring.
 	if "mirror" in restrict or \
 	   "nomirror" in restrict:
@@ -3501,7 +3536,8 @@ def fetch(myuris, mysettings, listonly=0, fetchonly=0, locks_in_subdir=".locks",
 		if not mysettings.get(var_name, None):
 			can_fetch = False
 
-	if can_fetch:
+	if can_fetch and not fetch_to_ro:
+		global _userpriv_test_write_file_cache
 		dirmode  = 02070
 		filemode =   060
 		modemask =    02
@@ -3519,7 +3555,17 @@ def fetch(myuris, mysettings, listonly=0, fetchonly=0, locks_in_subdir=".locks",
 			
 			for x in distdir_dirs:
 				mydir = os.path.join(mysettings["DISTDIR"], x)
+				write_test_file = os.path.join(
+					mydir, ".__portage_test_write__")
+
+				if os.path.isdir(mydir):
+					if not (userfetch or userpriv):
+						continue
+					if _userpriv_test_write_file(mysettings, write_test_file):
+						continue
+
 				if portage.util.ensure_dirs(mydir, gid=dir_gid, mode=dirmode, mask=modemask):
+					_userpriv_test_write_file_cache.pop(write_test_file, None)
 					writemsg("Adjusting permissions recursively: '%s'\n" % mydir,
 						noiselevel=-1)
 					def onerror(e):
-- 
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