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Hi all,
There is dangerous handling of world file updates throughout portage. The
attached patch wraps all world file updates in a write_atomic() function which
is designed to prevent interprocess interference and prevent corruption when an
'out of space' error occurs. Brian pointed out that portage_util.writedict()
already does a similar routine, but it is designed exclusively to write a
dictionary object.
Zac
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Index: portage-2.1_pre/pym/portage_util.py
===================================================================
--- portage-2.1_pre.orig/pym/portage_util.py
+++ portage-2.1_pre/pym/portage_util.py
@@ -452,3 +452,31 @@ def unique_array(s):
u.append(x)
return u
+def write_atomic(file_path, content):
+ """Write a file atomically via os.rename(). Atomic replacement prevents
+ interprocess interference and prevents corruption of the target
+ file when an 'out of space' error occurs."""
+ mystat = os.stat(file_path)
+ dirname,basename = os.path.split(file_path)
+ tmp_path=None
+ fd=None
+ try:
+ import tempfile
+ fd, tmp_path = tempfile.mkstemp(prefix=basename, dir=dirname)
+ os.write(fd,content)
+ os.close(fd)
+ os.chown(tmp_path, mystat.st_uid, mystat.st_gid)
+ os.chmod(tmp_path, mystat.st_mode)
+ os.rename(tmp_path,file_path)
+ finally:
+ # Make sure we've cleaned up even if an exception is raised.
+ if fd:
+ try:
+ os.close(fd)
+ except OSError, oe:
+ pass
+ if tmp_path:
+ try:
+ os.unlink(tmp_path)
+ except OSError, oe:
+ pass
Index: portage-2.1_pre/pym/portage.py
===================================================================
--- portage-2.1_pre.orig/pym/portage.py
+++ portage-2.1_pre/pym/portage.py
@@ -5850,10 +5850,7 @@ class dblink:
os.chown(pdir, 0, portage_gid)
os.chmod(pdir, 02770)
- myworld=open(self.myroot+WORLD_FILE,"w")
- for x in newworldlist:
- myworld.write(x+"\n")
- myworld.close()
+ portage_util.write_atomic(os.path.join(self.myroot,WORLD_FILE),"\n".join(newworldlist))
#do original postrm
if myebuildpath and os.path.exists(myebuildpath):
@@ -6862,10 +6859,7 @@ def do_upgrade(mykey):
if processed:
#update our internal mtime since we processed all our directives.
mtimedb["updates"][mykey]=os.stat(mykey)[stat.ST_MTIME]
- myworld=open("/"+WORLD_FILE,"w")
- for x in worldlist:
- myworld.write(x+"\n")
- myworld.close()
+ portage_util.write_atomic(WORLD_FILE,"\n".join(worldlist))
print ""
def commit_mtimedb():
Index: portage-2.1_pre/bin/emaint
===================================================================
--- portage-2.1_pre.orig/bin/emaint
+++ portage-2.1_pre/bin/emaint
@@ -6,7 +6,7 @@ from optparse import OptionParser, Optio
import re
-import os, portage, portage_const
+import os, portage, portage_const, portage_util
class WorldHandler(object):
def name():
@@ -39,7 +39,7 @@ class WorldHandler(object):
def fix(self):
errors = []
try:
- open(portage_const.WORLD_FILE, "w").write("\n".join(self.okay))
+ portage_util.write_atomic(portage_const.WORLD_FILE,"\n".join(self.okay))
except OSError:
errors.append(portage_const.WORLD_FILE + " could not be opened for writing")
return errors
Index: portage-2.1_pre/bin/regenworld
===================================================================
--- portage-2.1_pre.orig/bin/regenworld
+++ portage-2.1_pre/bin/regenworld
@@ -6,7 +6,7 @@
import sys
sys.path.insert(0, "/usr/lib/portage/pym")
-import portage, string, re
+import portage, portage_util, string, re
__candidatematcher__ = re.compile("^[0-9]+: \\*\\*\\* emerge ")
__noncandidatematcher__ = re.compile(" sync( |$)| clean( |$)| search( |$)|--oneshot| unmerge( |$)")
@@ -88,6 +88,4 @@ for mykey in biglist:
print "add to world:",myfavkey
worldlist.append(myfavkey)
-myfile=open(portage.WORLD_FILE, "w")
-myfile.write(string.join(worldlist, '\n')+'\n')
-myfile.close()
+portage_util.write_atomic(portage.WORLD_FILE,"\n".join(worldlist))
Index: portage-2.1_pre/bin/emerge
===================================================================
--- portage-2.1_pre.orig/bin/emerge
+++ portage-2.1_pre/bin/emerge
@@ -1904,7 +1904,7 @@ class depgraph:
myfavdict[myfavkey]=myfavkey
print ">>> Recording",myfavkey,"in \"world\" favorites file..."
if not "--fetchonly" in myopts:
- portage.writedict(myfavdict,portage.root+portage.WORLD_FILE,writekey=0)
+ portage_util.write_atomic(os.path.join(portage.root,portage.WORLD_FILE),"\n".join(myfavdict.values()))
portage.mtimedb["resume"]["mergelist"]=mymergelist[:]
@@ -2075,7 +2075,7 @@ class depgraph:
myfavdict[myfavkey]=myfavkey
print ">>> Recording",myfavkey,"in \"world\" favorites file..."
emergelog(" === ("+str(mergecount)+" of "+str(len(mymergelist))+") Updating world file ("+x[pkgindex]+")")
- portage.writedict(myfavdict,myroot+portage.WORLD_FILE,writekey=0)
+ portage_util.write_atomic(os.path.join(myroot,portage.WORLD_FILE),"\n".join(myfavdict.values()))
if ("noclean" not in portage.features) and (x[0] != "binary"):
short_msg = "emerge: ("+str(mergecount)+" of "+str(len(mymergelist))+") "+x[pkgindex]+" Clean Post"
