From 9e100285c6862e28da18ed2094197acc17a140b9 Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Fri, 22 Oct 2010 14:00:35 +0200
Subject: [PATCH] Add functions to read and compare file 'ID's
Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>
---
lib/utils.py | 40 +++++++++++++++++++++++++++++++++++
test/ganeti.utils_unittest.py | 19 +++++++++++++++++
2 files changed, 59 insertions(+)
diff --git a/lib/utils.py b/lib/utils.py
index 919eab11c..aa84cb1f8 100644
--- a/lib/utils.py
+++ b/lib/utils.py
@@ -1872,6 +1872,46 @@ def WriteFile(file_name, fn=None, data=None,
return result
+def GetFileID(path=None, fd=None):
+ """Returns the file 'id', i.e. the dev/inode and mtime information.
+
+ Either the path to the file or the fd must be given.
+
+ @param path: the file path
+ @param fd: a file descriptor
+ @return: a tuple of (device number, inode number, mtime)
+
+ """
+ if [path, fd].count(None) != 1:
+ raise errors.ProgrammerError("One and only one of fd/path must be given")
+
+ if fd is None:
+ st = os.stat(path)
+ else:
+ st = os.fstat(fd)
+
+ return (st.st_dev, st.st_ino, st.st_mtime)
+
+
+def VerifyFileID(fi_disk, fi_ours):
+ """Verifies that two file IDs are matching.
+
+ Differences in the inode/device are not accepted, but and older
+ timestamp for fi_disk is accepted.
+
+ @param fi_disk: tuple (dev, inode, mtime) representing the actual
+ file data
+ @param fi_ours: tuple (dev, inode, mtime) representing the last
+ written file data
+ @rtype: boolean
+
+ """
+ (d1, i1, m1) = fi_disk
+ (d2, i2, m2) = fi_ours
+
+ return (d1, i1) == (d2, i2) and m1 <= m2
+
+
def ReadOneLineFile(file_name, strict=False):
"""Return the first non-empty line from a file.
diff --git a/test/ganeti.utils_unittest.py b/test/ganeti.utils_unittest.py
index 08c753e3b..7fc93db1f 100755
--- a/test/ganeti.utils_unittest.py
+++ b/test/ganeti.utils_unittest.py
@@ -2356,5 +2356,24 @@ class TestFindMatch(unittest.TestCase):
self.assert_(utils.FindMatch(data, "Hello World") is None)
+class TestFileID(testutils.GanetiTestCase):
+ def testEquality(self):
+ name = self._CreateTempFile()
+ oldi = utils.GetFileID(path=name)
+ self.failUnless(utils.VerifyFileID(oldi, oldi))
+
+ def testUpdate(self):
+ name = self._CreateTempFile()
+ oldi = utils.GetFileID(path=name)
+ os.utime(name, None)
+ fd = os.open(name, os.O_RDWR)
+ try:
+ newi = utils.GetFileID(fd=fd)
+ self.failUnless(utils.VerifyFileID(oldi, newi))
+ self.failUnless(utils.VerifyFileID(newi, oldi))
+ finally:
+ os.close(fd)
+
+
if __name__ == '__main__':
testutils.GanetiTestProgram()
--
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