2fd7c53089
Reference:fa53c7f4089c7502a8012e17a0d6269f0efc474ebb414c78669cbd94dd576d817e94be0450a1faff
66 lines
2.3 KiB
Diff
66 lines
2.3 KiB
Diff
From 479c7201b61d674e54e2ee7c347cd90fc0aaf1d3 Mon Sep 17 00:00:00 2001
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From: Adam Collard <sparkiegeek@users.noreply.github.com>
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Date: Fri, 8 Apr 2022 20:20:18 +0100
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Subject: [PATCH 8/8] util: atomically update sym links to avoid Suppress
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FileNotFoundError when reading status (#1298)
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Reference:https://github.com/canonical/cloud-init/commit/0450a1faff9e5095e6da0865916501772b3972e9
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Conflict:change tests/unittests/test_util.py not cloudinit/tests/test_util.py.
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Atomically update the desired link file from a temporary file
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when a stale link already exists.
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This avoids FileNotFound errors due to races with
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cloud-init status --wait when the symlink
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/run/cloud-init/status.json already exists.
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LP:1962150
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---
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cloudinit/tests/test_util.py | 5 ++++-
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cloudinit/util.py | 7 ++++++-
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2 files changed, 10 insertions(+), 2 deletions(-)
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diff --git a/cloudinit/tests/test_util.py b/cloudinit/tests/test_util.py
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index 671b8bc..5fb2508 100644
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--- a/cloudinit/tests/test_util.py
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+++ b/cloudinit/tests/test_util.py
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@@ -328,13 +328,16 @@ class TestSymlink(CiTestCase):
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tmpd = self.tmp_dir()
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link = self.tmp_path("link", tmpd)
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target = self.tmp_path("target", tmpd)
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+ target2 = self.tmp_path("target2", tmpd)
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util.write_file(target, "hello")
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+ util.write_file(target2, "hello2")
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util.sym_link(target, link)
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self.assertTrue(os.path.exists(link))
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- util.sym_link(target, link, force=True)
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+ util.sym_link(target2, link, force=True)
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self.assertTrue(os.path.exists(link))
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+ self.assertEqual("hello2", util.load_file(link))
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def test_sym_link_dangling_link(self):
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tmpd = self.tmp_dir()
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diff --git a/cloudinit/util.py b/cloudinit/util.py
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index d5e8277..0e0fc04 100644
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--- a/cloudinit/util.py
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+++ b/cloudinit/util.py
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@@ -1797,7 +1797,12 @@ def is_link(path):
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def sym_link(source, link, force=False):
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LOG.debug("Creating symbolic link from %r => %r", link, source)
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if force and os.path.lexists(link):
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- del_file(link)
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+ # Provide atomic update of symlink to avoid races with status --wait
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+ # LP: #1962150
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+ tmp_link = os.path.join(os.path.dirname(link), "tmp" + rand_str(8))
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+ os.symlink(source, tmp_link)
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+ os.replace(tmp_link, link)
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+ return
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os.symlink(source, link)
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--
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2.40.0
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