[Bug 1555305] Re: resquashfs test fails if snap has symlinks
Tyler Hicks
tyhicks at canonical.com
Mon Dec 11 22:28:44 UTC 2017
I'm attaching a squashfs image containing a symlink named "link" and a
regular file named "file". The symlink has a timestamp of "25 Aug 91
20:57:08 GMT".
** Description changed:
+ [Impact]
+
+ * The unsquashfs utility does not preserve atime and mtime timestamps
+ of symlink inodes when unpacking squashfs images.
+
+ * This makes it impossible to use a combination of unsquashfs and
+ mksquashfs to sanity check snaps uploaded to the snap store since
+ the resulting snap will not match the original snap due to symlink
+ times being set to the current time when unsquashfs was executed.
+
+ [Test Case]
+
+ * TODO
+
+ [Regression Potential]
+
+ * The regression potential is small as long as there is no software
+ out there that depends on the behavior of setting symlink timestamps
+ to the current time. I highly doubt that there is anything out there
+ that relies on that behavior but there's always a chance.
+
+ [Original Descipription]
+
Create the files:
$ mkdir test
$ cd test
$ touch foo
$ ln -s foo bar
$ mkdir meta
$ cat >meta/snap.yaml <<EOM
name: test
version: 1.0
architectures: [all]
EOM
Create the initial snap
$ cd ..
$ snapcraft snap ./test
...
Snapped test_1.0_all.snap
Unsquash the snap:
$ unsquashfs -d unsquashed test_1.0_all.snap
Parallel unsquashfs: Using 4 processors
3 inodes (2 blocks) to write
[=======================================================================|]
2/2 100%
created 2 files
created 2 directories
created 1 symlinks
created 0 devices
created 0 fifos
Resquash the snap (the sleep is to make sure the time changes on the symlink):
$ unsquashfs -fstime ./test_1.0_all.snap
1457551603
$ mksquashfs ./unsquashed ./test_1.0_all.snap.repacked -fstime 1457551603 -noappend -comp xz -all-root -no-xattrs
...
-
Compare:
$ sha512sum test_1.0_all.snap
40a15430503783541b362942491ee614b16941676d6c3edd86005af7b6b0782374e41c0c006dccb3a164d2c0270ace66639fcdee5ece3571db1c7544d59030e3 test_1.0_all.snap
- $ sha512sum test_1.0_all.snap.repack
+ $ sha512sum test_1.0_all.snap.repack
d8b9626337b8f09288f6aab675041dba639523437dd1d8f11b3f883cfa73ea434f2be06f5cd9cdec4ac9bdf2a40f8b484dc516ec851870c81be133cbdebf35a4 test_1.0_all.snap.repack
-
Removing the symlink makes the check work.
** Attachment added: "lp1555305.squashfs"
https://bugs.launchpad.net/ubuntu/+source/squashfs-tools/+bug/1555305/+attachment/5021493/+files/lp1555305.squashfs
** Description changed:
[Impact]
- * The unsquashfs utility does not preserve atime and mtime timestamps
- of symlink inodes when unpacking squashfs images.
+ * The unsquashfs utility does not preserve atime and mtime timestamps
+ of symlink inodes when unpacking squashfs images.
- * This makes it impossible to use a combination of unsquashfs and
- mksquashfs to sanity check snaps uploaded to the snap store since
- the resulting snap will not match the original snap due to symlink
- times being set to the current time when unsquashfs was executed.
+ * This makes it impossible to use a combination of unsquashfs and
+ mksquashfs to sanity check snaps uploaded to the snap store since
+ the resulting snap will not match the original snap due to symlink
+ times being set to the current time when unsquashfs was executed.
[Test Case]
- * TODO
+ * Extract the test image:
+ $ unsquashfs -d lp1555305 lp1555305.squashfs
+
+ * Check the timestamp of the "link" file
+ $ ls -al lp1555305/link
+
+ * Incorrect output (timestamp will be current time):
+ lrwxrwxrwx 1 tyhicks tyhicks 4 Dec 11 22:05 link -> file
+
+ * Expected output:
+ lrwxrwxrwx 1 tyhicks tyhicks 4 Aug 25 1991 /tmp/lp1555305/link -> file
[Regression Potential]
- * The regression potential is small as long as there is no software
- out there that depends on the behavior of setting symlink timestamps
- to the current time. I highly doubt that there is anything out there
- that relies on that behavior but there's always a chance.
+ * The regression potential is small as long as there is no software
+ out there that depends on the behavior of setting symlink timestamps
+ to the current time. I highly doubt that there is anything out there
+ that relies on that behavior but there's always a chance.
[Original Descipription]
-
+
Create the files:
$ mkdir test
$ cd test
$ touch foo
$ ln -s foo bar
$ mkdir meta
$ cat >meta/snap.yaml <<EOM
name: test
version: 1.0
architectures: [all]
EOM
Create the initial snap
$ cd ..
$ snapcraft snap ./test
...
Snapped test_1.0_all.snap
Unsquash the snap:
$ unsquashfs -d unsquashed test_1.0_all.snap
Parallel unsquashfs: Using 4 processors
3 inodes (2 blocks) to write
[=======================================================================|]
2/2 100%
created 2 files
created 2 directories
created 1 symlinks
created 0 devices
created 0 fifos
Resquash the snap (the sleep is to make sure the time changes on the symlink):
$ unsquashfs -fstime ./test_1.0_all.snap
1457551603
$ mksquashfs ./unsquashed ./test_1.0_all.snap.repacked -fstime 1457551603 -noappend -comp xz -all-root -no-xattrs
...
Compare:
$ sha512sum test_1.0_all.snap
40a15430503783541b362942491ee614b16941676d6c3edd86005af7b6b0782374e41c0c006dccb3a164d2c0270ace66639fcdee5ece3571db1c7544d59030e3 test_1.0_all.snap
$ sha512sum test_1.0_all.snap.repack
d8b9626337b8f09288f6aab675041dba639523437dd1d8f11b3f883cfa73ea434f2be06f5cd9cdec4ac9bdf2a40f8b484dc516ec851870c81be133cbdebf35a4 test_1.0_all.snap.repack
Removing the symlink makes the check work.
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https://bugs.launchpad.net/bugs/1555305
Title:
resquashfs test fails if snap has symlinks
Status in click-reviewers-tools package in Ubuntu:
Invalid
Status in squashfs-tools package in Ubuntu:
In Progress
Status in squashfs-tools source package in Trusty:
In Progress
Status in squashfs-tools source package in Xenial:
In Progress
Status in squashfs-tools source package in Zesty:
In Progress
Status in squashfs-tools source package in Artful:
In Progress
Status in squashfs-tools source package in Bionic:
In Progress
Bug description:
[Impact]
* The unsquashfs utility does not preserve atime and mtime timestamps
of symlink inodes when unpacking squashfs images.
* This makes it impossible to use a combination of unsquashfs and
mksquashfs to sanity check snaps uploaded to the snap store since
the resulting snap will not match the original snap due to symlink
times being set to the current time when unsquashfs was executed.
[Test Case]
* Extract the test image:
$ unsquashfs -d lp1555305 lp1555305.squashfs
* Check the timestamp of the "link" file
$ ls -al lp1555305/link
* Incorrect output (timestamp will be current time):
lrwxrwxrwx 1 tyhicks tyhicks 4 Dec 11 22:05 link -> file
* Expected output:
lrwxrwxrwx 1 tyhicks tyhicks 4 Aug 25 1991 /tmp/lp1555305/link -> file
[Regression Potential]
* The regression potential is small as long as there is no software
out there that depends on the behavior of setting symlink timestamps
to the current time. I highly doubt that there is anything out there
that relies on that behavior but there's always a chance.
[Original Descipription]
Create the files:
$ mkdir test
$ cd test
$ touch foo
$ ln -s foo bar
$ mkdir meta
$ cat >meta/snap.yaml <<EOM
name: test
version: 1.0
architectures: [all]
EOM
Create the initial snap
$ cd ..
$ snapcraft snap ./test
...
Snapped test_1.0_all.snap
Unsquash the snap:
$ unsquashfs -d unsquashed test_1.0_all.snap
Parallel unsquashfs: Using 4 processors
3 inodes (2 blocks) to write
[=======================================================================|]
2/2 100%
created 2 files
created 2 directories
created 1 symlinks
created 0 devices
created 0 fifos
Resquash the snap (the sleep is to make sure the time changes on the symlink):
$ unsquashfs -fstime ./test_1.0_all.snap
1457551603
$ mksquashfs ./unsquashed ./test_1.0_all.snap.repacked -fstime 1457551603 -noappend -comp xz -all-root -no-xattrs
...
Compare:
$ sha512sum test_1.0_all.snap
40a15430503783541b362942491ee614b16941676d6c3edd86005af7b6b0782374e41c0c006dccb3a164d2c0270ace66639fcdee5ece3571db1c7544d59030e3 test_1.0_all.snap
$ sha512sum test_1.0_all.snap.repack
d8b9626337b8f09288f6aab675041dba639523437dd1d8f11b3f883cfa73ea434f2be06f5cd9cdec4ac9bdf2a40f8b484dc516ec851870c81be133cbdebf35a4 test_1.0_all.snap.repack
Removing the symlink makes the check work.
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