Hi Langer,
Here are some of my comments.
ZipEntry:
Optional<Set<...>> getPosixPermissions()
(1) Is "Optional" really necessary here. it's a little inconsistent
compared to the rest of
methods in the class. a "null" return might be just fine?
(2) Needs a <p> to separate the first line of the spec from the rest
(3) The wording probably needs more consideration. For example, it
might be more
straightforward to use some similar wording from other
methods, for example
... When read from a ZIP file, this is the posix permission stored in the
{@codeexternal
file attributes} field of the zip file entry'scentral directory record, if
there is
one.
Also, a @ImplNote might be the better place for "it's not available when read
from ZIS"?
void setPosixPermissions( Set<PosixFilePermission> permissions)
I can see the possible use case of using "null" as a special value
to reset the
permission field (and my proposal of simply returning a null from
getPosixPermissions()
when there is no one, brings some symmetry here?)
ZipUtil:
(1) those POSIX_... constants don't need to be public?
(2) I like the "stream" style implementation of permsTo/FromFlags
pair, but have some
concerns regarding their cost. "stream" is relative expensive
(when you take a look at
those supporting class underneath), as these two are supposed
to be invoked for every
entry inside a zip file, they can be hundreds and thousands
... just wonder, given most
of the entries likely to have the "same" permission set inside
a "normal" zip/jar file, is it
worth to put in some cache mechanism here, especially for the
"get" method, is it designed
to return a read-only set of permission? (in which we can use
some mechanism here).
That said PosixFileAttributes.getPermissions() actually
purposely returns a modifiable set
of permissions. It might be worth some discussion here, as the
ZipEntry.getPosixPermission()
needs to specify it, if it's going to return a immutable set.
Test: These days it is discouraged to check in a binary zip file as a
test target. It is preferred
to create the testing zip file on the fly.
-Sherman
On 9/25/18, 7:57 AM, Langer, Christoph wrote:
Hi all,
I had asked for opinions regarding adding posix permission support to
JDK’s zip handling libraries and tools [1]. Since I didn’t get clear
“no, you can’t do this” answers, I’m now concretely proposing some
enhancements in the area of java.util.zip, jdk.zipfs and jdk.jartool.
I have reopened the long standing bug report (6194856) which had been
set to “Won’t fix” quite recently for this purpose.
Here are the technical details:
The ZIP format specifications by infozip and pkware ([2] and [3]) do
not explicitly specify the handling of posix file permissions. But it
seems to be common sense that if file attribute compatibility is set
to “Unix” in the upper byte of CEN field “version made by”, the file
permissions bits are stored in CEN field “external file attributes”,
byte 3 and 4. My changes try to honor this in the least obtrusive way. 😊
The following changes are proposed:
java.util.zip.ZipEntry:
it will have an additional field “posixPerms”. A value of -1 means “no
permission information”, positive values will contain the flag values.
There will be 2 new public methods to read/set the permission information:
public Optional<Set<PosixFilePermission>>
getPosixPermissions()
public void
setPosixPermissions(Set<PosixFilePermission> permissions)
The usage of type “Optional” reflects that posix permissions are not
necessarily present in a zip file
java.util.zip.ZipFile:
it will have the capability to read the CEN fields and
set posixPerms if available
java.util.zip.ZipOutputStream:
it will store entries with associated posix
permissions as unix type in the CEN, together with the bit mask for
the permissions
jdk.jartool:
I propose to add and option "--preserve-posix" or short "-o" to honor
the posix bits that may be stored inside zip/jar files. By default the
option is not set and hence posix permissions are ignored. If the flag
is set and the file system that the jar tool is running on supports
posix, posix file permissions that exist in the file system will be
stored in newly created/update archives or restored to the file system
if such information is present in the archive.
jdk.zipfs:
I added the capability for posix file permissions in
the implementation. I decided to support PosixFileAttributes by
subclassing ZipFileAttributes from this superclass as well as
subclassing ZipFileAttributeView from PosixFileAttributeView. However,
as PosixFileAttributes also include groups and owners, I would throw
UnsupportedOperationExceptions in case of invoking methods to handle
these attributes. But this approach seems to be most consistent with
e.g. Files.setPosixFilePermissions and Files.getPosixFilePermissions.
java.nio.file.attribute.PosixFilePermissions:
As this class presents a collection of static helpers,
I added definitions for the posix file bit masks together with methods
to convert between Sets of PosixFilePermission to bit masks containing
the according switches and vice versa. These definitions could
theoretically also be moved inside the java.util.zip or jdk.zipfs
implementations where they wouldn’t be exposed as public APIs.
However, in that case the code would probably need to be duplicated.
I’ve also created two jtreg testcases for both, java.util.zip and
jdk.nio.zipfs.
The changes also contain a few further code cleanups.
Here are the links:
Bug: https://bugs.openjdk.java.net/browse/JDK-6194856
Webrev: http://cr.openjdk.java.net/~clanger/webrevs/6194856.0/
<http://cr.openjdk.java.net/%7Eclanger/webrevs/6194856.0/>
I’ll write a CSR once there’s some substantial feedback to my endeavor.
Thanks in advance for reviewing/commenting.
Best regards
Christoph
[1]
http://mail.openjdk.java.net/pipermail/core-libs-dev/2018-September/055375.html
[2] http://www.info-zip.org/doc/appnote-19970311-iz.zip
[3] https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
