RFR: 8350880: (zipfs) Add support for read-only zip file systems [v3]

[Jaikiran Pai]

On Mon, 12 May 2025 10:16:33 GMT, David Beaumont <duke at openjdk.org> wrote:

>> Adding read-only support to ZipFileSystem.
>> 
>> The new `accessMode` environment property allows for readOnly and readWrite values, and ensures that the requested mode is consistent with what's returned.
>> 
>> This involved a little refactoring to ensure that "read only" state was set initially and only unset at the end of initialization if appropriate.
>> 
>> By making 2 methods return values (rather than silently set non-final fields as a side effect) it's now clear in what order fields are initialized and which are final (sadly there are still non-final fields, but only a split of this class into two types can fix that, since determining multi-jar support requires reading the file system).
>
> David Beaumont has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix comment based on current behaviour.

src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java line 208:

> 206:         boolean shouldCreate = isTrue(env, "create");
> 207:         if (shouldCreate && forceReadOnly) {
> 208:             throw new IllegalArgumentException(

Although `IllegalArgumentException` seems reasonable here, the current contract of this constructor is to throw `IOException` and that then gets propagated through the public `FileSystemProvider.newFileSystem(...)` API which is specified to throw `IOException`.

So we will either have to throw `IOException` here (preferable) or we have to catch `IllegalArgumentException` at the call sites of this constructor and then rethrow it as a `IOException`, to prevent the unspecified `IllegalArgumentException` propagating out of the `FileSystemProvider.newFileSystem(...)` API.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25178#discussion_r2087216326