On Sun, 23 Mar 2025 09:28:38 GMT, Jaikiran Pai <j...@openjdk.org> wrote:
>> Can I please get a review of this change which proposes to fix an issue >> `java.util.zip.ZipFile` which would cause failures when multiple instances >> of `ZipFile` using non-UTF8 `Charset` were operating against the same >> underlying ZIP file? This addresses >> https://bugs.openjdk.org/browse/JDK-8347712. >> >> ZIP file specification allows for ZIP entries to mark a `UTF-8` flag to >> indicate that the entry name and comment are encoded using UTF8. A >> `java.util.zip.ZipFile` can be constructed by passing it a `Charset`. This >> `Charset` (which defaults to UTF-8) gets used for decoding entry names and >> comments for non-UTF8 entries. >> >> The internal implementation of `ZipFile` uses a `ZipCoder` (backed by >> `java.nio.charset.CharsetEncoder/CharsetDecoder` instance) for the given >> `Charset`. Except for UTF8 `ZipCoder`, other `ZipCoder`s are not thread safe. >> >> The internal implementation of `ZipFile` maintains a cache of >> `ZipFile$Source`. A `Source` corresponds to the underlying ZIP file and >> during construction, uses a `ZipCoder` for parsing the ZIP entries and once >> constructed holds on to the parsed ZIP structure. Multiple instances of a >> `ZipFile` which all correspond to the same ZIP file on the filesystem, share >> a single instance of `Source` (after the `Source` has been constructed and >> cached). Although `ZipFile` instances aren't expected to be thread-safe, the >> fact that multiple different instances of `ZipFile` could be sharing the >> same instance of `Source` in concurrent threads, mandates that the `Source` >> must be thread-safe. >> >> In Java 15, we did a performance optimization through >> https://bugs.openjdk.org/browse/JDK-8243469. As part of that change, we >> started holding on to the `ZipCoder` instance (corresponding to the >> `Charset` provided during `ZipFile` construction) in the `Source`. This >> stored `ZipCoder` was then used for `ZipFile` operations when working with >> the ZIP entries. As noted previously, any non-UTF8 `ZipCoder` is not >> thread-safe and as a result, any usages of `ZipCoder` in the `Source` makes >> `Source` not thread-safe too. That effectively violates the requirement that >> `Source` must be thread-safe to allow for its usage in multiple different >> `ZipFile` instances concurrently. This then causes `ZipFile` usages to fail >> in unexpected ways like the one shown in the linked >> https://bugs.openjdk.org/browse/JDK-8347712. >> >> The commit in this PR addresses the issue by not maintaining `ZipCoder` as a >> instance field of `Source`. Instead the `ZipCoder` is now mainta... > > Jaikiran Pai has updated the pull request incrementally with three additional > commits since the last revision: > > - improve code comment for ZipFile.zipCoder > - Alan's suggestion - change code comment about Source class being thread > safe > - Alan's suggestion - trim the javadoc of (internal) ZipCoder class I made another pass over the updated ZipFile comments and left some remarks. src/java.base/share/classes/java/util/zip/ZipCoder.java line 181: > 179: > 180: /** > 181: * {@return the {@link Charset} used this {@code ZipCoder}} Suggestion: * {@return the {@link Charset} used by this {@code ZipCoder}} src/java.base/share/classes/java/util/zip/ZipFile.java line 85: > 83: private final String filePath; // ZIP file path > 84: private final String fileName; // name of the file > 85: // ZipCoder for entry names and comments when not using UTF-8 "_when not using UTF-8_" could be confusing. The ZipCoder here may well be UTF-8, it's more about the entry not mandating UTF-8 by having its language encoding flag set. I think we should either clearly explain when this ZipCoder is used (when entries do not mandate UTF-8), or drop the information here and lean on it being explained in `zipCoderFor`. If we decide to drop it, this could be just: `// Used when decoding entry names and comments` If we decide to keep it, then something like: `// Used when decoding entry names and comments, unless entry flags mandate UTF-8` src/java.base/share/classes/java/util/zip/ZipFile.java line 1145: > 1143: static record EntryPos(String name, int pos) {} > 1144: > 1145: // Implementation note: This class is be thread safe. Suggestion: // Implementation note: This class is thread safe. src/java.base/share/classes/java/util/zip/ZipFile.java line 1432: > 1430: * where a ZIP file is re-opened after it has been modified). > 1431: * - The Charset, that was provided when constructing a ZipFile > instance, > 1432: * for reading non-UTF-8 entry names and comments. I think it would be sufficient to say "The Charset that was provided when constructing the ZipFile instance". Any non-UTF8-ness is better explained elsewhere. src/java.base/share/classes/java/util/zip/ZipFile.java line 1438: > 1436: private final BasicFileAttributes attrs; > 1437: private final File file; > 1438: // the Charset to be used for processing non-UTF-8 entry > names in the ZIP file Similarly this could just say "The Charset that was provided when constructing the ZipFile instance" ------------- PR Review: https://git.openjdk.org/jdk/pull/23986#pullrequestreview-2710281436 PR Review Comment: https://git.openjdk.org/jdk/pull/23986#discussion_r2010124278 PR Review Comment: https://git.openjdk.org/jdk/pull/23986#discussion_r2010184376 PR Review Comment: https://git.openjdk.org/jdk/pull/23986#discussion_r2010368552 PR Review Comment: https://git.openjdk.org/jdk/pull/23986#discussion_r2010375936 PR Review Comment: https://git.openjdk.org/jdk/pull/23986#discussion_r2010377989
