RFR: JDK-8319626: Override toString() for ZipFile [v7]

[Jaikiran Pai]

On Mon, 11 Dec 2023 05:44:38 GMT, Justin Lu <jlu at openjdk.org> wrote:

>> src/java.base/share/classes/java/util/zip/ZipFile.java line 494:
>> 
>>> 492:     @Override
>>> 493:     public String toString() {
>>> 494:         return res.zsrc.key.file.getName()
>> 
>> Hello Justin, relying on `res.zsrc.key.file` to get to the file name can cause troubles. For example, consider this usage (which I ran in jshell) with this proposed change in this PR:
>> 
>> 
>> jshell> import java.util.zip.*
>> 
>> jshell> ZipFile zf = new ZipFile("/tmp/workdir.zip")
>> zf ==> workdir.zip at 34c45dca
>> 
>> jshell> zf.close()
>> 
>> jshell> zf.toString()
>> |  Exception java.lang.NullPointerException: Cannot read field "key" because "this.res.zsrc" is null
>> |        at ZipFile.toString (ZipFile.java:494)
>> |        at (#4:1)
>> 
>> 
>> 
>> What I do here is that I call `ZipFile.toString()` after I (intentionally) close the `ZipFile`. The `toString()` call leads to `NullPointerException` because on closing the `ZipFile` instance we clean up the resource it holds on to.
>> 
>> I think what we can do here is, something like (the following diff was generated on top of the current state of this PR):
>> 
>> 
>> diff --git a/src/java.base/share/classes/java/util/zip/ZipFile.java b/src/java.base/share/classes/java/util/zip/ZipFile.java
>> index 67a5e65089f..2b6996294e1 100644
>> --- a/src/java.base/share/classes/java/util/zip/ZipFile.java
>> +++ b/src/java.base/share/classes/java/util/zip/ZipFile.java
>> @@ -95,7 +95,8 @@
>>   */
>>  public class ZipFile implements ZipConstants, Closeable {
>>  
>> -    private final String name;     // zip file name
>> +    private final String filePath;     // zip file path
>> +    private final String fileName;     // name of the file
>>      private volatile boolean closeRequested;
>>  
>>      // The "resource" used by this zip file that needs to be
>> @@ -245,7 +246,8 @@ public ZipFile(File file, int mode, Charset charset) throws IOException
>>          }
>>          Objects.requireNonNull(charset, "charset");
>>  
>> -        this.name = name;
>> +        this.filePath = name;
>> +        this.fileName = file.getName();
>>          long t0 = System.nanoTime();
>>  
>>          this.res = new CleanableResource(this, ZipCoder.get(charset), file, mode);
>> @@ -483,7 +485,7 @@ public int available() throws IOException {
>>       * @return the path name of the ZIP file
>>       */
>>      public String getName() {
>> -        return name;
>> +        return filePath;
>>      }
>>  
>>      /**
>> @@ -491,7 +493,7 @@ public String getName() {
>>       */
>>      @Override
>>      publi...
>
> Hi Jai,
> 
> Thank you for the detailed response and suggested alternative.
> 
> My intentions were to get the file name by leveraging the existing code without introducing an additional field if possible, but I did not realize the `NPE` it would cause when closing the ZipFile as you demonstrated.
> 
> I appreciate your guidance, updated the PR to reflect your suggestions. I don't see how this would cause any issues with tests as you stated, but checked tiers 1-3 and all is good there.

Hello Justin, thank you for doing the update and running the tests. This latest state of the PR (commit `4ba2bd47`) looks good to me. I have no other review comments.

Please wait for an additional review from someone else before integrating.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/16643#discussion_r1423725222