RFR: 8280409: JarFile::verifiableEntry can fail with NPE accessing ze.getName() [v2]

[Sean Mullan]

On Wed, 9 Feb 2022 21:16:08 GMT, Lance Andersen <lancea at openjdk.org> wrote:

>>> Nit, add space after "if"
>> 
>> will fix
>
> So a bit more on this.  If the ZipEntry passed to `ZipFile::getInputStream` does not represent an entry within the current Zip/Jar,  `ZipFile::getInputStream` will return a null for the InputStream:
> 
> 
>     @Test
>     public static void ZipFileZipEntryNullGetInputStreamTest() throws Exception {
>         try (ZipFile zf = new ZipFile(VALID_ENTRY_NAME_JAR.toFile())) {
>             var ze = new ZipEntry("org/gotham/Batcave.class");
>             var is = zf.getInputStream(ze);
>             // As the ZipEntry cannot be found, the returned InpuStream is null
>             assertNull(is);
>         }
>     }
> 
> 
>   JarFile::getInputStream will also return null when the jar is not signed or we are not verifying the jar:
> 
> 
>  @Test
>     public static void JarFileZipEntryNullGetInputStreamTest() throws Exception {
>         try (JarFile jf = new JarFile(VALID_ENTRY_NAME_JAR.toFile())) {
>             var ze = new ZipEntry("org/gotham/Batcave.class");
>             var is = jf.getInputStream(ze);
>             // As the ZipEntry cannot be found, the returned InpuStream is null
>             assertNull(is);
>         }
> 
>         try (JarFile jf = new JarFile(SIGNED_INVALID_ENTRY_NAME_JAR.toFile(), false)) {
>             var ze = new ZipEntry("org/gotham/Batcave.class");
>             var is = jf.getInputStream(ze);
>             // As the ZipEntry cannot be found, the returned InpuStream is null
>             assertNull(is);
>         }
>     }
> 
> 
> 
> This behavior dates back to at least JDK 1.3
> 
> So I think we should return null  instead of throwing an Exception when the resulting ZipEntry is null that is returned from the call to`JarFile::getJarEntry` (which calls `ZipFile::getEntry`) for consistency with ZipFile and when the Jar is not signed or not verified.
> 
> I also noticed that `ZipFile::getInputStream` and `JarFile::getInputStream` do not mention that a null will be returned if the specified ZipEntry is not found within the Jar/Zip.  I guess I could open a CSR as part of this fix to clarify this 20+ year behavior.

Agree on returning null to maintain current behavior. I would also lean towards amending the specification to specify what has been long-standing behavior.

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

PR: https://git.openjdk.java.net/jdk/pull/7348