Guillaume Boué created COMPRESS-379:
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Summary: isUnixSymlink returns true for Zip entries with Unix
permissions 177777
Key: COMPRESS-379
URL: https://issues.apache.org/jira/browse/COMPRESS-379
Project: Commons Compress
Issue Type: Bug
Components: Archivers
Affects Versions: 1.13
Reporter: Guillaume Boué
This issue was originally reported in MASSEMBLY-842, but it seems the root
cause in inside Commons Compress.
Consider the attached {{invalid-entry.jar}}, whose contents, as shown by the
{{zipinfo}} utility, is:
{noformat}
?rwsrwsrwt 2.0 unx 0 b- stor 17-Jan-15 16:06 META-INF/maven/
drwxr-xr-x 2.0 unx 0 b- stor 17-Jan-15 16:06 META-INF/
{noformat}
There are some JAR files created by the Maven Assembly Plugin with content
similar to this, and the entry {{META-INF/maven/}} has permissions 177777
(octal). Constructing a {{ZipFile}} from this file, the method
{{isUnixSymlink}} incorrectly returns {{true}} for the entry
{{META-INF/maven/}} (and it correctly returns {{false}} for the entry
{{META-INF/}}.
Here is a sample Java code that can be used to see the behaviour:
{code:java}
public static void main(String[] args) throws IOException {
try (ZipFile zipFile = new ZipFile(new File("invalid-entry.jar"))) {
printAttributes(zipFile, "META-INF/");
printAttributes(zipFile, "META-INF/maven/");
}
}
private static void printAttributes(ZipFile zipFile, String name) {
ZipArchiveEntry entry =
zipFile.getEntriesInPhysicalOrder(name).iterator().next();
System.out.printf("%-17s: symlink:%-5s - unixMode:%s%n", name,
entry.isUnixSymlink(), entry.getUnixMode());
}
{code}
This code outputs:
{noformat}
META-INF/ : symlink:false - unixMode:16877
META-INF/maven/ : symlink:true - unixMode:65535
{noformat}
The {{?rwsrwsrwt}} permissions show that the Zip entry is broken in the first
place, but I think {{isUnixSymlink}} should still return {{false}} in that
case, and not consider this entry to be a symlink.
It seems the fix would be to update {{isUnixSymlink}} and check whether the
unix mode is equal to {{SHORT_MASK}}, and return {{false}} in that case as it
would indicate a broken entry. This change does not break any existing tests,
but I'm not sure if this is the proper fix.
{code:java}
public boolean isUnixSymlink() {
int unixMode = getUnixMode();
return unixMode == SHORT_MASK ? false : (unixMode & UnixStat.LINK_FLAG) ==
UnixStat.LINK_FLAG;
}
{code}
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