For example, on xattr-supporting filesystems like ext4 and XFS with user namespaces, I executed the following commands:
```shell mkdir testdata touch testdata/a tar --format=pax --pax-option=SCHILY.xattr.user.gxattr=gvalue -cf testdata.tar testdata rm -rf testdata tar -xvf testdata.tar --xattrs getfattr -d -m ".*" testdata getfattr -d -m ".*" testdata/a ``` Expected both `testdata` and `testdata/a` to have the *user.gxattr="gvalue"* key-value pair, as per the specification stating that Global header content should be used when keys exist in the Global header but are absent from Extended headers. Notably, the pattern should actually be treated as keyword, while keyword should serve as pattern. This is because the `locate_handler` function uses the `keyword` field in *xhdr_tab* to perform prefix matching against input parameters (named "keyword") when selecting *xhdr_tab* entries. Therefore, I confirm this modification is correct based on: 1. Passing unit tests 2. Pattern is the actual keyword 3. Resolving the global header default value issue
