setMetaData() should only be used to store customized data in a file
that cannot be represented with existing information stored with a file.
Meta-data can significantly slow down the performance of loading a phar
archive if the data is large, or if there are many files containing meta-data.
It is important to note that file permissions are natively supported inside a
phar; it is possible to set them with the
PharFileInfo::chmod() method. As with all functionality that modifies the contents of
a phar, the phar.readonly INI variable
must be off in order to succeed if the file is within a Phar
archive. Files within PharData archives do not have
this restriction.
Some possible uses for meta-data include passing a user/group that should be set
when a file is extracted from the phar to disk. Other uses could include
explicitly specifying a MIME type to return. However, any useful data that
describes a file, but should not be contained inside of it may be stored.
Parameters
metadata
Any PHP variable containing information to store alongside a file