Loop over all the git attributes for a path.
A combination of GIT_ATTR_CHECK... flags.
The path inside the repo to check attributes. This does not have to exist, but if it does not, then it will be treated as a plain file (i.e. not a directory).
The function that will be invoked on each attribute and attribute value. The name parameter will be the name of the attribute and the value will be the value it is set to, including possibly NULL if the attribute is explicitly set to UNSPECIFIED using the ! sign. This will be invoked only once per attribute name, even if there are multiple rules for a given file. The highest priority rule will be used.
Passed on as extra parameter to callback function.