Look up the value of one git attribute for path with extended options.
Output of the value of the attribute. Use the GIT_ATTR_... macros to test for TRUE, FALSE, UNSPECIFIED, etc. or just use the string value for attributes set to a value. You should NOT modify or free this value.
The path to check for attributes. Relative paths are interpreted relative to the repo root. The file does not have to exist, but if it does not, then it will be treated as a plain file (not a directory).
The name of the attribute to look up.