gfileinfo: Document required attributes for helper getters
It doesn’t make sense to (for example) call g_file_info_get_name() if
the GFileInfo doesn’t contain G_FILE_ATTRIBUTE_STANDARD_NAME, given
that building the GFileInfo is typically a static process and entirely
under the control of the programmer.
By being this restrictive, we avoid having to return ‘unknown’ values
for some of these standard APIs, particularly the numeric ones such as
g_file_info_get_size(). If APIs like that were to work correctly in
the face of a GFileInfo without G_FILE_ATTRIBUTE_STANDARD_SIZE
specified, they’d have to be able to return a value to indicate the
attribute is missing. Returning 0 or G_MAXSIZE to indicate that
would be ambiguous.
Signed-off-by: Philip Withnall pwithnall@endlessos.org
Fixes: #2907 (closed)
Closes #2907 (closed)