Maps a file into memory. On UNIX, this is using the mmap() function.
If writable is TRUE, the mapped buffer may be modified, otherwise
it is an error to modify the mapped buffer. Modifications to the buffer
are not visible to other processes mapping the same file, and are not
written back to the file.
Note that modifications of the underlying file might affect the contents
of the GMappedFile. Therefore, mapping should only be used if the file
will not be modified, or if all modifications of the file are done
atomically (e.g. using g_file_set_contents()).
If filename is the name of an empty, regular file, the function
will successfully return an empty GMappedFile. In other cases of
size 0 (e.g. device files such as /dev/null), error will be set
to the GFileError value G_FILE_ERROR_INVAL.
Since 2.8
Maps a file into memory. On UNIX, this is using the mmap() function. If writable is TRUE, the mapped buffer may be modified, otherwise it is an error to modify the mapped buffer. Modifications to the buffer are not visible to other processes mapping the same file, and are not written back to the file. Note that modifications of the underlying file might affect the contents of the GMappedFile. Therefore, mapping should only be used if the file will not be modified, or if all modifications of the file are done atomically (e.g. using g_file_set_contents()). If filename is the name of an empty, regular file, the function will successfully return an empty GMappedFile. In other cases of size 0 (e.g. device files such as /dev/null), error will be set to the GFileError value G_FILE_ERROR_INVAL. Since 2.8