make_relative_filename(3) - Linux man page

Name

make_relative_filename - Tries to make a relative filename from absolute path and filename. Allegro game programming library.

Synopsis

#include <allegro.h>

char *make_relative_filename(char *dest, const char *path, const char *filename, int size);

Description

Attempts to make a relative filename from an absolute path and an absolute filename, storing at most 'size' bytes into the 'dest' buffer. This function won't work if the paths are not canonical under the current platform (see canonicalize_filename()). Also, 'dest' cannot be used as input value for 'path' or 'filename'. Example: 
char base[] = "/long/absolute/path/program.exe";
char user_input[] = "/nice/and/short.txt";
...
make_relative_filename(buf, base, user_input, sizeof(buf));
/* Under Unix buf would contain:
   ../../../nice/and/short.txt */

Return Value

Returns a copy of the 'dest' parameter if it succeeds or NULL if it fails (eg. under DOS, one path starts with "C:\" and another with "A:\").

See Also

make_absolute_filename(3), is_relative_filename(3), canonicalize_filename(3)