(PSA) GLib can now canonicalize file paths

Quick announcement: if you have a relative file path, and want to resolve it against another (absolute) path, GLib can do that now.

An example in C:

g_autofree gchar *path = NULL;
g_autofree gchar *another_path = NULL;

path = g_canonicalize_filename ("../../usr/bin", "/etc/foo");
another_path = g_canonicalize_filename ("../../usr/bin", NULL);

g_print ("%s \n", path); /* Result: "/usr/bin" */
g_print ("%s \n", another_path); /* Passing NULL uses the current working dir */

No I/O is involved. It handles double and triple slashes nicely too.

This is bug 111848. The bug was fixed exactly 15 years and 1 day after initially reported.

We wish you farewell, bug 111848.

(Thanks Philip Withnall for reviewing, and Endless for sponsoring this work. This bug was fixed entirely in my work time.)