:sig
String path_real(String path)

:params
path : path to resolve
return value : the canonical absolute path, or "" if it cannot be resolved

:content
Resolves a path to its canonical absolute form, following symlinks and collapsing `.` and `..` segments. The path must exist. Combine with `path_is_within()` to validate that user-supplied paths stay inside an allowed root.

:example
file_put_contents("/tmp/doc-real.txt", "x");
print(path_real("/tmp/../tmp/./doc-real.txt"), "\n");

:see
>sys
path_is_within
expand_path
file_symlink