`convertPathnameToDirName` fails to strip trailing slashes due to off‑by‑one index

[mugitya03]

Describe the bug
In convertPathnameToDirName(), the code attempts to remove trailing / characters with:

len = strlen(pathname);
while (pathname[len] == PATH_SEP) {
    pathname[len] = '\0';
    len--;
}

However, strlen(pathname) is the index of the terminating NUL. As a result pathname[len] is always '\0', never '/', so the loop never runs and trailing slashes remain.

To Reproduce

1. Call convertPathnameToDirName("foo/bar/").
2. Expect "foo/bar", but function returns "foo/bar/".