The man pages for glob give a few return values for the glob function itself:

      On successful completion, glob() returns zero.  Other possible
      returns are:

      GLOB_NOSPACE
             for running out of memory,

      GLOB_ABORTED
             for a read error, and

      GLOB_NOMATCH
             for no found matches.

It also describes the globfree function:

      The globfree() function frees the dynamically allocated storage
      from an earlier call to glob().

My question is: If I want to avoid leaking glob_t data, should I call globfree always after calling glob, or should I only call it if glob returns 0?

As far as I can see, the man page doesn't go into detail of whether or not an unsuccessful call to glob allocates memory (the GLOB_NOMATCH return value case is the most ambiguous to me). The example in the man page doesn't call globfree, either.

In other words, which of these, if any, is correct:

glob_t result;
if (!glob("*", 0, NULL, &result)) {
  /* do something with result */
}
globfree(&result);

Or:

glob_t result;
if (!glob("*", 0, NULL, &result)) {
  /* do something with result */
  globfree(&result);
}