readlink

/*
 *  call-seq:
 *     File.readlink(link_name) -> file_name
 *  
 *  Returns the name of the file referenced by the given link.
 *  Not available on all platforms.
 *     
 *     File.symlink("testfile", "link2test")   #=> 0
 *     File.readlink("link2test")              #=> "testfile"
 */

static VALUE
rb_file_s_readlink(klass, path)
    VALUE klass, path;
{
#ifdef HAVE_READLINK
    char *buf;
    int size = 100;
    int rv;
    VALUE v;

    SafeStringValue(path);
    buf = xmalloc(size);
    while ((rv = readlink(RSTRING(path)->ptr, buf, size)) == size
#ifdef _AIX
            || (rv < 0 && errno == ERANGE) /* quirky behavior of GPFS */
#endif
        ) {
        size *= 2;
        buf = xrealloc(buf, size);
    }
    if (rv < 0) {
        free(buf);
        rb_sys_fail(RSTRING(path)->ptr);
    }
    v = rb_tainted_str_new(buf, rv);
    free(buf);

    return v;
#else
    rb_notimplement();
    return Qnil;                /* not reached */
#endif
}