+/*
+ * str is supposed to be a substring of the strdup'd original string,
+ * and is valid only if it's a regular file path.
+ * This function keeps the pointer to the path as needed later.
+ *
+ * "external:/path/to/so\0" <- original pointer updated with strdup'd
+ * "external\0" <- above pointer after parsed, i.e. ->ioengine
+ * "/path/to/so\0" <- str argument, i.e. ->ioengine_so_path
+ */
+static int str_ioengine_external_cb(void *data, const char *str)
+{
+ struct thread_data *td = cb_data_to_td(data);
+ struct stat sb;
+ char *p;
+
+ if (!str) {
+ log_err("fio: null external ioengine path\n");
+ return 1;
+ }
+
+ p = (char *)str; /* str is mutable */
+ strip_blank_front(&p);
+ strip_blank_end(p);
+
+ if (stat(p, &sb) || !S_ISREG(sb.st_mode)) {
+ log_err("fio: invalid external ioengine path \"%s\"\n", p);
+ return 1;
+ }
+
+ td->o.ioengine_so_path = p;
+ return 0;
+}
+