+static const char *
+valid_db_path(const char *nominal)
+{
+ struct stat sb;
+#if USE_HASHED_DB
+ char suffix[] = DBM_SUFFIX;
+ size_t need = strlen(nominal) + sizeof(suffix);
+ char *result = malloc(need);
+
+ strcpy(result, nominal);
+ if (strcmp(result + need - sizeof(suffix), suffix)) {
+ strcat(result, suffix);
+ }
+#else
+ char *result = strdup(nominal);
+#endif
+
+ DEBUG(1, ("** stat(%s)", result));
+ if (stat(result, &sb) >= 0) {
+#if USE_HASHED_DB
+ if (!S_ISREG(sb.st_mode)
+ || access(result, R_OK | W_OK) != 0) {
+ DEBUG(1, ("...not a writable file"));
+ free(result);
+ result = 0;
+ }
+#else
+ if (!S_ISDIR(sb.st_mode)
+ || access(result, R_OK | W_OK | X_OK) != 0) {
+ DEBUG(1, ("...not a writable directory"));
+ free(result);
+ result = 0;
+ }
+#endif
+ } else {
+ /* check if parent is directory and is writable */
+ unsigned leaf = _nc_pathlast(result);
+
+ DEBUG(1, ("...not found"));
+ if (leaf) {
+ char save = result[leaf];
+ result[leaf] = 0;
+ if (stat(result, &sb) >= 0
+ && S_ISDIR(sb.st_mode)
+ && access(result, R_OK | W_OK | X_OK) == 0) {
+ result[leaf] = save;
+ } else {
+ DEBUG(1, ("...parent directory %s is not writable", result));
+ free(result);
+ result = 0;
+ }
+ } else {
+ DEBUG(1, ("... no parent directory"));
+ free(result);
+ result = 0;
+ }
+ }
+ return result;
+}
+