add more return value check on file operations and remind user meaningful message if failed

Signed-off-by: tymon.huang <[email protected]>

Author: tymon.huang

src/util.c

@@ -401,8 +401,14 @@ save_pid_file(const char *pf)
         FILE *f = fopen(pf, "w");
         if (f) {
             fprintf(f, "%d\n", getpid());
-            fclose(f);
+
+            int ret = fclose(f);
+            if (ret == EOF) /* check the return value of fclose */
+                debug(LOG_ERR, "fclose() on file %s was failed (%s)", pf, strerror(errno));
         }
+
+        /* fopen return NULL, open file failed */
+        debug(LOG_ERR, "fopen() on flie %s was failed (%s)", pf, strerror(errno));
     }
 
     return;