RFR: 8214776: Avoid GCC 8.X strncpy() errors in JFR code

[Severin Gehwolf]

Hi Simon,

On Mon, 2018-12-10 at 10:25 -0500, Simon Tooke wrote:
> This small patch fixes some simple warnings in JFR code, found by GCC 8.1
> Essentially, any code sequence of the pattern
> 
>     int l = strlen(somestring)
>     char* buffer = malloc(l + 1)
>     strncpy(buffer, somestring, l)
>     buffer[l] = 0
> 
> is replaced by
> 
>     int len = strlen(somestring)
>     char* buffer = malloc(len + 1)
>     strncpy(buffer, somestring, len + 1)
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8214776
> Webrev:
> http://cr.openjdk.java.net/~sgehwolf/webrevs/stooke/JDK-8214776/02/webrev/

Shouldn't these:

@@ -332,7 +331,7 @@
     if (NULL == emergency_dump_path) {
       return NULL;
     }
-    strncpy(emergency_dump_path, buffer, emergency_filename_length);
+    strncpy(emergency_dump_path, buffer, emergency_filename_length + 1);
     emergency_dump_path[emergency_filename_length] = '\0';
   }
   return emergency_dump_path;
@@ -407,7 +406,7 @@
   if (_path == NULL) {
     return false;
   }
-  strncpy(_path, path, path_len);
+  strncpy(_path, path, path_len + 1);
   _path[path_len] = '\0';

Be this instead?

@@ -332,8 +331,7 @@
     if (NULL == emergency_dump_path) {
       return NULL;
     }
-    strncpy(emergency_dump_path, buffer, emergency_filename_length);
-    emergency_dump_path[emergency_filename_length] = '\0';
+    strncpy(emergency_dump_path, buffer, emergency_filename_length + 1);
   }
   return emergency_dump_path;
 }
@@ -407,8 +405,7 @@
   if (_path == NULL) {
     return false;
   }
-  strncpy(_path, path, path_len);
-  _path[path_len] = '\0';
+  strncpy(_path, path, path_len + 1);

Thanks,
Severin