[jira] Commented: (HADOOP-6263) SerialUtils.cc: dynamic allocation of arrays based on runtime variable is not portable

["Brian Bockelman (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-6263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12756277#action_12756277 ] 

Brian Bockelman commented on HADOOP-6263:
-----------------------------------------

This is legal in C99, not C89.  Depends on which one you call ANSI C (I think it usually refers to C89) ;)

I believe it's better programming practice to allocate on the heap with malloc/free; I'm not sure if you gain any speed advantages either way.

> SerialUtils.cc: dynamic allocation of arrays based on runtime variable is not portable
> --------------------------------------------------------------------------------------
>
>                 Key: HADOOP-6263
>                 URL: https://issues.apache.org/jira/browse/HADOOP-6263
>             Project: Hadoop Common
>          Issue Type: Bug
>            Reporter: Allen Wittenauer
>
> In SerialUtils.cc, the following code appears:
>     int len;
>     if (b < -120) {
>       negative = true;
>       len = -120 - b;
>     } else {
>       negative = false;
>       len = -112 - b;
>     }
>     uint8_t barr[len];
> as far as I'm aware, this is not legal in ANSI C and will be rejected by ANSI compliant compilers.  Instead, this should be malloc()'d based upon the size of len and free()'d later.

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