JDK 9 RFR of 8148023: File.createTempFile is not adhering to the contract regarding file name lengths

Brian Burkhalter brian.burkhalter at oracle.com
Mon Dec 19 20:54:59 UTC 2016

Hi Roger,

Thanks for your suggestions. An updated version of the patch is here:


On Dec 19, 2016, at 11:04 AM, Roger Riggs <Roger.Riggs at Oracle.com> wrote:

> File.java:
> - 1906: shortenSubName might reasonably return the new length without
>   creating the intermediate string and save on the allocation.

So changed.

> - generateFile() line 1922 + --  I assume this slow path is infrequently used.
>  Otherwise, the computations involving excess could be done arithmetically without actually creating the string
>  and only create the name when the final length(s) are decided.


> - line 1952:  appending the generated name to the exception is ok but it should omit the directory name;
>   its not salient to the error and might expose a sensitive directory name.


> FileSystem.java
> - getNameMax;  the length could reasonably be just an int.  Long seems a bit excessive
>   and raises suspicion that something clever is going on when its just a normal value.
>  (Though I see the native code uses jlong)

Changed to an int except for the native Unix call. The invoking Java code clamps a highly unlikely out-of-range long to Integer.MAX_VALUE.



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