RFR: 8303942: FileMapInfo::write_bytes aborts on a short os::write

[Afshin Zafari]

On Mon, 3 Apr 2023 09:04:28 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Can this be the rationale for it?
>> The return value can be `-1` so the type is `ssize_t`. And it is also large enough to hold the maximum bytes transfer of `write()`:
>> From the [write() man page](https://man7.org/linux/man-pages/man2/write.2.html#:~:text=of%20bytes%20written.-,On%20Linux%2C,-write()%20(and%20similar)) 
>> 
>>        On Linux, write() (and similar system calls) will transfer at
>>        most 0x7ffff000 (2,147,479,552) bytes, returning the number of
>>        bytes actually transferred.  (This is true on both 32-bit and
>>        64-bit systems.)
>
> Ah! That is not in the version of the manpage on my system. But the one you link also has:
>> According to POSIX.1, if count is greater than SSIZE_MAX, the  result is implementation-defined; see NOTES for the upper limit  on Linux.
> 
> which explains things. Thanks.

`size` is checked to be `> 0` in loop's condition. Is assert for it still needed?

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PR Review Comment: https://git.openjdk.org/jdk/pull/13188#discussion_r1155695029