On Mon, Aug 09, 2004 at 04:38:13PM +0200, Michael T Kerrisk wrote:
> On Linux 2.4.26 and 2.6.7, if we connect a datagram socket and
> then use write() to send 0 bytes, a datagram is NOT generated
> (this happens in both the Unix and Internet domains).
> Datagrams are generated in this case for send() and sendto()
Some postings were made about this some time ago, it appears SUS has an
opinion on zero byte writes:
If nbyte is 0, write() will return 0 and have no other results if the file
is a regular file; otherwise, the results are unspecified.
The send(2) manpage states:
The send() function is identical to sendto() with a null pointer dest_len
argument, and to write() if no flags are used.
Which means that a zero byte send() without flags is unspecified.
Also note that it is hard if impossible to usefully inform userspace of the
reception of a zery byte packet - returning 0 from recvfrom may also mean an
Do you actually have a need for zero byte packets?
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