Hello,
I have a few questions about the send() syscall and its man page,
reproduced below.
In normal usage (blocking mode), send() blocks, but doesn't guarantee
that all bytes in the buffer are sent on success, right? In particular,
are there cases where a blocking send() "succeeds" while returning an
integer smaller than the length of the buffer?
In nonblocking mode, the man page says that send() "would fail" if the
message is long, and then I might interpret the "Return value" paragraph
to imply that it returns -1. However a simple test in that case shows
that send() returns the number of bytes sent, which is certainly a
sensible thing to do, pragmatically. Am I missing something in my
interpretation, or could the docs be reworded to better reflect the
actual behavior of send()?
Regards,
Li-yao
---
Excerpt from man 2 send, source:
http://man7.org/linux/man-pages/man2/sendmsg.2.html
When the message does not fit into the send buffer of the socket,
send() normally blocks, unless the socket has been placed in
nonblocking I/O mode. In nonblocking mode it would fail with the
error EAGAIN or EWOULDBLOCK in this case. The select(2) call may be
used to determine when it is possible to send more data.
...
Return value
On success, these calls return the number of bytes sent. On error,
-1 is returned, and errno is set appropriately.
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