I am using SOCK_SEQPACKET connection, and it is critical for me to ensure that whole buffer is sent with single write()/send() call. I am also operating with device driver that is designed to handle a complete block of data with single call. At the same time I want to handle the situation when write()/send() blocks due to buffer overflow, i.e. I want to have a feedback whether current implementation gets a bottleneck here. I'm working with glibc, Linux 2.6.
I need to implement a method that accepts a buffer, and it either sends a buffer completely or indicates a failure due to blocking (i.e. system buffer overflow).
It looks like using send(..., MSG_DONTWAIT)/fcntl(..., O_NONBLOCK) is not a solution as they accept partial write prior to reporting EWOULDBLOCK/EAGAIN. Is there a way to check whether there is enough space in outgoing buffer or is there a dedicated write-complete-or-fail method?
Alternatively, is it possible to detect block by other means? For example, timer+signal seems to be an option, but I do not like the idea to set it for each write.
Thank you in advance.
