PREFIX_ATTACH_MEM(3) libdill Library Functions PREFIX_ATTACH_MEM(3) NAME prefix_attach_mem - creates PREFIX protocol on top of underlying socket SYNOPSIS #include <libdill.h> int prefix_attach_mem( int s, size_t hdrlen, int flags, struct prefix_storage* mem); DESCRIPTION PREFIX is a message-based protocol to send binary messages prefixed by size. The protocol has no initial handshake. Terminal handshake is accom- plished by each peer sending size field filled by 0xff bytes. This function instantiates PREFIX protocol on top of the underlying proto- col. This function allows to avoid one dynamic memory allocation by storing the object in user-supplied memory. Unless you are hyper-optimizing use pre- fix_attach instead. s: Handle of the underlying socket. It must be a bytestream protocol. hdrlen: Size of the length field, in bytes. flags: If set to PREFIX_BIG_ENDIAN (also known as network byte order, the default option) the most significant byte of the size will be sent first on the wire. If set to PREFIX_LITTLE_ENDIAN the least signiticant byte will come first. mem: The structure to store the newly created object in. It must not be deallocated before the object is closed. The socket can be cleanly shut down using prefix_detach function. This function is not available if libdill is compiled with --disable-sock- ets option. RETURN VALUE In case of success the function returns newly created socket handle. In case of error it returns -1 and sets errno to one of the values below. ERRORS * EBADF: Invalid handle. * EINVAL: Invalid argument. * EMFILE: The maximum number of file descriptors in the process are already open. * ENFILE: The maximum number of file descriptors in the system are already open. * ENOMEM: Not enough memory. * ENOTSUP: The handle does not support this operation. * EPROTO: Underlying socket is not a bytestream socket. EXAMPLE int s = tcp_connect(&addr, -1); s = prefix_attach(s, 2, 0); msend(s, "ABC", 3, -1); char buf[256]; ssize_t sz = mrecv(s, buf, sizeof(buf), -1); s = prefix_detach(s, -1); tcp_close(s); SEE ALSO hclose(3) mrecv(3) mrecvl(3) msend(3) msendl(3) prefix_attach(3) prefix_de- tach(3) libdill PREFIX_ATTACH_MEM(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLE | SEE ALSO
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