libdill: Structured Concurrency for C

NAME

tcp_fromfd_mem - wraps an existing OS-level file descriptor

SYNOPSIS

#include <libdill.h>

int tcp_fromfd_mem(
    int fd,
    struct tcp_storage* mem);

DESCRIPTION

TCP protocol is a reliable bytestream protocol for transporting data over network. It is defined in RFC 793.

This function wraps an existing OS-level file descriptor.

This function allows to avoid one dynamic memory allocation by storing the object in user-supplied memory. Unless you are hyper-optimizing use tcp_fromfd instead.

fd: File descriptor of a connected TCP socket to wrap.

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 tcp_close function which will also close the underlying file descriptor.

There's no way to unwrap the file descriptor.

This function is not available if libdill is compiled with --disable-sockets 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

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.

EXAMPLE

int fd = socket(AF_INET, SOCK_STREAM, 0);
connect(fd, addr, sizeof(addr));
int s = tcp_fromfd(fd);
bsend(s, "ABC", 3, -1);
char buf[3];
brecv(s, buf, sizeof(buf), -1);
tcp_close(s);