README not finished yet.
- Dependencies
- Installation
- Deinstallation
- Advantages
- Disadvantages
- Documentation
- Implemented classes
- TCP socket example
$ git clone https://github.com/stnuessl/fdcpp
$ mkdir fdcpp/build
$ cd fdcpp/build
$ cmake ../
$ make
# make install
# rm -rf /usr/local/include/fdcpp /usr/local/lib/libfdcpp.so
- Nice C++ interface to write your own abstractions based on the library classes.
- No boilerplate code for error checking: errors are propagated via exceptions.
- Overloaded functions and default arguments to simplify interfaces.
- No file descriptor leaking.
- The use of class functions makes it impossible to call an inappropriate function on a file descriptor (e.g. calling accept() on an opened file).
- GNU/Linux only
- C header files leak into your sources via library includes.
- Not all functions for file descriptors are implemented.
All class function names have the same name as their corresponding system calls. This makes the library easy to use if you are already familiar with those interfaces and also makes an extra documentation for this library unnecassary. You can just type 'man ' into your terminal (or search for it on the web) and have the documentation right there. Notice that special file descriptor functions like epoll_ctl() and inotify_add_watch() degenerate to ctl() and add_watch() respectively. This means you can use the class like this:
auto epoll = fd::epoll();
epoll.ctl(...);
instead of
auto epoll = fd::epoll();
epoll.epoll_ctl(...);
Each of the following simple code snippets set up a TCP server socket using either plain C or the fdcpp library.
#include <stdio.h> // perror()
#include <unistd.h> // close()
#include <stdlib.h> // exit(): not really needed though
#include <sys/socket.h> // socket(), bind(), listen(), accept()
#include <netinet/in.h> // struct sockaddr_in
{
struct sockaddr_in addr;
int sock, err;
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
addr.sin_port = htons(5000);
sock = socket(AF_INET, SOCK_STREAM, 0);
if (sock < 0) {
perror("socket");
goto fail;
}
err = bind(sock, (struct sockaddr *) &addr, sizeof(addr));
if (err < 0) {
perror("bind");
goto fail;
}
err = listen(sock, 5);
if (err < 0) {
perror("listen");
goto fail;
}
int new_sock = accept(sock, NULL, NULL);
if (new_sock < 0) {
perror("accept");
goto fail;
}
/* handle connection here */
close(new_sock);
close(sock);
exit(EXIT_SUCCESS);
fail:
if (sock >= 0)
close(sock);
exit(EXIT_FAILURE);
}#include <iostream>
#include <fdcpp/fds/socket.hpp>
{
struct sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
addr.sin_port = htons(6000);
try {
auto socket = fd::socket(AF_INET, SOCK_STREAM);
socket.bind(addr);
socket.listen(); // = socket.listen(5)
auto conn = socket.accept();
/* handle connection here */
} catch (std::system_error &e) {
std::cerr << "** ERROR: socket initialization failed - " << e.what()
<< '\n';
}
}#include <iostream>
#include <fdcpp/easy/tcp_socket.hpp>
{
try {
auto conn = fd::easy::tcp_socket::server(INADDR_ANY, 7000).accept();
/* handle connection here */
} catch (std::system_error &e) {
std::cerr << "** ERROR: socket initialization failed - " << e.what()
<< '\n';
}
}The following code snippets show an example of descriptor passing via unix domain sockets. The first two snippets show the sender and receiver code in C. The last two snippets show the corresponding code in C++ with fdcpp library.
#include <unistd.h> /* close(), read() */
#include <stdlib.h> /* exit() */
#include <stdio.h> /* perror() */
#include <string.h> /* stpncpy() */
#include <sys/timerfd.h> /* timerfd_create(), timerfd_settime() */
#include <sys/socket.h> /* socket(), connect(), bind(), etc. */
#include <sys/un.h> /* sockaddr_un */
#include <time.h> /* CLOCK_MONOTONIC */
{
struct iovec iov;
struct msghdr msg;
struct cmsghdr *cmsg;
struct itimerspec its;
struct sockaddr_un addr;
char buf[CMSG_SPACE(sizeof(int))];
int tfd = -1, sock = -1, err;
its.it_value.tv_sec = 0;
its.it_value.tv_nsec = 100 * 1e3;
its.it_interval.tv_sec = 0;
its.it_interval.tv_nsec = 100 * 1e3;
tfd = timerfd_create(CLOCK_MONOTONIC, 0);
if (tfd < 0) {
perror("eventfd_create");
goto fail;
}
err = timerfd_settime(tfd, 0, &its, NULL);
if (err < 0) {
perror("eventfd_settime");
goto fail;
}
sock = socket(AF_UNIX, SOCK_DGRAM, 0);
if (sock < 0) {
perror("socket");
goto fail;
}
addr.sun_family = AF_UNIX;
*stpncpy(addr.sun_path, "/tmp/.unique.sock", sizeof(addr.sun_path)) = '\0';
err = connect(sock, (struct sockaddr *) &addr, sizeof(addr));
if (err < 0) {
perror("connect");
goto fail;
}
iov.iov_base = buf;
iov.iov_len = sizeof(buf);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = buf;
msg.msg_controllen = sizeof(buf);
msg.msg_name = NULL;
msg.msg_namelen = 0;
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
*(int *) CMSG_DATA(cmsg) = tfd;
err = sendmsg(sock, &msg, MSG_NOSIGNAL);
if (err < 0) {
perror("sendmsg");
goto fail;
}
close(tfd);
close(sock);
return;
fail:
if (tfd >= 0)
close(tfd);
if (sock >= 0)
close(sock);
exit(EXIT_FAILURE);
}#include <unistd.h> /* close(), read() */
#include <stdlib.h> /* exit() */
#include <stdio.h> /* perror() */
#include <string.h> /* stpncpy() */
#include <sys/timerfd.h> /* timerfd_create(), timerfd_settime() */
#include <sys/socket.h> /* socket(), connect(), bind(), etc. */
#include <sys/un.h> /* sockaddr_un */
#include <time.h> /* CLOCK_MONOTONIC */
#include <stdint.h> /* uint64_t */
{
struct iovec iov;
struct msghdr msg;
struct cmsghdr *cmsg;
struct sockaddr_un addr;
char buf[CMSG_SPACE(sizeof(int))];
int tfd = -1, sock = -1, count, err;
ssize_t n;
uint64_t val;
sock = socket(AF_UNIX, SOCK_DGRAM, 0);
if (sock < 0) {
perror("socket");
goto fail;
}
addr.sun_family = AF_UNIX;
*stpncpy(addr.sun_path, "/tmp/.unique.sock", sizeof(addr.sun_path)) = '\0';
unlink(addr.sun_path);
err = bind(sock, (struct sockaddr *) &addr, sizeof(addr));
if (err < 0) {
perror("bind");
goto fail;
}
iov.iov_base = buf;
iov.iov_len = sizeof(buf);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = buf;
msg.msg_controllen = sizeof(buf);
msg.msg_name = NULL;
msg.msg_namelen = 0;
err = recvmsg(sock, &msg, MSG_NOSIGNAL);
if (err < 0) {
perror("recvmsg");
goto fail;
}
tfd = *(int *) CMSG_DATA(CMSG_FIRSTHDR(&msg));
count = 1000;
while (count > 0) {
n = read(tfd, &val, sizeof(val));
if (n < 0) {
perror("read");
goto fail;
}
count -= val;
}
close(tfd);
close(sock);
return;
fail:
if (sock >= 0)
close(sock);
if (tfd >= 0)
close(tfd);
exit(EXIT_FAILURE);
}#include <iostream>
#include <fdcpp/easy/fdpass.hpp>
#include <fdcpp/fds/timerfd.hpp>
{
struct itimerspec its;
its.it_value.tv_sec = 0;
its.it_value.tv_nsec = 100 * 1e3;
its.it_interval.tv_sec = 0;
its.it_interval.tv_nsec = 100 * 1e3;
try {
auto tfd = fd::timerfd();
tfd.settime(its);
fd::easy::fdpass("/tmp/.unique.sock").send(tfd);
} catch (std::system_error &e) {
std::cerr << "** ERROR: " << e.what() << '\n';
}
}#include <iostream>
#include <fdcpp/easy/fdpass.hpp>
#include <fdcpp/fds/timerfd.hpp>
{
try {
auto v = fd::easy::fdpass("/tmp/.unique.sock").recv();
auto tfd = fd::timerfd(std::move(v[0]));
int count = 1000;
while (count > 0)
count -= tfd.read();
} catch (std::system_error &e) {
std::cerr << "** ERROR: " << e.what() << '\n';
}
}