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gsocket: Use SOCK_NONBLOCK to avoid a fcntl() syscall where possible

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If the libc and kernel support `SOCK_NONBLOCK`, we can specify that in
the `socket()` flags, and avoid a subsequent call to `fcntl()` to set
`O_NONBLOCK`.

For modern Linux distributions, this will save a syscall when creating a
socket.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
This commit is contained in:
Philip Withnall 2023-03-23 00:29:02 +00:00
parent 0be2555704
commit 8b0cf41d88
1 changed files with 51 additions and 38 deletions
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89
gio/gsocket.c
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@ -587,7 +587,38 @@ g_socket_details_from_fd (GSocket *socket)
socket_strerror (errsv)); socket_strerror (errsv));
} }
/* Wrapper around socket() that is shared with gnetworkmonitornetlink.c */ static void
socket_set_nonblock (int fd)
{
#ifndef G_OS_WIN32
GError *error = NULL;
#else
gulong arg;
#endif
/* Always use native nonblocking sockets, as Windows sets sockets to
* nonblocking automatically in certain operations. This way we make
* things work the same on all platforms.
*/
#ifndef G_OS_WIN32
if (!g_unix_set_fd_nonblocking (fd, TRUE, &error))
{
g_warning ("Error setting socket nonblocking: %s", error->message);
g_clear_error (&error);
}
#else
arg = TRUE;
if (ioctlsocket (fd, FIONBIO, &arg) == SOCKET_ERROR)
{
int errsv = get_socket_errno ();
g_warning ("Error setting socket status flags: %s", socket_strerror (errsv));
}
#endif
}
/* Wrapper around socket() that is shared with gnetworkmonitornetlink.c.
* It always sets SOCK_CLOEXEC | SOCK_NONBLOCK. */
gint gint
g_socket (gint domain, g_socket (gint domain,
gint type, gint type,
@ -596,13 +627,13 @@ g_socket (gint domain,
{ {
int fd, errsv; int fd, errsv;
#ifdef SOCK_CLOEXEC #if defined(SOCK_CLOEXEC) && defined(SOCK_NONBLOCK)
fd = socket (domain, type | SOCK_CLOEXEC, protocol); fd = socket (domain, type | SOCK_CLOEXEC | SOCK_NONBLOCK, protocol);
errsv = errno; errsv = errno;
if (fd != -1) if (fd != -1)
return fd; return fd;
/* It's possible that libc has SOCK_CLOEXEC but the kernel does not */ /* It's possible that libc has SOCK_CLOEXEC and/or SOCK_NONBLOCK but the kernel does not */
if (fd < 0 && (errsv == EINVAL || errsv == EPROTOTYPE)) if (fd < 0 && (errsv == EINVAL || errsv == EPROTOTYPE))
#endif #endif
fd = socket (domain, type, protocol); fd = socket (domain, type, protocol);
@ -644,9 +675,13 @@ g_socket (gint domain,
} }
#endif #endif
/* Ensure the socket is non-blocking. */
socket_set_nonblock (fd);
return fd; return fd;
} }
/* Returned socket has SOCK_CLOEXEC | SOCK_NONBLOCK set. */
static gint static gint
g_socket_create_socket (GSocketFamily family, g_socket_create_socket (GSocketFamily family,
GSocketType type, GSocketType type,
@ -696,44 +731,22 @@ g_socket_constructed (GObject *object)
GSocket *socket = G_SOCKET (object); GSocket *socket = G_SOCKET (object);
if (socket->priv->fd >= 0) if (socket->priv->fd >= 0)
/* create socket->priv info from the fd */ {
g_socket_details_from_fd (socket); /* create socket->priv info from the fd and ensure it’s non-blocking */
g_socket_details_from_fd (socket);
socket_set_nonblock (socket->priv->fd);
}
else else
/* create the fd from socket->priv info */ {
socket->priv->fd = g_socket_create_socket (socket->priv->family, /* create the fd from socket->priv info; this sets it non-blocking by construction */
socket->priv->type, socket->priv->fd = g_socket_create_socket (socket->priv->family,
socket->priv->protocol, socket->priv->type,
&socket->priv->construct_error); socket->priv->protocol,
&socket->priv->construct_error);
}
if (socket->priv->fd != -1) if (socket->priv->fd != -1)
{ {
#ifndef G_OS_WIN32
GError *error = NULL;
#else
gulong arg;
#endif
/* Always use native nonblocking sockets, as Windows sets sockets to
* nonblocking automatically in certain operations. This way we make
* things work the same on all platforms.
*/
#ifndef G_OS_WIN32
if (!g_unix_set_fd_nonblocking (socket->priv->fd, TRUE, &error))
{
g_warning ("Error setting socket nonblocking: %s", error->message);
g_clear_error (&error);
}
#else
arg = TRUE;
if (ioctlsocket (socket->priv->fd, FIONBIO, &arg) == SOCKET_ERROR)
{
int errsv = get_socket_errno ();
g_warning ("Error setting socket status flags: %s", socket_strerror (errsv));
}
#endif
#ifdef SO_NOSIGPIPE #ifdef SO_NOSIGPIPE
/* See note about SIGPIPE below. */ /* See note about SIGPIPE below. */
g_socket_set_option (socket, SOL_SOCKET, SO_NOSIGPIPE, TRUE, NULL); g_socket_set_option (socket, SOL_SOCKET, SO_NOSIGPIPE, TRUE, NULL);