Commit 3328b21b authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont
Browse files

net_Read: rewrite, fix corner cases (fix #8972)

This new implementation opportunistically tries to read data before
invoking poll(). This reduces latency when data is already waiting in
buffers, allows receiving pending data in non-blocking fashion even if
the object has been killed. This also gives GnuTLS a chance to dequeue
data from internal buffers.

Also the corner case of 0 read should now be handled correctly.

The corner case of an error after success read is no longer handled.
This was race-prone and useless.
parent 013044c3
......@@ -256,135 +256,91 @@ ssize_t
net_Read (vlc_object_t *restrict p_this, int fd, const v_socket_t *vs,
void *restrict p_buf, size_t i_buflen, bool waitall)
{
size_t i_total = 0;
struct pollfd ufd[2] = {
{ .fd = fd, .events = POLLIN },
{ .fd = vlc_object_waitpipe (p_this), .events = POLLIN },
};
struct pollfd ufd[2];
if (ufd[1].fd == -1)
return -1; /* vlc_object_waitpipe() sets errno */
ufd[0].fd = fd;
ufd[0].events = POLLIN;
ufd[1].fd = vlc_object_waitpipe (p_this);
ufd[1].events = POLLIN;
while (i_buflen > 0)
size_t i_total = 0;
do
{
if (poll (ufd, sizeof (ufd) / sizeof (ufd[0]), -1) < 0)
{
if (errno != EINTR)
goto error;
continue;
}
if (i_total > 0)
{
/* Errors (-1) and EOF (0) will be returned on next call,
* otherwise we'd "hide" the error from the caller, which is a
* bad idea™. */
if (ufd[0].revents & (POLLERR|POLLNVAL))
break;
if (ufd[1].revents)
break;
}
else
{
if (ufd[1].revents)
{
msg_Dbg (p_this, "socket %d polling interrupted", fd);
#if defined(_WIN32)
WSASetLastError (WSAEINTR);
#else
errno = EINTR;
#endif
goto silent;
}
}
assert (ufd[0].revents);
ssize_t n;
#if defined(_WIN32)
int error;
#endif
if (vs != NULL)
{
int canc = vlc_savecancel ();
n = vs->pf_recv (vs->p_sys, p_buf, i_buflen);
#if defined(_WIN32)
/* We must read last error immediately, because vlc_restorecancel()
* access thread local storage, and TlsGetValue() will call
* SetLastError() to indicate that the function succeeded, thus
* overwriting the error code coming from pf_recv().
* WSAGetLastError is just an alias for GetLastError these days.
*/
error = WSAGetLastError();
#endif
vlc_restorecancel (canc);
}
else
{
#ifdef _WIN32
n = recv (fd, p_buf, i_buflen, 0);
error = WSAGetLastError();
#else
n = read (fd, p_buf, i_buflen);
#endif
}
if (n == -1)
if (n < 0)
{
#if defined(_WIN32)
switch (error)
{
case WSAEWOULDBLOCK:
case WSAEINTR:
/* only happens with vs != NULL (TLS) - not really an error */
continue;
case WSAEMSGSIZE:
/* For UDP only */
/* On Win32, recv() fails if the datagram doesn't fit inside
* the passed buffer, even though the buffer will be filled
* with the first part of the datagram. */
msg_Err (p_this, "Receive error: "
"Increase the mtu size (--mtu option)");
n = i_buflen;
break;
}
#else
switch (errno)
switch (net_errno)
{
case EAGAIN: /* spurious wakeup or no TLS data */
#if (EAGAIN != EWOULDBLOCK)
case EWOULDBLOCK:
#endif
case EINTR: /* asynchronous signal */
continue;
}
break;
#ifdef _WIN32
case WSAEMSGSIZE: /* datagram too big */
n = i_buflen;
break;
#endif
goto error;
default:
goto error;
}
}
else
if (n > 0)
{
i_total += n;
p_buf = (char *)p_buf + n;
i_buflen -= n;
if (!waitall)
break;
}
else
break;/* end of stream or empty packet */
if (n == 0)
/* For streams, this means end of file, and there will not be any
* further data ever on the stream. For datagram sockets, this
* means empty datagram, and there could be more data coming.
* However, it makes no sense to set <waitall> with datagrams in the
* first place.
*/
break; // EOF
/* Wait for more data */
if (ufd[1].fd == -1)
{
errno = EINTR;
return -1;
}
while (poll (ufd, sizeof (ufd) / sizeof (ufd[0]), -1) < 0)
if (errno != EINTR)
goto error;
i_total += n;
p_buf = (char *)p_buf + n;
i_buflen -= n;
if (ufd[1].revents)
{
msg_Dbg (p_this, "socket %d polling interrupted", fd);
#if defined(_WIN32)
WSASetLastError (WSAEINTR);
#endif
errno = EINTR;
return -1;
}
if (!waitall)
break;
assert (ufd[0].revents);
}
while (i_buflen > 0);
return i_total;
error:
msg_Err (p_this, "Read error: %m");
silent:
msg_Err (p_this, "read error: %m");
return -1;
}
......
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