io/command: implement support for win32

The initial implementation was changing the pipe state created by GLib
to PIPE_NOWAIT, but it turns out it doesn't work (read/write returns an
error). Since reading may return less than the requested amount, it
seems to be non-blocking already. However, the IO operation may block
until the FD is ready, I can't find good sources of information, to be
safe we can just poll for readiness before.

Alternatively, we could setup the FDs ourself, and use UNIX sockets on
Windows, which can be used in blocking/non-blocking mode. I haven't
tried it, as I am not sure it is necessary.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20221006113657.2656108-6-marcandre.lureau@redhat.com>
This commit is contained in:
Marc-André Lureau 2022-10-06 15:36:56 +04:00
parent a95570e3e4
commit ec5b6c9c5d
2 changed files with 63 additions and 22 deletions

View File

@ -42,6 +42,9 @@ struct QIOChannelCommand {
int writefd;
int readfd;
GPid pid;
#ifdef WIN32
bool blocking;
#endif
};

View File

@ -26,7 +26,6 @@
#include "qemu/sockets.h"
#include "trace.h"
#ifndef WIN32
/**
* qio_channel_command_new_pid:
* @writefd: the FD connected to the command's stdin
@ -60,7 +59,13 @@ qio_channel_command_new_pid(int writefd,
ioc->writefd = writefd;
ioc->pid = pid;
trace_qio_channel_command_new_pid(ioc, writefd, readfd, pid);
trace_qio_channel_command_new_pid(ioc, writefd, readfd,
#ifdef WIN32
GetProcessId(pid)
#else
pid
#endif
);
return ioc;
}
@ -89,18 +94,6 @@ qio_channel_command_new_spawn(const char *const argv[],
return qio_channel_command_new_pid(stdinfd, stdoutfd, pid);
}
#else /* WIN32 */
QIOChannelCommand *
qio_channel_command_new_spawn(const char *const argv[],
int flags,
Error **errp)
{
error_setg_errno(errp, ENOSYS,
"Command spawn not supported on this platform");
return NULL;
}
#endif /* WIN32 */
#ifndef WIN32
static int qio_channel_command_abort(QIOChannelCommand *ioc,
Error **errp)
@ -143,6 +136,23 @@ static int qio_channel_command_abort(QIOChannelCommand *ioc,
return 0;
}
#else
static int qio_channel_command_abort(QIOChannelCommand *ioc,
Error **errp)
{
DWORD ret;
TerminateProcess(ioc->pid, 0);
ret = WaitForSingleObject(ioc->pid, 1000);
if (ret != WAIT_OBJECT_0) {
error_setg(errp,
"Process %llu refused to die",
(unsigned long long)GetProcessId(ioc->pid));
return -1;
}
return 0;
}
#endif /* ! WIN32 */
@ -166,13 +176,27 @@ static void qio_channel_command_finalize(Object *obj)
}
ioc->writefd = ioc->readfd = -1;
if (ioc->pid > 0) {
#ifndef WIN32
qio_channel_command_abort(ioc, NULL);
#endif
g_spawn_close_pid(ioc->pid);
}
}
#ifdef WIN32
static bool win32_fd_poll(int fd, gushort events)
{
GPollFD pfd = { .fd = _get_osfhandle(fd), .events = events };
int res;
do {
res = g_poll(&pfd, 1, 0);
} while (res < 0 && errno == EINTR);
if (res == 0) {
return false;
}
return true;
}
#endif
static ssize_t qio_channel_command_readv(QIOChannel *ioc,
const struct iovec *iov,
@ -184,6 +208,12 @@ static ssize_t qio_channel_command_readv(QIOChannel *ioc,
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
ssize_t ret;
#ifdef WIN32
if (!cioc->blocking && !win32_fd_poll(cioc->readfd, G_IO_IN)) {
return QIO_CHANNEL_ERR_BLOCK;
}
#endif
retry:
ret = readv(cioc->readfd, iov, niov);
if (ret < 0) {
@ -213,6 +243,12 @@ static ssize_t qio_channel_command_writev(QIOChannel *ioc,
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
ssize_t ret;
#ifdef WIN32
if (!cioc->blocking && !win32_fd_poll(cioc->writefd, G_IO_OUT)) {
return QIO_CHANNEL_ERR_BLOCK;
}
#endif
retry:
ret = writev(cioc->writefd, iov, niov);
if (ret <= 0) {
@ -233,14 +269,14 @@ static int qio_channel_command_set_blocking(QIOChannel *ioc,
bool enabled,
Error **errp)
{
#ifdef WIN32
/* command spawn is not supported on win32 */
g_assert_not_reached();
#else
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
if (!g_unix_set_fd_nonblocking(cioc->writefd, !enabled, NULL) ||
!g_unix_set_fd_nonblocking(cioc->readfd, !enabled, NULL)) {
#ifdef WIN32
cioc->blocking = enabled;
#else
if ((cioc->writefd >= 0 && !g_unix_set_fd_nonblocking(cioc->writefd, !enabled, NULL)) ||
(cioc->readfd >= 0 && !g_unix_set_fd_nonblocking(cioc->readfd, !enabled, NULL))) {
error_setg_errno(errp, errno, "Failed to set FD nonblocking");
return -1;
}
@ -281,6 +317,8 @@ static int qio_channel_command_close(QIOChannel *ioc,
(unsigned long long)cioc->pid);
return -1;
}
#else
WaitForSingleObject(cioc->pid, INFINITE);
#endif
if (rv < 0) {