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qemu-e2k/io/channel-command.c

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/*
* QEMU I/O channels external command driver
*
* Copyright (c) 2015 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include "io/channel-command.h"
#include "io/channel-watch.h"
#include "qapi/error.h"
#include "qemu/sockets.h"
#include "trace.h"
QIOChannelCommand *
qio_channel_command_new_pid(int writefd,
int readfd,
pid_t pid)
{
QIOChannelCommand *ioc;
ioc = QIO_CHANNEL_COMMAND(object_new(TYPE_QIO_CHANNEL_COMMAND));
ioc->readfd = readfd;
ioc->writefd = writefd;
ioc->pid = pid;
trace_qio_channel_command_new_pid(ioc, writefd, readfd, pid);
return ioc;
}
#ifndef WIN32
QIOChannelCommand *
qio_channel_command_new_spawn(const char *const argv[],
int flags,
Error **errp)
{
pid_t pid = -1;
int stdinfd[2] = { -1, -1 };
int stdoutfd[2] = { -1, -1 };
int devnull = -1;
bool stdinnull = false, stdoutnull = false;
QIOChannelCommand *ioc;
flags = flags & O_ACCMODE;
if (flags == O_RDONLY) {
stdinnull = true;
}
if (flags == O_WRONLY) {
stdoutnull = true;
}
if (stdinnull || stdoutnull) {
devnull = open("/dev/null", O_RDWR);
if (devnull < 0) {
error_setg_errno(errp, errno,
"Unable to open /dev/null");
goto error;
}
}
if ((!stdinnull && pipe(stdinfd) < 0) ||
(!stdoutnull && pipe(stdoutfd) < 0)) {
error_setg_errno(errp, errno,
"Unable to open pipe");
goto error;
}
pid = qemu_fork(errp);
if (pid < 0) {
goto error;
}
if (pid == 0) { /* child */
dup2(stdinnull ? devnull : stdinfd[0], STDIN_FILENO);
dup2(stdoutnull ? devnull : stdoutfd[1], STDOUT_FILENO);
/* Leave stderr connected to qemu's stderr */
if (!stdinnull) {
close(stdinfd[0]);
close(stdinfd[1]);
}
if (!stdoutnull) {
close(stdoutfd[0]);
close(stdoutfd[1]);
}
if (devnull != -1) {
close(devnull);
}
execv(argv[0], (char * const *)argv);
_exit(1);
}
if (!stdinnull) {
close(stdinfd[0]);
}
if (!stdoutnull) {
close(stdoutfd[1]);
}
ioc = qio_channel_command_new_pid(stdinnull ? devnull : stdinfd[1],
stdoutnull ? devnull : stdoutfd[0],
pid);
trace_qio_channel_command_new_spawn(ioc, argv[0], flags);
return ioc;
error:
if (devnull != -1) {
close(devnull);
}
if (stdinfd[0] != -1) {
close(stdinfd[0]);
}
if (stdinfd[1] != -1) {
close(stdinfd[1]);
}
if (stdoutfd[0] != -1) {
close(stdoutfd[0]);
}
if (stdoutfd[1] != -1) {
close(stdoutfd[1]);
}
return NULL;
}
#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)
{
pid_t ret;
int status;
int step = 0;
/* See if intermediate process has exited; if not, try a nice
* SIGTERM followed by a more severe SIGKILL.
*/
rewait:
trace_qio_channel_command_abort(ioc, ioc->pid);
ret = waitpid(ioc->pid, &status, WNOHANG);
trace_qio_channel_command_wait(ioc, ioc->pid, ret, status);
if (ret == (pid_t)-1) {
if (errno == EINTR) {
goto rewait;
} else {
error_setg_errno(errp, errno,
"Cannot wait on pid %llu",
(unsigned long long)ioc->pid);
return -1;
}
} else if (ret == 0) {
if (step == 0) {
kill(ioc->pid, SIGTERM);
} else if (step == 1) {
kill(ioc->pid, SIGKILL);
} else {
error_setg(errp,
"Process %llu refused to die",
(unsigned long long)ioc->pid);
return -1;
}
step++;
usleep(10 * 1000);
goto rewait;
}
return 0;
}
#endif /* ! WIN32 */
static void qio_channel_command_init(Object *obj)
{
QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
ioc->readfd = -1;
ioc->writefd = -1;
ioc->pid = -1;
}
static void qio_channel_command_finalize(Object *obj)
{
QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
if (ioc->readfd != -1) {
close(ioc->readfd);
}
if (ioc->writefd != -1 &&
ioc->writefd != ioc->readfd) {
close(ioc->writefd);
}
ioc->writefd = ioc->readfd = -1;
if (ioc->pid > 0) {
#ifndef WIN32
qio_channel_command_abort(ioc, NULL);
#endif
}
}
static ssize_t qio_channel_command_readv(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
int **fds,
size_t *nfds,
Error **errp)
{
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
ssize_t ret;
retry:
ret = readv(cioc->readfd, iov, niov);
if (ret < 0) {
if (errno == EAGAIN) {
return QIO_CHANNEL_ERR_BLOCK;
}
if (errno == EINTR) {
goto retry;
}
error_setg_errno(errp, errno,
"Unable to read from command");
return -1;
}
return ret;
}
static ssize_t qio_channel_command_writev(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
int *fds,
size_t nfds,
Error **errp)
{
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
ssize_t ret;
retry:
ret = writev(cioc->writefd, iov, niov);
if (ret <= 0) {
if (errno == EAGAIN) {
return QIO_CHANNEL_ERR_BLOCK;
}
if (errno == EINTR) {
goto retry;
}
error_setg_errno(errp, errno, "%s",
"Unable to write to command");
return -1;
}
return ret;
}
static int qio_channel_command_set_blocking(QIOChannel *ioc,
bool enabled,
Error **errp)
{
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
if (enabled) {
qemu_set_block(cioc->writefd);
qemu_set_block(cioc->readfd);
} else {
qemu_set_nonblock(cioc->writefd);
qemu_set_nonblock(cioc->readfd);
}
return 0;
}
static int qio_channel_command_close(QIOChannel *ioc,
Error **errp)
{
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
int rv = 0;
#ifndef WIN32
pid_t wp;
#endif
/* We close FDs before killing, because that
* gives a better chance of clean shutdown
*/
if (cioc->readfd != -1 &&
close(cioc->readfd) < 0) {
rv = -1;
}
if (cioc->writefd != -1 &&
cioc->writefd != cioc->readfd &&
close(cioc->writefd) < 0) {
rv = -1;
}
cioc->writefd = cioc->readfd = -1;
#ifndef WIN32
do {
wp = waitpid(cioc->pid, NULL, 0);
} while (wp == (pid_t)-1 && errno == EINTR);
if (wp == (pid_t)-1) {
error_setg_errno(errp, errno, "Failed to wait for pid %llu",
(unsigned long long)cioc->pid);
return -1;
}
#endif
if (rv < 0) {
error_setg_errno(errp, errno, "%s",
"Unable to close command");
}
return rv;
}
static void qio_channel_command_set_aio_fd_handler(QIOChannel *ioc,
AioContext *ctx,
IOHandler *io_read,
IOHandler *io_write,
void *opaque)
{
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
aio_set_fd_handler(ctx, cioc->readfd, false, io_read, NULL, NULL, opaque);
aio_set_fd_handler(ctx, cioc->writefd, false, NULL, io_write, NULL, opaque);
}
static GSource *qio_channel_command_create_watch(QIOChannel *ioc,
GIOCondition condition)
{
QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
return qio_channel_create_fd_pair_watch(ioc,
cioc->readfd,
cioc->writefd,
condition);
}
static void qio_channel_command_class_init(ObjectClass *klass,
void *class_data G_GNUC_UNUSED)
{
QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
ioc_klass->io_writev = qio_channel_command_writev;
ioc_klass->io_readv = qio_channel_command_readv;
ioc_klass->io_set_blocking = qio_channel_command_set_blocking;
ioc_klass->io_close = qio_channel_command_close;
ioc_klass->io_create_watch = qio_channel_command_create_watch;
ioc_klass->io_set_aio_fd_handler = qio_channel_command_set_aio_fd_handler;
}
static const TypeInfo qio_channel_command_info = {
.parent = TYPE_QIO_CHANNEL,
.name = TYPE_QIO_CHANNEL_COMMAND,
.instance_size = sizeof(QIOChannelCommand),
.instance_init = qio_channel_command_init,
.instance_finalize = qio_channel_command_finalize,
.class_init = qio_channel_command_class_init,
};
static void qio_channel_command_register_types(void)
{
type_register_static(&qio_channel_command_info);
}
type_init(qio_channel_command_register_types);
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