io/channel-command.c - qemu - Git at Google

 /*
  * 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 2.1 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/module.h"
 #include "qemu/sockets.h"
 #include "trace.h"

 #ifndef WIN32
 /**
  * qio_channel_command_new_pid:
  * @writefd: the FD connected to the command's stdin
  * @readfd: the FD connected to the command's stdout
  * @pid: the PID of the running child command
  * @errp: pointer to a NULL-initialized error object
  *
  * Create a channel for performing I/O with the
  * previously spawned command identified by @pid.
  * The two file descriptors provide the connection
  * to command's stdio streams, either one or which
  * may be -1 to indicate that stream is not open.
  *
  * The channel will take ownership of the process
  * @pid and will kill it when closing the channel.
  * Similarly it will take responsibility for
  * closing the file descriptors @writefd and @readfd.
  *
  * Returns: the command channel object, or NULL on error
  */
 static 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;
 }

 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 && !g_unix_open_pipe(stdinfd, FD_CLOEXEC, NULL)) ||
         (!stdoutnull && !g_unix_open_pipe(stdoutfd, FD_CLOEXEC, NULL))) {
         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)
 {
 #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)) {
         error_setg_errno(errp, errno, "Failed to set FD nonblocking");
         return -1;
     }
 #endif
     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, NULL, opaque);
     aio_set_fd_handler(ctx, cioc->writefd, false,
                        NULL, io_write, NULL, 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);
	/*
	* 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 2.1 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/module.h"
	#include "qemu/sockets.h"
	#include "trace.h"

	#ifndef WIN32
	/**
	* qio_channel_command_new_pid:
	* @writefd: the FD connected to the command's stdin
	* @readfd: the FD connected to the command's stdout
	* @pid: the PID of the running child command
	* @errp: pointer to a NULL-initialized error object
	*
	* Create a channel for performing I/O with the
	* previously spawned command identified by @pid.
	* The two file descriptors provide the connection
	* to command's stdio streams, either one or which
	* may be -1 to indicate that stream is not open.
	*
	* The channel will take ownership of the process
	* @pid and will kill it when closing the channel.
	* Similarly it will take responsibility for
	* closing the file descriptors @writefd and @readfd.
	*
	* Returns: the command channel object, or NULL on error
	*/
	static 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;
	}

	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 && !g_unix_open_pipe(stdinfd, FD_CLOEXEC, NULL)) \|\|
	(!stdoutnull && !g_unix_open_pipe(stdoutfd, FD_CLOEXEC, NULL))) {
	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)
	{
	#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)) {
	error_setg_errno(errp, errno, "Failed to set FD nonblocking");
	return -1;
	}
	#endif
	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, NULL, opaque);
	aio_set_fd_handler(ctx, cioc->writefd, false,
	NULL, io_write, NULL, 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);