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authorDaniel P. Berrange <berrange@redhat.com>2015-08-27 16:25:30 +0100
committerDaniel P. Berrange <berrange@redhat.com>2015-12-18 12:18:31 +0000
commit195e14d0262c5676cb9ff4b253e4b2b15c19d3f0 (patch)
tree5f75e92f0f06e28e516b7fbcb213cb0d453094df /io
parent2d1d0e70cf3eadca967427e71b2c5c7d031bc5c8 (diff)
downloadqemu-arm-195e14d0262c5676cb9ff4b253e4b2b15c19d3f0.tar.gz
io: add QIOChannelCommand class
Add a QIOChannel subclass that is capable of performing I/O to/from a separate process, via a pair of pipes. The command can be used for unidirectional or bi-directional I/O. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Diffstat (limited to 'io')
-rw-r--r--io/Makefile.objs1
-rw-r--r--io/channel-command.c357
2 files changed, 358 insertions, 0 deletions
diff --git a/io/Makefile.objs b/io/Makefile.objs
index e3771b1ac1..1a58ccb5c2 100644
--- a/io/Makefile.objs
+++ b/io/Makefile.objs
@@ -1,4 +1,5 @@
io-obj-y = channel.o
+io-obj-y += channel-command.o
io-obj-y += channel-file.o
io-obj-y += channel-socket.o
io-obj-y += channel-tls.o
diff --git a/io/channel-command.c b/io/channel-command.c
new file mode 100644
index 0000000000..598fdab5a3
--- /dev/null
+++ b/io/channel-command.c
@@ -0,0 +1,357 @@
+/*
+ * 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 "io/channel-command.h"
+#include "io/channel-watch.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) {
+ 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]);
+ }
+
+ 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 (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;
+ }
+ 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);
+ ioc->readfd = -1;
+ }
+ if (ioc->writefd != -1) {
+ close(ioc->writefd);
+ ioc->writefd = -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 ||
+ errno == EWOULDBLOCK) {
+ 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 ||
+ errno == EWOULDBLOCK) {
+ 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;
+
+ /* We close FDs before killing, because that
+ * gives a better chance of clean shutdown
+ */
+ if (close(cioc->writefd) < 0) {
+ rv = -1;
+ }
+ if (close(cioc->readfd) < 0) {
+ rv = -1;
+ }
+#ifndef WIN32
+ if (qio_channel_command_abort(cioc, errp) < 0) {
+ return -1;
+ }
+#endif
+ if (rv < 0) {
+ error_setg_errno(errp, errno, "%s",
+ "Unable to close command");
+ }
+ return rv;
+}
+
+
+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;
+}
+
+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);