[Qemu-devel] [PATCH v2 15/27] migration: convert exec socket protocol to use QIOChannel

["Daniel P. Berrange" <berrange@redhat.com>]

Convert the exec socket migration protocol driver to use
QIOChannel and QEMUFileChannel, instead of the stdio
popen APIs. It can be unconditionally built because the
QIOChannelCommand class can report suitable error messages
on platforms which can't fork processes.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 migration/Makefile.objs |  3 +--
 migration/exec.c        | 64 ++++++++++++++++++++++++-------------------------
 migration/migration.c   |  4 ----
 trace-events            |  4 ++++
 4 files changed, 37 insertions(+), 38 deletions(-)

diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index 0987bb6..86dd050 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -1,11 +1,10 @@
-common-obj-y += migration.o socket.o fd.o
+common-obj-y += migration.o socket.o fd.o exec.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
 common-obj-y += qemu-file-channel.o
 common-obj-y += xbzrle.o postcopy-ram.o
 
 common-obj-$(CONFIG_RDMA) += rdma.o
-common-obj-$(CONFIG_POSIX) += exec.o
 
 common-obj-y += block.o
 
diff --git a/migration/exec.c b/migration/exec.c
index 62f892d..4617dad 100644
--- a/migration/exec.c
+++ b/migration/exec.c
@@ -3,10 +3,12 @@
  *
  * Copyright IBM, Corp. 2008
  * Copyright Dell MessageOne 2008
+ * Copyright Red Hat, Inc. 2015-2016
  *
  * Authors:
  *  Anthony Liguori   <aliguori@us.ibm.com>
  *  Charles Duffy     <charles_duffy@messageone.com>
+ *  Daniel P. Berrange <berrange@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -15,55 +17,53 @@
  * GNU GPL, version 2 or (at your option) any later version.
  */
 
-#include "qemu/osdep.h"
-#include "qemu-common.h"
-#include "qemu/sockets.h"
-#include "qemu/main-loop.h"
 #include "migration/migration.h"
-#include "migration/qemu-file.h"
-#include "block/block.h"
-#include <sys/wait.h>
+#include "io/channel-command.h"
+#include "trace.h"
 
-//#define DEBUG_MIGRATION_EXEC
-
-#ifdef DEBUG_MIGRATION_EXEC
-#define DPRINTF(fmt, ...) \
-    do { printf("migration-exec: " fmt, ## __VA_ARGS__); } while (0)
-#else
-#define DPRINTF(fmt, ...) \
-    do { } while (0)
-#endif
 
 void exec_start_outgoing_migration(MigrationState *s, const char *command, Error **errp)
 {
-    s->to_dst_file = qemu_popen_cmd(command, "w");
-    if (s->to_dst_file == NULL) {
-        error_setg_errno(errp, errno, "failed to popen the migration target");
+    QIOChannel *ioc;
+    const char *argv[] = { "/bin/sh", "-c", command, NULL };
+
+    trace_migration_exec_outgoing(command);
+    ioc = QIO_CHANNEL(qio_channel_command_new_spawn(argv,
+                                                    O_WRONLY,
+                                                    errp));
+    if (!ioc) {
         return;
     }
 
-    migrate_fd_connect(s);
+    migration_set_outgoing_channel(s, ioc);
+    object_unref(OBJECT(ioc));
 }
 
-static void exec_accept_incoming_migration(void *opaque)
+static gboolean exec_accept_incoming_migration(QIOChannel *ioc,
+                                               GIOCondition condition,
+                                               gpointer opaque)
 {
-    QEMUFile *f = opaque;
-
-    qemu_set_fd_handler(qemu_get_fd(f), NULL, NULL, NULL);
-    process_incoming_migration(f);
+    migration_set_incoming_channel(migrate_get_current(), ioc);
+    object_unref(OBJECT(ioc));
+    return FALSE; /* unregister */
 }
 
 void exec_start_incoming_migration(const char *command, Error **errp)
 {
-    QEMUFile *f;
+    QIOChannel *ioc;
+    const char *argv[] = { "/bin/sh", "-c", command, NULL };
 
-    DPRINTF("Attempting to start an incoming migration\n");
-    f = qemu_popen_cmd(command, "r");
-    if(f == NULL) {
-        error_setg_errno(errp, errno, "failed to popen the migration source");
+    trace_migration_exec_incoming(command);
+    ioc = QIO_CHANNEL(qio_channel_command_new_spawn(argv,
+                                                    O_RDONLY,
+                                                    errp));
+    if (!ioc) {
         return;
     }
 
-    qemu_set_fd_handler(qemu_get_fd(f), exec_accept_incoming_migration, NULL,
-                        f);
+    qio_channel_add_watch(ioc,
+                          G_IO_IN,
+                          exec_accept_incoming_migration,
+                          NULL,
+                          NULL);
 }
diff --git a/migration/migration.c b/migration/migration.c
index 9f5fb16..19ef9be 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -311,10 +311,8 @@ void qemu_start_incoming_migration(const char *uri, Error **errp)
     } else if (strstart(uri, "rdma:", &p)) {
         rdma_start_incoming_migration(p, errp);
 #endif
-#if !defined(WIN32)
     } else if (strstart(uri, "exec:", &p)) {
         exec_start_incoming_migration(p, errp);
-#endif
     } else if (strstart(uri, "unix:", &p)) {
         unix_start_incoming_migration(p, errp);
     } else if (strstart(uri, "fd:", &p)) {
@@ -1041,10 +1039,8 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
     } else if (strstart(uri, "rdma:", &p)) {
         rdma_start_outgoing_migration(s, p, &local_err);
 #endif
-#if !defined(WIN32)
     } else if (strstart(uri, "exec:", &p)) {
         exec_start_outgoing_migration(s, p, &local_err);
-#endif
     } else if (strstart(uri, "unix:", &p)) {
         unix_start_outgoing_migration(s, p, &local_err);
     } else if (strstart(uri, "fd:", &p)) {
diff --git a/trace-events b/trace-events
index 241e8c5..4ca6967 100644
--- a/trace-events
+++ b/trace-events
@@ -1603,6 +1603,10 @@ postcopy_ram_incoming_cleanup_entry(void) ""
 postcopy_ram_incoming_cleanup_exit(void) ""
 postcopy_ram_incoming_cleanup_join(void) ""
 
+# migration/exec.c
+migration_exec_outgoing(const char *cmd) "cmd=%s"
+migration_exec_incoming(const char *cmd) "cmd=%s"
+
 # migration/fd.c
 migration_fd_outgoing(int fd) "fd=%d"
 migration_fd_incoming(int fd) "fd=%d"
-- 
2.5.0