migration (outgoing): add error propagation for all protocols
Error propagation is already there for socket backends. Add it to other
protocols, simplifying code that tests for errors that will never happen.
With all protocols understanding Error, the code can be simplified
further by removing the return value.
Unfortunately, the quality of error messages varies depending
on where the error is detected, because no Error is passed to the
NonBlockingConnectHandler. Thus, the exact error message still cannot
be sent to the user if the OS reports it asynchronously via SO_ERROR.
If NonBlockingConnectHandler received an Error**, we could for
example report the error class and/or message via a new field of the
query-migration command even if it is reported asynchronously.
Before:
(qemu) migrate fd:ffff
migrate: An undefined error has occurred
(qemu) info migrate
(qemu)
After:
(qemu) migrate fd:ffff
migrate: File descriptor named 'ffff' has not been found
(qemu) info migrate
capabilities: xbzrle: off
Migration status: failed
total time: 0 milliseconds
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/migration-exec.c b/migration-exec.c
index 6c97db9..5f3f4b2 100644
--- a/migration-exec.c
+++ b/migration-exec.c
@@ -60,22 +60,18 @@
return ret;
}
-int exec_start_outgoing_migration(MigrationState *s, const char *command)
+void exec_start_outgoing_migration(MigrationState *s, const char *command, Error **errp)
{
FILE *f;
f = popen(command, "w");
if (f == NULL) {
- DPRINTF("Unable to popen exec target\n");
- goto err_after_popen;
+ error_setg_errno(errp, errno, "failed to popen the migration target");
+ return;
}
s->fd = fileno(f);
- if (s->fd == -1) {
- DPRINTF("Unable to retrieve file descriptor for popen'd handle\n");
- goto err_after_open;
- }
-
+ assert(s->fd != -1);
socket_set_nonblock(s->fd);
s->opaque = qemu_popen(f, "w");
@@ -85,12 +81,6 @@
s->write = file_write;
migrate_fd_connect(s);
- return 0;
-
-err_after_open:
- pclose(f);
-err_after_popen:
- return -1;
}
static void exec_accept_incoming_migration(void *opaque)
diff --git a/migration-fd.c b/migration-fd.c
index 7335167..a7c800a 100644
--- a/migration-fd.c
+++ b/migration-fd.c
@@ -73,30 +73,19 @@
return 0;
}
-int fd_start_outgoing_migration(MigrationState *s, const char *fdname)
+void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp)
{
- s->fd = monitor_get_fd(cur_mon, fdname, NULL);
+ s->fd = monitor_get_fd(cur_mon, fdname, errp);
if (s->fd == -1) {
- DPRINTF("fd_migration: invalid file descriptor identifier\n");
- goto err_after_get_fd;
+ return;
}
- if (fcntl(s->fd, F_SETFL, O_NONBLOCK) == -1) {
- DPRINTF("Unable to set nonblocking mode on file descriptor\n");
- goto err_after_open;
- }
-
+ fcntl(s->fd, F_SETFL, O_NONBLOCK);
s->get_error = fd_errno;
s->write = fd_write;
s->close = fd_close;
migrate_fd_connect(s);
- return 0;
-
-err_after_open:
- close(s->fd);
-err_after_get_fd:
- return -1;
}
static void fd_accept_incoming_migration(void *opaque)
diff --git a/migration-tcp.c b/migration-tcp.c
index e8bc76a..5e54e68 100644
--- a/migration-tcp.c
+++ b/migration-tcp.c
@@ -68,22 +68,13 @@
}
}
-int tcp_start_outgoing_migration(MigrationState *s, const char *host_port,
- Error **errp)
+void tcp_start_outgoing_migration(MigrationState *s, const char *host_port, Error **errp)
{
- Error *local_err = NULL;
-
s->get_error = socket_errno;
s->write = socket_write;
s->close = tcp_close;
- s->fd = inet_nonblocking_connect(host_port, tcp_wait_for_connect, s, &local_err);
- if (local_err != NULL) {
- error_propagate(errp, local_err);
- return -1;
- }
-
- return 0;
+ s->fd = inet_nonblocking_connect(host_port, tcp_wait_for_connect, s, errp);
}
static void tcp_accept_incoming_migration(void *opaque)
diff --git a/migration-unix.c b/migration-unix.c
index 5387c21..34a413a 100644
--- a/migration-unix.c
+++ b/migration-unix.c
@@ -68,20 +68,13 @@
}
}
-int unix_start_outgoing_migration(MigrationState *s, const char *path, Error **errp)
+void unix_start_outgoing_migration(MigrationState *s, const char *path, Error **errp)
{
- Error *local_err = NULL;
-
s->get_error = unix_errno;
s->write = unix_write;
s->close = unix_close;
- s->fd = unix_nonblocking_connect(path, unix_wait_for_connect, s, &local_err);
- if (local_err != NULL) {
- error_propagate(errp, local_err);
- return -1;
- }
- return 0;
+ s->fd = unix_nonblocking_connect(path, unix_wait_for_connect, s, errp);
}
static void unix_accept_incoming_migration(void *opaque)
diff --git a/migration.c b/migration.c
index e631f18..ef171d2 100644
--- a/migration.c
+++ b/migration.c
@@ -487,7 +487,6 @@
MigrationState *s = migrate_get_current();
MigrationParams params;
const char *p;
- int ret;
params.blk = blk;
params.shared = inc;
@@ -509,27 +508,23 @@
s = migrate_init(¶ms);
if (strstart(uri, "tcp:", &p)) {
- ret = tcp_start_outgoing_migration(s, p, &local_err);
+ tcp_start_outgoing_migration(s, p, &local_err);
#if !defined(WIN32)
} else if (strstart(uri, "exec:", &p)) {
- ret = exec_start_outgoing_migration(s, p);
+ exec_start_outgoing_migration(s, p, &local_err);
} else if (strstart(uri, "unix:", &p)) {
- ret = unix_start_outgoing_migration(s, p, &local_err);
+ unix_start_outgoing_migration(s, p, &local_err);
} else if (strstart(uri, "fd:", &p)) {
- ret = fd_start_outgoing_migration(s, p);
+ fd_start_outgoing_migration(s, p, &local_err);
#endif
} else {
error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
return;
}
- if (ret < 0 || local_err) {
+ if (local_err) {
migrate_fd_error(s);
- if (!local_err) {
- error_set_errno(errp, -ret, QERR_UNDEFINED_ERROR);
- } else {
- error_propagate(errp, local_err);
- }
+ error_propagate(errp, local_err);
return;
}
diff --git a/migration.h b/migration.h
index 92e0aa9..c805e28 100644
--- a/migration.h
+++ b/migration.h
@@ -59,20 +59,19 @@
int exec_start_incoming_migration(const char *host_port);
-int exec_start_outgoing_migration(MigrationState *s, const char *host_port);
+void exec_start_outgoing_migration(MigrationState *s, const char *host_port, Error **errp);
int tcp_start_incoming_migration(const char *host_port, Error **errp);
-int tcp_start_outgoing_migration(MigrationState *s, const char *host_port,
- Error **errp);
+void tcp_start_outgoing_migration(MigrationState *s, const char *host_port, Error **errp);
int unix_start_incoming_migration(const char *path, Error **errp);
-int unix_start_outgoing_migration(MigrationState *s, const char *path, Error **errp);
+void unix_start_outgoing_migration(MigrationState *s, const char *path, Error **errp);
int fd_start_incoming_migration(const char *path);
-int fd_start_outgoing_migration(MigrationState *s, const char *fdname);
+void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp);
void migrate_fd_error(MigrationState *s);
