This patch adds the pass-fd QMP command using the QAPI framework.
Like the getfd command, it is used to pass a file descriptor via
SCM_RIGHTS and associate it with a name. However, the pass-fd
command also returns the received file descriptor, which is a
difference in behavior from the getfd command, which returns
nothing. pass-fd also supports a boolean "force" argument that
can be used to specify that an existing file descriptor is
associated with the specified name, and that it should become a
copy of the newly passed file descriptor.
The closefd command can be used to close a file descriptor that was
passed with the pass-fd command.
Note that when using getfd or pass-fd, there are some commands
(e.g. migrate with fd:name) that implicitly close the named fd.
When this is not the case, closefd must be used to avoid fd leaks.
Signed-off-by: Corey Bryant <cor...@linux.vnet.ibm.com>
---
v2:
-Introduce new QMP command to pass/return fd (lcapitul...@redhat.com)
-Use passfd as command name (berra...@redhat.com)
v3:
-Use pass-fd as command name (lcapitul...@redhat.com)
-Fail pass-fd if fdname already exists (lcapitul...@redhat.com)
-Add notes to QMP command describing behavior in more detail
(lcapitul...@redhat.com, ebl...@redhat.com)
-Add note about fd leakage (ebl...@redhat.com)
v4:
-Don't return same error class twice (lcapitul...@redhat.com)
-Share code for qmp_gefd and qmp_pass_fd (lcapitul...@redhat.com)
-Update qmp_closefd to call monitor_get_fd
-Add support for "force" argument to pass-fd (ebl...@redhat.com)
dump.c | 3 +-
migration-fd.c | 2 +-
monitor.c | 96 +++++++++++++++++++++++++++++++++++-------------------
monitor.h | 2 +-
net.c | 6 ++--
qapi-schema.json | 36 ++++++++++++++++++++
qmp-commands.hx | 42 +++++++++++++++++++++++-
7 files changed, 146 insertions(+), 41 deletions(-)
diff --git a/dump.c b/dump.c
index 4412d7a..2fd8ced 100644
--- a/dump.c
+++ b/dump.c
@@ -836,9 +836,8 @@ void qmp_dump_guest_memory(bool paging, const char *file,
bool has_begin,
#if !defined(WIN32)
if (strstart(file, "fd:", &p)) {
- fd = monitor_get_fd(cur_mon, p);
+ fd = monitor_get_fd(cur_mon, p, errp);
if (fd == -1) {
- error_set(errp, QERR_FD_NOT_FOUND, p);
return;
}
}
diff --git a/migration-fd.c b/migration-fd.c
index 50138ed..7335167 100644
--- a/migration-fd.c
+++ b/migration-fd.c
@@ -75,7 +75,7 @@ static int fd_close(MigrationState *s)
int fd_start_outgoing_migration(MigrationState *s, const char *fdname)
{
- s->fd = monitor_get_fd(cur_mon, fdname);
+ s->fd = monitor_get_fd(cur_mon, fdname, NULL);
if (s->fd == -1) {
DPRINTF("fd_migration: invalid file descriptor identifier\n");
goto err_after_get_fd;
diff --git a/monitor.c b/monitor.c
index 1a7f7e7..3433c06 100644
--- a/monitor.c
+++ b/monitor.c
@@ -814,7 +814,7 @@ static int add_graphics_client(Monitor *mon, const QDict
*qdict, QObject **ret_d
CharDriverState *s;
if (strcmp(protocol, "spice") == 0) {
- int fd = monitor_get_fd(mon, fdname);
+ int fd = monitor_get_fd(mon, fdname, NULL);
int skipauth = qdict_get_try_bool(qdict, "skipauth", 0);
int tls = qdict_get_try_bool(qdict, "tls", 0);
if (!using_spice) {
@@ -828,18 +828,18 @@ static int add_graphics_client(Monitor *mon, const QDict
*qdict, QObject **ret_d
return 0;
#ifdef CONFIG_VNC
} else if (strcmp(protocol, "vnc") == 0) {
- int fd = monitor_get_fd(mon, fdname);
+ int fd = monitor_get_fd(mon, fdname, NULL);
int skipauth = qdict_get_try_bool(qdict, "skipauth", 0);
- vnc_display_add_client(NULL, fd, skipauth);
- return 0;
+ vnc_display_add_client(NULL, fd, skipauth);
+ return 0;
#endif
} else if ((s = qemu_chr_find(protocol)) != NULL) {
- int fd = monitor_get_fd(mon, fdname);
- if (qemu_chr_add_client(s, fd) < 0) {
- qerror_report(QERR_ADD_CLIENT_FAILED);
- return -1;
- }
- return 0;
+ int fd = monitor_get_fd(mon, fdname, NULL);
+ if (qemu_chr_add_client(s, fd) < 0) {
+ qerror_report(QERR_ADD_CLIENT_FAILED);
+ return -1;
+ }
+ return 0;
}
qerror_report(QERR_INVALID_PARAMETER, "protocol");
@@ -2182,57 +2182,69 @@ static void do_inject_mce(Monitor *mon, const QDict
*qdict)
}
#endif
-void qmp_getfd(const char *fdname, Error **errp)
+static int monitor_put_fd(Monitor *mon, const char *fdname, bool replace,
+ bool copy, Error **errp)
{
mon_fd_t *monfd;
int fd;
- fd = qemu_chr_fe_get_msgfd(cur_mon->chr);
+ fd = qemu_chr_fe_get_msgfd(mon->chr);
if (fd == -1) {
error_set(errp, QERR_FD_NOT_SUPPLIED);
- return;
+ return -1;
}
if (qemu_isdigit(fdname[0])) {
error_set(errp, QERR_INVALID_PARAMETER_VALUE, "fdname",
"a name not starting with a digit");
- return;
+ return -1;
}
- QLIST_FOREACH(monfd, &cur_mon->fds, next) {
+ QLIST_FOREACH(monfd, &mon->fds, next) {
if (strcmp(monfd->name, fdname) != 0) {
continue;
}
- close(monfd->fd);
- monfd->fd = fd;
- return;
+ if (replace) {
+ /* the existing fd is replaced with the new fd */
+ close(monfd->fd);
+ monfd->fd = fd;
+ return fd;
+ }
+
+ if (copy) {
+ /* the existing fd becomes a copy of the new fd */
+ if (dup2(fd, monfd->fd) == -1) {
+ error_set(errp, QERR_UNDEFINED_ERROR);
+ return -1;
+ }
+ close(fd);
+ return monfd->fd;
+ }
+
+ error_set(errp, QERR_INVALID_PARAMETER, "fdname");
+ return -1;
+ }
+
+ if (copy) {
+ error_set(errp, QERR_INVALID_PARAMETER, "fdname");
+ return -1;
}
monfd = g_malloc0(sizeof(mon_fd_t));
monfd->name = g_strdup(fdname);
monfd->fd = fd;
- QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next);
+ QLIST_INSERT_HEAD(&mon->fds, monfd, next);
+ return fd;
}
void qmp_closefd(const char *fdname, Error **errp)
{
- mon_fd_t *monfd;
-
- QLIST_FOREACH(monfd, &cur_mon->fds, next) {
- if (strcmp(monfd->name, fdname) != 0) {
- continue;
- }
-
- QLIST_REMOVE(monfd, next);
- close(monfd->fd);
- g_free(monfd->name);
- g_free(monfd);
- return;
+ int fd = monitor_get_fd(cur_mon, fdname, errp);
+ if (fd != -1) {
+ close(fd);
}
-
- error_set(errp, QERR_FD_NOT_FOUND, fdname);
}
static void do_loadvm(Monitor *mon, const QDict *qdict)
@@ -2247,7 +2259,7 @@ static void do_loadvm(Monitor *mon, const QDict *qdict)
}
}
-int monitor_get_fd(Monitor *mon, const char *fdname)
+int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
{
mon_fd_t *monfd;
@@ -2268,9 +2280,25 @@ int monitor_get_fd(Monitor *mon, const char *fdname)
return fd;
}
+ error_set(errp, QERR_FD_NOT_FOUND, fdname);
return -1;
}
+int64_t qmp_pass_fd(const char *fdname, bool has_force, bool force,
+ Error **errp)
+{
+ bool replace = false;
+ bool copy = has_force ? force : false;
+ return monitor_put_fd(cur_mon, fdname, replace, copy, errp);
+}
+
+void qmp_getfd(const char *fdname, Error **errp)
+{
+ bool replace = true;
+ bool copy = false;
+ monitor_put_fd(cur_mon, fdname, replace, copy, errp);
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
diff --git a/monitor.h b/monitor.h
index cd1d878..8fa515d 100644
--- a/monitor.h
+++ b/monitor.h
@@ -63,7 +63,7 @@ int monitor_read_block_device_key(Monitor *mon, const char
*device,
BlockDriverCompletionFunc *completion_cb,
void *opaque);
-int monitor_get_fd(Monitor *mon, const char *fdname);
+int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp);
void monitor_vprintf(Monitor *mon, const char *fmt, va_list ap)
GCC_FMT_ATTR(2, 0);
diff --git a/net.c b/net.c
index 4aa416c..28860b8 100644
--- a/net.c
+++ b/net.c
@@ -730,12 +730,14 @@ int qemu_find_nic_model(NICInfo *nd, const char * const
*models,
int net_handle_fd_param(Monitor *mon, const char *param)
{
int fd;
+ Error *local_err = NULL;
if (!qemu_isdigit(param[0]) && mon) {
- fd = monitor_get_fd(mon, param);
+ fd = monitor_get_fd(mon, param, &local_err);
if (fd == -1) {
- error_report("No file descriptor named %s found", param);
+ qerror_report_err(local_err);
+ error_free(local_err);
return -1;
}
} else {
diff --git a/qapi-schema.json b/qapi-schema.json
index 26a6b84..2ac1261 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1864,6 +1864,41 @@
{ 'command': 'netdev_del', 'data': {'id': 'str'} }
##
+# @pass-fd:
+#
+# Pass a file descriptor via SCM rights and assign it a name
+#
+# @fdname: file descriptor name
+#
+# @force: #optional true specifies that an existing file descriptor is
+# associated with @fdname, and that it should become a copy of the
+# newly passed file descriptor.
+#
+# Returns: The QEMU file descriptor that is assigned to @fdname
+# If file descriptor was not received, FdNotSupplied
+# If @fdname is not valid, InvalidParameterValue
+# If @fdname already exists, and @force is not true, InvalidParameter
+# If @fdname does not already exist, and @force is true,
+# InvalidParameter
+# If @force fails to copy the passed file descriptor,
+# UndefinedError
+#
+# Since: 1.2.0
+#
+# Notes: If @fdname already exists, and @force is not true, the
+# command will fail.
+#
+# If @fdname already exists, and @force is true, the value of
+# the existing file descriptor is returned when the command is
+# successful.
+#
+# The 'closefd' command can be used to explicitly close the
+# file descriptor when it is no longer needed.
+##
+{ 'command': 'pass-fd', 'data': {'fdname': 'str', '*force': 'bool'},
+ 'returns': 'int' }
+
+##
# @getfd:
#
# Receive a file descriptor via SCM rights and assign it a name
@@ -1879,6 +1914,7 @@
# Notes: If @fdname already exists, the file descriptor assigned to
# it will be closed and replaced by the received file
# descriptor.
+#
# The 'closefd' command can be used to explicitly close the
# file descriptor when it is no longer needed.
##
diff --git a/qmp-commands.hx b/qmp-commands.hx
index e3cf3c5..7e3c07e 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -869,9 +869,49 @@ Example:
EQMP
{
+ .name = "pass-fd",
+ .args_type = "fdname:s,force:b?",
+ .params = "pass-fd fdname force",
+ .help = "pass a file descriptor via SCM rights and assign it a
name",
+ .mhandler.cmd_new = qmp_marshal_input_pass_fd,
+ },
+
+SQMP
+pass-fd
+-------
+
+Pass a file descriptor via SCM rights and assign it a name.
+
+Arguments:
+
+- "fdname": file descriptor name (json-string)
+- "force": true specifies that an existing file descriptor is associated
+ with "fdname", and that it should become a copy of the newly
+ passed file descriptor. (json-bool, optional)
+
+Return a json-int with the QEMU file descriptor that is assigned to "fdname".
+
+Example:
+
+-> { "execute": "pass-fd", "arguments": { "fdname": "fd1" } }
+<- { "return": 42 }
+
+Notes:
+
+(1) If the name specified by the "fdname" argument already exists, and
+ "force" is not true, the command will fail.
+(2) If the name specified by the "fdname" argument already exists, and
+ "force" is true, the value of the existing file descriptor is
+ returned when the command is successful.
+(3) The 'closefd' command can be used to explicitly close the file
+ descriptor when it is no longer needed.
+
+EQMP
+
+ {
.name = "getfd",
.args_type = "fdname:s",
- .params = "getfd name",
+ .params = "getfd fdname",
.help = "receive a file descriptor via SCM rights and assign it
a name",
.mhandler.cmd_new = qmp_marshal_input_getfd,
},
--
1.7.10.2
