[libvirt] [Qemu-devel] [PATCH v2 2/4] qapi: Add passfd QMP command
Corey Bryant
coreyb at linux.vnet.ibm.com
Wed Jun 13 20:25:24 UTC 2012
On 06/13/2012 03:46 PM, Luiz Capitulino wrote:
> On Fri, 8 Jun 2012 11:42:57 -0400
> Corey Bryant <coreyb at linux.vnet.ibm.com> wrote:
>
>> This patch adds the passfd QMP command using the QAPI framework.
>> Like the getfd command, it is used to pass a file descriptor via
>> SCM_RIGHTS. However, the passfd command also returns the received
>> file descriptor, which is a difference in behavior from the getfd
>> command, which returns nothing.
>
> Let's call it pass-fd instead.
Sure, that works for me.
>
> Also, getfd automatically closes a fd if an existing fdname is passed again.
> I don't think this is a good behavior, I think pass-fd should fail instead
> (note that we can't fix getfd though).
>
I agree. It makes sense to fail rather than blindly closing the
existing fd. It can be closed explicitly with closefd if the user wants
it closed.
>>
>> The closefd command can be used to close a file descriptor that was
>> passed with the passfd command.
>>
>> v2:
>> -Introduce new QMP command to pass/return fd (lcapitulino at redhat.com)
>> -Use passfd as command name (berrange at redhat.com)
>>
>> Signed-off-by: Corey Bryant <coreyb at linux.vnet.ibm.com>
>> ---
>> monitor.c | 14 ++++++++++----
>> qapi-schema.json | 15 +++++++++++++++
>> qmp-commands.hx | 27 +++++++++++++++++++++++++++
>> 3 files changed, 52 insertions(+), 4 deletions(-)
>>
>> diff --git a/monitor.c b/monitor.c
>> index 4c53cb6..980a226 100644
>> --- a/monitor.c
>> +++ b/monitor.c
>> @@ -2182,7 +2182,7 @@ static void do_inject_mce(Monitor *mon, const QDict *qdict)
>> }
>> #endif
>>
>> -void qmp_getfd(const char *fdname, Error **errp)
>> +int64_t qmp_passfd(const char *fdname, Error **errp)
>> {
>> mon_fd_t *monfd;
>> int fd;
>> @@ -2190,13 +2190,13 @@ void qmp_getfd(const char *fdname, Error **errp)
>> fd = qemu_chr_fe_get_msgfd(cur_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) {
>> @@ -2206,7 +2206,7 @@ void qmp_getfd(const char *fdname, Error **errp)
>>
>> close(monfd->fd);
>> monfd->fd = fd;
>> - return;
>> + return fd;
>> }
>>
>> monfd = g_malloc0(sizeof(mon_fd_t));
>> @@ -2214,6 +2214,12 @@ void qmp_getfd(const char *fdname, Error **errp)
>> monfd->fd = fd;
>>
>> QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next);
>> + return fd;
>> +}
>> +
>> +void qmp_getfd(const char *fdname, Error **errp)
>> +{
>> + qmp_passfd(fdname, errp);
>> return;
>> }
>>
>> diff --git a/qapi-schema.json b/qapi-schema.json
>> index 6be1d90..15da1b8 100644
>> --- a/qapi-schema.json
>> +++ b/qapi-schema.json
>> @@ -1864,6 +1864,21 @@
>> { 'command': 'netdev_del', 'data': {'id': 'str'} }
>>
>> ##
>> +# @passfd:
>> +#
>> +# Pass a file descriptor via SCM rights and assign it a name
>> +#
>> +# @fdname: file descriptor name
>> +#
>> +# Returns: The QEMU file descriptor that was received
>> +# If file descriptor was not received, FdNotSupplied
>> +# If @fdname is not valid, InvalidParameterType
>> +#
>> +# Since: 1.2.0
>> +##
>> +{ 'command': 'passfd', 'data': {'fdname': 'str'}, 'returns': 'int' }
>> +
>> +##
>> # @getfd:
>> #
>> # Receive a file descriptor via SCM rights and assign it a name
>> diff --git a/qmp-commands.hx b/qmp-commands.hx
>> index f8c0f68..338a0b3 100644
>> --- a/qmp-commands.hx
>> +++ b/qmp-commands.hx
>> @@ -869,6 +869,33 @@ Example:
>> EQMP
>>
>> {
>> + .name = "passfd",
>> + .args_type = "fdname:s",
>> + .params = "passfd name",
>> + .help = "pass a file descriptor via SCM rights and assign it a name",
>> + .mhandler.cmd_new = qmp_marshal_input_passfd,
>> + },
>> +
>> +SQMP
>> +passfd
>> +------
>> +
>> +Pass a file descriptor via SCM rights and assign it a name.
>> +
>> +Arguments:
>> +
>> +- "fdname": file descriptor name (json-string)
>> +
>> +Return a json-int with the QEMU file descriptor that was received.
>> +
>> +Example:
>> +
>> +-> { "execute": "passfd", "arguments": { "fdname": "fd1" } }
>> +<- { "return": 42 }
>> +
>> +EQMP
>> +
>> + {
>> .name = "getfd",
>> .args_type = "fdname:s",
>> .params = "getfd name",
>
--
Regards,
Corey
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