[Qemu-devel] [PATCH 7/7] chardev: add hotplug support.

[Gerd Hoffmann <kraxel@redhat.com>]

This patch adds chardev_add and chardev_del monitor commands.

chardev_del is pretty straight forward, it just takes an id argument and
zaps the chardev specified.

chardev_add is more tricky as there are tons of arguments for the
different backends.  The hmp version limited to the most common use
cases, especially when it comes to sockets:  You can only specify port
(tcp) or path (unix) and qemu will create a listening socket.  For
example this ...

   (qemu) chardev_add foo socket 42

... will do the same as ...

   -chardev socket,id=foo,port=42,server,nowait

on the qemu command line.

The qmp version has full support for everything the -chardev command
line switch can handle.  The implementation is pretty straight
forward: It just puts all arguments it got into a QemuOpts, then goes
call qemu_chr_new_from_opts().

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hmp-commands.hx  |   49 +++++++++++++++++++++++++++++++++++
 hmp.c            |   39 ++++++++++++++++++++++++++++
 hmp.h            |    2 +
 qapi-schema.json |   46 +++++++++++++++++++++++++++++++++
 qemu-char.c      |   74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qmp-commands.hx  |   61 ++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 271 insertions(+), 0 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index e0b537d..e5590f4 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1404,6 +1404,55 @@ passed since 1970, i.e. unix epoch.
 ETEXI
 
     {
+        .name       = "chardev_add",
+        .args_type  = "id:s,backend:s,arg:s?",
+        .params     = "id backend [ name | port | path ]",
+        .help       = "add chardev",
+        .mhandler.cmd = hmp_chardev_add,
+    },
+
+STEXI
+@item chardev_add id backend [ name | port | path ]
+@findex chardev_add
+
+Create chardev with the specified @var{id} and @var{backend}.  The hmp
+version is limited to a commonly used subset, if you need more control
+use qmp instead.
+
+If @var{backend} is 'spicevmc' @var{arg} is assumed to be the spice
+channel name.
+
+If @var{backend} is 'udp' @var{arg} is assumed to be a port number.
+
+If @var{backend} is 'socket' and @var{arg} starts with a digit the
+argument is assumed to be a port number and a tcp socket is created
+(in server mode).
+
+If @var{backend} is 'socket' and @var{arg} doesn't start with a digit
+@var{arg} is assumed to be a path and a unix socket is created (in
+server mode).
+
+In all other cases @var{arg} is assumed to be a path.
+
+ETEXI
+
+    {
+        .name       = "chardev_del",
+        .args_type  = "id:s",
+        .params     = "id",
+        .help       = "del chardev",
+        .mhandler.cmd = hmp_chardev_del,
+    },
+
+STEXI
+@item chardev_del id
+@findex chardev_del
+
+Removes the chardev @var{id}.
+
+ETEXI
+
+    {
         .name       = "info",
         .args_type  = "item:s?",
         .params     = "[subcommand]",
diff --git a/hmp.c b/hmp.c
index 70bdec2..e84d7f8 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1209,3 +1209,42 @@ void hmp_screen_dump(Monitor *mon, const QDict *qdict)
     qmp_screendump(filename, &err);
     hmp_handle_error(mon, &err);
 }
+
+void hmp_chardev_add(Monitor *mon, const QDict *qdict)
+{
+    const char *backend = qdict_get_str(qdict, "backend");
+    const char *arg = qdict_get_str(qdict, "arg");
+    const char *id = qdict_get_str(qdict, "id");
+    const char *path = NULL, *name = NULL, *port = NULL, *host = NULL;
+    Error *err = NULL;
+
+    if (arg) {
+        if (strcmp(backend, "spicevmc") == 0) {
+            name = arg;
+        } else if (strcmp(backend, "udp") == 0) {
+            port = arg;
+        } else if (strcmp(backend, "socket") == 0 && isdigit(arg[0])) {
+            port = arg;
+        } else {
+            path = arg;
+        }
+    }
+
+    qmp_chardev_add(id, backend,
+                    path, name, host, port,
+                    true,  /* server      */
+                    false, /* wait        */
+                    false, /* ipv4 (only) */
+                    false, /* ipv6 (only) */
+                    false, /* telnet      */
+                    &err);
+    hmp_handle_error(mon, &err);
+}
+
+void hmp_chardev_del(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+    qmp_chardev_del(qdict_get_str(qdict, "id"),
+                    &err);
+    hmp_handle_error(mon, &err);
+}
diff --git a/hmp.h b/hmp.h
index 71ea384..080afaa 100644
--- a/hmp.h
+++ b/hmp.h
@@ -75,5 +75,7 @@ void hmp_getfd(Monitor *mon, const QDict *qdict);
 void hmp_closefd(Monitor *mon, const QDict *qdict);
 void hmp_send_key(Monitor *mon, const QDict *qdict);
 void hmp_screen_dump(Monitor *mon, const QDict *qdict);
+void hmp_chardev_add(Monitor *mon, const QDict *qdict);
+void hmp_chardev_del(Monitor *mon, const QDict *qdict);
 
 #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index f9dbdae..98d92ad 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2796,3 +2796,49 @@
 # Since: 0.14.0
 ##
 { 'command': 'screendump', 'data': {'filename': 'str'} }
+
+##
+# @chardev_add:
+#
+# Add a chardev
+#
+# @id: the chardev's ID, must be unique
+# @backend: the chardev backend: "file", "socket", ...
+# @path: file / device / unix socket path
+# @name: spice channel name
+# @host: host name
+# @port: port number
+# @server: create socket in server mode
+# @wait: wait for connect
+# @ipv4: force ipv4-only
+# @ipv6: force ipv6-only
+# @telnet: telnet negotiation
+#
+# Returns: Nothing on success
+#
+# Since: 1.3.0
+##
+{ 'command': 'chardev_add', 'data': {'id'      : 'str',
+                                     'backend' : 'str',
+                                     'path'    : 'str',
+                                     'name'    : 'str',
+                                     'host'    : 'str',
+                                     'port'    : 'str',
+                                     'server'  : 'bool',
+                                     'wait'    : 'bool',
+                                     'ipv4'    : 'bool',
+                                     'ipv6'    : 'bool',
+                                     'telnet'  : 'bool' } }
+
+##
+# @chardev_del:
+#
+# Remove a chardev
+#
+# @id: the chardev's ID, must exist and not be in use
+#
+# Returns: Nothing on success
+#
+# Since: 1.3.0
+##
+{ 'command': 'chardev_del', 'data': {'id': 'str'} }
diff --git a/qemu-char.c b/qemu-char.c
index b082bae..2f9d860 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2900,3 +2900,77 @@ CharDriverState *qemu_char_get_next_serial(void)
     return serial_hds[next_serial++];
 }
 
+void qmp_chardev_add(const char *id, const char *backend,
+                     const char *path, const char *name,
+                     const char *host, const char *port,
+                     bool server, bool wait,
+                     bool ipv4, bool ipv6,
+                     bool telnet, Error **errp)
+{
+    CharDriverState *chr;
+    QemuOpts *opts;
+
+    chr = qemu_chr_find(id);
+    if (NULL != chr) {
+        error_setg(errp, "Chardev id '%s' exists already\n", id);
+        return;
+    }
+
+    opts = qemu_opts_create(qemu_find_opts("chardev"), id, 1, errp);
+    if (error_is_set(errp)) {
+        return;
+    }
+    qemu_opt_set(opts, "backend", backend);
+    if (path) {
+        qemu_opt_set(opts, "path", path);
+    }
+    if (name) {
+        qemu_opt_set(opts, "name", name);
+    }
+    if (host) {
+        qemu_opt_set(opts, "host", host);
+    }
+    if (port) {
+        qemu_opt_set(opts, "port", port);
+    }
+    if (server) {
+        qemu_opt_set(opts, "server", "on");
+    }
+    if (!wait) {
+        qemu_opt_set(opts, "wait", "off");
+    }
+    if (ipv4) {
+        qemu_opt_set(opts, "ipv4", "on");
+    }
+    if (ipv6) {
+        qemu_opt_set(opts, "ipv6", "on");
+    }
+    if (telnet) {
+        qemu_opt_set(opts, "telnet", "on");
+    }
+
+    chr = qemu_chr_new_from_opts(opts, NULL);
+    qemu_opts_del(opts);
+
+    if (chr == NULL) {
+        error_setg(errp, "Creating chardev failed\n");
+        return;
+    }
+}
+
+void qmp_chardev_del(const char *id, Error **errp)
+{
+    CharDriverState *chr;
+
+    chr = qemu_chr_find(id);
+    if (NULL == chr) {
+        error_setg(errp, "Chardev '%s' not found\n", id);
+        return;
+    }
+    if (chr->chr_can_read || chr->chr_read ||
+        chr->chr_event || chr->handler_opaque) {
+        error_setg(errp, "Chardev '%s' is busy\n", id);
+        return;
+    }
+    qemu_chr_delete(chr);
+}
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 2f8477e..b904df2 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -2576,3 +2576,64 @@ EQMP
         .args_type  = "",
         .mhandler.cmd_new = qmp_marshal_input_query_target,
     },
+
+    {
+        .name       = "chardev_add",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_chardev_add,
+    },
+
+SQMP
+chardev_add
+-----------
+
+Add a chardev.
+
+Arguments:
+
+- "id": the chardev's ID, must be unique (json-string)
+- "backend": the chardev backend: "file", "socket", ... (json-string)
+- "path": file / device / unix socket path (json-string, optional)
+- "name": spice channel name (json-string, optional)
+- "host": host name (json-string, optional)
+- "port": port number (json-string, optional)
+- "server": create socket in server mode (json-bool, optional)
+- "wait": wait for connect (json-bool, optional)
+- "ipv4": force ipv4-only (json-bool, optional)
+- "ipv6": force ipv6-only (json-bool, optional)
+- "telnet": telnet negotiation (json-bool, optional)
+
+Example:
+
+-> { "execute": "chardev_add", "arguments": { "id"      : "foo",
+                                              "backend" : "socket",
+                                              "path"    : "/tmp/foo",
+                                              "server"  : "on",
+                                              "wait"    : "off" } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "chardev_del",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_chardev_del,
+    },
+
+
+SQMP
+chardev_del
+-----------
+
+Remove a chardev.
+
+Arguments:
+
+- "id": the chardev's ID, must exist and not be in use (json-string)
+
+Example:
+
+-> { "execute": "chardev_del", "arguments": { "id" : "foo" } }
+<- { "return": {} }
+
+EQMP
-- 
1.7.1