Merge tag 'chr-pull-request' of https://gitlab.com/marcandre.lureau/qemu into staging

chardev: introduce 'reconnect-ms' and deprecate 'reconnect'
chardev: add path option for pty backend

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# gpg:                 aka "Marc-André Lureau <marcandre.lureau@gmail.com>" [full]
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* tag 'chr-pull-request' of https://gitlab.com/marcandre.lureau/qemu:
  chardev: add path option for pty backend
  chardev: introduce 'reconnect-ms' and deprecate 'reconnect'

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

chardev/char-pty.c

@@ -29,6 +29,7 @@
 #include "qemu/sockets.h"
 #include "qemu/error-report.h"
 #include "qemu/module.h"
+#include "qemu/option.h"
 #include "qemu/qemu-print.h"
 
 #include "chardev/char-io.h"
@@ -41,6 +42,7 @@ struct PtyChardev {
 
     int connected;
     GSource *timer_src;
+    char *path;
 };
 typedef struct PtyChardev PtyChardev;
 
@@ -204,6 +206,12 @@ static void char_pty_finalize(Object *obj)
     Chardev *chr = CHARDEV(obj);
     PtyChardev *s = PTY_CHARDEV(obj);
 
+    /* unlink symlink */
+    if (s->path) {
+        unlink(s->path);
+        g_free(s->path);
+    }
+
     pty_chr_state(chr, 0);
     object_unref(OBJECT(s->ioc));
     pty_chr_timer_cancel(s);
@@ -330,6 +338,7 @@ static void char_pty_open(Chardev *chr,
     int master_fd, slave_fd;
     char pty_name[PATH_MAX];
     char *name;
+    char *path = backend->u.pty.data->path;
 
     master_fd = qemu_openpty_raw(&slave_fd, pty_name);
     if (master_fd < 0) {
@@ -354,12 +363,36 @@ static void char_pty_open(Chardev *chr,
     g_free(name);
     s->timer_src = NULL;
     *be_opened = false;
+
+    /* create symbolic link */
+    if (path) {
+        int res = symlink(pty_name, path);
+
+        if (res != 0) {
+            error_setg_errno(errp, errno, "Failed to create PTY symlink");
+        } else {
+            s->path = g_strdup(path);
+        }
+    }
+}
+
+static void char_pty_parse(QemuOpts *opts, ChardevBackend *backend,
+                           Error **errp)
+{
+    const char *path = qemu_opt_get(opts, "path");
+    ChardevPty *pty;
+
+    backend->type = CHARDEV_BACKEND_KIND_PTY;
+    pty = backend->u.pty.data = g_new0(ChardevPty, 1);
+    qemu_chr_parse_common(opts, qapi_ChardevPty_base(pty));
+    pty->path = g_strdup(path);
 }
 
 static void char_pty_class_init(ObjectClass *oc, void *data)
 {
     ChardevClass *cc = CHARDEV_CLASS(oc);
 
+    cc->parse = char_pty_parse;
     cc->open = char_pty_open;
     cc->chr_write = char_pty_chr_write;
     cc->chr_update_read_handler = pty_chr_update_read_handler;

chardev/char-socket.c

@@ -74,7 +74,7 @@ static void qemu_chr_socket_restart_timer(Chardev *chr)
     assert(!s->reconnect_timer);
     name = g_strdup_printf("chardev-socket-reconnect-%s", chr->label);
     s->reconnect_timer = qemu_chr_timeout_add_ms(chr,
-                                                 s->reconnect_time * 1000,
+                                                 s->reconnect_time_ms,
                                                  socket_reconnect_timeout,
                                                  chr);
     g_source_set_name(s->reconnect_timer, name);
@@ -481,7 +481,7 @@ static void tcp_chr_disconnect_locked(Chardev *chr)
     if (emit_close) {
         qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
     }
-    if (s->reconnect_time && !s->reconnect_timer) {
+    if (s->reconnect_time_ms && !s->reconnect_timer) {
         qemu_chr_socket_restart_timer(chr);
     }
 }
@@ -1080,9 +1080,9 @@ static int tcp_chr_wait_connected(Chardev *chr, Error **errp)
         } else {
             Error *err = NULL;
             if (tcp_chr_connect_client_sync(chr, &err) < 0) {
-                if (s->reconnect_time) {
+                if (s->reconnect_time_ms) {
                     error_free(err);
-                    g_usleep(s->reconnect_time * 1000ULL * 1000ULL);
+                    g_usleep(s->reconnect_time_ms * 1000ULL);
                 } else {
                     error_propagate(errp, err);
                     return -1;
@@ -1267,13 +1267,13 @@ skip_listen:
 
 
 static int qmp_chardev_open_socket_client(Chardev *chr,
-                                          int64_t reconnect,
+                                          int64_t reconnect_ms,
                                           Error **errp)
 {
     SocketChardev *s = SOCKET_CHARDEV(chr);
 
-    if (reconnect > 0) {
-        s->reconnect_time = reconnect;
+    if (reconnect_ms > 0) {
+        s->reconnect_time_ms = reconnect_ms;
         tcp_chr_connect_client_async(chr);
         return 0;
     } else {
@@ -1354,6 +1354,12 @@ static bool qmp_chardev_validate_socket(ChardevSocket *sock,
         }
     }
 
+    if (sock->has_reconnect_ms && sock->has_reconnect) {
+        error_setg(errp,
+            "'reconnect' and 'reconnect-ms' are mutually exclusive");
+        return false;
+    }
+
     return true;
 }
 
@@ -1371,7 +1377,7 @@ static void qmp_chardev_open_socket(Chardev *chr,
     bool is_tn3270      = sock->has_tn3270  ? sock->tn3270  : false;
     bool is_waitconnect = sock->has_wait    ? sock->wait    : false;
     bool is_websock     = sock->has_websocket ? sock->websocket : false;
-    int64_t reconnect   = sock->has_reconnect ? sock->reconnect : 0;
+    int64_t reconnect_ms = 0;
     SocketAddress *addr;
 
     s->is_listen = is_listen;
@@ -1443,7 +1449,13 @@ static void qmp_chardev_open_socket(Chardev *chr,
             return;
         }
     } else {
-        if (qmp_chardev_open_socket_client(chr, reconnect, errp) < 0) {
+        if (sock->has_reconnect) {
+            reconnect_ms = sock->reconnect * 1000ULL;
+        } else if (sock->has_reconnect_ms) {
+            reconnect_ms = sock->reconnect_ms;
+        }
+
+        if (qmp_chardev_open_socket_client(chr, reconnect_ms, errp) < 0) {
             return;
         }
     }
@@ -1509,6 +1521,9 @@ static void qemu_chr_parse_socket(QemuOpts *opts, ChardevBackend *backend,
     sock->wait = qemu_opt_get_bool(opts, "wait", true);
     sock->has_reconnect = qemu_opt_find(opts, "reconnect");
     sock->reconnect = qemu_opt_get_number(opts, "reconnect", 0);
+    sock->has_reconnect_ms = qemu_opt_find(opts, "reconnect-ms");
+    sock->reconnect_ms = qemu_opt_get_number(opts, "reconnect-ms", 0);
+
     sock->tls_creds = g_strdup(qemu_opt_get(opts, "tls-creds"));
     sock->tls_authz = g_strdup(qemu_opt_get(opts, "tls-authz"));
 

chardev/char.c

@@ -428,6 +428,11 @@ QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename,
         qemu_opt_set(opts, "path", p, &error_abort);
         return opts;
     }
+    if (strstart(filename, "pty:", &p)) {
+        qemu_opt_set(opts, "backend", "pty", &error_abort);
+        qemu_opt_set(opts, "path", p, &error_abort);
+        return opts;
+    }
     if (strstart(filename, "tcp:", &p) ||
         strstart(filename, "telnet:", &p) ||
         strstart(filename, "tn3270:", &p) ||
@@ -888,6 +893,9 @@ QemuOptsList qemu_chardev_opts = {
         },{
             .name = "reconnect",
             .type = QEMU_OPT_NUMBER,
+        },{
+            .name = "reconnect-ms",
+            .type = QEMU_OPT_NUMBER,
         },{
             .name = "telnet",
             .type = QEMU_OPT_BOOL,

docs/about/deprecated.rst

@@ -394,6 +394,12 @@ Backend ``memory`` (since 9.0)
 
 ``memory`` is a deprecated synonym for ``ringbuf``.
 
+``reconnect`` (since 9.2)
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The ``reconnect`` option only allows specifiying second granularity timeouts,
+which is not enough for all types of use cases, use ``reconnect-ms`` instead.
+
 CPU device properties
 '''''''''''''''''''''
 

include/chardev/char-socket.h

@@ -74,7 +74,7 @@ struct SocketChardev {
     bool is_websock;
 
     GSource *reconnect_timer;
-    int64_t reconnect_time;
+    int64_t reconnect_time_ms;
     bool connect_err_reported;
 
     QIOTask *connect_task;

qapi/char.json

@@ -273,7 +273,19 @@
 #
 # @reconnect: For a client socket, if a socket is disconnected, then
 #     attempt a reconnect after the given number of seconds.  Setting
-#     this to zero disables this function.  (default: 0) (Since: 2.2)
+#     this to zero disables this function.  The use of this member is
+#     deprecated, use @reconnect-ms instead. (default: 0) (Since: 2.2)
+#
+# @reconnect-ms: For a client socket, if a socket is disconnected,
+#     then attempt a reconnect after the given number of milliseconds.
+#     Setting this to zero disables this function.  This member is
+#     mutually exclusive with @reconnect.
+#     (default: 0) (Since: 9.2)
+#
+# Features:
+#
+# @deprecated: Member @reconnect is deprecated.  Use @reconnect-ms
+#     instead.
 #
 # Since: 1.4
 ##
@@ -287,7 +299,8 @@
             '*telnet': 'bool',
             '*tn3270': 'bool',
             '*websocket': 'bool',
-            '*reconnect': 'int' },
+            '*reconnect': { 'type': 'int', 'features': [ 'deprecated' ] },
+            '*reconnect-ms': 'int' },
   'base': 'ChardevCommon' }
 
 ##
@@ -431,6 +444,20 @@
   'base': 'ChardevCommon',
   'if': 'CONFIG_SPICE_PROTOCOL' }
 
+##
+# @ChardevPty:
+#
+# Configuration info for pty implementation.
+#
+# @path: optional path to create a symbolic link that points to the
+#     allocated PTY
+#
+# Since: 9.2
+##
+{ 'struct': 'ChardevPty',
+  'data': { '*path': 'str' },
+  'base': 'ChardevCommon' }
+
 ##
 # @ChardevBackendKind:
 #
@@ -642,6 +669,17 @@
 { 'struct': 'ChardevRingbufWrapper',
   'data': { 'data': 'ChardevRingbuf' } }
 
+
+##
+# @ChardevPtyWrapper:
+#
+# @data: Configuration info for pty chardevs
+#
+# Since: 9.2
+##
+{ 'struct': 'ChardevPtyWrapper',
+  'data': { 'data': 'ChardevPty' } }
+
 ##
 # @ChardevBackend:
 #
@@ -662,7 +700,7 @@
             'pipe': 'ChardevHostdevWrapper',
             'socket': 'ChardevSocketWrapper',
             'udp': 'ChardevUdpWrapper',
-            'pty': 'ChardevCommonWrapper',
+            'pty': 'ChardevPtyWrapper',
             'null': 'ChardevCommonWrapper',
             'mux': 'ChardevMuxWrapper',
             'msmouse': 'ChardevCommonWrapper',

qemu-options.hx

@@ -3712,7 +3712,7 @@ DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
     "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
     "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
 #else
-    "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+    "-chardev pty,id=id[,path=path][,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
     "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
 #endif
 #ifdef CONFIG_BRLAPI
@@ -3951,12 +3951,22 @@ The available backends are:
 
     ``path`` specifies the name of the serial device to open.
 
-``-chardev pty,id=id``
-    Create a new pseudo-terminal on the host and connect to it. ``pty``
-    does not take any options.
+``-chardev pty,id=id[,path=path]``
+    Create a new pseudo-terminal on the host and connect to it.
 
     ``pty`` is not available on Windows hosts.
 
+    If ``path`` is specified, QEMU will create a symbolic link at
+    that location which points to the new PTY device.
+
+    This avoids having to make QMP or HMP monitor queries to find out
+    what the new PTY device path is.
+
+    Note that while QEMU will remove the symlink when it exits
+    gracefully, it will not do so in case of crashes or on certain
+    startup errors. It is recommended that the user checks and removes
+    the symlink after QEMU terminates to account for this.
+
 ``-chardev stdio,id=id[,signal=on|off]``
     Connect to standard input and standard output of the QEMU process.
 
@@ -4314,8 +4324,19 @@ SRST
 
             vc:80Cx24C
 
-    ``pty``
-        [Linux only] Pseudo TTY (a new PTY is automatically allocated)
+    ``pty[:path]``
+        [Linux only] Pseudo TTY (a new PTY is automatically allocated).
+
+        If ``path`` is specified, QEMU will create a symbolic link at
+        that location which points to the new PTY device.
+
+        This avoids having to make QMP or HMP monitor queries to find
+        out what the new PTY device path is.
+
+        Note that while QEMU will remove the symlink when it exits
+        gracefully, it will not do so in case of crashes or on certain
+        startup errors. It is recommended that the user checks and
+        removes the symlink after QEMU terminates to account for this.
 
     ``none``
         No device is allocated. Note that for machine types which