meta/recipes-devtools/qemu/qemu/chardev-connect-socket-to-a-spawned-command.patch

   1 From 3bb3100c22eb30146a69656480bdffeef8663575 Mon Sep 17 00:00:00 2001
   2 From: Alistair Francis <alistair.francis@xilinx.com>
   3 Date: Thu, 21 Dec 2017 11:35:16 -0800
   4 Subject: [PATCH] chardev: connect socket to a spawned command
   5
   6 The command is started in a shell (sh -c) with stdin connect to QEMU
   7 via a Unix domain stream socket. QEMU then exchanges data via its own
   8 end of the socket, just like it normally does.
   9
  10 "-chardev socket" supports some ways of connecting via protocols like
  11 telnet, but that is only a subset of the functionality supported by
  12 tools socat. To use socat instead, for example to connect via a socks
  13 proxy, use:
  14
  15   -chardev 'socket,id=socat,cmd=exec socat FD:0 SOCKS4A:socks-proxy.localdomain:example.com:9999,,socksuser=nobody' \
  16   -device usb-serial,chardev=socat
  17
  18 Beware that commas in the command must be escaped as double commas.
  19
  20 Or interactively in the console:
  21    (qemu) chardev-add socket,id=cat,cmd=cat
  22    (qemu) device_add usb-serial,chardev=cat
  23    ^ac
  24    # cat >/dev/ttyUSB0
  25    hello
  26    hello
  27
  28 Another usage is starting swtpm from inside QEMU. swtpm will
  29 automatically shut down once it looses the connection to the parent
  30 QEMU, so there is no risk of lingering processes:
  31
  32   -chardev 'socket,id=chrtpm0,cmd=exec swtpm socket --terminate --ctrl type=unixio,,clientfd=0 --tpmstate dir=... --log file=swtpm.log' \
  33   -tpmdev emulator,id=tpm0,chardev=chrtpm0 \
  34   -device tpm-tis,tpmdev=tpm0
  35
  36 The patch was discussed upstream, but QEMU developers believe that the
  37 code calling QEMU should be responsible for managing additional
  38 processes. In OE-core, that would imply enhancing runqemu and
  39 oeqa. This patch is a simpler solution.
  40
  41 Because it is not going upstream, the patch was written so that it is
  42 as simple as possible.
  43
  44 Upstream-Status: Inappropriate [embedded specific]
  45
  46 Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
  47 ---
  48  chardev/char-socket.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++---
  49  chardev/char.c        |  3 ++
  50  qapi/char.json        |  5 +++
  51  3 files changed, 90 insertions(+), 4 deletions(-)
  52
  53 diff --git a/chardev/char-socket.c b/chardev/char-socket.c
  54 index 53eda8ef00..f566107c35 100644
  55 --- a/chardev/char-socket.c
  56 +++ b/chardev/char-socket.c
  57 @@ -852,6 +852,68 @@ static gboolean socket_reconnect_timeout(gpointer opaque)
  58      return false;
  59  }
  60
  61 +#ifndef _WIN32
  62 +static void chardev_open_socket_cmd(Chardev *chr,
  63 +                                    const char *cmd,
  64 +                                    Error **errp)
  65 +{
  66 +    int fds[2] = { -1, -1 };
  67 +    QIOChannelSocket *sioc = NULL;
  68 +    pid_t pid = -1;
  69 +    const char *argv[] = { "/bin/sh", "-c", cmd, NULL };
  70 +
  71 +    /*
  72 +     * We need a Unix domain socket for commands like swtpm and a single
  73 +     * connection, therefore we cannot use qio_channel_command_new_spawn()
  74 +     * without patching it first. Duplicating the functionality is easier.
  75 +     */
  76 +    if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0, fds)) {
  77 +        error_setg_errno(errp, errno, "Error creating socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC)");
  78 +        goto error;
  79 +    }
  80 +
  81 +    pid = qemu_fork(errp);
  82 +    if (pid < 0) {
  83 +        goto error;
  84 +    }
  85 +
  86 +    if (!pid) {
  87 +        /* child */
  88 +        dup2(fds[1], STDIN_FILENO);
  89 +        execv(argv[0], (char * const *)argv);
  90 +        _exit(1);
  91 +    }
  92 +
  93 +    /*
  94 +     * Hand over our end of the socket pair to the qio channel.
  95 +     *
  96 +     * We don't reap the child because it is expected to keep
  97 +     * running. We also don't support the "reconnect" option for the
  98 +     * same reason.
  99 +     */
 100 +    sioc = qio_channel_socket_new_fd(fds[0], errp);
 101 +    if (!sioc) {
 102 +        goto error;
 103 +    }
 104 +    fds[0] = -1;
 105 +
 106 +    g_free(chr->filename);
 107 +    chr->filename = g_strdup_printf("cmd:%s", cmd);
 108 +    tcp_chr_new_client(chr, sioc);
 109 +
 110 + error:
 111 +    if (fds[0] >= 0) {
 112 +        close(fds[0]);
 113 +    }
 114 +    if (fds[1] >= 0) {
 115 +        close(fds[1]);
 116 +    }
 117 +    if (sioc) {
 118 +        object_unref(OBJECT(sioc));
 119 +    }
 120 +}
 121 +#endif
 122 +
 123  static void qmp_chardev_open_socket(Chardev *chr,
 124                                      ChardevBackend *backend,
 125                                      bool *be_opened,
 126 @@ -859,6 +921,9 @@
 127  {
 128      SocketChardev *s = SOCKET_CHARDEV(chr);
 129      ChardevSocket *sock = backend->u.socket.data;
 130 +#ifndef _WIN32
 131 +    const char *cmd     = sock->cmd;
 132 +#endif
 133      bool do_nodelay     = sock->has_nodelay ? sock->nodelay : false;
 134      bool is_listen      = sock->has_server  ? sock->server  : true;
 135      bool is_telnet      = sock->has_telnet  ? sock->telnet  : false;
 136 @@ -925,7 +990,14 @@
 137      } else if (reconnect > 0) {
 138          s->reconnect_time = reconnect;
 139      }
 140 -
 141 +#ifndef _WIN32
 142 +    if (cmd) {
 143 +        chardev_open_socket_cmd(chr, cmd, errp);
 144 +
 145 +        /* everything ready (or failed permanently) before we return */
 146 +        *be_opened = true;
 147 +    } else
 148 +#endif
 149      if (s->reconnect_time) {
 150          sioc = qio_channel_socket_new();
 151          tcp_chr_set_client_ioc_name(chr, sioc);
 152 @@ -985,10 +1057,26 @@
 153      const char *host = qemu_opt_get(opts, "host");
 154      const char *port = qemu_opt_get(opts, "port");
 155      const char *tls_creds = qemu_opt_get(opts, "tls-creds");
 156 +#ifndef _WIN32
 157 +    const char *cmd = qemu_opt_get(opts, "cmd");
 158 +#endif
 159      SocketAddressLegacy *addr;
 160      ChardevSocket *sock;
 161
 162      backend->type = CHARDEV_BACKEND_KIND_SOCKET;
 163 +#ifndef _WIN32
 164 +    if (cmd) {
 165 +        /*
 166 +         * Here we have to ensure that no options are set which are incompatible with
 167 +         * spawning a command, otherwise unmodified code that doesn't know about
 168 +         * command spawning (like socket_reconnect_timeout()) might get called.
 169 +         */
 170 +        if (path || is_listen || is_telnet || is_tn3270 || reconnect || host || port || tls_creds) {
 171 +            error_setg(errp, "chardev: socket: cmd does not support any additional options");
 172 +            return;
 173 +        }
 174 +    } else
 175 +#endif
 176      if (!path) {
 177          if (!host) {
 178              error_setg(errp, "chardev: socket: no host given");
 179 @@ -1021,13 +1109,24 @@
 180      sock->has_reconnect = true;
 181      sock->reconnect = reconnect;
 182      sock->tls_creds = g_strdup(tls_creds);
 183 +#ifndef _WIN32
 184 +    sock->cmd = g_strdup(cmd);
 185 +#endif
 186
 187      addr = g_new0(SocketAddressLegacy, 1);
 188 +#ifndef _WIN32
 189 +    if (path || cmd) {
 190 +#else
 191      if (path) {
 192 +#endif
 193          UnixSocketAddress *q_unix;
 194          addr->type = SOCKET_ADDRESS_LEGACY_KIND_UNIX;
 195          q_unix = addr->u.q_unix.data = g_new0(UnixSocketAddress, 1);
 196 +#ifndef _WIN32
 197 +        q_unix->path = cmd ? g_strdup_printf("cmd:%s", cmd) : g_strdup(path);
 198 +#else
 199          q_unix->path = g_strdup(path);
 200 +#endif
 201      } else {
 202          addr->type = SOCKET_ADDRESS_LEGACY_KIND_INET;
 203          addr->u.inet.data = g_new(InetSocketAddress, 1);
 204 diff --git a/chardev/char.c b/chardev/char.c
 205 index 2ae4f465ec..5d52cd5de5 100644
 206 --- a/chardev/char.c
 207 +++ b/chardev/char.c
 208 @@ -792,6 +792,9 @@ QemuOptsList qemu_chardev_opts = {
 209          },{
 210              .name = "path",
 211              .type = QEMU_OPT_STRING,
 212 +        },{
 213 +            .name = "cmd",
 214 +            .type = QEMU_OPT_STRING,
 215          },{
 216              .name = "host",
 217              .type = QEMU_OPT_STRING,
 218 diff --git a/qapi/char.json b/qapi/char.json
 219 index ae19dcd1ed..6de0f29bcd 100644
 220 --- a/qapi/char.json
 221 +++ b/qapi/char.json
 222 @@ -241,6 +241,10 @@
 223  #
 224  # @addr: socket address to listen on (server=true)
 225  #        or connect to (server=false)
 226 +# @cmd: command to run via "sh -c" with stdin as one end of
 227 +#       a AF_UNIX SOCK_DSTREAM socket pair. The other end
 228 +#       is used by the chardev. Either an addr or a cmd can
 229 +#       be specified, but not both.
 230  # @tls-creds: the ID of the TLS credentials object (since 2.6)
 231  # @server: create server socket (default: true)
 232  # @wait: wait for incoming connection on server
 233 @@ -258,6 +262,7 @@
 234  # Since: 1.4
 235  ##
 236  { 'struct': 'ChardevSocket', 'data': { 'addr'       : 'SocketAddressLegacy',
 237 +                                     '*cmd'       : 'str',
 238                                       '*tls-creds'  : 'str',
 239                                       '*server'    : 'bool',
 240                                       '*wait'      : 'bool',
 241 --
 242 2.14.1