chardev/char-pty.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24 #include "qemu/osdep.h"
  25 #include "qapi/error.h"
  26 #include "qemu-common.h"
  27 #include "chardev/char.h"
  28 #include "io/channel-file.h"
  29 #include "qemu/sockets.h"
  30 #include "qemu/error-report.h"
  31
  32 #include "chardev/char-io.h"
  33
  34 #if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__)      \
  35     || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) \
  36     || defined(__GLIBC__)
  37
  38 typedef struct {
  39     Chardev parent;
  40     QIOChannel *ioc;
  41     int read_bytes;
  42
  43     /* Protected by the Chardev chr_write_lock.  */
  44     int connected;
  45     GSource *timer_src;
  46     GSource *open_source;
  47 } PtyChardev;
  48
  49 #define PTY_CHARDEV(obj) OBJECT_CHECK(PtyChardev, (obj), TYPE_CHARDEV_PTY)
  50
  51 static void pty_chr_update_read_handler_locked(Chardev *chr);
  52 static void pty_chr_state(Chardev *chr, int connected);
  53
  54 static void pty_chr_timer_cancel(PtyChardev *s)
  55 {
  56     if (s->timer_src) {
  57         g_source_destroy(s->timer_src);
  58         g_source_unref(s->timer_src);
  59         s->timer_src = NULL;
  60     }
  61 }
  62
  63 static void pty_chr_open_src_cancel(PtyChardev *s)
  64 {
  65     if (s->open_source) {
  66         g_source_destroy(s->open_source);
  67         g_source_unref(s->open_source);
  68         s->open_source = NULL;
  69     }
  70 }
  71
  72 static gboolean pty_chr_timer(gpointer opaque)
  73 {
  74     struct Chardev *chr = CHARDEV(opaque);
  75     PtyChardev *s = PTY_CHARDEV(opaque);
  76
  77     qemu_mutex_lock(&chr->chr_write_lock);
  78     pty_chr_timer_cancel(s);
  79     pty_chr_open_src_cancel(s);
  80     if (!s->connected) {
  81         /* Next poll ... */
  82         pty_chr_update_read_handler_locked(chr);
  83     }
  84     qemu_mutex_unlock(&chr->chr_write_lock);
  85     return FALSE;
  86 }
  87
  88 /* Called with chr_write_lock held.  */
  89 static void pty_chr_rearm_timer(Chardev *chr, int ms)
  90 {
  91     PtyChardev *s = PTY_CHARDEV(chr);
  92     char *name;
  93
  94     pty_chr_timer_cancel(s);
  95     name = g_strdup_printf("pty-timer-%s", chr->label);
  96     s->timer_src = qemu_chr_timeout_add_ms(chr, ms, pty_chr_timer, chr);
  97     g_source_set_name(s->timer_src, name);
  98     g_free(name);
  99 }
 100
 101 /* Called with chr_write_lock held.  */
 102 static void pty_chr_update_read_handler_locked(Chardev *chr)
 103 {
 104     PtyChardev *s = PTY_CHARDEV(chr);
 105     GPollFD pfd;
 106     int rc;
 107     QIOChannelFile *fioc = QIO_CHANNEL_FILE(s->ioc);
 108
 109     pfd.fd = fioc->fd;
 110     pfd.events = G_IO_OUT;
 111     pfd.revents = 0;
 112     do {
 113         rc = g_poll(&pfd, 1, 0);
 114     } while (rc == -1 && errno == EINTR);
 115     assert(rc >= 0);
 116
 117     if (pfd.revents & G_IO_HUP) {
 118         pty_chr_state(chr, 0);
 119     } else {
 120         pty_chr_state(chr, 1);
 121     }
 122 }
 123
 124 static void pty_chr_update_read_handler(Chardev *chr)
 125 {
 126     qemu_mutex_lock(&chr->chr_write_lock);
 127     pty_chr_update_read_handler_locked(chr);
 128     qemu_mutex_unlock(&chr->chr_write_lock);
 129 }
 130
 131 /* Called with chr_write_lock held.  */
 132 static int char_pty_chr_write(Chardev *chr, const uint8_t *buf, int len)
 133 {
 134     PtyChardev *s = PTY_CHARDEV(chr);
 135
 136     if (!s->connected) {
 137         /* guest sends data, check for (re-)connect */
 138         pty_chr_update_read_handler_locked(chr);
 139         if (!s->connected) {
 140             return len;
 141         }
 142     }
 143     return io_channel_send(s->ioc, buf, len);
 144 }
 145
 146 static GSource *pty_chr_add_watch(Chardev *chr, GIOCondition cond)
 147 {
 148     PtyChardev *s = PTY_CHARDEV(chr);
 149     if (!s->connected) {
 150         return NULL;
 151     }
 152     return qio_channel_create_watch(s->ioc, cond);
 153 }
 154
 155 static int pty_chr_read_poll(void *opaque)
 156 {
 157     Chardev *chr = CHARDEV(opaque);
 158     PtyChardev *s = PTY_CHARDEV(opaque);
 159
 160     s->read_bytes = qemu_chr_be_can_write(chr);
 161     return s->read_bytes;
 162 }
 163
 164 static gboolean pty_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
 165 {
 166     Chardev *chr = CHARDEV(opaque);
 167     PtyChardev *s = PTY_CHARDEV(opaque);
 168     gsize len;
 169     uint8_t buf[CHR_READ_BUF_LEN];
 170     ssize_t ret;
 171
 172     len = sizeof(buf);
 173     if (len > s->read_bytes) {
 174         len = s->read_bytes;
 175     }
 176     if (len == 0) {
 177         return TRUE;
 178     }
 179     ret = qio_channel_read(s->ioc, (char *)buf, len, NULL);
 180     if (ret <= 0) {
 181         pty_chr_state(chr, 0);
 182         return FALSE;
 183     } else {
 184         pty_chr_state(chr, 1);
 185         qemu_chr_be_write(chr, buf, ret);
 186     }
 187     return TRUE;
 188 }
 189
 190 static gboolean qemu_chr_be_generic_open_func(gpointer opaque)
 191 {
 192     Chardev *chr = CHARDEV(opaque);
 193     PtyChardev *s = PTY_CHARDEV(opaque);
 194
 195     s->open_source = NULL;
 196     qemu_chr_be_event(chr, CHR_EVENT_OPENED);
 197     return FALSE;
 198 }
 199
 200 /* Called with chr_write_lock held.  */
 201 static void pty_chr_state(Chardev *chr, int connected)
 202 {
 203     PtyChardev *s = PTY_CHARDEV(chr);
 204
 205     if (!connected) {
 206         pty_chr_open_src_cancel(s);
 207         remove_fd_in_watch(chr);
 208         s->connected = 0;
 209         /* (re-)connect poll interval for idle guests: once per second.
 210          * We check more frequently in case the guests sends data to
 211          * the virtual device linked to our pty. */
 212         pty_chr_rearm_timer(chr, 1000);
 213     } else {
 214         pty_chr_timer_cancel(s);
 215         if (!s->connected) {
 216             g_assert(s->open_source == NULL);
 217             s->open_source = g_idle_source_new();
 218             s->connected = 1;
 219             g_source_set_callback(s->open_source,
 220                                   qemu_chr_be_generic_open_func,
 221                                   chr, NULL);
 222             g_source_attach(s->open_source, chr->gcontext);
 223         }
 224         if (!chr->gsource) {
 225             chr->gsource = io_add_watch_poll(chr, s->ioc,
 226                                                pty_chr_read_poll,
 227                                                pty_chr_read,
 228                                                chr, chr->gcontext);
 229         }
 230     }
 231 }
 232
 233 static void char_pty_finalize(Object *obj)
 234 {
 235     Chardev *chr = CHARDEV(obj);
 236     PtyChardev *s = PTY_CHARDEV(obj);
 237
 238     qemu_mutex_lock(&chr->chr_write_lock);
 239     pty_chr_state(chr, 0);
 240     object_unref(OBJECT(s->ioc));
 241     pty_chr_timer_cancel(s);
 242     qemu_mutex_unlock(&chr->chr_write_lock);
 243     qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
 244 }
 245
 246 static void char_pty_open(Chardev *chr,
 247                           ChardevBackend *backend,
 248                           bool *be_opened,
 249                           Error **errp)
 250 {
 251     PtyChardev *s;
 252     int master_fd, slave_fd;
 253     char pty_name[PATH_MAX];
 254     char *name;
 255
 256     master_fd = qemu_openpty_raw(&slave_fd, pty_name);
 257     if (master_fd < 0) {
 258         error_setg_errno(errp, errno, "Failed to create PTY");
 259         return;
 260     }
 261
 262     close(slave_fd);
 263     qemu_set_nonblock(master_fd);
 264
 265     chr->filename = g_strdup_printf("pty:%s", pty_name);
 266     error_report("char device redirected to %s (label %s)",
 267                  pty_name, chr->label);
 268
 269     s = PTY_CHARDEV(chr);
 270     s->ioc = QIO_CHANNEL(qio_channel_file_new_fd(master_fd));
 271     name = g_strdup_printf("chardev-pty-%s", chr->label);
 272     qio_channel_set_name(QIO_CHANNEL(s->ioc), name);
 273     g_free(name);
 274     s->timer_src = NULL;
 275     *be_opened = false;
 276 }
 277
 278 static void char_pty_class_init(ObjectClass *oc, void *data)
 279 {
 280     ChardevClass *cc = CHARDEV_CLASS(oc);
 281
 282     cc->open = char_pty_open;
 283     cc->chr_write = char_pty_chr_write;
 284     cc->chr_update_read_handler = pty_chr_update_read_handler;
 285     cc->chr_add_watch = pty_chr_add_watch;
 286 }
 287
 288 static const TypeInfo char_pty_type_info = {
 289     .name = TYPE_CHARDEV_PTY,
 290     .parent = TYPE_CHARDEV,
 291     .instance_size = sizeof(PtyChardev),
 292     .instance_finalize = char_pty_finalize,
 293     .class_init = char_pty_class_init,
 294 };
 295
 296 static void register_types(void)
 297 {
 298     type_register_static(&char_pty_type_info);
 299 }
 300
 301 type_init(register_types);
 302
 303 #endif