fix missing deref of tty data when destroyed (#2)

This patch allows multiple clients to open the ttynvt device at the same time.
This is useful if an application wants to get/set termios (ioctls) while the
device is already opened by an other application.

src/ttynvt.c

@@ -55,14 +55,17 @@ static struct ttynvt_param {
 typedef struct {
     pthread_mutex_t tty_lock;
     pthread_mutex_t poll_lock;
+    pthread_mutex_t read_lock;
+    pthread_mutex_t write_lock;
+    pthread_mutex_t ioctl_lock;
     pthread_t       ptid_poll;
     pthread_t       ptid_read;
 
     struct fuse_pollhandle *ph;
 
     volatile int    rel_pending;
-    volatile int    slave_suspended;    /*waiting for application to read data */
-    volatile int    master_suspended;   /*server is not ready to receive data */
+    volatile int    slave_suspended;    /* Waiting for application to read data */
+    volatile int    master_suspended;   /* Server is not ready to receive data */
     struct pollfd   fds[3];
 
     char            net_buf[NET_BUF_SIZE];
@@ -80,8 +83,18 @@ typedef struct {
     int             epipe;
 
     tn_ctx_t       *tn;
+
+    int             seq;
+    struct ttynvt_cli_s *cli;
 } ttynvt_t;
 
+static ttynvt_t *ptty = NULL;
+
+typedef struct ttynvt_cli_s {
+    int             id;
+    ttynvt_t       *tty;
+    struct ttynvt_cli_s *next;
+} ttynvt_cli_t;
 
 static pthread_mutex_t access_lock = PTHREAD_MUTEX_INITIALIZER;
 
@@ -114,7 +127,6 @@ static void ttynvt_interrupted(fuse_req_t req, void *data)
     pthread_kill(thread, SIGUSR2);
 }
 
-
 static void _ttynvt_sleep_us(unsigned int tus)
 {
     struct timespec ts;
@@ -143,7 +155,6 @@ static int _check_dev(void)
     return rc;
 }
 
-
 static void _fd_close(int fd)
 {
     if (fd >= 0)
@@ -406,24 +417,49 @@ static void _ttynvt_ctx_destroy(ttynvt_t * tty)
 
 static void ttynvt_open(fuse_req_t req, struct fuse_file_info *info)
 {
-    ttynvt_t       *tty;
+    ttynvt_t       *tty = ptty;
+    ttynvt_cli_t   *tty_cli;
     char           *slave_name;
     struct termios  ios;
     int             fd;
     int             res;
     int             n;
 
-    pthread_mutex_lock(&access_lock);
 
-    nvt_log(LOG_INFO, "Connecting to server: %s\n", ttynvt_param.server);
-
-    tty = _ttynvt_ctx_create();
-    if (!tty)
+    tty_cli = calloc(1, sizeof(ttynvt_cli_t));
+    if (!tty_cli)
     {
         fuse_reply_err(req, ENOMEM);
         return;
     }
 
+    pthread_mutex_lock(&access_lock);
+
+    if (tty == NULL)
+        tty = _ttynvt_ctx_create();
+    if (!tty)
+    {
+        fuse_reply_err(req, ENOMEM);
+        free(tty_cli);
+        pthread_mutex_unlock(&access_lock);
+        return;
+    }
+
+    tty_cli->id = tty->seq++;
+    tty_cli->tty = tty;
+    tty_cli->next = tty->cli;
+
+    tty->cli = tty_cli;
+
+    nvt_log(LOG_INFO, "Client open (%d)\n", tty_cli->id);
+
+    if (ptty)
+        goto out;
+
+    ptty = tty;
+
+    nvt_log(LOG_INFO, "Connecting to server: %s\n", ttynvt_param.server);
+
     fd = socket_create_client(ttynvt_param.server);
     if (fd < 0)
     {
@@ -435,7 +471,7 @@ static void ttynvt_open(fuse_req_t req, struct fuse_file_info *info)
     tty->fds[FD_NET].events = POLLIN;
     tty->net_cnt = 0;
 
-    if ((fd = open("/dev/ptmx", O_RDWR)) < 0)   /* open master */
+    if ((fd = open("/dev/ptmx", O_RDWR)) < 0)   /* Open master */
         goto open_err;
 
     tty->fds[FD_MASTER].fd = fd;
@@ -453,11 +489,11 @@ static void ttynvt_open(fuse_req_t req, struct fuse_file_info *info)
     if (ioctl(fd, TCSETS, &ios) < 0)
         goto open_err;
 
-    grantpt(fd);                /* change permission of slave */
-    unlockpt(fd);               /* unlock slave */
-    slave_name = ptsname(fd);   /* get name of slave */
+    grantpt(fd);                /* Change permission of slave */
+    unlockpt(fd);               /* Unlock slave */
+    slave_name = ptsname(fd);   /* Get name of slave */
 
-    if ((fd = open(slave_name, O_RDWR | O_NOCTTY)) < 0) /* open slave */
+    if ((fd = open(slave_name, O_RDWR | O_NOCTTY)) < 0) /* Open slave */
         goto open_err;
 
     ioctl(fd, TCGETS, &tty->tio);
@@ -478,26 +514,34 @@ static void ttynvt_open(fuse_req_t req, struct fuse_file_info *info)
 
     if ((res = pthread_mutex_init(&tty->tty_lock, NULL) < 0) ||
         (res = pthread_mutex_init(&tty->poll_lock, NULL) < 0) ||
+        (res = pthread_mutex_init(&tty->ioctl_lock, NULL) < 0) ||
+        (res = pthread_mutex_init(&tty->read_lock, NULL) < 0) ||
+        (res = pthread_mutex_init(&tty->write_lock, NULL) < 0) ||
         (res = pthread_create(&tty->ptid_poll, NULL, &_read_net, tty)))
     {
         errno = res;
         goto open_err;
     }
 
-    info->fh = (uintptr_t) tty;
+    nvt_log(LOG_INFO, "Connected to server: %s\n", ttynvt_param.server);
+
+  out:
+    info->fh = (uintptr_t) tty_cli;
     info->nonseekable = 1;
     info->direct_io = 1;
 
-    nvt_log(LOG_INFO, "Connected to server: %s\n", ttynvt_param.server);
-
     fuse_reply_open(req, info);
+
+    pthread_mutex_unlock(&access_lock);
     return;
 
   open_err:
     for (n = 0; n < 3; n++)
         _fd_close(tty->fds[n].fd);
 
+    free(tty_cli);
     _ttynvt_ctx_destroy(tty);
+    ptty = NULL;
 
     fuse_reply_err(req, errno);
 
@@ -511,11 +555,14 @@ static void
 ttynvt_read(fuse_req_t req, size_t size, off_t off,
             struct fuse_file_info *info)
 {
-    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
+    ttynvt_cli_t   *tty_cli = (ttynvt_cli_t *) (uintptr_t) info->fh;
+    ttynvt_t       *tty = tty_cli->tty;
     char            buf[TMP_BUF_SIZE];
     int             res, nr;
 
-    DBG2("%s\n", __func__);
+    pthread_mutex_lock(&tty->read_lock);
+
+    DBG2("%s (%d)\n", __func__, tty_cli->id);
 
     if (tty->error)
     {
@@ -529,7 +576,7 @@ ttynvt_read(fuse_req_t req, size_t size, off_t off,
         else
             fuse_reply_err(req, EBADFD);
 
-        return;
+        goto out;
     }
 
     if (size > TMP_BUF_SIZE)
@@ -556,36 +603,42 @@ ttynvt_read(fuse_req_t req, size_t size, off_t off,
     {
         DBG2("%s: error: %m\n", __func__);
         fuse_reply_err(req, errno);
-        return;
+        goto out;
     }
 
-    DBG2("%s: fd=%d: sz=%u/%u: '%.*s'\n", __func__,
-         tty->fds[FD_SLAVE].fd, res, (int)size, res, buf);
+    DBG2("%s (%d): fd=%d: sz=%u/%u: '%.*s'\n", __func__,
+         tty_cli->id, tty->fds[FD_SLAVE].fd, res, (int)size, res, buf);
 
     fuse_reply_buf(req, buf, res);
+
+  out:
+    pthread_mutex_unlock(&tty->read_lock);
 }
 
 static void
 ttynvt_write(fuse_req_t req, const char *data, size_t size, off_t off,
              struct fuse_file_info *info)
 {
-    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
+    ttynvt_cli_t   *tty_cli = (ttynvt_cli_t *) (uintptr_t) info->fh;
+    ttynvt_t       *tty = tty_cli->tty;
     int             res;
 
-    DBG2("%s: fd=%d: sz=%u: '%.*s'\n", __func__,
-         tty->fds[FD_SLAVE].fd, (int)size, (int)size, data);
+    pthread_mutex_lock(&tty->write_lock);
+
+    DBG2("%s (%d): fd=%d: sz=%u: '%.*s'\n", __func__,
+         tty_cli->id, tty->fds[FD_SLAVE].fd, (int)size, (int)size, data);
 
     if (size == 0)
     {
         fuse_reply_write(req, 0);
-        return;
+        goto out;
     }
 
     if (tty->error)
     {
         DBG2("%s: tty->error=%d\n", __func__, tty->error);
         fuse_reply_err(req, EPIPE);
-        return;
+        goto out;
     }
 
     res = write(tty->fds[FD_SLAVE].fd, data, size);
@@ -594,7 +647,7 @@ ttynvt_write(fuse_req_t req, const char *data, size_t size, off_t off,
         DBG2("%s: error: %m\n", __func__);
         tty->error = 1;
         fuse_reply_err(req, errno);
-        return;
+        goto out;
     }
     else if (res != (int)size)
     {
@@ -603,6 +656,9 @@ ttynvt_write(fuse_req_t req, const char *data, size_t size, off_t off,
     }
 
     fuse_reply_write(req, res);
+
+  out:
+    pthread_mutex_unlock(&tty->write_lock);
 }
 
 static int baudrate(speed_t speed)
@@ -780,7 +836,8 @@ ttynvt_ioctl(fuse_req_t req, int cmd, void *arg,
              struct fuse_file_info *info, unsigned int flags,
              const void *in_buf, size_t in_bufsz, size_t out_bufsz)
 {
-    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
+    ttynvt_cli_t   *tty_cli = (ttynvt_cli_t *) (uintptr_t) info->fh;
+    ttynvt_t       *tty = tty_cli->tty;
     struct termios2 *tio = &tty->tio;
     struct winsize  ws;
     unsigned int    tiocm, baud;
@@ -790,14 +847,16 @@ ttynvt_ioctl(fuse_req_t req, int cmd, void *arg,
     uint8_t         byte;
     uint32_t        byte4;
 
-    DBG("%s: cmd=%s arg=%p ibuf=%p:%u obuf=:%u\n", __func__,
-        _ioctl_name(cmd), arg, in_buf,
+    pthread_mutex_lock(&tty->ioctl_lock);
+
+    DBG("%s (%d): cmd=%s arg=%p ibuf=%p:%u obuf=:%u\n", __func__,
+        tty_cli->id, _ioctl_name(cmd), arg, in_buf,
         (unsigned int)in_bufsz, (unsigned int)out_bufsz);
 
     if (ttynvt_param.raw)
     {
         fuse_reply_ioctl(req, 0, 0, 0);
-        return;
+        goto out;
     }
 
     switch (cmd)
@@ -988,7 +1047,7 @@ ttynvt_ioctl(fuse_req_t req, int cmd, void *arg,
         if (res < 0)
         {
             fuse_reply_err(req, errno);
-            return;
+            goto out;
         }
         fuse_reply_ioctl(req, 0, &ws, sizeof(struct winsize));
         break;
@@ -999,7 +1058,7 @@ ttynvt_ioctl(fuse_req_t req, int cmd, void *arg,
         if (res < 0)
         {
             fuse_reply_err(req, errno);
-            return;
+            goto out;
         }
         fuse_reply_ioctl(req, 0, &ws, sizeof(struct winsize));
         break;
@@ -1060,17 +1119,21 @@ ttynvt_ioctl(fuse_req_t req, int cmd, void *arg,
         }
         break;
     }
+
+  out:
+    pthread_mutex_unlock(&tty->ioctl_lock);
 }
 
 static void
 ttynvt_poll(fuse_req_t req, struct fuse_file_info *info,
             struct fuse_pollhandle *ph)
 {
-    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
+    ttynvt_cli_t   *tty_cli = (ttynvt_cli_t *) (uintptr_t) info->fh;
+    ttynvt_t       *tty = tty_cli->tty;
     int             revents = 0;
 
-    DBG2("%s: tty->pollin=%d tty->error/epipe=%d/%d\n",
-         __func__, tty->pollin, tty->error, tty->epipe);
+    DBG2("%s (%d): tty->pollin=%d tty->error/epipe=%d/%d\n",
+         __func__, tty_cli->id, tty->pollin, tty->error, tty->epipe);
 
     _update_notify(tty, ph);
 
@@ -1097,16 +1160,38 @@ ttynvt_poll(fuse_req_t req, struct fuse_file_info *info,
 
 static void ttynvt_release(fuse_req_t req, struct fuse_file_info *info)
 {
-    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
+    ttynvt_cli_t   *tty_cli = (ttynvt_cli_t *) (uintptr_t) info->fh;
+    ttynvt_t       *tty = tty_cli->tty;
+    ttynvt_cli_t   *tmp, *prev;
 
     DBG("%s\n", __func__);
 
+    pthread_mutex_lock(&access_lock);
+
+    for (tmp = tty->cli, prev = NULL; tmp; prev = tmp, tmp = tmp->next)
+        if (tmp == tty_cli)
+        {
+            nvt_log(LOG_INFO, "Client release (%d)\n", tmp->id);
+            if (prev)
+                prev->next = tmp->next;
+            else
+                tty->cli = tmp->next;
+            free(tmp);
+            break;
+        }
+
+    if (tty->cli)
+        goto out;
+
     tty->rel_pending = 1;
 
     pthread_cancel(tty->ptid_poll);
     pthread_join(tty->ptid_poll, NULL);
     pthread_mutex_destroy(&tty->tty_lock);
     pthread_mutex_destroy(&tty->poll_lock);
+    pthread_mutex_destroy(&tty->ioctl_lock);
+    pthread_mutex_destroy(&tty->read_lock);
+    pthread_mutex_destroy(&tty->write_lock);
 
     if (ttynvt_param.close_delay_us)
         _ttynvt_sleep_us(ttynvt_param.close_delay_us);
@@ -1119,11 +1204,13 @@ static void ttynvt_release(fuse_req_t req, struct fuse_file_info *info)
         fuse_pollhandle_destroy(tty->ph);
 
     _ttynvt_ctx_destroy(tty);
-
-    fuse_reply_err(req, 0);
+    ptty = NULL;
 
     nvt_log(LOG_INFO, "Disconnected from server: %s\n", ttynvt_param.server);
 
+  out:
+    fuse_reply_err(req, 0);
+
     pthread_mutex_unlock(&access_lock);
 }