drivers/pty: support pty write to send signal, like serial driver

The interaction between the shell service in adb and adbd occurs through a pseudo-terminal (pty).
so, when a command is launched through adb shell from a PC, users now have the ability to pause
or kill the launched,application by inputting specific commands CONFIG_TTY_SIGTSTP_CHAR or
CONFIG_TTY_SIGTINT_CHAR, akin to the capabilities provided by nsh.

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>

drivers/serial/pty.c

@@ -44,6 +44,7 @@
 #include <nuttx/semaphore.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/serial/pty.h>
+#include <nuttx/signal.h>
 
 #include "pty.h"
 
@@ -77,6 +78,9 @@ struct pty_dev_s
   struct file pd_sink;          /* Accepts data from write() method (pipe input) */
   bool pd_master;               /* True: this is the master */
   uint8_t pd_escape;            /* Number of the character to be escaped */
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP)
+  pid_t pd_pid;                 /* Thread PID to receive signals (-1 if none) */
+#endif
   tcflag_t pd_iflag;            /* Terminal input modes */
   tcflag_t pd_lflag;            /* Terminal local modes */
   tcflag_t pd_oflag;            /* Terminal output modes */
@@ -540,6 +544,9 @@ static ssize_t pty_write(FAR struct file *filep,
   FAR struct pty_dev_s *dev;
   ssize_t ntotal;
   ssize_t nwritten;
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP)
+  pid_t pid;
+#endif
   size_t i;
   char ch;
 
@@ -547,6 +554,14 @@ static ssize_t pty_write(FAR struct file *filep,
   dev   = inode->i_private;
   DEBUGASSERT(dev != NULL);
 
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP)
+  pid = dev->pd_devpair->pp_master.pd_pid;
+  if (dev->pd_master)
+    {
+      pid = dev->pd_devpair->pp_slave.pd_pid;
+    }
+#endif
+
   /* Do output post-processing */
 
   if ((dev->pd_oflag & OPOST) != 0)
@@ -599,6 +614,22 @@ static ssize_t pty_write(FAR struct file *filep,
                 }
             }
 
+#ifdef CONFIG_TTY_SIGINT
+          if (pid > 0 && ch == CONFIG_TTY_SIGINT_CHAR)
+            {
+              nxsig_kill(pid, SIGINT);
+              return 1;
+            }
+#endif
+
+#ifdef CONFIG_TTY_SIGTSTP
+          if (pid > 0 && ch == CONFIG_TTY_SIGTSTP_CHAR)
+            {
+              nxsig_kill(pid, SIGTSTP);
+              return 1;
+            }
+#endif
+
           /* Transfer the (possibly translated) character..  This will block
            * if the sink pipe is full
            *
@@ -798,6 +829,33 @@ static int pty_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
         }
         break;
 
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP)
+      /* Make the controlling terminal of the calling process */
+
+      case TIOCSCTTY:
+        {
+          /* Save the PID of the recipient of the SIGINT signal. */
+
+          if ((int)arg < 0 || dev->pd_pid >= 0)
+            {
+              ret = -EINVAL;
+            }
+          else
+            {
+              dev->pd_pid = (pid_t)arg;
+              ret = 0;
+            }
+        }
+        break;
+
+      case TIOCNOTTY:
+        {
+          dev->pd_pid = INVALID_PROCESS_ID;
+          ret = 0;
+        }
+        break;
+#endif
+
       /* Any unrecognized IOCTL commands will be passed to the contained
        * pipe driver.
        *
@@ -1017,6 +1075,12 @@ int pty_register2(int minor, bool susv1)
   devpair->pp_slave.pd_devpair  = devpair;
   devpair->pp_slave.pd_oflag    = OPOST | ONLCR;
   devpair->pp_slave.pd_lflag    = ECHO;
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP)
+  /* Initialize  of the task that will receive SIGINT signals. */
+
+  devpair->pp_master.pd_pid = INVALID_PROCESS_ID;
+  devpair->pp_slave.pd_pid = INVALID_PROCESS_ID;
+#endif
 
   /* Register the master device
    *