drivers/serial: Add support for Ctrl-Z. This works just like the recently added Ctrl-C support except that SIGSTP is sent when the Ctrl-Z characters is encountered vs. SIGINT.

drivers/serial/Kconfig

@@ -165,17 +165,55 @@ config TTY_SIGINT
 		should cause an immediate End-of-File result.
 
 config TTY_SIGINT_CHAR
-	int "Serial parse SIGINT characters"
+	hex "Serial parse SIGINT characters"
-	default 3 if SERIAL_CONSOLE
+	default 0x03 if SERIAL_CONSOLE
-	default 4 if !SERIAL_CONSOLE
+	default 0x04 if !SERIAL_CONSOLE
 	depends on TTY_SIGINT
 	---help---
-		Use ASCII 3 (Ctrl-c) or 4 (ctrl-d) inputs to determine whether to
+		Use ASCII 0x03 (Ctrl-c) or 0x04 (ctrl-d) inputs to determine whether
-		send a SIGINT event.  Other characters may also be selected.
+		to send a SIGINT event.  Other characters may also be selected.
 
 		REVISIT:  Traditionally Ctrl-C would generate SIGINT.  Ctrl-D is the
 		End-of-File character that should close the stream.
 
+config TTY_SIGSTP
+	bool "Support SIGSTP"
+	default n
+	select CONFIG_SIG_SIGSTOP_ACTION
+	depends on !DISABLE_SIGNALS && SERIAL_TERMIOS
+	---help---
+		Whether support Ctrl-z event.  Enabled automatically for console
+		devices.  May be enabled for other serial devices using the ISIG bit
+		in the Termios c_lflag.
+
+		REVISIT:  This implementation is compliant but incomplete.  The
+		c_lflag ISIG bit normally enables/disables INTR, QUIT, SUSP, and
+		DSUSP character processing.  The relationship between these names,
+		standard signals, and typical key presses are as follows:
+
+		  INTR   SIGINT   Ctrl-C  ETX(0x03) Interrupt
+		  KILL   SIGKILL  Ctrl-U  NAK(0x15) Kill
+		  QUIT   SIGQUIT  Ctrl-\  FS (0x1c) Quit
+		  SUSP   SIGSTP   Ctrl-Z  SUB(0x1a) Suspend
+		  DSUSP  SIGSTP   Ctrl-Y  EM (0x19) Delayed suspend
+
+		Additional requirements:
+		  - SIGKILL cannot be caught or ignored.  Compared to SIGTERM which
+		    is like SIGKILL but can be caught or ignored.
+		  - SIGQUIT is like SIGINT but causes generation of a core dump
+		  - SIGSTOP cannot be caught or ignored.  SIGSTP is like SIGSTOP but
+		    can be caught or ignored ignored.
+		  - The delayed suspend (DSUSD) is like suspend (SUPD), except that
+		    the suspension is delayed until the next read operation
+
+config TTY_SIGSTP_CHAR
+	hex "Serial parse SIGSTP characters"
+	default 0x1a
+	depends on TTY_SIGSTP
+	---help---
+		Use ASCII 0x1a (Ctrl-z) input to determine whether to send a SIGSTP
+		event.  Other characters may also be selected.
+
 #
 # Serial console selection
 #

drivers/serial/serial.c

@@ -1372,7 +1372,7 @@ static int uart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
             break;
 #endif
 
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
           /* Make the given terminal the controlling terminal of the calling process */
 
           case TIOCSCTTY:
@@ -1436,7 +1436,7 @@ static int uart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
               dev->tc_oflag = termiosp->c_oflag;
               dev->tc_lflag = termiosp->c_lflag;
 
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
               /* If the ISIG flag has been cleared in c_lflag, then un-
                * register the controlling terminal.
                */
@@ -1611,7 +1611,7 @@ errout:
 
 int uart_register(FAR const char *path, FAR uart_dev_t *dev)
 {
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
   /* Initialize  of the task that will receive SIGINT signals. */
 
   dev->pid = (pid_t)-1;

drivers/serial/serial_dma.c

@@ -53,58 +53,81 @@
  ************************************************************************************/
 
 /************************************************************************************
- * Name: uart_check_sigint
+ * Name: uart_check_signo
  *
  * Description:
- *   Check if the SIGINT character is in the contiguous Rx DMA buffer region.
+ *   Check if the SIGINT or SIGSTP character is in the contiguous Rx DMA buffer
+ *   region.  The first signal associated with the first such character is returned.
+ *
+ *   If there multiple such characters in the buffer, only the signal associated
+ *   with the first is returned (this a bug!)
+ *
+ * Returned Value:
+ *   0 if a signal-related character does not appear in the.  Otherwise, SIGKILL or
+ *   SIGSTP may be returned to indicate the appropriate signal action.
  *
  ************************************************************************************/
 
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
-static bool uart_check_sigint(const char *buf, size_t size)
+static int uart_check_signo(const char *buf, size_t size)
 {
   size_t i;
 
   for (i = 0; i < size; i++)
     {
+#ifdef CONFIG_TTY_SIGINT
       if (buf[i] == CONFIG_TTY_SIGINT_CHAR)
         {
-          return true;
+          return SIGINT;
         }
+#endif
+
+#ifdef CONFIG_TTY_SIGSTP
+      if (buf[i] == CONFIG_TTY_SIGSTP_CHAR)
+        {
+          return SIGSTP;
+        }
+#endif
     }
 
-  return false;
+  return 0;
 }
 #endif
 
 /************************************************************************************
- * Name: uart_recvchars_sigkill
+ * Name: uart_recvchars_signo
  *
  * Description:
  *   Check if the SIGINT character is anywhere in the newly received DMA buffer.
  *
- *   REVISIT:  We must also remove the SIGINT character from the Rx buffer.  It
+ *   REVISIT:  We must also remove the SIGINT/SIGSTP character from the Rx buffer.  It
  *   should not be read as normal data by the caller.
  *
  ************************************************************************************/
 
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
-static bool uart_recvchars_sigkill(FAR uart_dev_t *dev)
+static int uart_recvchars_signo(FAR uart_dev_t *dev)
 {
   FAR struct uart_dmaxfer_s *xfer = &dev->dmarx;
+  int signo;
+
+  /* Check if the valid DMAed data is in one or two contiguous regions */
 
   if (xfer->nbytes <= xfer->length)
     {
-      return uart_check_sigint(xfer->buffer, xfer->nbytes);
+      return uart_check_signo(xfer->buffer, xfer->nbytes);
     }
   else
     {
-      if (uart_check_sigint(xfer->buffer, xfer->length))
+      /* REVISIT:  Additional signals could be in the second region. */
+
+      signo = uart_check_signo(xfer->buffer, xfer->length);
+      if (signo != 0)
         {
-          return true;
+          return signo;
         }
 
-      return uart_check_sigint(xfer->nbuffer, xfer->nbytes - xfer->length);
+      return uart_check_signo(xfer->nbuffer, xfer->nbytes - xfer->length);
     }
 }
 #endif
@@ -324,14 +347,14 @@ void uart_recvchars_done(FAR uart_dev_t *dev)
   FAR struct uart_dmaxfer_s *xfer = &dev->dmarx;
   FAR struct uart_buffer_s *rxbuf = &dev->recv;
   size_t nbytes = xfer->nbytes;
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
-  bool needkill = false;
+  int signo = 0;
 
   /* Check if the SIGINT character is anywhere in the newly received DMA buffer. */
 
-  if (dev->pid >= 0 && uart_recvchars_sigkill(dev))
+  if (dev->pid >= 0)
     {
-      needkill = true;
+      signo = uart_recvchars_signo(dev);
     }
 #endif
 
@@ -350,12 +373,12 @@ void uart_recvchars_done(FAR uart_dev_t *dev)
       uart_datareceived(dev);
     }
 
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
-  /* Send the SIGINT signal if needed */
+  /* Send the signal if necessary */
 
-  if (needkill)
+  if (signo != 0)
     {
-      kill(dev->pid, SIGINT);
+      kill(dev->pid, signo);
       uart_reset_sem(dev);
     }
 #endif

drivers/serial/serial_io.c

@@ -122,12 +122,12 @@ void uart_recvchars(FAR uart_dev_t *dev)
   FAR struct uart_buffer_s *rxbuf = &dev->recv;
 #ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
   unsigned int watermark;
-#endif
-#ifdef CONFIG_TTY_SIGINT
-  bool needkill = false;
 #endif
   unsigned int status;
   int nexthead = rxbuf->head + 1;
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
+  int signo = 0;
+#endif
   uint16_t nbytes = 0;
 
   if (nexthead >= rxbuf->size)
@@ -136,7 +136,7 @@ void uart_recvchars(FAR uart_dev_t *dev)
     }
 
 #ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
-  /* Pre-calcuate the watermark level that we will need to test against. */
+  /* Pre-calculate the watermark level that we will need to test against. */
 
   watermark = (CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK * rxbuf->size) / 100;
 #endif
@@ -210,7 +210,27 @@ void uart_recvchars(FAR uart_dev_t *dev)
            * into the Rx buffer.  It should not be read as normal data.
            */
 
-          needkill = true;
+          signo = SIGINT;
+        }
+      else
+#endif
+#ifdef CONFIG_TTY_SIGSTP
+      /* Is this the special character that will generate the SIGSTP signal? */
+
+      if (dev->pid >= 0 && ch == CONFIG_TTY_SIGSTP_CHAR)
+        {
+#ifdef CONFIG_TTY_SIGINT
+          /* Give precedence to SIGINT */
+
+          if (signo == 0)
+#endif
+            {
+              /* Note that the kill is needed and do not put the character
+               * into the Rx buffer.  It should not be read as normal data.
+               */
+
+              signo = SIGSTP;
+            }
         }
       else
 #endif
@@ -249,12 +269,12 @@ void uart_recvchars(FAR uart_dev_t *dev)
       uart_datareceived(dev);
     }
 
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
-  /* Send the SIGINT signal if needed */
+  /* Send the signal if necessary */
 
-  if (needkill)
+  if (signo != 0)
     {
-      kill(dev->pid, SIGINT);
+      kill(dev->pid, signo);
       uart_reset_sem(dev);
     }
 #endif

include/nuttx/serial/serial.h

@@ -286,8 +286,8 @@ struct uart_dev_s
   tcflag_t             tc_iflag;     /* Input modes */
   tcflag_t             tc_oflag;     /* Output modes */
   tcflag_t             tc_lflag;     /* Local modes */
-#ifdef CONFIG_TTY_SIGINT
+#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
-  pid_t                pid;          /* Thread PID to receive SIGINT signals (-1 if none) */
+  pid_t                pid;          /* Thread PID to receive signals (-1 if none) */
 #endif
 #endif
 

sched/signal/sig_default.c

@@ -39,6 +39,7 @@
 
 #include <nuttx/config.h>
 
+#include <sys/wait.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
@@ -240,6 +241,12 @@ static void nxsig_abnormal_termination(int signo)
 static void nxsig_stop_task(int signo)
 {
   FAR struct tcb_s *rtcb = (FAR struct tcb_s *)this_task();
+#if defined(CONFIG_SCHED_WAITPID) && !defined(CONFIG_SCHED_HAVE_PARENT)
+  FAR struct task_group_s *group;
+
+  DEBUGASSERT(rtcb != NULL && rtcb->group != NULL);
+  group = rtcb->group;
+#endif
 
   /* Careful:  In the multi-threaded task, the signal may be handled on a
    * child pthread.
@@ -254,7 +261,7 @@ static void nxsig_stop_task(int signo)
   group_suspendchildren(rtcb);
 #endif
 
-  /* Lock the scheudler so this thread is not pre-empted until after we
+  /* Lock the scheduler so this thread is not pre-empted until after we
    * call sched_suspend().
    */
 
@@ -266,7 +273,7 @@ static void nxsig_stop_task(int signo)
    * waitpid flags.
    */
 
-  if (group->tg_waitflags & WUNTRACED) != 0)
+  if ((group->tg_waitflags & WUNTRACED) != 0)
     {
       /* Return zero for exit status (we are not exiting, however) */