Suppress SIGTTOU when handling errors

Calls to error () can cause SIGTTOU to send gdb to the background.

For example, on an Arm build:
  (gdb) b main
  Breakpoint 1 at 0x10774: file /build/gdb/testsuite/../../../src/binutils-gdb/gdb/testsuite/gdb.base/watchpoint.c, line 174.
  (gdb) r
  Starting program: /build/gdb/testsuite/outputs/gdb.base/watchpoint/watchpoint

  [1]+  Stopped                 ../gdb ./outputs/gdb.base/watchpoint/watchpoint
  localhost$ fg
  ../gdb ./outputs/gdb.base/watchpoint/watchpoint
  Cannot parse expression `.L1199 4@r4'.
  warning: Probes-based dynamic linker interface failed.
  Reverting to original interface.

The SIGTTOU is raised whilst inside a syscall during the call to tcdrain.
Fix is to use scoped_ignore_sigttou to ensure SIGTTOU is blocked.

In addition fix include comments - job_control is not included via terminal.h

gdb/ChangeLog:

	* event-top.c: Remove include comment.
	* inflow.c (class scoped_ignore_sigttou): Move from here...
	* inflow.h (class scoped_ignore_sigttou): ...to here.
	* ser-unix.c (hardwire_drain_output): Block SIGTTOU during drain.
	* top.c:  Remove include comment.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 2d8bec90cea0baad095b39e952c86ae3fa3e0966..15fe856541aab5bf40c6ba359e8cf9e400a9ce4d 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2019-05-28  Alan Hayward  <alan.hayward@arm.com>
+
+       * event-top.c: Remove include comment.
+       * inflow.c (class scoped_ignore_sigttou): Move from here...
+       * inflow.h (class scoped_ignore_sigttou): ...to here.
+       * ser-unix.c (hardwire_drain_output): Block SIGTTOU during drain.
+       * top.c:  Remove include comment.
+
 2019-05-27  Tom Tromey  <tom@tromey.com>
 
        * NEWS: Fix typo.

diff --git a/gdb/event-top.c b/gdb/event-top.c
index 3ccf136ff12d3478bd18c81aa3eb043b3f164cee..93b7d2d28bcdb924b44d9721922dd1af1cfe6155 100644 (file)
--- a/gdb/event-top.c
+++ b/gdb/event-top.c
@@ -24,7 +24,7 @@
 #include "inferior.h"
 #include "infrun.h"
 #include "target.h"
-#include "terminal.h"          /* for job_control */
+#include "terminal.h"
 #include "event-loop.h"
 #include "event-top.h"
 #include "interps.h"

diff --git a/gdb/inflow.c b/gdb/inflow.c
index 339b55c0bc69e3ef52cd96636c5b5ea63b84847f..eba7a931f467c3f97e1006136c3618941bc015fb 100644 (file)
--- a/gdb/inflow.c
+++ b/gdb/inflow.c
@@ -106,35 +106,6 @@ static serial_ttystate initial_gdb_ttystate;
 
 static struct terminal_info *get_inflow_inferior_data (struct inferior *);
 
-/* RAII class used to ignore SIGTTOU in a scope.  */
-
-class scoped_ignore_sigttou
-{
-public:
-  scoped_ignore_sigttou ()
-  {
-#ifdef SIGTTOU
-    if (job_control)
-      m_osigttou = signal (SIGTTOU, SIG_IGN);
-#endif
-  }
-
-  ~scoped_ignore_sigttou ()
-  {
-#ifdef SIGTTOU
-    if (job_control)
-      signal (SIGTTOU, m_osigttou);
-#endif
-  }
-
-  DISABLE_COPY_AND_ASSIGN (scoped_ignore_sigttou);
-
-private:
-#ifdef SIGTTOU
-  sighandler_t m_osigttou = NULL;
-#endif
-};
-
 /* While the inferior is running, we want SIGINT and SIGQUIT to go to the
    inferior only.  If we have job control, that takes care of it.  If not,
    we save our handlers in these two variables and set SIGINT and SIGQUIT

diff --git a/gdb/inflow.h b/gdb/inflow.h
index c32aa1443310d2eb304f84e64c0f44b478941019..5dd5c37bd2b708bcaeaf2155ed46540df12b2dff 100644 (file)
--- a/gdb/inflow.h
+++ b/gdb/inflow.h
@@ -21,5 +21,36 @@
 #define INFLOW_H
 
 #include <unistd.h>
+#include <signal.h>
+#include "common/job-control.h"
+
+/* RAII class used to ignore SIGTTOU in a scope.  */
+
+class scoped_ignore_sigttou
+{
+public:
+  scoped_ignore_sigttou ()
+  {
+#ifdef SIGTTOU
+    if (job_control)
+      m_osigttou = signal (SIGTTOU, SIG_IGN);
+#endif
+  }
+
+  ~scoped_ignore_sigttou ()
+  {
+#ifdef SIGTTOU
+    if (job_control)
+      signal (SIGTTOU, m_osigttou);
+#endif
+  }
+
+  DISABLE_COPY_AND_ASSIGN (scoped_ignore_sigttou);
+
+private:
+#ifdef SIGTTOU
+  sighandler_t m_osigttou = NULL;
+#endif
+};
 
 #endif /* inflow.h */

diff --git a/gdb/ser-unix.c b/gdb/ser-unix.c
index 5a9965bf744a0a67cd7c0a92a77c11b9f977d931..3492619f2d6e50d039b3432a1cb040e83a5fd03e 100644 (file)
--- a/gdb/ser-unix.c
+++ b/gdb/ser-unix.c
@@ -32,6 +32,7 @@
 #include "gdbcmd.h"
 #include "common/filestuff.h"
 #include <termios.h>
+#include "inflow.h"
 
 struct hardwire_ttystate
   {
@@ -164,6 +165,9 @@ hardwire_print_tty_state (struct serial *scb,
 static int
 hardwire_drain_output (struct serial *scb)
 {
+  /* Ignore SIGTTOU which may occur during the drain.  */
+  scoped_ignore_sigttou ignore_sigttou;
+
   return tcdrain (scb->fd);
 }
 

diff --git a/gdb/top.c b/gdb/top.c
index bacd684dbaaf005e95226c4222829d9f250ac300..1e17ebee87c8769bd33649ce240df9e0f540fcac 100644 (file)
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -34,7 +34,7 @@
 #include "expression.h"
 #include "value.h"
 #include "language.h"
-#include "terminal.h"          /* For job_control.  */
+#include "terminal.h"
 #include "common/job-control.h"
 #include "annotate.h"
 #include "completer.h"