Re: RFC: Do not call write_pc for "signal SIGINT"

[Daniel Jacobowitz <drow at false dot org>]

On Thu, Aug 28, 2008 at 06:32:32PM -0400, Daniel Jacobowitz wrote:
> On Thu, Aug 28, 2008 at 11:34:37AM -0700, Michael Snyder wrote:
> > More than a testcase.  This isn't very well explained.
> > You didn't reference the PR in your original post, and
> 
> It was in the ChangeLog entry, sorry.

Here it is with a testcase.

To recap: there is a tricky bug in signal_command.  If any non-zero
signal is specified, it performs a jump to the current address instead
of just resuming there.  This causes any pending system call to be
interrupted, in a way that leaves a kernel-internal value in the
return value register.  If we just delete that code, and the FIXME
that goes with it, the right thing happens: instead of "Unknown
error 514", the system call returns EINTR and the loop continues.

Michael, is that clearer?

-- 
Daniel Jacobowitz
CodeSourcery

2008-11-17  Daniel Jacobowitz  <dan@codesourcery.com>

	PR gdb/2241
	* infcmd.c (signal_command): Do not specify a resume PC.

2008-11-17  Daniel Jacobowitz  <dan@codesourcery.com>

	PR gdb/2241
	* gdb.base/interrupt.c (sigint_handler): New.
	(main): Install a SIGINT handler if SIGNALS is defined.  Exit
	on error.
	* gdb.base/interrupt.exp: Define SIGNALS unless gdb,nosignals.
	Test "signal SIGINT".

Index: infcmd.c
===================================================================
RCS file: /cvs/src/src/gdb/infcmd.c,v
retrieving revision 1.222
diff -u -p -r1.222 infcmd.c
--- infcmd.c	5 Nov 2008 20:23:07 -0000	1.222
+++ infcmd.c	17 Nov 2008 21:27:58 -0000
@@ -1147,11 +1147,7 @@ signal_command (char *signum_exp, int fr
     }
 
   clear_proceed_status ();
-  /* "signal 0" should not get stuck if we are stopped at a breakpoint.
-     FIXME: Neither should "signal foo" but when I tried passing
-     (CORE_ADDR)-1 unconditionally I got a testsuite failure which I haven't
-     tried to track down yet.  */
-  proceed (oursig == TARGET_SIGNAL_0 ? (CORE_ADDR) -1 : stop_pc, oursig, 0);
+  proceed ((CORE_ADDR) -1, oursig, 0);
 }
 
 /* Proceed until we reach a different source line with pc greater than
Index: testsuite/gdb.base/interrupt.c
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/interrupt.c,v
retrieving revision 1.1.1.2
diff -u -p -r1.1.1.2 interrupt.c
--- testsuite/gdb.base/interrupt.c	28 Jun 1999 16:03:16 -0000	1.1.1.2
+++ testsuite/gdb.base/interrupt.c	17 Nov 2008 21:29:38 -0000
@@ -2,6 +2,16 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
+
+#ifdef SIGNALS
+#include <signal.h>
+
+static void
+sigint_handler (int signo)
+{
+}
+#endif
+
 int
 main ()
 {
@@ -11,6 +21,9 @@ main ()
   set_debug_traps();
   breakpoint();
 #endif
+#ifdef SIGNALS
+  signal (SIGINT, sigint_handler);
+#endif
   printf ("talk to me baby\n");
   while (1)
     {
@@ -20,7 +33,10 @@ main ()
 #ifdef EINTR
 	  if (errno != EINTR)
 #endif
-	    perror ("");
+	    {
+	      perror ("");
+	      return 1;
+	    }
 	}
       else if (nbytes == 0)
 	{
Index: testsuite/gdb.base/interrupt.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/interrupt.exp,v
retrieving revision 1.12
diff -u -p -r1.12 interrupt.exp
--- testsuite/gdb.base/interrupt.exp	6 Aug 2008 12:52:07 -0000	1.12
+++ testsuite/gdb.base/interrupt.exp	17 Nov 2008 21:29:38 -0000
@@ -34,7 +34,13 @@ set bug_id 0
 set testfile interrupt
 set srcfile ${testfile}.c
 set binfile ${objdir}/${subdir}/${testfile}
-if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+
+set options { debug }
+if { ! [target_info exists gdb,nosignals] } {
+    lappend options "additional_flags=-DSIGNALS"
+}
+
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable $options] != "" } {
      untested interrupt.exp
      return -1
 }
@@ -165,7 +171,35 @@ if ![file exists $binfile] then {
 	    eof { fail "echo data (eof)" }
 	}
 
-	setup_xfail "i*86-pc-linux*-gnu*"
+ 	if { ! [target_info exists gdb,nosignals] } {
+	    # Wait until the program is in the read system call again.
+	    sleep 2
+
+	    # Stop the program for another test.
+	    set msg "Send Control-C, second time"
+	    send_gdb "\003"
+	    gdb_test_multiple "" "$msg" {
+		-re "Program received signal SIGINT.*$gdb_prompt $" {
+		    pass "$msg"
+		}
+	    }
+
+	    # The "signal" command should deliver the correctg signal and
+	    # return to the loop.
+	    set msg "signal SIGINT"
+	    gdb_test_multiple "signal SIGINT" "$msg" {
+		-re "^signal SIGINT\r\nContinuing with signal SIGINT.\r\n(\r\n|)$" { pass "$msg" }
+	    }
+
+	    # We should be back in the loop.
+	    send_gdb "more data\n"
+	    gdb_expect {
+		-re "^(\r\n|)more data\r\n(|more data\r\n)$" { pass "echo more data" }
+		timeout { fail "echo more data (timeout)" }
+		eof { fail "echo more data (eof)" }
+	    }
+	}
+
 	send_gdb "\004"
 	gdb_expect {
 	    -re "end of file.*Program exited normally.*$gdb_prompt $" {