[python] [patch] PR python/13329

[Phil Muldoon <pmuldoon at redhat dot com>]

This patch changes the behavior of 'python stack-print' to three modes:
full, message or none.  The default has been set to "message".

  full - will print the exception message and the stack.
  message - will print the exception type and message only.
  none - nothing will be printed.

This patch also fixes a bug where we were calling gdbpy_print_stack
after a few PyRun_SimpleString calls.  This is not necessary as that
API deals with the exception internally and prints its own stack.

This is backwards compatible with the deprecated maint set python print-sack.

on - will set the mode to "full".
off - will set the mode to "none".

Tested with no regressions.

Cheers,

Phil

--

2011-11-09  Phil Muldoon  <pmuldoon@redhat.com>

        PR python/13329

	* python/python.c: Declare python_excp_none, python_excp_full,
	python_excp_message, python_excp_enums
	(set_python_excp_mode): New function.
	(_initialize_python): Set 'print-stack' command to an enum
	accepting command.
	(gdbpy_print_stack): Rewrite.
	(eval_python_from_control_command): Do not call gdbpy_print_stack.
	(python_command): Ditto.
        * NEWS: Update 'print-stack' text.

2011-11-09  Phil Muldoon  <pmuldoon@redhat.com>

        PR python/13329

	* gdb.texinfo (Python Commands): Update 'print-stack' to reflect
	the three values it can now take.

2011-11-09  Phil Muldoon  <pmuldoon@redhat.com>

        PR python/13329

	* gdb.python/py-function.exp: Set python print-stack "on" to "full.
	* gdb.python/python.exp: Ditto.
--

diff --git a/gdb/NEWS b/gdb/NEWS
index 1713049..ecf6849 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -23,9 +23,10 @@
      existing one.
 
   ** The "maint set python print-stack on|off" command has been
-     deprecated, and a new command: "set python print-stack on|off" has
-     replaced it.  Additionally, the default for "print-stack" is now
-     "off".
+     deprecated, and a new command: "set python print-stack
+     none|full|message" has replaced it.  Additionally, the default
+     for "print-stack" is now "message", which just prints the error
+     message without the stack trace.
    
   ** A prompt substitution hook (prompt_hook) is now available to the
      Python API.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index d2bdefa..dc5daa9 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21348,11 +21348,12 @@ print-stack}
 
 @kindex set python print-stack
 @item set python print-stack
-By default, @value{GDBN} will not print a stack trace when an error
-occurs in a Python script.  This can be controlled using @code{set
-python print-stack}: if @code{on}, then Python stack printing is
-enabled; if @code{off}, the default, then Python stack printing is
-disabled.
+By default, @value{GDBN} will print only the message component of a
+Python exception when an error occurs in a Python script.  This can be
+controlled using @code{set python print-stack}: if @code{full}, then
+full Python stack printing is enabled; if @code{none}, then Python stack
+and message printing is disabled; if @code{message}, the default, only
+the message component of the error is printed.
 @end table
 
 It is also possible to execute a Python script from the @value{GDBN}
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 108e542..93a80c6 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -35,9 +35,29 @@
 
 #include <ctype.h>
 
-/* True if we should print the stack when catching a Python error,
-   false otherwise.  */
-static int gdbpy_should_print_stack = 0;
+/* Declared constants and enum for python stack printing.  */
+static const char python_excp_none[] = "none";
+static const char python_excp_full[] = "full";
+static const char python_excp_message[] = "message";
+
+/* set python print-stack choices.  */
+static const char *python_excp_enums[] = {
+  python_excp_none,
+  python_excp_full,
+  python_excp_message,
+  NULL
+};
+
+/* 0 if we should not print the stack when catching a Python error,
+   1 to print the full stack, 2 to just print the message.  */
+static int gdbpy_should_print_stack = 2;
+
+/* The extended exception printing variable.  'full' if we want to
+   print the error message and stack, 'none' if we want to print
+   nothing, and 'message' if we only want to print the error
+   message.  */
+static const char *gdbpy_should_print_stack_extended =
+  python_excp_message;
 
 #ifdef HAVE_PYTHON
 
@@ -233,10 +253,7 @@ eval_python_from_control_command (struct command_line *cmd)
   ret = PyRun_SimpleString (script);
   xfree (script);
   if (ret)
-    {
-      gdbpy_print_stack ();
-      error (_("Error while executing Python code."));
-    }
+    error (_("Error while executing Python code."));
 
   do_cleanups (cleanup);
 }
@@ -258,10 +275,7 @@ python_command (char *arg, int from_tty)
   if (arg && *arg)
     {
       if (PyRun_SimpleString (arg))
-	{
-	  gdbpy_print_stack ();
-	  error (_("Error while executing Python code."));
-	}
+	error (_("Error while executing Python code."));
     }
   else
     {
@@ -881,22 +895,57 @@ gdbpy_flush (PyObject *self, PyObject *args, PyObject *kw)
   Py_RETURN_NONE;
 }
 
-/* Print a python exception trace, or print nothing and clear the
-   python exception, depending on gdbpy_should_print_stack.  Only call
-   this if a python exception is set.  */
+/* Print a python exception trace, print just a message, or print
+   nothing and clear the python exception, depending on
+   gdbpy_should_print_stack.  Only call this if a python exception is
+   set.  */
 void
 gdbpy_print_stack (void)
 {
-  if (gdbpy_should_print_stack)
+  switch (gdbpy_should_print_stack)
     {
+      PyObject *ptype, *pvalue, *ptraceback;
+      char *msg = NULL, *type = NULL;
+
+    case 0:
+      /* Print "none", just clear exception.  */
+      PyErr_Clear ();
+      break;
+
+    case 1:
+      /* Print "full" message and backtrace.  */
       PyErr_Print ();
       /* PyErr_Print doesn't necessarily end output with a newline.
 	 This works because Python's stdout/stderr is fed through
 	 printf_filtered.  */
       begin_line ();
+      break;
+
+    case 2:
+      /* Print "message", just error print message.  */
+      PyErr_Fetch (&ptype, &pvalue, &ptraceback);
+
+      /* Fetch the error message contained within ptype, pvalue.  */
+      msg = gdbpy_exception_to_string (ptype, pvalue);
+      type = gdbpy_obj_to_string (ptype);
+      if (msg == NULL)
+	{
+	  /* An error occurred computing the string representation of the
+	     error message.  */
+	  fprintf_filtered (gdb_stderr,
+			    _("Error occurred computing Python error" \
+			      "message.\n"));
+	}
+      else
+	fprintf_filtered (gdb_stderr, "Python Exception %s %s: \n",
+			  type, msg);
+
+      Py_XDECREF (ptype);
+      Py_XDECREF (pvalue);
+      Py_XDECREF (ptraceback);
+      xfree (msg);
+      break;
     }
-  else
-    PyErr_Clear ();
 }
 
 
@@ -1106,6 +1155,21 @@ user_show_python (char *args, int from_tty)
   cmd_show_list (user_show_python_list, from_tty, "");
 }
 
+/* When setting the 'python print-stack' with an enum, set the
+   gdbpy_should_print_stack correspondingly.  */
+static void
+set_python_excp_mode (char *args, int i, struct cmd_list_element *c)
+{
+  const char *user_arg = *(const char **) c->var;
+
+  if (strncmp (user_arg, python_excp_none, 4) == 0)
+      gdbpy_should_print_stack = 0;
+  else if (strncmp (user_arg, python_excp_full, 3) == 0)
+      gdbpy_should_print_stack = 1;
+  else if (strncmp (user_arg, python_excp_message, 7) == 0)
+      gdbpy_should_print_stack = 2;
+}
+
 /* Initialize the Python code.  */
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */
@@ -1176,14 +1240,16 @@ Enables or disables printing of Python stack traces."),
 		  &user_set_python_list, "set python ", 0,
 		  &setlist);
 
-  add_setshow_boolean_cmd ("print-stack", no_class,
-			   &gdbpy_should_print_stack, _("\
-Enable or disable printing of Python stack dump on error."), _("\
-Show whether Python stack will be printed on error."), _("\
-Enables or disables printing of Python stack traces."),
-			   NULL, NULL,
-			   &user_set_python_list,
-			   &user_show_python_list);
+  add_setshow_enum_cmd ("print-stack", no_class, python_excp_enums,
+			&gdbpy_should_print_stack_extended, _("\
+Set mode for Python stack dump on error."), _("\
+Show the mode of Python stack printing on error."), _("\
+none  == no stack or message will be printed.\n\
+full == a message and a stack will be printed.\n\
+message == an error message without a stack will be printed."),
+			set_python_excp_mode, NULL,
+			&user_set_python_list,
+			&user_show_python_list);
 
 #ifdef HAVE_PYTHON
 #ifdef WITH_PYTHON_PATH
diff --git a/gdb/testsuite/gdb.python/py-function.exp b/gdb/testsuite/gdb.python/py-function.exp
index d579435..f670d52 100644
--- a/gdb/testsuite/gdb.python/py-function.exp
+++ b/gdb/testsuite/gdb.python/py-function.exp
@@ -93,7 +93,7 @@ gdb_py_test_multiple "Test Normal Error" \
   "NormalError ()" "" \
   "end" ""
 
-gdb_test_no_output "set python print-stack on"
+gdb_test_no_output "set python print-stack full"
 gdb_test "print \$normalerror()" "Traceback.*File.*line 5.*in invoke.*RuntimeError.*This is a Normal Error.*" \
     "Test a Runtime error.  There should be a stack trace."
 
diff --git a/gdb/testsuite/gdb.python/py-prettyprint.exp b/gdb/testsuite/gdb.python/py-prettyprint.exp
index b0e7d62..9786d71 100644
--- a/gdb/testsuite/gdb.python/py-prettyprint.exp
+++ b/gdb/testsuite/gdb.python/py-prettyprint.exp
@@ -97,7 +97,7 @@ proc run_lang_tests {exefile lang} {
     gdb_test_no_output "python pp_ls_encoding = 'UTF-8'"
     gdb_test "print estring2" "\"embedded \", <incomplete sequence \\\\302>"
 
-    gdb_test_no_output "set python print-stack on"
+    gdb_test_no_output "set python print-stack full"
     gdb_test "print hint_error" "Exception: hint failed\r\nhint_error_val"
 
     gdb_test "print c" " = container \"container\" with 2 elements = {$nl *.0. = 23,$nl *.1. = 72$nl}"
diff --git a/gdb/testsuite/gdb.python/python.exp b/gdb/testsuite/gdb.python/python.exp
index 94d6d0d..2062d00 100644
--- a/gdb/testsuite/gdb.python/python.exp
+++ b/gdb/testsuite/gdb.python/python.exp
@@ -203,12 +203,13 @@ gdb_test "maint set python print-stack off" \
     "Warning: command 'maintenance set python print-stack' is deprecated.*Use 'set python print-stack'.*" \
     "Test deprecation maint set warning."
 gdb_test "show python print-stack" \
-    "Whether Python stack will be printed on error is off.*" \
+    "The mode of Python stack printing on error is \"message\".*" \
     "Test print-backtrace show setting. Default off."
-gdb_py_test_silent_cmd "set python print-stack on" \
+gdb_py_test_silent_cmd "set python print-stack full" \
     "Test print-backtrace set setting" 1
 gdb_test "show python print-stack" \
-    "Whether Python stack will be printed on error is on.*" \
+    "The mode of Python stack printing on error is \"full\".*" \
+    "Test print-backtrace show setting to full."
 
 # Test prompt substituion
 
@@ -313,7 +314,7 @@ gdb_test_multiple "set extended-prompt \\w " \
 
 gdb_test_multiple "set extended-prompt some param \\p{python print-stack} " \
     "set extended prompt parameter" {
-    -re "\[\r\n\]some param True $" {
+    -re "\[\r\n\]some param full $" {
 	pass "set extended prompt parameter"
     }
 }