Re: [PATCH] add -s option to make -break-insert support dprintf

[Hui Zhu <teawater@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 3760 bytes --]

Hi Tom,

Thanks for your review.

On Wed, May 8, 2013 at 4:49 AM, Tom Tromey <tromey@redhat.com> wrote:
>>>>>> "Hui" == Hui Zhu <teawater@gmail.com> writes:
>
> Hui> According to your comments.  I did some update with these patches to
> Hui> added special command -dprintf-insert to insert dprintf.  Its format
> Hui> is close to simple dprintf command:
> Hui> -dprintf-insert LOCATION FORMAT ARG ARG ...
>
> I like this approach much more.
> Thanks for doing it.
>
> Hui> +static char *
> Hui> +mi_argv_to_format (int format_num, char **argv, int argc)
>
> This needs an introductory comment explaining the arguments and result.

Add:
/* Convert arguments in ARGV to the string in "format",argv,argv...
   and return it.  */

>
> Hui> +  /* If all the string need convert to \ddd mode, so * 2.
> Hui> +     + 2 for two ".
> Hui> +     + 1 for \0.  */
> Hui> +  format_size = strlen (argv[format_num]) * 4 + 3;
>
> The comment says "* 2" but the code says "* 4".
> Personally I'd just use an obstack rather than mess around with explicit
> reallocs and the like.

Obstack is better than what I did in before.   Thanks for that.
Updated patch for it.

>
> Hui> +      sprintf (format + format_current_size, "\\%o",
> Hui> +               argv[format_num][i]);
>
> It seems that this could do the wrong thing for a char that
> sign-extends.

I changed this part to:
sprintf (tmp, "\\%o", (unsigned char)argv[format_num][i]);

>
> Hui> +  /* Apply other argv to FORMAT.  */
> Hui> +  for (i = format_num + 1; i < argc; i++)
>
> It seems to me that it would be better to just pass in argv+argc to
> mi_argv_to_format, and omit the format_num argument entirely.

Fixed.

>
> Hui> +static void
> Hui> +mi_cmd_break_insert_1 (int dprintf, char *command, char **argv, int argc)
>
> Intro comment.

/* Insert breakpoint.
   If dprintf is true, it will insert dprintf.
   If not, it will insert other type breakpoint.  */

>
> Hui> +      extra_string = mi_argv_to_format (oind + 1, argv, argc);
> Hui> +      make_cleanup (xfree, extra_string);
>
> This makes a dangling cleanup.

Fixed.

>
> Hui> +  if (tracepoint)
> Hui> +    {
> Hui> +      /* Note that to request a fast tracepoint, the client uses the
> Hui> +   "hardware" flag, although there's nothing of hardware related to
> Hui> +   fast tracepoints -- one can implement slow tracepoints with
> Hui> +   hardware breakpoints, but fast tracepoints are always software.
> Hui> +   "fast" is a misnomer, actually, "jump" would be more appropriate.
> Hui> +   A simulator or an emulator could conceivably implement fast
> Hui> +   regular non-jump based tracepoints.  */
> Hui> +      type_wanted = hardware ? bp_fast_tracepoint : bp_tracepoint;
> Hui> +      ops = &tracepoint_breakpoint_ops;
> Hui> +    }
> Hui> +  else if (dprintf)
> Hui> +    {
>
> It seems that 'tracepoint' and 'dprintf' are exclusive, so this should
> be checked above where "hardware" is checked.

Fixed.

I post  the new patches that updated according to your comments.

Thanks,
Hui

2013-05-10  Hui Zhu  <hui@codesourcery.com>

	* breakpoint.c (dprintf_breakpoint_ops): Remove its static.
	* breakpoint.h (dprintf_breakpoint_ops): Add extern.
	* mi/mi-cmd-break.c (ctype.h): New include.
	(gdb_obstack.h): New include.
	(mi_argv_to_format, mi_cmd_break_insert_1): New.
	(mi_cmd_break_insert): Call mi_cmd_break_insert_1.
	(mi_cmd_dprintf_insert): New.
	* mi/mi-cmds.c (mi_cmds): Add "dprintf-insert".
	* mi/mi-cmds.h (mi_cmd_dprintf_insert): New extern.

2013-05-10  Hui Zhu  <hui@codesourcery.com>

	* gdb.texinfo (GDB/MI Breakpoint Commands): Describe the
	"-dprintf-insert" command.

2013-05-10  Hui Zhu  <hui@codesourcery.com>

	* gdb.mi/Makefile.in (PROGS): Add "mi-dprintf".
	* gdb.mi/mi-dprintf.exp, gdb.mi/mi-dprintf.c: New.

[-- Attachment #2: mi-dprintf.txt --]
[-- Type: text/plain, Size: 7530 bytes --]

--- a/breakpoint.c
+++ b/breakpoint.c
@@ -301,7 +301,7 @@ struct breakpoint_ops bkpt_breakpoint_op
 static struct breakpoint_ops bkpt_probe_breakpoint_ops;
 
 /* Dynamic printf class type.  */
-static struct breakpoint_ops dprintf_breakpoint_ops;
+struct breakpoint_ops dprintf_breakpoint_ops;
 
 /* The style in which to perform a dynamic printf.  This is a user
    option because different output options have different tradeoffs;
--- a/breakpoint.h
+++ b/breakpoint.h
@@ -1212,6 +1212,7 @@ extern void tbreak_command (char *, int)
 extern struct breakpoint_ops base_breakpoint_ops;
 extern struct breakpoint_ops bkpt_breakpoint_ops;
 extern struct breakpoint_ops tracepoint_breakpoint_ops;
+extern struct breakpoint_ops dprintf_breakpoint_ops;
 
 extern void initialize_breakpoint_ops (void);
 
--- a/mi/mi-cmd-break.c
+++ b/mi/mi-cmd-break.c
@@ -30,6 +30,8 @@
 #include "observer.h"
 #include "mi-main.h"
 #include "mi-cmd-break.h"
+#include "gdb_obstack.h"
+#include <ctype.h>
 
 enum
   {
@@ -84,11 +86,82 @@ setup_breakpoint_reporting (void)
 }
 
 
-/* Implements the -break-insert command.
-   See the MI manual for the list of possible options.  */
+/* Convert arguments in ARGV to the string in "format",argv,argv...
+   and return it.  */
 
-void
-mi_cmd_break_insert (char *command, char **argv, int argc)
+static char *
+mi_argv_to_format (char **argv, int argc)
+{
+  int i;
+  struct obstack obstack;
+  char *ret;
+
+  obstack_init (&obstack);
+
+  /* Convert ARGV[OIND + 1] to format string and save to FORMAT.  */
+  obstack_1grow (&obstack, '\"');
+  for (i = 0; i < strlen (argv[0]); i++)
+    {
+      switch (argv[0][i])
+	{
+	case '\\':
+	  obstack_grow (&obstack, "\\\\", 2);
+	  break;
+	case '\a':
+	  obstack_grow (&obstack, "\\a", 2);
+	  break;
+	case '\b':
+	  obstack_grow (&obstack, "\\b", 2);
+	  break;
+	case '\f':
+	  obstack_grow (&obstack, "\\f", 2);
+	  break;
+	case '\n':
+	  obstack_grow (&obstack, "\\n", 2);
+	  break;
+	case '\r':
+	  obstack_grow (&obstack, "\\r", 2);
+	  break;
+	case '\t':
+	  obstack_grow (&obstack, "\\t", 2);
+	  break;
+	case '\v':
+	  obstack_grow (&obstack, "\\v", 2);
+	  break;
+	default:
+	  if (isprint(argv[0][i]))
+	    obstack_grow (&obstack, argv[0] + i, 1);
+	  else
+	    {
+	      char tmp[5];
+	      sprintf (tmp, "\\%o", (unsigned char)argv[0][i]);
+	      obstack_grow (&obstack, tmp, strlen (tmp));
+	    }
+	  break;
+	}
+    }
+  obstack_1grow (&obstack, '\"');
+
+  /* Apply other argv to FORMAT.  */
+  for (i = 1; i < argc; i++)
+    {
+      obstack_1grow (&obstack, ',');
+      obstack_grow (&obstack, argv[i], strlen (argv[i]));
+    }
+  obstack_1grow (&obstack, '\0');
+
+  ret = xstrdup (obstack_finish (&obstack));
+  obstack_free (&obstack, NULL);
+
+  return ret;
+}
+
+/* Insert breakpoint.
+   If dprintf is true, it will insert dprintf.
+   If not, it will insert other type breakpoint.  */
+
+static void
+mi_cmd_break_insert_1 (int dprintf, char *command, char **argv, int argc)
 {
   char *address = NULL;
   int hardware = 0;
@@ -102,6 +175,8 @@ mi_cmd_break_insert (char *command, char
   struct cleanup *back_to;
   enum bptype type_wanted;
   struct breakpoint_ops *ops;
+  char *extra_string = NULL;
+  struct cleanup *extra_string_cleanup;
 
   enum opt
     {
@@ -163,35 +238,81 @@ mi_cmd_break_insert (char *command, char
     }
 
   if (oind >= argc)
-    error (_("-break-insert: Missing <location>"));
-  if (oind < argc - 1)
-    error (_("-break-insert: Garbage following <location>"));
+    error (_("-%s-insert: Missing <location>"),
+	   dprintf ? "dprintf" : "break");
   address = argv[oind];
+  if (dprintf)
+    {
+      int format_num = oind + 1;
+
+      if (hardware || tracepoint)
+	error (_("-dprintf-insert: does not support -h or -a"));
+      if (format_num >= argc)
+	error (_("-dprintf-insert: Missing <format>"));
+
+      extra_string = mi_argv_to_format (argv + format_num, argc - format_num);
+      extra_string_cleanup = make_cleanup (xfree, extra_string);
+    }
+  else
+    {
+      if (oind < argc - 1)
+	error (_("-break-insert: Garbage following <location>"));
+    }
 
   /* Now we have what we need, let's insert the breakpoint!  */
   back_to = setup_breakpoint_reporting ();
 
-  /* Note that to request a fast tracepoint, the client uses the
-     "hardware" flag, although there's nothing of hardware related to
-     fast tracepoints -- one can implement slow tracepoints with
-     hardware breakpoints, but fast tracepoints are always software.
-     "fast" is a misnomer, actually, "jump" would be more appropriate.
-     A simulator or an emulator could conceivably implement fast
-     regular non-jump based tracepoints.  */
-  type_wanted = (tracepoint
-		 ? (hardware ? bp_fast_tracepoint : bp_tracepoint)
-		 : (hardware ? bp_hardware_breakpoint : bp_breakpoint));
-  ops = tracepoint ? &tracepoint_breakpoint_ops : &bkpt_breakpoint_ops;
+  if (tracepoint)
+    {
+      /* Note that to request a fast tracepoint, the client uses the
+	 "hardware" flag, although there's nothing of hardware related to
+	 fast tracepoints -- one can implement slow tracepoints with
+	 hardware breakpoints, but fast tracepoints are always software.
+	 "fast" is a misnomer, actually, "jump" would be more appropriate.
+	 A simulator or an emulator could conceivably implement fast
+	 regular non-jump based tracepoints.  */
+      type_wanted = hardware ? bp_fast_tracepoint : bp_tracepoint;
+      ops = &tracepoint_breakpoint_ops;
+    }
+  else if (dprintf)
+    {
+      type_wanted = bp_dprintf;
+      ops = &dprintf_breakpoint_ops;
+    }
+  else
+    {
+      type_wanted = hardware ? bp_hardware_breakpoint : bp_breakpoint;
+      ops = &bkpt_breakpoint_ops;
+    }
 
   create_breakpoint (get_current_arch (), address, condition, thread,
-		     NULL,
+		     extra_string,
 		     0 /* condition and thread are valid.  */,
 		     temp_p, type_wanted,
 		     ignore_count,
 		     pending ? AUTO_BOOLEAN_TRUE : AUTO_BOOLEAN_FALSE,
 		     ops, 0, enabled, 0, 0);
   do_cleanups (back_to);
+  if (dprintf)
+    do_cleanups (extra_string_cleanup);
+}
+
+/* Implements the -break-insert command.
+   See the MI manual for the list of possible options.  */
 
+void
+mi_cmd_break_insert (char *command, char **argv, int argc)
+{
+  mi_cmd_break_insert_1 (0, command, argv, argc);
+}
+
+/* Implements the -dprintf-insert command.
+   See the MI manual for the list of possible options.  */
+
+void
+mi_cmd_dprintf_insert (char *command, char **argv, int argc)
+{
+  mi_cmd_break_insert_1 (1, command, argv, argc);
 }
 
 enum wp_type
--- a/mi/mi-cmds.c
+++ b/mi/mi-cmds.c
@@ -61,6 +61,8 @@ static struct mi_cmd mi_cmds[] =
   DEF_MI_CMD_CLI ("break-info", "info break", 1),
   DEF_MI_CMD_MI_1 ("break-insert", mi_cmd_break_insert,
 		   &mi_suppress_notification.breakpoint),
+  DEF_MI_CMD_MI_1 ("dprintf-insert", mi_cmd_dprintf_insert,
+		   &mi_suppress_notification.breakpoint),
   DEF_MI_CMD_CLI ("break-list", "info break", 0),
   DEF_MI_CMD_MI_1 ("break-passcount", mi_cmd_break_passcount,
 		   &mi_suppress_notification.breakpoint),
--- a/mi/mi-cmds.h
+++ b/mi/mi-cmds.h
@@ -39,6 +39,7 @@ typedef void (mi_cmd_argv_ftype) (char *
 extern mi_cmd_argv_ftype mi_cmd_ada_task_info;
 extern mi_cmd_argv_ftype mi_cmd_add_inferior;
 extern mi_cmd_argv_ftype mi_cmd_break_insert;
+extern mi_cmd_argv_ftype mi_cmd_dprintf_insert;
 extern mi_cmd_argv_ftype mi_cmd_break_commands;
 extern mi_cmd_argv_ftype mi_cmd_break_passcount;
 extern mi_cmd_argv_ftype mi_cmd_break_watch;

[-- Attachment #3: mi-dprintf-doc.txt --]
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--- a/NEWS
+++ b/NEWS
@@ -60,6 +60,8 @@ show debug nios2
   ** The -trace-save MI command can optionally save trace buffer in Common
      Trace Format now.
 
+  ** The new command -dprintf-insert sets a dynamic printf breakpoint.
+
 *** Changes in GDB 7.6
 
 * Target record has been renamed to record-full.
--- a/doc/gdb.texinfo
+++ b/doc/gdb.texinfo
@@ -28971,6 +28971,84 @@ times="0"@}]@}
 @c (gdb)
 @end smallexample
 
+@subheading The @code{-dprintf-insert} Command
+@findex -dprintf-insert
+
+@subsubheading Synopsis
+
+@smallexample
+ -dprintf-insert [ -t ] [ -f ] [ -d ]
+    [ -c @var{condition} ] [ -i @var{ignore-count} ]
+    [ -p @var{thread-id} ] [ @var{location} ] [ @var{format} ]
+    [ @var{argument} ]
+@end smallexample
+
+@noindent
+If specified, @var{location}, can be one of:
+
+@itemize @bullet
+@item function
+@c @item +offset
+@c @item -offset
+@c @item linenum
+@item filename:linenum
+@item filename:function
+@item *address
+@end itemize
+
+The possible optional parameters of this command are:
+
+@table @samp
+@item -t
+Insert a temporary breakpoint.
+@item -f
+If @var{location} cannot be parsed (for example if it
+refers to unknown files or functions), create a pending
+breakpoint. Without this flag, @value{GDBN} will report
+an error, and won't create a breakpoint, if @var{location}
+cannot be parsed.
+@item -d
+Create a disabled breakpoint.
+@item -c @var{condition}
+Make the breakpoint conditional on @var{condition}.
+@item -i @var{ignore-count}
+Initialize the @var{ignore-count}.
+@item -p @var{thread-id}
+Restrict the breakpoint to the specified @var{thread-id}.
+@end table
+
+@subsubheading Result
+
+@xref{GDB/MI Breakpoint Information}, for details on the format of the
+resulting breakpoint.
+
+Note: this format is open to change.
+@c An out-of-band breakpoint instead of part of the result?
+
+@subsubheading @value{GDBN} Command
+
+The corresponding @value{GDBN} commands are @samp{dprintf}.
+
+@subsubheading Example
+
+@smallexample
+(gdb)
+4-dprintf-insert foo "At foo entry\n"
+4^done,bkpt=@{number="1",type="dprintf",disp="keep",enabled="y",
+addr="0x000000000040061b",func="foo",file="mi-dprintf.c",
+fullname="mi-dprintf.c",line="25",thread-groups=["i1"],
+times="0",script=@{"printf \"At foo entry\\n\"","continue"@},
+original-location="foo"@}
+(gdb)
+5-dprintf-insert 26 "arg=%d, g=%d\n" arg g
+5^done,bkpt=@{number="2",type="dprintf",disp="keep",enabled="y",
+addr="0x000000000040062a",func="foo",file="mi-dprintf.c",
+fullname="mi-dprintf.c",line="26",thread-groups=["i1"],
+times="0",script=@{"printf \"arg=%d, g=%d\\n\", arg, g","continue"@},
+original-location="mi-dprintf.c:26"@}
+(gdb)
+@end smallexample
+
 @subheading The @code{-break-list} Command
 @findex -break-list
 

[-- Attachment #4: mi-dprintf-test.txt --]
[-- Type: text/plain, Size: 7444 bytes --]

--- a/testsuite/gdb.mi/Makefile.in
+++ b/testsuite/gdb.mi/Makefile.in
@@ -3,7 +3,7 @@ srcdir = @srcdir@
 
 PROGS = basics c_variable cpp_variable var-cmd dw2-ref-missing-frame	\
 	gdb669-pthreads gdb701 gdb792 mi-async mi-basics mi-break	\
-	mi-cli mi-console mi-disassemble mi-eval mi-file		\
+	mi-cli mi-console mi-disassemble mi-dprintf mi-eval mi-file	\
 	mi-file-transfer mi-non-stop mi-non-stop-exit			\
 	mi-ns-stale-regcache mi-nsintrall mi-nsmoribund mi-nsthrexec	\
 	mi-pending mi-pthreads mi-read-memory mi-regs mi-return		\
--- /dev/null
+++ b/testsuite/gdb.mi/mi-dprintf.c
@@ -0,0 +1,59 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   Contributed by Hui Zhu  <hui@codesourcery.com>
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+static int g;
+
+void
+foo (int arg)
+{
+  g += arg;
+  g *= 2; /* set dprintf 1 here */
+  g /= 2.5; /* set breakpoint 1 here */
+}
+
+int
+main (int argc, char *argv[])
+{
+  int loc = 1234;
+
+  /* Ensure these functions are available.  */
+  printf ("kickoff %d\n", loc);
+  fprintf (stderr, "also to stderr %d\n", loc);
+
+  foo (loc++);
+  foo (loc++);
+  foo (loc++);
+  return g;
+}
+
+/* Make sure function 'malloc' is linked into program.  On some bare-metal
+   port, if we don't use 'malloc', it will not be linked in program.  'malloc'
+   is needed, otherwise we'll see such error message
+   evaluation of this expression requires the program to have a function
+   "malloc".  */
+
+void
+bar (void)
+{
+  void *p = malloc (16);
+
+  free (p);
+}
--- /dev/null
+++ b/testsuite/gdb.mi/mi-dprintf.exp
@@ -0,0 +1,145 @@
+#   Copyright (C) 2013 Free Software Foundation, Inc.
+#   Contributed by Hui Zhu  <hui@codesourcery.com>
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib mi-support.exp
+set MIFLAGS "-i=mi"
+
+gdb_exit
+if [mi_gdb_start] {
+    continue
+}
+
+standard_testfile
+
+if {[build_executable $testfile.exp $testfile $srcfile {debug}] == -1} {
+    untested "failed to compile $testfile"
+    return -1
+}
+
+mi_delete_breakpoints
+
+set bp_location1 [gdb_get_line_number "set breakpoint 1 here"]
+set dp_location1 [gdb_get_line_number "set dprintf 1 here"]
+
+mi_run_to_main
+
+mi_gdb_test "1-dprintf-insert" \
+    "1\\^error,msg=\"-dprintf-insert: Missing <location>\"" "mi insert without location"
+
+mi_gdb_test "2-dprintf-insert foo" \
+    "2\\^error,msg=\"-dprintf-insert: Missing <format>\"" "mi insert breakpoint without format string"
+
+mi_gdb_test "3-dprintf-insert 29" \
+    "3\\^error,msg=\"-dprintf-insert: Missing <format>\"" "mi insert second breakpoint without format string"
+
+mi_gdb_test "-break-insert main" ".*" "mi insert breakpoint main"
+mi_delete_breakpoints
+
+mi_gdb_test "4-dprintf-insert foo \"At foo entry\\n\"" \
+    "4\\^done,bkpt=\{number=\".*\",type=\"dprintf\".*func=\"foo\",file=\".*mi-dprintf.c\",fullname=\".*mi-dprintf.c\",line=\".*\".*" "mi insert dprintf foo"
+
+mi_gdb_test "5-dprintf-insert $dp_location1 \"arg=%d, g=%d\\n\" arg g" \
+    "5\\^done,bkpt=\{number=\".*\",type=\"dprintf\".*func=\"foo\",file=\".*mi-dprintf.c\",fullname=\".*mi-dprintf.c\",line=\"$dp_location1\".*" \
+    "mi insert dprintf dp_location1"
+
+mi_gdb_test "6-break-info" \
+    "6\\^done,BreakpointTable=\{nr_rows=\".\",nr_cols=\".\",hdr=\\\[\{width=\".*\",alignment=\".*\",col_name=\"number\",colhdr=\"Num\"\},\{width=\".*\",alignment=\".*\",col_name=\"type\",colhdr=\"Type\"\},\{width=\".*\",alignment=\".*\",col_name=\"disp\",colhdr=\"Disp\"\},\{width=\".*\",alignment=\".*\",col_name=\"enabled\",colhdr=\"Enb\"\},\{width=\".*\",alignment=\".*\",col_name=\"addr\",colhdr=\"Address\"\},\{width=\".*\",alignment=\".*\",col_name=\"what\",colhdr=\"What\"\}\\\],body=\\\[bkpt=\{number=\"3\",type=\"dprintf\".*func=\"foo\",file=\".*mi-dprintf.c\",fullname=\".*mi-dprintf.c\",line=\".*\".*,bkpt=\{number=\".*\",type=\"dprintf\".*func=\"foo\",file=\".*mi-dprintf.c\",fullname=\".*mi-dprintf.c\",line=\"$dp_location1\".*" \
+    "mi info dprintf"
+
+mi_gdb_test "-break-insert $bp_location1" ".*" "mi insert breakpoint bp_location1"
+
+proc mi_continue_dprintf {args} {
+    with_test_prefix $args {
+	global mi_gdb_prompt
+
+	mi_run_cmd
+	set msg "mi 1st dprintf"
+	gdb_expect {
+            -re ".*At foo entry.*arg=1234, g=1234.*" {
+		pass $msg
+	    }
+	    -re ".*$mi_gdb_prompt$" {
+		fail $msg
+	    }
+            timeout {
+		fail $msg
+            }
+	}
+	mi_expect_stop ".*" ".*" ".*" ".*" ".*" "" "$msg stop"
+
+	set msg "mi 2nd dprintf"
+	mi_send_resuming_command "exec-continue" "$msg continue"
+	gdb_expect {
+            -re ".*At foo entry.*arg=1235, g=2222.*" {
+		pass $msg
+	    }
+	    -re ".*$mi_gdb_prompt$" {
+		fail $msg
+	    }
+            timeout {
+		fail $msg
+            }
+	}
+    }
+}
+
+mi_continue_dprintf "gdb"
+
+# The "call" style depends on having I/O functions available, so test.
+
+if ![target_info exists gdb,noinferiorio] {
+
+    # Now switch styles and rerun; in the absence of redirection the
+    # output should be the same.
+
+    mi_gdb_test "set dprintf-style call" ".*" "mi set dprintf style to call"
+    mi_continue_dprintf "call"
+
+    mi_gdb_test "set dprintf-function fprintf" ".*" "mi set dprintf-channel stderr"
+    mi_gdb_test "set dprintf-channel stderr" ".*" "mi set dprintf channel"
+    mi_continue_dprintf "fprintf"
+}
+
+set target_can_dprintf 0
+set msg "set dprintf style to agent"
+send_gdb "set dprintf-style agent\n"
+gdb_expect {
+    -re "warning: Target cannot run dprintf commands, falling back to GDB printf.*$mi_gdb_prompt$" {
+	unsupported "$msg"
+    }
+    -re ".*done.*$mi_gdb_prompt$" {
+	set target_can_dprintf 1
+	pass "$msg"
+    }
+    -re ".*$mi_gdb_prompt$" {
+	fail "$msg"
+    }
+    timeout {
+	fail "$msg"
+    }
+}
+
+if $target_can_dprintf {
+    mi_run_cmd
+
+    mi_gdb_test "continue" ".*breakpoint-hit.*func=\"foo\".*" "mi 1st dprintf, agent"
+
+    mi_gdb_test "continue" ".*breakpoint-hit.*func=\"foo\".*" "mi 2nd dprintf, agent"
+
+    mi_gdb_test "6-break-info" ".*modified.*" "mi info dprintf second time"
+}
+
+mi_gdb_test "set dprintf-style foobar" ".*error.*" "mi set dprintf style to an unrecognized type"