Make gdb.base/dprintf.exp use gdb_test_stdio

This one needed a larger revamp.  The issue is that the "info
breakpoints" test at the bottom of the file is broken on targets that
can do both server-side dprintf, and inferior I/O, because then
neither the breakpoint numbers match nor the "already hit N times"
output.

Address that by making the test restart gdb from scratch when
switching between dprintf styles.  Test groups are factored into
procedures, and we now use with_test_prefix.  While we're changing
test messages, lowercase a few test messages, and then while at it,
modernize a couple things here and there.

gdb/testsuite/ChangeLog:
2015-07-29  Pedro Alves  <palves@redhat.com>

	* gdb.base/dprintf.exp: Use standard_testfile.  Change
	prepare_for_testing call.
	(srcfile): Don't set.
	(restart): New procedure.
	(test_dprintf): New procecure, use to continue over dprintfs.
	(test_call, test_agent): New procedures, tests moved here.
	Restart gdb and recreate dprintfs.  Adjust expected output.

gdb/testsuite/ChangeLog

@@ -1,3 +1,13 @@
+2015-07-29  Pedro Alves  <palves@redhat.com>
+
+	* gdb.base/dprintf.exp: Use standard_testfile.  Change
+	prepare_for_testing call.
+	(srcfile): Don't set.
+	(restart): New procedure.
+	(test_dprintf): New procecure, use to continue over dprintfs.
+	(test_call, test_agent): New procedures, tests moved here.
+	Restart gdb and recreate dprintfs.  Adjust expected output.
+
 2015-07-29  Pedro Alves  <palves@redhat.com>
 
 	* gdb.base/catch-gdb-caused-signals.exp: Use gdb_test_stdio.

gdb/testsuite/gdb.base/dprintf.exp

@@ -13,13 +13,12 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+standard_testfile
 
-if { [prepare_for_testing dprintf.exp "dprintf" {} {debug}] } {
+if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
     return -1
 }
 
-set srcfile dprintf.c
-
 set bp_location1 [gdb_get_line_number "set breakpoint 1 here"]
 set dp_location1 [gdb_get_line_number "set dprintf 1 here"]
 
@@ -65,38 +64,82 @@ gdb_test "continue" "arg=1234, g=1234.*" "1st dprintf, gdb"
 
 gdb_test "continue" "At foo entry.*arg=1235, g=2222.*" "2nd dprintf, gdb"
 
-# The "call" style depends on having I/O functions available, so test.
+# Restart GDB and set set up for testing.
 
-if ![target_info exists gdb,noinferiorio] {
+proc restart {} {
+    global binfile
+    global bp_location1 dp_location1
+
+    clean_restart $binfile
+
+    if ![runto main] {
+	return -1
+    }
+
+    gdb_test "dprintf foo,\"At foo entry\\n\"" \
+	"Dprintf .*"
+
+    gdb_test "dprintf $dp_location1,\"arg=%d, g=%d\\n\", arg, g" \
+	"Dprintf .*"
+
+    gdb_test "break $bp_location1" "Breakpoint .*"
+}
+
+# Test continuing across a dprintf.  PATTERN matches the output
+# generated by the dprintf.  MSG is used as test message.
+
+proc test_dprintf {pattern msg} {
+    gdb_test_stdio "continue" $pattern "" "$msg"
+}
+
+# Test the "call" style.
+
+proc test_call {} {
+    global binfile
+    global bp_location1
 
     # Now switch styles and rerun; in the absence of redirection the
     # output should be the same.
 
-    gdb_test_no_output "set dprintf-style call" "Set dprintf style to call"
+    with_test_prefix "printf" {
+	restart
 
-    gdb_run_cmd
+	gdb_test_no_output "set dprintf-style call" "set dprintf style to call"
 
-    gdb_test "" "Breakpoint"
+	test_dprintf "At foo entry.*arg=1234, g=1234\r\n" "1st dprintf"
 
-    gdb_test "continue" "At foo entry.*arg=1234, g=1234.*" "1st dprintf, call"
-
-    gdb_test "continue" "At foo entry.*arg=1235, g=2222.*" "2nd dprintf, call"
-
-    gdb_test_no_output "set dprintf-function fprintf" "Set dprintf function"
-    gdb_test_no_output "set dprintf-channel stderr" "Set dprintf channel"
-
-    gdb_run_cmd
-
-    gdb_test "" "Breakpoint"
-
-    gdb_test "continue" "At foo entry.*arg=1234, g=1234.*" \
-	"1st dprintf, fprintf"
-
-    gdb_test "continue" "At foo entry.*arg=1235, g=2222.*" \
-	"2nd dprintf, fprintf"
+	test_dprintf "At foo entry.*arg=1235, g=2222\r\n" "2nd dprintf"
     }
 
-# Now test the "agent" style.
+    with_test_prefix "fprintf" {
+	restart
+
+	gdb_test_no_output "set dprintf-function fprintf" "set dprintf function"
+	gdb_test_no_output "set dprintf-channel stderr" "set dprintf channel"
+
+	gdb_test_no_output "set dprintf-style call" "set dprintf style to call"
+
+	test_dprintf "At foo entry.*arg=1234, g=1234\r\n" "1st dprintf"
+
+	test_dprintf "At foo entry.*arg=1235, g=2222\r\n" "2nd dprintf"
+    }
+}
+
+# The "call" style depends on having I/O functions available.
+
+if ![target_info exists gdb,noinferiorio] {
+    with_test_prefix "call" {
+	test_call
+    }
+}
+
+# Test the "agent" style.
+
+proc test_agent {} {
+    global binfile
+    global gdb_prompt
+
+    restart
 
     set target_can_dprintf 1
     set msg "set dprintf style to agent"
@@ -113,17 +156,16 @@ gdb_test_multiple "set dprintf-style agent" $msg {
 	}
     }
 
-if $target_can_dprintf {
-    gdb_run_cmd
-
-    gdb_test "" "Breakpoint"
+    if !$target_can_dprintf {
+	return
+    }
 
     # Even if the the target reports that it does support target side
     # commands, we can only tell that it supports them in combination
     # with a particular breakpoint type (Z0, Z1, etc.) when we try to
     # insert the breakpoint.  When "set breakpoint always-inserted is
     # off", that'll be on next continue.
-    set msg "1st dprintf, agent"
+    set msg "1st dprintf"
     gdb_test_multiple "continue" $msg {
 	-re "Warning:.*Target doesn't support breakpoints that have target side commands.*\r\n$gdb_prompt $" {
 	    set target_can_dprintf 0
@@ -135,22 +177,26 @@ if $target_can_dprintf {
     }
 
     if $target_can_dprintf {
-	gdb_test "continue" "Breakpoint \[0-9\]+, foo .*" "2nd dprintf, agent"
+	gdb_test "continue" "Breakpoint \[0-9\]+, foo .*" "2nd dprintf"
 
-	gdb_test_sequence "info breakpoints" "dprintf info 2" {
+	gdb_test_sequence "info breakpoints" "dprintf info" {
 	    "\[\r\n\]Num     Type           Disp Enb Address +What"
-	    "\[\r\n\]2       breakpoint"
-	    "\[\r\n\]\tbreakpoint already hit 2 times"
-	    "\[\r\n\]3       dprintf"
-	    "\[\r\n\]\tbreakpoint already hit 2 times"
+	    "\[\r\n\]1       breakpoint"
+	    "\[\r\n\]\tbreakpoint already hit 1 time"
+	    "\[\r\n\]2       dprintf"
 	    "\[\r\n\]        agent-printf \"At foo entry\\\\n\""
-	    "\[\r\n\]4       dprintf"
-	    "\[\r\n\]\tbreakpoint already hit 2 times"
+	    "\[\r\n\]3       dprintf"
 	    "\[\r\n\]        agent-printf \"arg=%d, g=%d\\\\n\", arg, g"
+	    "\[\r\n\]4       breakpoint"
+	    "\[\r\n\]\tbreakpoint already hit 2 times"
 	}
     }
 }
 
+with_test_prefix "agent" {
+    test_agent
+}
+
 gdb_test "set dprintf-style foobar" "Undefined item: \"foobar\"." \
     "Set dprintf style to an unrecognized type"