[PATCH v4] Introduce target_is_gdbserver

[Simon Marchi <simon dot marchi at ericsson dot com>]

This patch introduces a function in gdbserver-support.exp to find out
whether the current target is GDBserver.

The code was inspired from gdb.trace/qtro.exp, so it replaces the code
there by a call to the new function.

New in v4:
- Return -1 on error, and check for -1 in qtro.exp.
- Use gdb_caching_proc to cache result.

gdb/testsuite/ChangeLog:

	* gdb.trace/qtro.exp: Replace gdbserver detection code by...
	* lib/gdbserver-support.exp (target_is_gdbserver): New
	fonction.
---
 gdb/testsuite/gdb.trace/qtro.exp        | 13 +------------
 gdb/testsuite/lib/gdbserver-support.exp | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/gdb/testsuite/gdb.trace/qtro.exp b/gdb/testsuite/gdb.trace/qtro.exp
index 22b5051..d8ffc40 100644
--- a/gdb/testsuite/gdb.trace/qtro.exp
+++ b/gdb/testsuite/gdb.trace/qtro.exp
@@ -98,18 +98,7 @@ if { $traceframe_info_supported == -1 } {
 }
 
 # Check whether we're testing with our own GDBserver.
-set is_gdbserver -1
-set test "probe for GDBserver"
-gdb_test_multiple "monitor help" $test {
-    -re "The following monitor commands are supported.*debug-hw-points.*remote-debug.*GDBserver.*$gdb_prompt $" {
-	set is_gdbserver 1
-	pass $test
-    }
-    -re "$gdb_prompt $" {
-	set is_gdbserver 0
-	pass $test
-    }
-}
+set is_gdbserver [target_is_gdbserver]
 if { $is_gdbserver == -1 } {
     return -1
 }
diff --git a/gdb/testsuite/lib/gdbserver-support.exp b/gdb/testsuite/lib/gdbserver-support.exp
index 026a937..e3f421e 100644
--- a/gdb/testsuite/lib/gdbserver-support.exp
+++ b/gdb/testsuite/lib/gdbserver-support.exp
@@ -436,3 +436,28 @@ proc mi_gdbserver_start_multi { } {
 
     return [mi_gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport]
 }
+
+# Return 1 if the current remote target is an instance of gdbserver, 0
+# otherwise. Return -1 if there was an error and we can't tell.
+
+gdb_caching_proc target_is_gdbserver {
+    global gdb_prompt
+
+    set is_gdbserver -1
+    set test "Probing for GDBserver"
+
+    gdb_test_multiple "monitor help" $test {
+	-re "The following monitor commands are supported.*Quit GDBserver.*$gdb_prompt $" {
+		set is_gdbserver 1
+	}
+	-re "$gdb_prompt $" {
+		set is_gdbserver 0
+	}
+    }
+
+    if { $is_gdbserver == -1 } {
+	verbose -log "Unable to tell whether we are using gdbserver or not."
+    }
+
+    return $is_gdbserver
+}
-- 
2.1.0