[PATCH 1/2] Make parse_static_tracepoint_marker_definition work with multiple static tracepoint definitions

[Simon Marchi <simon dot marchi at polymtl dot ca>]

Since I modify the parse_static_tracepoint_marker_definition function in
the next patch, I wanted to write a unit test for it.  Doing so showed
that it doesn't handle multiple consecutive static tracepoint
definitions separated by commas.  However, the RSP documentation [1]
states that servers may return multiple definitions, like:

  1234:6d61726b657231:6578747261207374756666,abba:6d61726b657232:

The problem is that the function uses strlen to compute the length of
the last field (the extra field).  If there are additional definitions
in addition to the one we are currently parsing, the returned length
will include those definitions, and we'll try to hex-decode past the
extra field.

This patch changes parse_static_tracepoint_marker_definition to consider
the case where the current definition is followed by a comma and more
definitions.  It also adds the unit test that found the issue in the
first place.

I don't think this causes any backwards compatibility issues, because
the previous code only handled single static tracepoint definitions, and
the new code handles that correctly.

gdb/ChangeLog:

	* tracepoint.c (parse_static_tracepoint_marker_definition):
	Consider case where the definition is followed by more
	definitions.
	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
	tracepoint-selftests.c.
	* unittests/tracepoint-selftests.c: New.

[1] https://sourceware.org/gdb/onlinedocs/gdb/Tracepoint-Packets.html#qTfSTM
---
 gdb/Makefile.in                      |  1 +
 gdb/tracepoint.c                     | 14 ++++++--
 gdb/unittests/tracepoint-selftests.c | 70 ++++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 3 deletions(-)
 create mode 100644 gdb/unittests/tracepoint-selftests.c

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 957654c9bd..5a2f4c8cac 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -427,6 +427,7 @@ SUBDIR_UNITTESTS_SRCS = \
 	unittests/scoped_fd-selftests.c \
 	unittests/scoped_mmap-selftests.c \
 	unittests/scoped_restore-selftests.c \
+	unittests/tracepoint-selftests.c \
 	unittests/xml-utils-selftests.c
 
 SUBDIR_UNITTESTS_OBS = $(patsubst %.c,%.o,$(SUBDIR_UNITTESTS_SRCS))
diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c
index f34f103875..843041f739 100644
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -3720,12 +3720,20 @@ parse_static_tracepoint_marker_definition (const char *line, const char **pp,
   p += 2 * end;
   p++;  /* skip a colon */
 
-  marker->extra = (char *) xmalloc (strlen (p) + 1);
-  end = hex2bin (p, (gdb_byte *) marker->extra, strlen (p) / 2);
+  /* This definition may be followed by another one, separated by a comma.  */
+  int hex_len;
+  endp = strchr (p, ',');
+  if (endp != nullptr)
+    hex_len = endp - p;
+  else
+    hex_len = strlen (p);
+
+  marker->extra = (char *) xmalloc (hex_len / 2 + 1);
+  end = hex2bin (p, (gdb_byte *) marker->extra, hex_len / 2);
   marker->extra[end] = '\0';
 
   if (pp)
-    *pp = p;
+    *pp = p + hex_len;
 }
 
 /* Release a static tracepoint marker's contents.  Note that the
diff --git a/gdb/unittests/tracepoint-selftests.c b/gdb/unittests/tracepoint-selftests.c
new file mode 100644
index 0000000000..21ca3d0914
--- /dev/null
+++ b/gdb/unittests/tracepoint-selftests.c
@@ -0,0 +1,70 @@
+/* Self tests for tracepoint-related code for GDB, the GNU debugger.
+
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 "defs.h"
+#include "selftest.h"
+#include "tracepoint.h"
+
+namespace selftests {
+namespace tracepoint_tests {
+
+static void
+test_parse_static_tracepoint_marker_definition ()
+{
+  static_tracepoint_marker marker;
+  const char def[] = ("1234:6d61726b657231:6578747261207374756666,"
+		      "abba:6d61726b657232:,"
+		      "cafe:6d61726b657233:6d6f72657374756666");
+  const char *start = def;
+  const char *end;
+
+  parse_static_tracepoint_marker_definition (start, &end, &marker);
+
+  SELF_CHECK (marker.address == 0x1234);
+  SELF_CHECK (strcmp (marker.str_id, "marker1") == 0);
+  SELF_CHECK (strcmp (marker.extra, "extra stuff") == 0);
+  SELF_CHECK (end == strchr (start, ','));
+
+  start = end + 1;
+  parse_static_tracepoint_marker_definition (start, &end, &marker);
+
+  SELF_CHECK (marker.address == 0xabba);
+  SELF_CHECK (strcmp (marker.str_id, "marker2") == 0);
+  SELF_CHECK (strcmp (marker.extra, "") == 0);
+  SELF_CHECK (end == strchr (start, ','));
+
+  start = end + 1;
+  parse_static_tracepoint_marker_definition (start, &end, &marker);
+
+  SELF_CHECK (marker.address == 0xcafe);
+  SELF_CHECK (strcmp (marker.str_id, "marker3") == 0);
+  SELF_CHECK (strcmp (marker.extra, "morestuff") == 0);
+  SELF_CHECK (end == def + strlen (def));
+}
+
+} /* namespace tracepoint_tests */
+} /* namespace selftests */
+
+void
+_initialize_tracepoint_selftests ()
+{
+  selftests::register_test
+    ("parse_static_tracepoint_marker_definition",
+     selftests::tracepoint_tests::test_parse_static_tracepoint_marker_definition);
+}
-- 
2.16.1