tui-disasm: Fix window content buffer overrun

A user reported a GDB crash with TUI when trying to debug a function
with a long demangled C++ method name.  It turned out that the logic for
displaying the TUI disassembly window has a bug that can cause a buffer
overrun, possibly overwriting GDB-internal data structures.  In
particular, the logic performs an unguarded strcpy.

Another (harmless) bug in tui_alloc_source_buffer causes the buffer to
be two lines longer than needed.  This may have made the crash appear
less frequently.

gdb/ChangeLog:

	* tui/tui-disasm.c (tui_set_disassem_content): Fix line buffer
	overrun due to unchecked strcpy.

gdb/testsuite/ChangeLog:

	* gdb.base/tui-layout.c: New file.
	* gdb.base/tui-layout.exp: Use tui-layout.c, to ensure that the
	disassembly window contains very long lines.

1 files changed, 47 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.base/tui-layout.c b/gdb/testsuite/gdb.base/tui-layout.c
new file mode 100644
index 0000000..4049f9b
--- /dev/null
+++ b/gdb/testsuite/gdb.base/tui-layout.c
@@ -0,0 +1,47 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 Free Software Foundation, Inc.
+
+   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/>.  */
+
+#define LONGER_NAME(x) x ## x
+#define LONGER(x) LONGER_NAME(x)
+#define LONGNAME1 d_this_identifier_of_32_chars_an
+#define LONGNAME2 LONGER (LONGER (LONGER (LONGER (LONGER (LONGNAME1)))))
+
+/* Construct a long identifier name.  If SHORT_IDENTIFIERS is set, limit
+   it to 1024 chars.  */
+
+#ifdef SHORT_IDENTIFIERS
+#define LONGNAME3 LONGNAME2
+#else
+#define LONGNAME3 LONGER (LONGER (LONGER (LONGER (LONGER (LONGNAME2)))))
+#endif
+
+void LONGNAME3 (void);
+
+int
+main ()
+{
+  LONGNAME3 ();
+  return 0;
+}
+
+/* Function with a long name.  Placing it after main makes it more likely
+   to be shown in the disassembly window on startup.  */
+
+void
+LONGNAME3 (void)
+{
+}