[PATCH 04/13] gdb: fix crash in "maint canonicalize" without argument

[Simon Marchi <simon.marchi@efficios.com>]

Running "maint canonicalize" without an argument crashes GDB:

    $ ./gdb -nx -q --data-directory=data-directory -ex "maint canon" -batch
    /home/smarchi/src/binutils-gdb/gdb/cp-support.c:105:27: runtime error: load of null pointer of type 'const char'

This message is from UBSan, otherwise we get a segfault.

maintenance_canonicalize passes the NULL ARGS straight to
cp_canonicalize_string.  Error out with error_no_arg if no argument is
given.

Add a test in gdb.base/maint.exp.

Change-Id: I2924a6e8d2a0a5ea77bdee5595a75c8c0fb59673
---
 gdb/maint.c                      | 3 +++
 gdb/testsuite/gdb.base/maint.exp | 1 +
 2 files changed, 4 insertions(+)

diff --git a/gdb/maint.c b/gdb/maint.c
index 22954f624efe..7864458ba136 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -118,6 +118,9 @@ maintenance_demangle (const char *args, int from_tty)
 static void
 maintenance_canonicalize (const char *args, int from_tty)
 {
+  if (args == nullptr)
+    error_no_arg (_("name"));
+
   gdb::unique_xmalloc_ptr<char> canon = cp_canonicalize_string (args);
   if (canon == nullptr)
     gdb_printf ("No change.\n");
diff --git a/gdb/testsuite/gdb.base/maint.exp b/gdb/testsuite/gdb.base/maint.exp
index f0c183c8c417..d13dab21fbe9 100644
--- a/gdb/testsuite/gdb.base/maint.exp
+++ b/gdb/testsuite/gdb.base/maint.exp
@@ -456,5 +456,6 @@ gdb_test "maint canonicalize int short" "canonical = short"
 gdb_test "maint canonicalize fn<ty<int>>" \
     "canonical = fn<ty<int> >"
 gdb_test "maint canonical unsigned int" "No change\\."
+gdb_test "maint canonicalize" "Argument required \\(name\\)\\."
 
 gdb_exit
-- 
2.56.0