Fix tracepoint.c:parse_tracepoint_definition leak (and one more)

Coverity points out that gdb/tracepoint.c:parse_tracepoint_definition
can leak 'cond' in this line:

      cond = (char *) xmalloc (2 * xlen + 1);

That can leak because we're in a loop and 'cond' may have already been
xmalloc'ed into in a previous iteration.  That won't normally happen,
because we don't expect to see a tracepoint definition with multiple
conditions listed, but, it doesn't hurt to be pedantically correct,
in case some stub manages to send something odd back to GDB.

At first I thought I'd just replace the xmalloc call with:

      cond = (char *) xrealloc (cond, 2 * xlen + 1);

and be done with it.  However, my pedantic self realizes that
warning() can throw as well (due to pagination + Ctrl-C), so I fixed
it using gdb::unique_xmalloc_ptr instead.

While doing this, I noticed that these vectors in struct uploaded_tp:

  std::vector<char *> actions;
  std::vector<char *> step_actions;

hold heap-allocated strings, but nothing is freeing the strings,
AFAICS.

So I ended up switching all the heap-allocated strings in uploaded_tp
to unique pointers.  This patch is the result of that.

I also wrote an alternative, but similar patch that uses std::string
throughout instead of gdb::unique_xmalloc_ptr, but in the end reverted
it because the code didn't look that much better, and I kind of
dislike replacing pointers with fat std::string's (3 or 4 times the
size of a pointer) in structures.

gdb/ChangeLog:
2019-01-10  Pedro Alves  <palves@redhat.com>

	* breakpoint.c (read_uploaded_action)
	(create_tracepoint_from_upload): Adjust to use
	gdb::unique_xmalloc_ptr.
	* ctf.c (ctf_write_uploaded_tp):
	(SET_ARRAY_FIELD): Use emplace_back.
	(SET_STRING_FIELD): Adjust to use gdb::unique_xmalloc_ptr.
	* tracefile-tfile.c (tfile_write_uploaded_tp):
	* tracepoint.c (parse_tracepoint_definition): Adjust to use
	gdb::unique_xmalloc_ptr.
	* tracepoint.h (struct uploaded_tp) <cond, actions, step_actions,
	at_string, cond_string, cmd_strings>: Replace char pointers
	with gdb::unique_xmalloc_ptr.

1 files changed, 3 insertions, 3 deletions

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 48a1c64..2ab8a76 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -14686,7 +14686,7 @@ read_uploaded_action (void)
 
   if (next_cmd < this_utp->cmd_strings.size ())
     {
-      rslt = this_utp->cmd_strings[next_cmd];
+      rslt = this_utp->cmd_strings[next_cmd].get ();
       next_cmd++;
     }
 
@@ -14707,7 +14707,7 @@ create_tracepoint_from_upload (struct uploaded_tp *utp)
   struct tracepoint *tp;
 
   if (utp->at_string)
-    addr_str = utp->at_string;
+    addr_str = utp->at_string.get ();
   else
     {
       /* In the absence of a source location, fall back to raw
@@ -14731,7 +14731,7 @@ create_tracepoint_from_upload (struct uploaded_tp *utp)
 							 current_language);
   if (!create_breakpoint (get_current_arch (),
 			  location.get (),
-			  utp->cond_string, -1, addr_str,
+			  utp->cond_string.get (), -1, addr_str,
 			  0 /* parse cond/thread */,
 			  0 /* tempflag */,
 			  utp->type /* type_wanted */,