gdb: objc-lang: check symbol name before accessing memory

The current ObjC logic will check both the symbol name and the target
address space when trying to locate an appropriate selector.  The problem
is that first the target address space is checked before the symbol name.
This may lead to a lot of unnecessary host<->target transactions when
dealing with a non-OjbC target that does use function descriptors to
describe functions as every symbol will have its FD read just to have the
result thrown away with non-matching symbol names.

It also may lead to problems when a non-FD symbol is found that points near
the end of the address space as the target will throw up a memory_error().
One such example are symbols that are not functions, smaller than a FD,
and are the last valid location.  Obviously treating it as a larger data
struct can cause memory overflows.

So to speed things up and not screw over such targets, check the symbol
name (which we already have locally) first before attempting to read the
function's descriptor.  This fixes breakpoints with Blackfin Linux FDPIC
ELFs, and seems to cause no native regressions on my x86_64/Linux system.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 39f0fbf74343b3eab263deb0cfbf8f75581b2814..690878b29465354576c9f7673ea896321e7a2373 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2010-04-19  Mike Frysinger  <vapier@gentoo.org>
+
+       * objc-lang.c (find_methods): Move symname check up.
+
 2010-04-19  Pedro Alves  <pedro@codesourcery.com>
 
        * ada-lang.c (print_recreate_exception)

diff --git a/gdb/objc-lang.c b/gdb/objc-lang.c
index a050f154ce66c78ceea4d34744475b1d18a12066..1731fa720120578a34559a1a31b911d5bda1f900 100644 (file)
--- a/gdb/objc-lang.c
+++ b/gdb/objc-lang.c
@@ -1178,6 +1178,16 @@ find_methods (struct symtab *symtab, char type,
 
          QUIT;
 
+         /* Check the symbol name first as this can be done entirely without
+            sending any query to the target.  */
+         symname = SYMBOL_NATURAL_NAME (msymbol);
+         if (symname == NULL)
+           continue;
+
+         if ((symname[0] != '-' && symname[0] != '+') || (symname[1] != '['))
+           /* Not a method name.  */
+           continue;
+
          /* The minimal symbol might point to a function descriptor;
             resolve it to the actual code address instead.  */
          pc = gdbarch_convert_from_func_ptr_addr (gdbarch, pc,
@@ -1188,14 +1198,7 @@ find_methods (struct symtab *symtab, char type,
              /* Not in the specified symtab.  */
              continue;
 
-         symname = SYMBOL_NATURAL_NAME (msymbol);
-         if (symname == NULL)
-           continue;
-
-         if ((symname[0] != '-' && symname[0] != '+') || (symname[1] != '['))
-           /* Not a method name.  */
-           continue;
-      
+         /* Now that thinks are a bit sane, clean up the symname.  */
          while ((strlen (symname) + 1) >= tmplen)
            {
              tmplen = (tmplen == 0) ? 1024 : tmplen * 2;