This is the mail archive of the gdb-cvs@sourceware.org mailing list for the GDB project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[binutils-gdb] Fix 4K leak in open_source_file each time next/step changes of function.


https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=8e6a5953e1ddb327d870b79e6ccd2fd4a92d6fde

commit 8e6a5953e1ddb327d870b79e6ccd2fd4a92d6fde
Author: Philippe Waroquiers <philippe.waroquiers@skynet.be>
Date:   Sun Nov 4 17:48:57 2018 +0100

    Fix 4K leak in open_source_file each time next/step changes of function.
    
    When current function changes after a next/step, GDB shows a message such as:
      (gdb) s
      info_fun1 ()
          at /bd/home/philippe/gdb/git/build_smallthing/gdb/testsuite/../../../smallthing/gdb/testsuite/gdb.base/info_qt.c:41
      41	  info_qt_inc++;
      (gdb)
    
    Valgrind reports a 4K definite leak for each such message (full stacktrace of
    the leak below).
    
    This patch fixes this leak, by transferring the current s->fullname to the
    unique_xmalloc_ptr fullname given to find_and_open_source.
    
    Note that I do not understand why find_and_open_source always tries to
    re-execute the substitution rules on the provided fullname, as source.c
    symtab_to_fullname just blindly returns a non NULL s->fullname, counting on
    forget_cached_source_info to be called if search dir or substitution rules are
    changed.  Similarly, psymtab_to_fullname also just returns a non NULL
    ps->fullname.
    
    ==15309== VALGRIND_GDB_ERROR_BEGIN
    ==15309== 69,632 bytes in 17 blocks are definitely lost in loss record 3,158 of 3,186
    ==15309==    at 0x4C2BE2D: malloc (vg_replace_malloc.c:299)
    ==15309==    by 0x5BF0987: realpath@@GLIBC_2.3 (canonicalize.c:78)
    ==15309==    by 0x41F713: gdb_realpath(char const*) (pathstuff.c:72)
    ==15309==    by 0x608833: openp(char const*, enum_flags<openp_flag>, char const*, int, std::unique_ptr<char, gdb::xfree_deleter<char> >*) (source.c:861)
    ==15309==    by 0x608B89: find_and_open_source(char const*, char const*, std::unique_ptr<char, gdb::xfree_deleter<char> >*) (source.c:1049)
    ==15309==    by 0x608D0B: open_source_file(symtab*) (source.c:1074)
    ==15309==    by 0x609101: print_source_lines_base(symtab*, int, int, enum_flags<print_source_lines_flag>) (source.c:1291)
    ==15309==    by 0x614ADF: print_frame_info(frame_info*, int, print_what, int, int) (stack.c:911)
    ==15309==    by 0x614C45: print_stack_frame(frame_info*, int, print_what, int) (stack.c:181)
    ==15309==    by 0x511D5E: print_stop_location (infrun.c:8044)
    ==15309==    by 0x511D5E: print_stop_event(ui_out*) (infrun.c:8061)
    ==15309==    by 0x40DD6D: cli_on_normal_stop(bpstats*, int) (cli-interp.c:145)
    ==15309==    by 0x512409: operator() (functional:2127)
    ==15309==    by 0x512409: notify (observable.h:106)
    ==15309==    by 0x512409: normal_stop() (infrun.c:8334)
    ==15309==    by 0x5156D8: fetch_inferior_event(void*) (infrun.c:3955)
    ==15309==    by 0x4B3EEC: gdb_wait_for_event(int) (event-loop.c:859)
    ==15309==    by 0x4B3FF6: gdb_do_one_event() [clone .part.4] (event-loop.c:322)
    ==15309==    by 0x4B41B4: gdb_do_one_event (common-exceptions.h:219)
    ==15309==    by 0x4B41B4: start_event_loop() (event-loop.c:371)
    ==15309==    by 0x551217: captured_command_loop() (main.c:330)
    ==15309==    by 0x55220C: captured_main (main.c:1177)
    ==15309==    by 0x55220C: gdb_main(captured_main_args*) (main.c:1193)
    ==15309==    by 0x29B4F7: main (gdb.c:32)
    ==15309==
    ==15309== VALGRIND_GDB_ERROR_END
    
    gdb/ChangeLog
    2018-11-04  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
    
    	* source.c (open_source_file): Fix leak by transferring the
    	current s->fullname to the unique_xmalloc_ptr fullname given
    	to find_and_open_source.

Diff:
---
 gdb/source.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gdb/source.c b/gdb/source.c
index ec0ea3b..3cdf0b9 100644
--- a/gdb/source.c
+++ b/gdb/source.c
@@ -1070,7 +1070,8 @@ open_source_file (struct symtab *s)
   if (!s)
     return -1;
 
-  gdb::unique_xmalloc_ptr<char> fullname;
+  gdb::unique_xmalloc_ptr<char> fullname (s->fullname);
+  s->fullname = NULL;
   int fd = find_and_open_source (s->filename, SYMTAB_DIRNAME (s), &fullname);
   s->fullname = fullname.release ();
   return fd;


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]