From 8e6a5953e1ddb327d870b79e6ccd2fd4a92d6fde Mon Sep 17 00:00:00 2001 From: Philippe Waroquiers Date: Sun, 4 Nov 2018 17:48:57 +0100 Subject: [PATCH] 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, char const*, int, std::unique_ptr >*) (source.c:861) ==15309== by 0x608B89: find_and_open_source(char const*, char const*, std::unique_ptr >*) (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) (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 * 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. --- gdb/source.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/gdb/source.c b/gdb/source.c index ec0ea3b81e3..3cdf0b9ec77 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 fullname; + gdb::unique_xmalloc_ptr fullname (s->fullname); + s->fullname = NULL; int fd = find_and_open_source (s->filename, SYMTAB_DIRNAME (s), &fullname); s->fullname = fullname.release (); return fd; -- 2.30.2