Re: [PUSHED/OBVIOUS] Re-fix leak in source.c (open_source_file).

[Philippe Waroquiers <philippe dot waroquiers at skynet dot be>]

On Thu, 2018-11-29 at 16:29 -0700, Tom Tromey wrote:
> > > > > > "Philippe" == Philippe Waroquiers <philippe.waroquiers@skynet.be> writes:
> 
> Philippe> Note that after having run all GDB tests under valgrind, I still
> Philippe> see some 4K leaks in open_source_file appearing (I suspect)
> Philippe> when GDB reloads an executable that has changed.
> 
> What are the leaks?  I wonder if the "fullname"s in the psymtabs aren't
> being freed.
> 
> I have been wondering lately if this field should be pulled out into
> some separate hash table.  This would save a little memory if there are
> file names, which seems likely.

Yes, the 4K leak is the fullname (but fullname is freed now in all tests
except in the 4 below tests, which all have something to do with reloading
an executable/reload symbols ...
  Note gdb.ada/exec_changed also has a bad behaviour under valgrind:
  ==28802== Stack overflow in thread #1: can't grow stack to 0x1ffe801000
  ==28802== 
  ==28802== Process terminating with default action of signal 11 (SIGSEGV)
  ==28802==  Access not within mapped region at address 0x1FFE801FE8
  ==28802== Stack overflow in thread #1: can't grow stack to 0x1ffe801000
  ==28802==    at 0x5BF7DC8: __find_specmb (printf-parse.h:108)
  ==28802==    by 0x5BF7DC8: vfprintf (vfprintf.c:1312)
  Not yet analysed ...

grep -n -ie 'open_source_file' $(ls -rt $(find . -name '*valgrind.log'))
./testsuite/outputs/gdb.ada/exec_changed/valgrind.log:291:==28802==    by 0x60ABFC: open_source_file(symtab*) (source.c:1074)
./testsuite/outputs/gdb.ada/exec_changed/valgrind.log:329:   fun:_Z16open_source_fileP6symtab
./testsuite/outputs/gdb.base/chng-syms/valgrind.log:69:==12362==    by 0x60ABFC: open_source_file(symtab*) (source.c:1074)
./testsuite/outputs/gdb.base/chng-syms/valgrind.log:98:   fun:_Z16open_source_fileP6symtab
./testsuite/outputs/gdb.base/reread/valgrind.log:1885:==2245==    by 0x60ABFC: open_source_file(symtab*) (source.c:1074)
./testsuite/outputs/gdb.base/reread/valgrind.log:1914:   fun:_Z16open_source_fileP6symtab
./testsuite/outputs/gdb.dwarf2/gdb-index/valgrind.log:19:==13830==    by 0x60ABFC: open_source_file(symtab*) (source.c:1074)
./testsuite/outputs/gdb.dwarf2/gdb-index/valgrind.log:57:   fun:_Z16open_source_fileP6symtab


chng-syms full output (other tests contains similar leaks) is:
==12362== Memcheck, a memory error detector
==12362== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==12362== Using Valgrind-3.15.0.GIT and LibVEX; rerun with -h for copyright info
==12362== Command: /bd/home/philippe/gdb/git/build_obvious/gdb/gdb -nw -nx -data-directory /bd/home/philippe/gdb/git/build_obvious/gdb/testsuite/../data-directory
==12362== Parent PID: 12361
==12362== 
==12362== 
==12362== HEAP SUMMARY:
==12362==     in use at exit: 4,043,008 bytes in 4,040 blocks
==12362==   total heap usage: 79,418 allocs, 75,378 frees, 99,134,863 bytes allocated
==12362== 
==12362== VALGRIND_GDB_ERROR_BEGIN
==12362== 88 bytes in 1 blocks are definitely lost in loss record 829 of 3,086
==12362==    at 0x4C2E273: realloc (vg_replace_malloc.c:826)
==12362==    by 0x41B58C: xrealloc (common-utils.c:62)
==12362==    by 0x60AF20: find_source_lines(symtab*, int) (source.c:1201)
==12362==    by 0x60B41B: print_source_lines_base(symtab*, int, int, enum_flags<print_source_lines_flag>) (source.c:1347)
==12362==    by 0x616AAF: print_frame_info(frame_info*, int, print_what, int, int) (stack.c:911)
==12362==    by 0x616C15: print_stack_frame(frame_info*, int, print_what, int) (stack.c:181)
==12362==    by 0x51235E: print_stop_location (infrun.c:7987)
==12362==    by 0x51235E: print_stop_event(ui_out*) (infrun.c:8004)
==12362==    by 0x40DC9D: cli_on_normal_stop(bpstats*, int) (cli-interp.c:145)
==12362==    by 0x512A09: operator() (functional:2127)
==12362==    by 0x512A09: notify (observable.h:106)
==12362==    by 0x512A09: normal_stop() (infrun.c:8277)
==12362==    by 0x515FB0: fetch_inferior_event(void*) (infrun.c:3907)
==12362==    by 0x4B388C: gdb_wait_for_event(int) (event-loop.c:859)
==12362==    by 0x4B3996: gdb_do_one_event() [clone .part.4] (event-loop.c:322)
==12362==    by 0x4B3B54: gdb_do_one_event (common-exceptions.h:219)
==12362==    by 0x4B3B54: start_event_loop() (event-loop.c:371)
==12362==    by 0x551BD7: captured_command_loop() (main.c:330)
==12362==    by 0x552BCC: captured_main (main.c:1177)
==12362==    by 0x552BCC: gdb_main(captured_main_args*) (main.c:1193)
==12362==    by 0x29B317: main (gdb.c:32)
==12362== 
==12362== VALGRIND_GDB_ERROR_END
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:realloc
   fun:xrealloc
   fun:_Z17find_source_linesP6symtabi
   fun:_ZL23print_source_lines_baseP6symtabii10enum_flagsI23print_source_lines_flagE
   fun:_Z16print_frame_infoP10frame_infoi10print_whatii
   fun:_Z17print_stack_frameP10frame_infoi10print_whati
   fun:print_stop_location
   fun:_Z16print_stop_eventP6ui_out
   fun:_ZL18cli_on_normal_stopP7bpstatsi
   fun:operator()
   fun:notify
   fun:_Z11normal_stopv
   fun:_Z20fetch_inferior_eventPv
   fun:_ZL18gdb_wait_for_eventi
   fun:_Z16gdb_do_one_eventv.part.4
   fun:gdb_do_one_event
   fun:_Z16start_event_loopv
   fun:_ZL21captured_command_loopv
   fun:captured_main
   fun:_Z8gdb_mainP18captured_main_args
   fun:main
}
==12362== VALGRIND_GDB_ERROR_BEGIN
==12362== 4,096 bytes in 1 blocks are definitely lost in loss record 2,999 of 3,086
==12362==    at 0x4C2BE2D: malloc (vg_replace_malloc.c:299)
==12362==    by 0x5BF0987: realpath@@GLIBC_2.3 (canonicalize.c:78)
==12362==    by 0x41F643: gdb_realpath(char const*) (pathstuff.c:72)
==12362==    by 0x60A98F: find_and_open_source(char const*, char const*, std::unique_ptr<char, gdb::xfree_deleter<char> >*) (source.c:995)
==12362==    by 0x60ABFC: open_source_file(symtab*) (source.c:1074)
==12362==    by 0x60B028: print_source_lines_base(symtab*, int, int, enum_flags<print_source_lines_flag>) (source.c:1283)
==12362==    by 0x616AAF: print_frame_info(frame_info*, int, print_what, int, int) (stack.c:911)
==12362==    by 0x616C15: print_stack_frame(frame_info*, int, print_what, int) (stack.c:181)
==12362==    by 0x51235E: print_stop_location (infrun.c:7987)
==12362==    by 0x51235E: print_stop_event(ui_out*) (infrun.c:8004)
==12362==    by 0x40DC9D: cli_on_normal_stop(bpstats*, int) (cli-interp.c:145)
==12362==    by 0x512A09: operator() (functional:2127)
==12362==    by 0x512A09: notify (observable.h:106)
==12362==    by 0x512A09: normal_stop() (infrun.c:8277)
==12362==    by 0x515FB0: fetch_inferior_event(void*) (infrun.c:3907)
==12362==    by 0x4B388C: gdb_wait_for_event(int) (event-loop.c:859)
==12362==    by 0x4B3996: gdb_do_one_event() [clone .part.4] (event-loop.c:322)
==12362==    by 0x4B3B54: gdb_do_one_event (common-exceptions.h:219)
==12362==    by 0x4B3B54: start_event_loop() (event-loop.c:371)
==12362==    by 0x551BD7: captured_command_loop() (main.c:330)
==12362==    by 0x552BCC: captured_main (main.c:1177)
==12362==    by 0x552BCC: gdb_main(captured_main_args*) (main.c:1193)
==12362==    by 0x29B317: main (gdb.c:32)
==12362== 
==12362== VALGRIND_GDB_ERROR_END
{
   <insert_a_suppression_name_here>
   Memcheck:Leak
   match-leak-kinds: definite
   fun:malloc
   fun:realpath@@GLIBC_2.3
   fun:_Z12gdb_realpathPKc
   fun:_Z20find_and_open_sourcePKcS0_PSt10unique_ptrIcN3gdb13xfree_deleterIcEEE
   fun:_Z16open_source_fileP6symtab
   fun:_ZL23print_source_lines_baseP6symtabii10enum_flagsI23print_source_lines_flagE
   fun:_Z16print_frame_infoP10frame_infoi10print_whatii
   fun:_Z17print_stack_frameP10frame_infoi10print_whati
   fun:print_stop_location
   fun:_Z16print_stop_eventP6ui_out
   fun:_ZL18cli_on_normal_stopP7bpstatsi
   fun:operator()
   fun:notify
   fun:_Z11normal_stopv
   fun:_Z20fetch_inferior_eventPv
   fun:_ZL18gdb_wait_for_eventi
   fun:_Z16gdb_do_one_eventv.part.4
   fun:gdb_do_one_event
   fun:_Z16start_event_loopv
   fun:_ZL21captured_command_loopv
   fun:captured_main
   fun:_Z8gdb_mainP18captured_main_args
   fun:main
}
==12362== LEAK SUMMARY:
==12362==    definitely lost: 4,184 bytes in 2 blocks
==12362==    indirectly lost: 0 bytes in 0 blocks
==12362==      possibly lost: 143,232 bytes in 164 blocks
==12362==    still reachable: 3,895,464 bytes in 3,867 blocks
==12362==         suppressed: 128 bytes in 7 blocks
==12362== Reachable blocks (those to which a pointer was found) are not shown.
==12362== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==12362== 
==12362== For counts of detected and suppressed errors, rerun with: -v
==12362== ERROR SUMMARY: 67 errors from 67 contexts (suppressed: 1476 from 235)