Problem: -------- Vim version 7.1.298 on linux. Vim crashes processing received netbeans messages while redrawing the windows. This happens about once every five times when running the pyclewn test case described at the end of this mail. There is also another case where Vim crashes, with clewn this time, when fast stepping (pressing the 'S' key continuously, causing the gdb 'step' command to run continuously). The crash happens with the clewn case after about 20 seconds and the gdb backtrace is the same as in the pyclewn test case.
The gdb backtrace with the pyclewn test is:
#0 0xffffe410 in __kernel_vsyscall ()
#1 0xb7973c76 in kill () from /lib/tls/libc.so.6
#2 0x081443b6 in may_core_dump () at os_unix.c:3024
#3 0x0814434a in mch_exit (r=1) at os_unix.c:2989
#4 0x080ec128 in getout (exitval=1) at main.c:1342
#5 0x0810f965 in preserve_exit () at misc1.c:8370
#6 0x08142802 in deathtrap (sigarg=11) at os_unix.c:1048
#7 <signal handler called>
#8 0x081940c4 in in_id_list (cur_si=0x83733c0, list=0x74,
ssp=0x8387e7c, contained=0) at syntax.c:5863
#9 0x0818d504 in syn_current_attr (syncing=0, displaying=1,
can_spell=0x0, keep_state=0) at syntax.c:1975
#10 0x0818cfe5 in get_syntax_attr (col=8, can_spell=0x0, keep_state=0)
at syntax.c:1771
#11 0x0815ebdb in win_line (wp=0x820ebf0, lnum=8, startrow=7,
endrow=26, nochange=1) at screen.c:3896
#12 0x0815b989 in win_update (wp=0x820ebf0) at screen.c:1765
#13 0x08159d08 in update_screen (type=40) at screen.c:522
#14 0x080ebd91 in main_loop (cmdwin=0, noexmode=0) at main.c:1110
#15 0x080eba46 in main (argc=7, argv=0xbfb17254) at main.c:940
Gdb debug session:
------------------
Program received signal SIGSEGV, Segmentation fault.
0x081940c4 in in_id_list (cur_si=0x8362b78, list=0x74, ssp=0x8386ff4,
contained=0) at syntax.c:5863
(gdb) print current_state
$3 = {ga_len = 1, ga_maxlen = 6, ga_itemsize = 80, ga_growsize = 3,
ga_data = 0x8382820}
Note that the following invariant is false (hence the crash):
ga_data <= cur_si < ga_data + 6 * 80
Valgrind session:
-----------------
When pyclewn is instrumented to run valgrind on top of Vim (see test
case below), the following memory error reported by Valgrind occurs
systematically when running the pyclewn test case (but not causing a
SEGV each time).
It shows that the netbeans callback (invoked through ui_breakcheck)
modifies the syntax.c 'current_state' data structure by calling
invalidate_current_state() under the feet of syn_current_attr().
==4908== Invalid read of size 4
==4908== at 0x818D4F9: syn_current_attr (syntax.c:1975)
==4908== by 0x818CFE4: get_syntax_attr (syntax.c:1771)
==4908== by 0x815EBDA: win_line (screen.c:3896)
==4908== by 0x815B988: win_update (screen.c:1765)
==4908== by 0x8159D07: update_screen (screen.c:522)
==4908== by 0x80EBD90: main_loop (main.c:1110)
==4908== by 0x80EBA45: main (main.c:940)
==4908== by 0x1BE4FE22: __libc_start_main (in /lib/tls/libc-2.3.6.so)
==4908== by 0x806B12C: (within
/home/xavier/src/packages/vim/vim_svn/vim7/src/vim)
==4908== Address 0x1C604594 is 68 bytes inside a block of size 240 free'd
==4908== at 0x1B901382: free (vg_replace_malloc.c:235)
==4908== by 0x8111FE1: vim_free (misc2.c:1584)
==4908== by 0x8112221: ga_clear (misc2.c:1881)
==4908== by 0x818B5BF: clear_current_state (syntax.c:660)
==4908== by 0x818CD57: invalidate_current_state (syntax.c:1615)
==4908== by 0x818B255: syntax_start (syntax.c:517)
==4908== by 0x815CCC7: win_line (screen.c:2719)
==4908== by 0x815B988: win_update (screen.c:1765)
==4908== by 0x8159D07: update_screen (screen.c:522)
==4908== by 0x81C92D5: nb_do_cmd (netbeans.c:2079)
==4908== by 0x81C7288: nb_parse_cmd (netbeans.c:839)
==4908== by 0x81C6FBE: nb_parse_messages (netbeans.c:667)
==4908== by 0x81C710D: messageFromNetbeans (netbeans.c:754)
==4908== by 0x1BBE8872: (within /usr/lib/libgdk-x11-2.0.so.0.400.14)
==4908== by 0x1BD5C9C6: (within /usr/lib/libglib-2.0.so.0.400.8)
==4908== by 0x1BD387BA: g_main_context_dispatch (in
/usr/lib/libglib-2.0.so.0.400.8)
==4908== by 0x1BD3A241: (within
/usr/lib/libglib-2.0.so.0.400.8)==4908== by 0x1BD3A727:
g_main_context_iteration (in /usr/lib/libglib-2.0.so.0.400.8)
==4908== by 0x1BA2671C: gtk_main_iteration_do (in
/usr/lib/libgtk-x11-2.0.so.0.400.14)
==4908== by 0x81C2651: gui_mch_update (gui_gtk_x11.c:6382)
==4908== by 0x81A33A2: ui_breakcheck (ui.c:365)
==4908== by 0x810F9EA: fast_breakcheck (misc1.c:8423)
==4908== by 0x81544B1: regmatch (regexp.c:3788)
==4908== by 0x8154249: regtry (regexp.c:3656)
==4908== by 0x815406B: vim_regexec_both (regexp.c:3545)
==4908== by 0x8153B67: vim_regexec_multi (regexp.c:3354)
==4908== by 0x818EF79: syn_regexec (syntax.c:3100)
==4908== by 0x818D591: syn_current_attr (syntax.c:2002)
==4908== by 0x818CFE4: get_syntax_attr (syntax.c:1771)
==4908== by 0x815EBDA: win_line (screen.c:3896)
==4908== by 0x815B988: win_update (screen.c:1765)
==4908== by 0x8159D07: update_screen (screen.c:522)
==4908== by 0x80EBD90: main_loop (main.c:1110)
==4908== by 0x80EBA45: main (main.c:940)
==4908== by 0x1BE4FE22: __libc_start_main (in /lib/tls/libc-2.3.6.so)
==4908== by 0x806B12C: (within
/home/xavier/src/packages/vim/vim_svn/vim7/src/vim)
Solution:
---------
See patch below (also attached to this mail as vim_callback.diff).
Implement a global flag named 'callback_restricted' that restrict the
use of Vim functions by the gdk callbacks to the scope of the
normal_cmd() function within the main loop (where it is considered to be
safe to use the full set of Vim functions).
The following tests have been completed successfully with this patch:
* no Vim crash with the pyclewn test case
* no error reported by Valgrind with the pyclewn test case
* Vim does not crash when doing fast stepping with clewn
* netbeans does process messages when Vim is idle in normal_cmd()
* the full pyclewn regression test suite runs Ok.
Note that attempting to prevent netbeans to recursively call win_update
is not good enough. In that case more memory errors occur after netbeans
call buf_jump_open_win or set_curbuf.
=== patch -d vim7 -p0 < vim_callback.diff =========================
Index: src/netbeans.c
===================================================================
--- src/netbeans.c (revision 1011)
+++ src/netbeans.c (working copy)
@@ -749,8 +749,11 @@
return; /* don't try to parse it */
}
- /* Parse the messages, but avoid recursion. */
- if (level == 1)
+ /* Parse the messages, but avoid recursion
+ * and do not process messages when the use
+ * of vim functions is restricted within callbacks.
+ */
+ if (level == 1 && ! callback_restricted)
nb_parse_messages();
--level;
Index: src/main.c
===================================================================
--- src/main.c (revision 1011)
+++ src/main.c (working copy)
@@ -1178,7 +1178,19 @@
do_exmode(exmode_active == EXMODE_VIM);
}
else
+ {
+#ifdef FEAT_NETBEANS_INTG
+ /* Allow full use of vim functions in callbacks,
+ * but not within the command-line window or in
+ * ":global/path/visual" commands.*/
+ if (!cmdwin && !noexmode)
+ callback_restricted = FALSE;
+#endif
normal_cmd(&oa, TRUE);
+#ifdef FEAT_NETBEANS_INTG
+ callback_restricted = TRUE;
+#endif
+ }
}
}
Index: src/globals.h
===================================================================
--- src/globals.h (revision 1011)
+++ src/globals.h (working copy)
@@ -1008,6 +1008,11 @@
/* set after swap write error msg */
EXTERN int undo_off INIT(= FALSE); /* undo switched off for now */
EXTERN int global_busy INIT(= 0); /* set when :global is executing */
+#ifdef FEAT_NETBEANS_INTG
+EXTERN int callback_restricted INIT(= TRUE);/* callbacks have a restricted
+ * use of vim functions when
+ * this flag is set */
+#endif
EXTERN int listcmd_busy INIT(= FALSE); /* set when :argdo, :windo or
:bufdo is executing */
EXTERN int need_start_insertmode INIT(= FALSE);
===========================================================
Test case:
----------
Get pyclewn from the subversion repository
(see http://pyclewn.wiki.sourceforge.net/svn+).
This is currently pyclewn subversion revision 13.
Install pyclewn
Run pyclewn from the pyclewn distribution directory:
./pyclewn -l nbdebug -f logfile --gdb=async
Once pyclewn is started, run the following Vim commands:
:Cmapkeys | Cfile testsuite/foobar | Cbreak main | Crun
CTRL-W W
:q
S
Vim crashes on average once every five times (the 'S' key must be hit
quickly after ':q').
To use Valgrind, the pyclewn code must be instrumented:
* edit clewn/dispatcher.py and search for 'valgrind'
* uncomment the two lines that enable valgrind
* you need also to insert before the two uncommented lines, the
following two lines, to increase valgring stack depth:
args[:0] = ["--num-callers=50"]
args[:0] = ["--show-below-main=yes"]
The test is run as above with the same Vim commands, except that pyclewn
is started without logs and that you don't need to be fast when typing
the last two Vim commands, the error is systematic:
./pyclewn --gdb=async
-- Xavier
Les Chemins de Lokoti -- http://lokoti.alwaysdata.net
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vim_callback.diff
Description: Binary data
