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chrisboyle / sgtpuzzles

Android port of Simon Tatham's Puzzles
https://chris.boyle.name/puzzles
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SIGSEGV/SIGBUS in fetch_preset/get_text #1

Closed chrisboyle closed 14 years ago

chrisboyle commented 14 years ago

Since the release of 8750.5 I have had 9 crash reports in the same place (and one other unrelated). Seen on 1.5, 1.6 and 2.0, on a range of devices. The traces all decode like this:

[two frames in libdvm.so, addresses vary by Android version]
00006d68 android.c:516:     const char * c = (*env)->GetStringUTFChars(env, j, NULL);
[the first call to _(some_string) in some game's fetch_preset]
00042220 midend.c:893           while (me->ourgame->fetch_preset(me->npresets, &name, &preset)) {
00007188 android.c:642      if ((n = midend_num_presets(_fe->me)) > 0) {
[one more frame in libdvm.so]

Here is an extract from a typical report (from a Sprint Hero on 1.5), with frame 03 annotated:

12-03 21:46:40.499 10692 10692 D SGTPuzzles: startGame: -1, 326 bytes
...
12-03 21:46:41.010    40    40 I DEBUG   : signal 11 (SIGSEGV), fault addr 705862c8
...
12-03 21:46:42.789    40    40 I DEBUG   :          # 00  pc 00047bea  /system/lib/libdvm.so
12-03 21:46:42.799    40    40 I DEBUG   :          # 01  pc 00041410  /system/lib/libdvm.so
12-03 21:46:42.830    40    40 I DEBUG   :          # 02  pc 00006d68  /data/data/name.boyle.chris.sgtpuzzles/lib/libpuzzles.so
12-03 21:46:42.830    40    40 I DEBUG   :          # 03  pc 00009e2c  /data/data/name.boyle.chris.sgtpuzzles/lib/libpuzzles.so
blackbox.c:74           sprintf(str, _("%dx%d, %d balls"),  ret->w, ret->h, ret->minballs);
12-03 21:46:42.830    40    40 I DEBUG   :          # 04  pc 00042220  /data/data/name.boyle.chris.sgtpuzzles/lib/libpuzzles.so
12-03 21:46:42.830    40    40 I DEBUG   :          # 05  pc 00007188  /data/data/name.boyle.chris.sgtpuzzles/lib/libpuzzles.so
12-03 21:46:42.839    40    40 I DEBUG   :          # 06  pc 0000e434  /system/lib/libdvm.so

This means we were starting a game (either resuming it because the app was started, or New Game was pressed, or a custom game was started; it doesn't matter, there have been reports from all these cases) and we finished android_deserialise, continued on to fill in the "Type" menu, and on trying to call from C up to Java to translate the first item for that menu, we crashed somewhere in the mechanics of GetStringUTFChars. Perhaps either env or j was invalid.

There have been over 3000 downloads on Android Market since this release went out, and only these 9 reports, so even allowing for under-reporting, this suggests that this issue is rare. Perhaps a threading issue or some such.

chrisboyle commented 14 years ago

Well this is now up to 27 reports, and I'm not really any closer to solving it. There being two frames and it being a SIGSEGV/SIGBUS suggests dvmCreateCstrFromString() as the innermost frame and j (that is, the return from CallObjectMethod(...,getText,...)) being invalid. No closer to knowing why, except that I probably fail at thread safety somehow.

chrisboyle commented 14 years ago

No reports of this in 8853.1 or newer. I think commit 9750c6836dda2e1ad00a7299ca6ce9b05072eee1, comit 131bfbbd4be1d21702f878de627a68f1f66515b7, commit 92f474dcb09f4cdd228e5bfd95b8333b5fc46cd5 may actually have helped! :-) Closing, to be reopened on further crash reports.