Prevent segmentation fault in notmuch_database_close

Prevent segmentation fault in notmuch_database_close

[Justus Winter]

I've seen some segmentation faults lately again and rechecked the
python bindings and while I actually found and fixed some error
handling issues I overlooked last time, I think I also found a bug in
notmuch_database_close.

The problem can easily be reproduced with the following program:

~~~ snip ~~~
import os
import time
import notmuch

db_path = os.path.expanduser('~/Maildir')

os.fork()
with notmuch.Database(db_path, mode=notmuch.Database.MODE.READ_WRITE) as db:
    time.sleep(5)
~~~ snap ~~~

The top of the resulting stack trace is

~~~ snip ~~~
#0  0x00007fa2b6ac8104 in Xapian::WritableDatabase::commit() ()
   from /usr/lib/libxapian.so.22
#1  0x00007fa2b7839de8 in Xapian::WritableDatabase::flush (this=0x0)
    at /usr/include/xapian/database.h:579
#2  0x00007fa2b78367aa in notmuch_database_close (notmuch=0x121ea70)
    at lib/database.cc:722
#3  0x00007fa2b7836749 in notmuch_database_open (path=
    0x7fa2b948ac94 "/home/teythoon/Maildir",
    mode=NOTMUCH_DATABASE_MODE_READ_WRITE) at lib/database.cc:705
~~~ snap ~~~

Cheers,
Justus

[PATCH] Prevent segmentation fault in notmuch_database_close

[Justus Winter]

Previously opening a notmuch database in read write mode that has been
locked resulted in the notmuch_database_open function executing
notmuch_database_close as a cleanup function. notmuch_database_close
failed to check whether the xapian database has in fact been created.

Add a check whether the xapian database object has actually been
created before trying to call its flush method.

Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>
---
 lib/database.cc |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/lib/database.cc b/lib/database.cc
index c928d02..5efa85e 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -716,7 +716,8 @@ void
 notmuch_database_close (notmuch_database_t *notmuch)
 {
     try {
-	if (notmuch->mode == NOTMUCH_DATABASE_MODE_READ_WRITE)
+	if (notmuch->xapian_db != NULL &&
+	    notmuch->mode == NOTMUCH_DATABASE_MODE_READ_WRITE)
 	    (static_cast <Xapian::WritableDatabase *> (notmuch->xapian_db))->flush ();
     } catch (const Xapian::Error &error) {
 	if (! notmuch->exception_reported) {
-- 
1.7.9

Re: [PATCH] Prevent segmentation fault in notmuch_database_close

[Austin Clements]

Quoth Justus Winter on Feb 19 at 12:56 am:
> Previously opening a notmuch database in read write mode that has been
> locked resulted in the notmuch_database_open function executing
> notmuch_database_close as a cleanup function. notmuch_database_close
> failed to check whether the xapian database has in fact been created.
> 
> Add a check whether the xapian database object has actually been
> created before trying to call its flush method.
> 
> Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>

LGTM.  Nice catch.

> ---
>  lib/database.cc |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/lib/database.cc b/lib/database.cc
> index c928d02..5efa85e 100644
> --- a/lib/database.cc
> +++ b/lib/database.cc
> @@ -716,7 +716,8 @@ void
>  notmuch_database_close (notmuch_database_t *notmuch)
>  {
>      try {
> -	if (notmuch->mode == NOTMUCH_DATABASE_MODE_READ_WRITE)
> +	if (notmuch->xapian_db != NULL &&
> +	    notmuch->mode == NOTMUCH_DATABASE_MODE_READ_WRITE)
>  	    (static_cast <Xapian::WritableDatabase *> (notmuch->xapian_db))->flush ();
>      } catch (const Xapian::Error &error) {
>  	if (! notmuch->exception_reported) {

Re: [PATCH] Prevent segmentation fault in notmuch_database_close

[David Bremner]

On Sun, 19 Feb 2012 00:56:57 +0100, Justus Winter <4winter@informatik.uni-hamburg.de> wrote:
> Previously opening a notmuch database in read write mode that has been
> locked resulted in the notmuch_database_open function executing
> notmuch_database_close as a cleanup function. notmuch_database_close
> failed to check whether the xapian database has in fact been created.
> 

Pushed.

d