[Libguestfs] [PATCH nbdkit nbd] nbd: Unsuccessful attempt to fix memory leak.

[Richard W.M. Jones]

Hi Eric,

There's a memory leak in the nbd client.  The message (below) is not
very useful because somehow debuginfo is missing in the plugin.
However it's easily reproducible by doing:

  make check-valgrind TESTS=test-nbd

I tried the attached patch to fix what I thought was the bug, but
sadly the fix doesn't work for me :-(  So I guess something else is
going on, but it does look as if the transactions list also needs to
be freed.

Rich.

==20307== 
==20307== HEAP SUMMARY:
==20307==     in use at exit: 2,267 bytes in 23 blocks
==20307==   total heap usage: 2,298 allocs, 2,275 frees, 307,606 bytes allocated
==20307== 
==20307== 96 bytes in 3 blocks are definitely lost in loss record 4 of 10
==20307==    at 0x4C2FA1E: calloc (vg_replace_malloc.c:711)
==20307==    by 0x77EBBAF: ???
==20307==    by 0x77EBD17: ???
==20307==    by 0x40595C: handle_request (connections.c:894)
==20307==    by 0x40595C: recv_request_send_reply (connections.c:1061)
==20307==    by 0x405AE7: connection_worker (connections.c:200)
==20307==    by 0x55DC55A: start_thread (in /usr/lib64/libpthread-2.26.9000.so)
==20307==    by 0x58E85AE: clone (in /usr/lib64/libc-2.26.9000.so)
==20307== 
==20307== 320 bytes in 10 blocks are definitely lost in loss record 9 of 10
==20307==    at 0x4C2FA1E: calloc (vg_replace_malloc.c:711)
==20307==    by 0x77EBBAF: ???
==20307==    by 0x77EBD98: ???
==20307==    by 0x405986: handle_request (connections.c:884)
==20307==    by 0x405986: recv_request_send_reply (connections.c:1061)
==20307==    by 0x405AE7: connection_worker (connections.c:200)
==20307==    by 0x55DC55A: start_thread (in /usr/lib64/libpthread-2.26.9000.so)
==20307==    by 0x58E85AE: clone (in /usr/lib64/libc-2.26.9000.so)
==20307== 
==20307== LEAK SUMMARY:
==20307==    definitely lost: 416 bytes in 13 blocks
==20307==    indirectly lost: 0 bytes in 0 blocks
==20307==      possibly lost: 0 bytes in 0 blocks
==20307==    still reachable: 411 bytes in 5 blocks
==20307==         suppressed: 1,440 bytes in 5 blocks
==20307== Reachable blocks (those to which a pointer was found) are not shown.
==20307== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==20307== 
==20307== For counts of detected and suppressed errors, rerun with: -v
==20307== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 3 from 3)