LMDB

build script

gcc -ggdb -std=c11 -Wall -I ~/proj/py-lmdb/lib lmdb_crash1.c ~/proj/py-lmdb/lib/{mdb.c,midl.c} -lpthread -o mdb_c_exe

gdb output

(gdb) run
Starting program: /home/nic/proj/lmdb_crash_test/mdb_c_exe 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Running LMDB 0.9.21: (June 1, 2017)

Program received signal SIGSEGV, Segmentation fault.
0x00000000004146d5 in mdb_dbi_open (txn=0x61e810, name=0x41a551 "another_db", flags=262144, dbi=0x7fffffffd74c) at /home/nic/proj/py-lmdb/lib/mdb.c:9772
9772                    WITH_CURSOR_TRACKING(mc,
(gdb) bt
#0  0x00000000004146d5 in mdb_dbi_open (txn=0x61e810, name=0x41a551 "another_db", flags=262144, dbi=0x7fffffffd74c) at /home/nic/proj/py-lmdb/lib/mdb.c:9772
#1  0x0000000000401b94 in cause_crash () at lmdb_crash1.c:31
#2  0x0000000000401c3d in main (argc=1, argv=0x7fffffffd878) at lmdb_crash1.c:49

lmdb_crash1.c

#include <stdio.h>
#include "lmdb.h"

void cause_crash()
{
    MDB_env *env;
    MDB_txn *txn;
    MDB_dbi dbi;
    int rc;
    int line_fail = 0;
    rc = mdb_env_create(&env);
    if (rc) { line_fail = __LINE__; goto fail; }

    rc = mdb_env_open(env, "foo.lmdb", 0, 0777);
    if (rc) { line_fail = __LINE__; goto fail; }

    mdb_env_close(env);

    rc = mdb_env_create(&env);
    if (rc) { line_fail = __LINE__; goto fail; }

    rc = mdb_env_set_maxdbs(env, 10);
    if (rc) { line_fail = __LINE__; goto fail; }

    rc = mdb_env_open(env, "foo.lmdb", MDB_RDONLY, 0777);
    if (rc) { line_fail = __LINE__; goto fail; }

    rc = mdb_txn_begin(env, NULL, MDB_RDONLY, &txn);
    if (rc) { line_fail = __LINE__; goto fail; }

    /* Crashes on next line. */
    rc = mdb_dbi_open(txn, "another_db", MDB_CREATE, &dbi);
    if (rc) { line_fail = __LINE__; goto fail; }

    rc = mdb_txn_commit(txn);
    if (rc) { line_fail = __LINE__; goto fail; }

    mdb_dbi_close(env, dbi);
    mdb_env_close(env);

    return;

fail:
    printf("Failed with error %d on line %d\n", rc, line_fail);
}

int main(int argc, char **argv)
{
    printf("Running %s\n", MDB_VERSION_STRING);
    cause_crash();
    printf("Didn't crash!\n");
    return 0;
}