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avoid using cursor-fetched values after closing cursor

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The wterl:session_get function was fetching a value using a cursor, then
closing the cursor, and then trying to use the fetched value to create the
return binary. According to the WiredTiger documentation, this is a no-no
-- a value is good only until the next operation on the cursor used to
fetch it. We've been seeing occasional segmentation violations in the
memcpy for the fetched value, and this might explain it.
This commit is contained in:
Steve Vinoski 2012-04-04 20:13:58 -04:00
parent 2618ba24e7
commit 2e37fc1bd1
1 changed files with 12 additions and 13 deletions
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25
c_src/wterl.c
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@ -333,7 +333,7 @@ static ERL_NIF_TERM wterl_session_delete(ErlNifEnv* env, int argc, const ERL_NIF
raw_key.size = key.size;
cursor->set_key(cursor, &raw_key);
rc = cursor->remove(cursor);
(void)cursor->close(cursor);
cursor->close(cursor);
return rc == 0 ? ATOM_OK : wterl_strerror(env, rc);
}
}
@ -365,18 +365,17 @@ static ERL_NIF_TERM wterl_session_get(ErlNifEnv* env, int argc, const ERL_NIF_TE
if (rc == 0)
{
rc = cursor->get_value(cursor, &raw_value);
if (rc == 0)
{
ERL_NIF_TERM value;
unsigned char* bin = enif_make_new_binary(env, raw_value.size, &value);
memcpy(bin, raw_value.data, raw_value.size);
cursor->close(cursor);
return enif_make_tuple2(env, ATOM_OK, value);
}
}
(void)cursor->close(cursor);
if (rc == 0)
{
ERL_NIF_TERM value;
memcpy(enif_make_new_binary(env, raw_value.size, &value), raw_value.data, raw_value.size);
return enif_make_tuple2(env, ATOM_OK, value);
}
else
{
return wterl_strerror(env, rc);
}
cursor->close(cursor);
return wterl_strerror(env, rc);
}
}
return enif_make_badarg(env);
@ -408,7 +407,7 @@ static ERL_NIF_TERM wterl_session_put(ErlNifEnv* env, int argc, const ERL_NIF_TE
raw_value.size = value.size;
cursor->set_value(cursor, &raw_value);
rc = cursor->insert(cursor);
(void)cursor->close(cursor);
cursor->close(cursor);
return rc == 0 ? ATOM_OK : wterl_strerror(env, rc);
}
}