(ITS#7875) lmdb MDB_GET_BOTH unexpected success

[mail@arnedebruijn.nl]

Full_Name: Arne de Bruijn
Version: mdb.master a93810c
OS: Linux
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (94.210.130.16)


MDB_GET_BOTH seems to unexpectedly return success if a data-value before the
first data-value for a key is requested.

The example program sets 1:b and 1:c and requests 1:a. It prints:
get_both: key=1 val=b

While I would expect:
get_both: err=MDB_NOTFOUND: No matching key/data pair found

(curiously it works when it only sets 1:b)

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "lmdb.h"

void set_val(MDB_val *v, char *s) {
	v->mv_size = strlen(s);
	v->mv_data = s;
}

int main() {
	int rc;
	MDB_env *menv = NULL;
	MDB_dbi mdbi;
	MDB_txn *mtxn = NULL;
	MDB_val key, val;
	MDB_cursor *mc;
	
	if ((rc = mdb_env_create(&menv)))
		goto err;
	if ((rc = unlink("testdb")))
		goto err;
	if ((rc = mdb_env_open(menv, "testdb", MDB_NOSUBDIR, 0666)))
		goto err;
	if ((rc = mdb_txn_begin(menv, NULL, 0, &mtxn)))
		goto err;
	if ((rc = mdb_dbi_open(mtxn, NULL, MDB_DUPSORT | MDB_CREATE, &mdbi)))
		goto err;
	set_val(&key, "1");
	set_val(&val, "b");
	if ((rc = mdb_put(mtxn, mdbi, &key, &val, 0)))
		goto err;
	set_val(&key, "1");
	set_val(&val, "c");
	if ((rc = mdb_put(mtxn, mdbi, &key, &val, 0)))
		goto err;
	
	if ((rc = mdb_cursor_open(mtxn, mdbi, &mc)))
		goto err;
	
	set_val(&key, "1");
	set_val(&val, "a");
	rc = mdb_cursor_get(mc, &key, &val, MDB_GET_BOTH);
	if (rc)
		printf("get_both: err=%s\n", mdb_strerror(rc));
	else
		printf("get_both: key=%.*s val=%.*s\n", key.mv_size, (char *)key.mv_data,
val.mv_size, (char *)val.mv_data);

	mdb_cursor_close(mc);
	
	if ((rc = mdb_txn_commit(mtxn))) {
		mdb_dbi_close(menv, mdbi);
		goto err;
	}
	mdb_env_close(menv);
	return 0;
err:
	if (mtxn)
		mdb_txn_abort(mtxn);
	if (menv)
		mdb_env_close(menv);
	fprintf(stderr, "Error: %s\n", mdb_strerror(rc));
	return 1;
}