https://bugs.openldap.org/show_bug.cgi?id=9861

Issue ID: 9861 Summary: Read-only databases can't be opened - regression introduced with da0527ac Product: LMDB Version: unspecified Hardware: aarch64 OS: Mac OS Status: UNCONFIRMED Keywords: needs_review Severity: normal Priority: --- Component: liblmdb Assignee: bugs@openldap.org Reporter: jocke@ordo.one Target Milestone: ---

Created attachment 905 --> https://bugs.openldap.org/attachment.cgi?id=905&action=edit Reduced simple test to open the environment that fails

The ability to open an environment in read-only mode when the file permissions is 'read only' for the user is no longer possible after the commit da0527ac75b811419b7007202799f96b2edb5aef.

It is simply reproduced by creating a database with e.g. mtest.c, then changing the permissions to read-only, then running another trivial program trying to open the environment in read-only mode / no-lock mode fails.

Specifically, after some investigation it seems that the check on line 5516 "if (!(flags & (MDB_RDONLY|MDB_WRITEMAP))) {" was removed in the above commit such that mdb_fopen() is called (presumably incorrectly?).

Returning that guard check seems to restore functionality, but I'm not familiar enough with the code base to say that is a valid fix - but seems likely.

I applied that single change here: https://github.com/hassila/swift-lmdb/tree/hassila-mdb-merge-patch with this commit: https://github.com/hassila/swift-lmdb/commit/c940b4c807c278cea43d2e3858dc22f...

To reproduce with a clean checkout: 1. make 2. mkdir tested 3. ./mtest 4. chmod -wx testdb/data.mdb 5. run the attached program (reduced from real code base)