On Mon, 2011-02-28 at 14:33 -0500, Richard Hipp wrote: > On Mon, Feb 28, 2011 at 1:00 PM, Paweł Hajdan, Jr.
[many interesting things snipped ...] > <phajdan...@chromium.org>wrote: > > What do you think about adding a call like below to the VFS interface? > > > > int (*xOpenWrapper)(const char *path, int flags, int mode); > > > > There are 2 billion instances of SQLite in active use today. We don't want > to go changing interfaces unless we absolutely have to. > > And there are additional complications. Based on what we can figure out > about how your sandbox works, you'll also need overloads for access(), > stat(), and unlink(). Presumably you have no need for dlopen() which is > used for run-time loadable extensions to SQLite, but if you use that > features you'll need an overload for it too. We might yet think of others, > but already we see there are at least three interfaces (we could probably > combine access and stat) that need to be overloaded. > > We are also concerned about locking. The documentation on Chromium > sandboxing implies that a separate process does the open() and then sends > over a file descriptor using IPC. (I didn't know you could do that in > unix. In fact, I bet it requires a linux-only extension of some kind. > Correct me if I'm wrong.) But that makes us very concerned about how posix > advisory locking will behave. Posix advisory locks are mis-designed. See > > http://www.sqlite.org/src/artifact/64a2e0ebbb?ln=621,685 > > Are you sure that posix advisory locking will work on a file descriptor that > was allocated in a different process? Have you tested it? > > So this all gets very complicated very fast. And very hard to test. I'm only beginning to delve into the possibilities offered by the VFS API in SQLite. However, from what I have seen so far, it seems like a very complete abstraction to me. Why is it not possible to create a custom VFS for the intended purpose and register it for the connections that need it? _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
