remove legacy (bsd-style) locking

flock() may be implemented via fcntl(), which may cause the process to
deadlock itself when trying to apply both types of locks. this is the
case even on linux when the file lives on NFS.

it's unlikely that anything except mbsync would try to access the
.uidvalidity files anyway, so there is no point in trying to be
compatible with anything else ...

REFMAIL: uddy4g589ym.fsf@eismej-u14.spgear.lab.emc.com

src/drv_maildir.c

@@ -33,15 +33,10 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <sys/stat.h>
-#include <sys/file.h>
 #include <errno.h>
 #include <time.h>
 #include <utime.h>
 
-#ifdef __linux__
-# define LEGACY_FLOCK 1
-#endif
-
 #if !defined(_POSIX_SYNCHRONIZED_IO) || _POSIX_SYNCHRONIZED_IO <= 0
 # define fdatasync fsync
 #endif
@@ -550,13 +545,6 @@ maildir_uidval_lock( maildir_store_t *ctx )
 		/* The unlock timer is active, so we are obviously already locked. */
 		return DRV_OK;
 	}
-#ifdef LEGACY_FLOCK
-	/* This is legacy only */
-	if (flock( ctx->uvfd, LOCK_EX ) < 0) {
-		error( "Maildir error: cannot flock UIDVALIDITY.\n" );
-		return DRV_BOX_BAD;
-	}
-#endif
 	/* This (theoretically) works over NFS. Let's hope nobody else did
 	   the same in the opposite order, as we'd deadlock then. */
 #if SEEK_SET != 0
@@ -628,10 +616,6 @@ maildir_uidval_unlock( maildir_store_t *ctx )
 #endif /* USE_DB */
 	lck.l_type = F_UNLCK;
 	fcntl( ctx->uvfd, F_SETLK, &lck );
-#ifdef LEGACY_FLOCK
-	/* This is legacy only */
-	flock( ctx->uvfd, LOCK_UN );
-#endif
 }
 
 static void