pull in ncruces/go-sqlite3 v0.20.3 with tetratelabs/wazero v1.8.2 (#3574)

1 files changed, 18 insertions, 7 deletions

diff --git a/vendor/github.com/ncruces/go-sqlite3/vfs/os_bsd.go b/vendor/github.com/ncruces/go-sqlite3/vfs/os_bsd.go
index 56713e359..cc5da7cab 100644
--- a/vendor/github.com/ncruces/go-sqlite3/vfs/os_bsd.go
+++ b/vendor/github.com/ncruces/go-sqlite3/vfs/os_bsd.go
@@ -15,9 +15,15 @@ func osGetSharedLock(file *os.File) _ErrorCode {
 func osGetReservedLock(file *os.File) _ErrorCode {
 	rc := osLock(file, unix.LOCK_EX|unix.LOCK_NB, _IOERR_LOCK)
 	if rc == _BUSY {
-		// The documentation states the lock is upgraded by releasing the previous lock,
-		// then acquiring the new lock.
-		// This is a race, so return BUSY_SNAPSHOT to ensure the transaction is aborted.
+		// The documentation states that a lock is upgraded by
+		// releasing the previous lock, then acquiring the new lock.
+		// Going over the source code of various BSDs, though,
+		// with LOCK_NB, the lock is not released,
+		// and EAGAIN is returned holding the shared lock.
+		// Still, if we're already in a transaction, we want to abort it,
+		// so return BUSY_SNAPSHOT here. If there's no transaction active,
+		// SQLite will change this back to SQLITE_BUSY,
+		// and invoke the busy handler if appropriate.
 		return _BUSY_SNAPSHOT
 	}
 	return rc
@@ -33,9 +39,11 @@ func osGetExclusiveLock(file *os.File, state *LockLevel) _ErrorCode {
 func osDowngradeLock(file *os.File, _ LockLevel) _ErrorCode {
 	rc := osLock(file, unix.LOCK_SH|unix.LOCK_NB, _IOERR_RDLOCK)
 	if rc == _BUSY {
-		// The documentation states the lock is upgraded by releasing the previous lock,
-		// then acquiring the new lock.
-		// This is a race, so return IOERR_RDLOCK to ensure the transaction is aborted.
+		// The documentation states that a lock is downgraded by
+		// releasing the previous lock then acquiring the new lock.
+		// Going over the source code of various BSDs, though,
+		// with LOCK_SH|LOCK_NB this should never happen.
+		// Return IOERR_RDLOCK, as BUSY would cause an assert to fail.
 		return _IOERR_RDLOCK
 	}
 	return _OK
@@ -50,7 +58,10 @@ func osReleaseLock(file *os.File, _ LockLevel) _ErrorCode {
 }
 
 func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
-	// Test the RESERVED lock.
+	// Test the RESERVED lock with fcntl(F_GETLK).
+	// This only works on systems where fcntl and flock are compatible.
+	// However, SQLite only calls this while holding a shared lock,
+	// so the difference is immaterial.
 	lock, rc := osTestLock(file, _RESERVED_BYTE, 1)
 	return lock == unix.F_WRLCK, rc
 }