Adding upstream version 1.16.10.upstream/1.16.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 544 insertions, 0 deletions

diff --git a/src/database/sql/driver/driver.go b/src/database/sql/driver/driver.go
new file mode 100644
index 0000000..5bbcf20
--- /dev/null
+++ b/src/database/sql/driver/driver.go
@@ -0,0 +1,544 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package driver defines interfaces to be implemented by database
+// drivers as used by package sql.
+//
+// Most code should use package sql.
+//
+// The driver interface has evolved over time. Drivers should implement
+// Connector and DriverContext interfaces.
+// The Connector.Connect and Driver.Open methods should never return ErrBadConn.
+// ErrBadConn should only be returned from Validator, SessionResetter, or
+// a query method if the connection is already in an invalid (e.g. closed) state.
+//
+// All Conn implementations should implement the following interfaces:
+// Pinger, SessionResetter, and Validator.
+//
+// If named parameters or context are supported, the driver's Conn should implement:
+// ExecerContext, QueryerContext, ConnPrepareContext, and ConnBeginTx.
+//
+// To support custom data types, implement NamedValueChecker. NamedValueChecker
+// also allows queries to accept per-query options as a parameter by returning
+// ErrRemoveArgument from CheckNamedValue.
+//
+// If multiple result sets are supported, Rows should implement RowsNextResultSet.
+// If the driver knows how to describe the types present in the returned result
+// it should implement the following interfaces: RowsColumnTypeScanType,
+// RowsColumnTypeDatabaseTypeName, RowsColumnTypeLength, RowsColumnTypeNullable,
+// and RowsColumnTypePrecisionScale. A given row value may also return a Rows
+// type, which may represent a database cursor value.
+//
+// Before a connection is returned to the connection pool after use, IsValid is
+// called if implemented. Before a connection is reused for another query,
+// ResetSession is called if implemented. If a connection is never returned to the
+// connection pool but immediately reused, then ResetSession is called prior to
+// reuse but IsValid is not called.
+package driver
+
+import (
+	"context"
+	"errors"
+	"reflect"
+)
+
+// Value is a value that drivers must be able to handle.
+// It is either nil, a type handled by a database driver's NamedValueChecker
+// interface, or an instance of one of these types:
+//
+//   int64
+//   float64
+//   bool
+//   []byte
+//   string
+//   time.Time
+//
+// If the driver supports cursors, a returned Value may also implement the Rows interface
+// in this package. This is used, for example, when a user selects a cursor
+// such as "select cursor(select * from my_table) from dual". If the Rows
+// from the select is closed, the cursor Rows will also be closed.
+type Value interface{}
+
+// NamedValue holds both the value name and value.
+type NamedValue struct {
+	// If the Name is not empty it should be used for the parameter identifier and
+	// not the ordinal position.
+	//
+	// Name will not have a symbol prefix.
+	Name string
+
+	// Ordinal position of the parameter starting from one and is always set.
+	Ordinal int
+
+	// Value is the parameter value.
+	Value Value
+}
+
+// Driver is the interface that must be implemented by a database
+// driver.
+//
+// Database drivers may implement DriverContext for access
+// to contexts and to parse the name only once for a pool of connections,
+// instead of once per connection.
+type Driver interface {
+	// Open returns a new connection to the database.
+	// The name is a string in a driver-specific format.
+	//
+	// Open may return a cached connection (one previously
+	// closed), but doing so is unnecessary; the sql package
+	// maintains a pool of idle connections for efficient re-use.
+	//
+	// The returned connection is only used by one goroutine at a
+	// time.
+	Open(name string) (Conn, error)
+}
+
+// If a Driver implements DriverContext, then sql.DB will call
+// OpenConnector to obtain a Connector and then invoke
+// that Connector's Connect method to obtain each needed connection,
+// instead of invoking the Driver's Open method for each connection.
+// The two-step sequence allows drivers to parse the name just once
+// and also provides access to per-Conn contexts.
+type DriverContext interface {
+	// OpenConnector must parse the name in the same format that Driver.Open
+	// parses the name parameter.
+	OpenConnector(name string) (Connector, error)
+}
+
+// A Connector represents a driver in a fixed configuration
+// and can create any number of equivalent Conns for use
+// by multiple goroutines.
+//
+// A Connector can be passed to sql.OpenDB, to allow drivers
+// to implement their own sql.DB constructors, or returned by
+// DriverContext's OpenConnector method, to allow drivers
+// access to context and to avoid repeated parsing of driver
+// configuration.
+type Connector interface {
+	// Connect returns a connection to the database.
+	// Connect may return a cached connection (one previously
+	// closed), but doing so is unnecessary; the sql package
+	// maintains a pool of idle connections for efficient re-use.
+	//
+	// The provided context.Context is for dialing purposes only
+	// (see net.DialContext) and should not be stored or used for
+	// other purposes. A default timeout should still be used
+	// when dialing as a connection pool may call Connect
+	// asynchronously to any query.
+	//
+	// The returned connection is only used by one goroutine at a
+	// time.
+	Connect(context.Context) (Conn, error)
+
+	// Driver returns the underlying Driver of the Connector,
+	// mainly to maintain compatibility with the Driver method
+	// on sql.DB.
+	Driver() Driver
+}
+
+// ErrSkip may be returned by some optional interfaces' methods to
+// indicate at runtime that the fast path is unavailable and the sql
+// package should continue as if the optional interface was not
+// implemented. ErrSkip is only supported where explicitly
+// documented.
+var ErrSkip = errors.New("driver: skip fast-path; continue as if unimplemented")
+
+// ErrBadConn should be returned by a driver to signal to the sql
+// package that a driver.Conn is in a bad state (such as the server
+// having earlier closed the connection) and the sql package should
+// retry on a new connection.
+//
+// To prevent duplicate operations, ErrBadConn should NOT be returned
+// if there's a possibility that the database server might have
+// performed the operation. Even if the server sends back an error,
+// you shouldn't return ErrBadConn.
+var ErrBadConn = errors.New("driver: bad connection")
+
+// Pinger is an optional interface that may be implemented by a Conn.
+//
+// If a Conn does not implement Pinger, the sql package's DB.Ping and
+// DB.PingContext will check if there is at least one Conn available.
+//
+// If Conn.Ping returns ErrBadConn, DB.Ping and DB.PingContext will remove
+// the Conn from pool.
+type Pinger interface {
+	Ping(ctx context.Context) error
+}
+
+// Execer is an optional interface that may be implemented by a Conn.
+//
+// If a Conn implements neither ExecerContext nor Execer,
+// the sql package's DB.Exec will first prepare a query, execute the statement,
+// and then close the statement.
+//
+// Exec may return ErrSkip.
+//
+// Deprecated: Drivers should implement ExecerContext instead.
+type Execer interface {
+	Exec(query string, args []Value) (Result, error)
+}
+
+// ExecerContext is an optional interface that may be implemented by a Conn.
+//
+// If a Conn does not implement ExecerContext, the sql package's DB.Exec
+// will fall back to Execer; if the Conn does not implement Execer either,
+// DB.Exec will first prepare a query, execute the statement, and then
+// close the statement.
+//
+// ExecerContext may return ErrSkip.
+//
+// ExecerContext must honor the context timeout and return when the context is canceled.
+type ExecerContext interface {
+	ExecContext(ctx context.Context, query string, args []NamedValue) (Result, error)
+}
+
+// Queryer is an optional interface that may be implemented by a Conn.
+//
+// If a Conn implements neither QueryerContext nor Queryer,
+// the sql package's DB.Query will first prepare a query, execute the statement,
+// and then close the statement.
+//
+// Query may return ErrSkip.
+//
+// Deprecated: Drivers should implement QueryerContext instead.
+type Queryer interface {
+	Query(query string, args []Value) (Rows, error)
+}
+
+// QueryerContext is an optional interface that may be implemented by a Conn.
+//
+// If a Conn does not implement QueryerContext, the sql package's DB.Query
+// will fall back to Queryer; if the Conn does not implement Queryer either,
+// DB.Query will first prepare a query, execute the statement, and then
+// close the statement.
+//
+// QueryerContext may return ErrSkip.
+//
+// QueryerContext must honor the context timeout and return when the context is canceled.
+type QueryerContext interface {
+	QueryContext(ctx context.Context, query string, args []NamedValue) (Rows, error)
+}
+
+// Conn is a connection to a database. It is not used concurrently
+// by multiple goroutines.
+//
+// Conn is assumed to be stateful.
+type Conn interface {
+	// Prepare returns a prepared statement, bound to this connection.
+	Prepare(query string) (Stmt, error)
+
+	// Close invalidates and potentially stops any current
+	// prepared statements and transactions, marking this
+	// connection as no longer in use.
+	//
+	// Because the sql package maintains a free pool of
+	// connections and only calls Close when there's a surplus of
+	// idle connections, it shouldn't be necessary for drivers to
+	// do their own connection caching.
+	//
+	// Drivers must ensure all network calls made by Close
+	// do not block indefinitely (e.g. apply a timeout).
+	Close() error
+
+	// Begin starts and returns a new transaction.
+	//
+	// Deprecated: Drivers should implement ConnBeginTx instead (or additionally).
+	Begin() (Tx, error)
+}
+
+// ConnPrepareContext enhances the Conn interface with context.
+type ConnPrepareContext interface {
+	// PrepareContext returns a prepared statement, bound to this connection.
+	// context is for the preparation of the statement,
+	// it must not store the context within the statement itself.
+	PrepareContext(ctx context.Context, query string) (Stmt, error)
+}
+
+// IsolationLevel is the transaction isolation level stored in TxOptions.
+//
+// This type should be considered identical to sql.IsolationLevel along
+// with any values defined on it.
+type IsolationLevel int
+
+// TxOptions holds the transaction options.
+//
+// This type should be considered identical to sql.TxOptions.
+type TxOptions struct {
+	Isolation IsolationLevel
+	ReadOnly  bool
+}
+
+// ConnBeginTx enhances the Conn interface with context and TxOptions.
+type ConnBeginTx interface {
+	// BeginTx starts and returns a new transaction.
+	// If the context is canceled by the user the sql package will
+	// call Tx.Rollback before discarding and closing the connection.
+	//
+	// This must check opts.Isolation to determine if there is a set
+	// isolation level. If the driver does not support a non-default
+	// level and one is set or if there is a non-default isolation level
+	// that is not supported, an error must be returned.
+	//
+	// This must also check opts.ReadOnly to determine if the read-only
+	// value is true to either set the read-only transaction property if supported
+	// or return an error if it is not supported.
+	BeginTx(ctx context.Context, opts TxOptions) (Tx, error)
+}
+
+// SessionResetter may be implemented by Conn to allow drivers to reset the
+// session state associated with the connection and to signal a bad connection.
+type SessionResetter interface {
+	// ResetSession is called prior to executing a query on the connection
+	// if the connection has been used before. If the driver returns ErrBadConn
+	// the connection is discarded.
+	ResetSession(ctx context.Context) error
+}
+
+// Validator may be implemented by Conn to allow drivers to
+// signal if a connection is valid or if it should be discarded.
+//
+// If implemented, drivers may return the underlying error from queries,
+// even if the connection should be discarded by the connection pool.
+type Validator interface {
+	// IsValid is called prior to placing the connection into the
+	// connection pool. The connection will be discarded if false is returned.
+	IsValid() bool
+}
+
+// Result is the result of a query execution.
+type Result interface {
+	// LastInsertId returns the database's auto-generated ID
+	// after, for example, an INSERT into a table with primary
+	// key.
+	LastInsertId() (int64, error)
+
+	// RowsAffected returns the number of rows affected by the
+	// query.
+	RowsAffected() (int64, error)
+}
+
+// Stmt is a prepared statement. It is bound to a Conn and not
+// used by multiple goroutines concurrently.
+type Stmt interface {
+	// Close closes the statement.
+	//
+	// As of Go 1.1, a Stmt will not be closed if it's in use
+	// by any queries.
+	//
+	// Drivers must ensure all network calls made by Close
+	// do not block indefinitely (e.g. apply a timeout).
+	Close() error
+
+	// NumInput returns the number of placeholder parameters.
+	//
+	// If NumInput returns >= 0, the sql package will sanity check
+	// argument counts from callers and return errors to the caller
+	// before the statement's Exec or Query methods are called.
+	//
+	// NumInput may also return -1, if the driver doesn't know
+	// its number of placeholders. In that case, the sql package
+	// will not sanity check Exec or Query argument counts.
+	NumInput() int
+
+	// Exec executes a query that doesn't return rows, such
+	// as an INSERT or UPDATE.
+	//
+	// Deprecated: Drivers should implement StmtExecContext instead (or additionally).
+	Exec(args []Value) (Result, error)
+
+	// Query executes a query that may return rows, such as a
+	// SELECT.
+	//
+	// Deprecated: Drivers should implement StmtQueryContext instead (or additionally).
+	Query(args []Value) (Rows, error)
+}
+
+// StmtExecContext enhances the Stmt interface by providing Exec with context.
+type StmtExecContext interface {
+	// ExecContext executes a query that doesn't return rows, such
+	// as an INSERT or UPDATE.
+	//
+	// ExecContext must honor the context timeout and return when it is canceled.
+	ExecContext(ctx context.Context, args []NamedValue) (Result, error)
+}
+
+// StmtQueryContext enhances the Stmt interface by providing Query with context.
+type StmtQueryContext interface {
+	// QueryContext executes a query that may return rows, such as a
+	// SELECT.
+	//
+	// QueryContext must honor the context timeout and return when it is canceled.
+	QueryContext(ctx context.Context, args []NamedValue) (Rows, error)
+}
+
+// ErrRemoveArgument may be returned from NamedValueChecker to instruct the
+// sql package to not pass the argument to the driver query interface.
+// Return when accepting query specific options or structures that aren't
+// SQL query arguments.
+var ErrRemoveArgument = errors.New("driver: remove argument from query")
+
+// NamedValueChecker may be optionally implemented by Conn or Stmt. It provides
+// the driver more control to handle Go and database types beyond the default
+// Values types allowed.
+//
+// The sql package checks for value checkers in the following order,
+// stopping at the first found match: Stmt.NamedValueChecker, Conn.NamedValueChecker,
+// Stmt.ColumnConverter, DefaultParameterConverter.
+//
+// If CheckNamedValue returns ErrRemoveArgument, the NamedValue will not be included in
+// the final query arguments. This may be used to pass special options to
+// the query itself.
+//
+// If ErrSkip is returned the column converter error checking
+// path is used for the argument. Drivers may wish to return ErrSkip after
+// they have exhausted their own special cases.
+type NamedValueChecker interface {
+	// CheckNamedValue is called before passing arguments to the driver
+	// and is called in place of any ColumnConverter. CheckNamedValue must do type
+	// validation and conversion as appropriate for the driver.
+	CheckNamedValue(*NamedValue) error
+}
+
+// ColumnConverter may be optionally implemented by Stmt if the
+// statement is aware of its own columns' types and can convert from
+// any type to a driver Value.
+//
+// Deprecated: Drivers should implement NamedValueChecker.
+type ColumnConverter interface {
+	// ColumnConverter returns a ValueConverter for the provided
+	// column index. If the type of a specific column isn't known
+	// or shouldn't be handled specially, DefaultValueConverter
+	// can be returned.
+	ColumnConverter(idx int) ValueConverter
+}
+
+// Rows is an iterator over an executed query's results.
+type Rows interface {
+	// Columns returns the names of the columns. The number of
+	// columns of the result is inferred from the length of the
+	// slice. If a particular column name isn't known, an empty
+	// string should be returned for that entry.
+	Columns() []string
+
+	// Close closes the rows iterator.
+	Close() error
+
+	// Next is called to populate the next row of data into
+	// the provided slice. The provided slice will be the same
+	// size as the Columns() are wide.
+	//
+	// Next should return io.EOF when there are no more rows.
+	//
+	// The dest should not be written to outside of Next. Care
+	// should be taken when closing Rows not to modify
+	// a buffer held in dest.
+	Next(dest []Value) error
+}
+
+// RowsNextResultSet extends the Rows interface by providing a way to signal
+// the driver to advance to the next result set.
+type RowsNextResultSet interface {
+	Rows
+
+	// HasNextResultSet is called at the end of the current result set and
+	// reports whether there is another result set after the current one.
+	HasNextResultSet() bool
+
+	// NextResultSet advances the driver to the next result set even
+	// if there are remaining rows in the current result set.
+	//
+	// NextResultSet should return io.EOF when there are no more result sets.
+	NextResultSet() error
+}
+
+// RowsColumnTypeScanType may be implemented by Rows. It should return
+// the value type that can be used to scan types into. For example, the database
+// column type "bigint" this should return "reflect.TypeOf(int64(0))".
+type RowsColumnTypeScanType interface {
+	Rows
+	ColumnTypeScanType(index int) reflect.Type
+}
+
+// RowsColumnTypeDatabaseTypeName may be implemented by Rows. It should return the
+// database system type name without the length. Type names should be uppercase.
+// Examples of returned types: "VARCHAR", "NVARCHAR", "VARCHAR2", "CHAR", "TEXT",
+// "DECIMAL", "SMALLINT", "INT", "BIGINT", "BOOL", "[]BIGINT", "JSONB", "XML",
+// "TIMESTAMP".
+type RowsColumnTypeDatabaseTypeName interface {
+	Rows
+	ColumnTypeDatabaseTypeName(index int) string
+}
+
+// RowsColumnTypeLength may be implemented by Rows. It should return the length
+// of the column type if the column is a variable length type. If the column is
+// not a variable length type ok should return false.
+// If length is not limited other than system limits, it should return math.MaxInt64.
+// The following are examples of returned values for various types:
+//   TEXT          (math.MaxInt64, true)
+//   varchar(10)   (10, true)
+//   nvarchar(10)  (10, true)
+//   decimal       (0, false)
+//   int           (0, false)
+//   bytea(30)     (30, true)
+type RowsColumnTypeLength interface {
+	Rows
+	ColumnTypeLength(index int) (length int64, ok bool)
+}
+
+// RowsColumnTypeNullable may be implemented by Rows. The nullable value should
+// be true if it is known the column may be null, or false if the column is known
+// to be not nullable.
+// If the column nullability is unknown, ok should be false.
+type RowsColumnTypeNullable interface {
+	Rows
+	ColumnTypeNullable(index int) (nullable, ok bool)
+}
+
+// RowsColumnTypePrecisionScale may be implemented by Rows. It should return
+// the precision and scale for decimal types. If not applicable, ok should be false.
+// The following are examples of returned values for various types:
+//   decimal(38, 4)    (38, 4, true)
+//   int               (0, 0, false)
+//   decimal           (math.MaxInt64, math.MaxInt64, true)
+type RowsColumnTypePrecisionScale interface {
+	Rows
+	ColumnTypePrecisionScale(index int) (precision, scale int64, ok bool)
+}
+
+// Tx is a transaction.
+type Tx interface {
+	Commit() error
+	Rollback() error
+}
+
+// RowsAffected implements Result for an INSERT or UPDATE operation
+// which mutates a number of rows.
+type RowsAffected int64
+
+var _ Result = RowsAffected(0)
+
+func (RowsAffected) LastInsertId() (int64, error) {
+	return 0, errors.New("LastInsertId is not supported by this driver")
+}
+
+func (v RowsAffected) RowsAffected() (int64, error) {
+	return int64(v), nil
+}
+
+// ResultNoRows is a pre-defined Result for drivers to return when a DDL
+// command (such as a CREATE TABLE) succeeds. It returns an error for both
+// LastInsertId and RowsAffected.
+var ResultNoRows noRows
+
+type noRows struct{}
+
+var _ Result = noRows{}
+
+func (noRows) LastInsertId() (int64, error) {
+	return 0, errors.New("no LastInsertId available after DDL statement")
+}
+
+func (noRows) RowsAffected() (int64, error) {
+	return 0, errors.New("no RowsAffected available after DDL statement")
+}