// 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.
// Type conversions for Scan.
package sql
import (
"database/sql/driver"
"errors"
"fmt"
"reflect"
"strconv"
"time"
"unicode"
"unicode/utf8"
)
var errNilPtr = errors.New("destination pointer is nil") // embedded in descriptive error
func describeNamedValue(nv *driver.NamedValue) string {
if len(nv.Name) == 0 {
return fmt.Sprintf("$%d", nv.Ordinal)
}
return fmt.Sprintf("with name %q", nv.Name)
}
func validateNamedValueName(name string) error {
if len(name) == 0 {
return nil
}
r, _ := utf8.DecodeRuneInString(name)
if unicode.IsLetter(r) {
return nil
}
return fmt.Errorf("name %q does not begin with a letter", name)
}
// ccChecker wraps the driver.ColumnConverter and allows it to be used
// as if it were a NamedValueChecker. If the driver ColumnConverter
// is not present then the NamedValueChecker will return driver.ErrSkip.
type ccChecker struct {
cci driver.ColumnConverter
want int
}
func (c ccChecker) CheckNamedValue(nv *driver.NamedValue) error {
if c.cci == nil {
return driver.ErrSkip
}
// The column converter shouldn't be called on any index
// it isn't expecting. The final error will be thrown
// in the argument converter loop.
index := nv.Ordinal - 1
if c.want <= index {
return nil
}
// First, see if the value itself knows how to convert
// itself to a driver type. For example, a NullString
// struct changing into a string or nil.
if vr, ok := nv.Value.(driver.Valuer); ok {
sv, err := callValuerValue(vr)
if err != nil {
return err
}
if !driver.IsValue(sv) {
return fmt.Errorf("non-subset type %T returned from Value", sv)
}
nv.Value = sv
}
// Second, ask the column to sanity check itself. For
// example, drivers might use this to make sure that
// an int64 values being inserted into a 16-bit
// integer field is in range (before getting
// truncated), or that a nil can't go into a NOT NULL
// column before going across the network to get the
// same error.
var err error
arg := nv.Value
nv.Value, err = c.cci.ColumnConverter(index).ConvertValue(arg)
if err != nil {
return err
}
if !driver.IsValue(nv.Value) {
return fmt.Errorf("driver ColumnConverter error converted %T to unsupported type %T", arg, nv.Value)
}
return nil
}
// defaultCheckNamedValue wraps the default ColumnConverter to have the same
// function signature as the CheckNamedValue in the driver.NamedValueChecker
// interface.
func defaultCheckNamedValue(nv *driver.NamedValue) (err error) {
nv.Value, err = driver.DefaultParameterConverter.ConvertValue(nv.Value)
return err
}
// driverArgsConnLocked converts arguments from callers of Stmt.Exec and
// Stmt.Query into driver Values.
//
// The statement ds may be nil, if no statement is available.
//
// ci must be locked.
func driverArgsConnLocked(ci driver.Conn, ds *driverStmt, args []interface{}) ([]driver.NamedValue, error) {
nvargs := make([]driver.NamedValue, len(args))
// -1 means the driver doesn't know how to count the number of
// placeholders, so we won't sanity check input here and instead let the
// driver deal with errors.
want := -1
var si driver.Stmt
var cc ccChecker
if ds != nil {
si = ds.si
want = ds.si.NumInput()
cc.want = want
}
// Check all types of interfaces from the start.
// Drivers may opt to use the NamedValueChecker for special
// argument types, then return driver.ErrSkip to pass it along
// to the column converter.
nvc, ok := si.(driver.NamedValueChecker)
if !ok {
nvc, ok = ci.(driver.NamedValueChecker)
}
cci, ok := si.(driver.ColumnConverter)
if ok {
cc.cci = cci
}
// Loop through all the arguments, checking each one.
// If no error is returned simply increment the index
// and continue. However if driver.ErrRemoveArgument
// is returned the argument is not included in the query
// argument list.
var err error
var n int
for _, arg := range args {
nv := &nvargs[n]
if np, ok := arg.(NamedArg); ok {
if err = validateNamedValueName(np.Name); err != nil {
return nil, err
}
arg = np.Value
nv.Name = np.Name
}
nv.Ordinal = n + 1
nv.Value = arg
// Checking sequence has four routes:
// A: 1. Default
// B: 1. NamedValueChecker 2. Column Converter 3. Default
// C: 1. NamedValueChecker 3. Default
// D: 1. Column Converter 2. Default
//
// The only time a Column Converter is called is first
// or after NamedValueConverter. If first it is handled before
// the nextCheck label. Thus for repeats tries only when the
// NamedValueConverter is selected should the Column Converter
// be used in the retry.
checker := defaultCheckNamedValue
nextCC := false
switch {
case nvc != nil:
nextCC = cci != nil
checker = nvc.CheckNamedValue
case cci != nil:
checker = cc.CheckNamedValue
}
nextCheck:
err = checker(nv)
switch err {
case nil:
n++
continue
case driver.ErrRemoveArgument:
nvargs = nvargs[:len(nvargs)-1]
continue
case driver.ErrSkip:
if nextCC {
nextCC = false
checker = cc.CheckNamedValue
} else {
checker = defaultCheckNamedValue
}
goto nextCheck
default:
return nil, fmt.Errorf("sql: converting argument %s type: %v", describeNamedValue(nv), err)
}
}
// Check the length of arguments after conversion to allow for omitted
// arguments.
if want != -1 && len(nvargs) != want {
return nil, fmt.Errorf("sql: expected %d arguments, got %d", want, len(nvargs))
}
return nvargs, nil
}
// convertAssign is the same as convertAssignRows, but without the optional
// rows argument.
func convertAssign(dest, src interface{}) error {
return convertAssignRows(dest, src, nil)
}
// convertAssignRows copies to dest the value in src, converting it if possible.
// An error is returned if the copy would result in loss of information.
// dest should be a pointer type. If rows is passed in, the rows will
// be used as the parent for any cursor values converted from a
// driver.Rows to a *Rows.
func convertAssignRows(dest, src interface{}, rows *Rows) error {
// Common cases, without reflect.
switch s := src.(type) {
case string:
switch d := dest.(type) {
case *string:
if d == nil {
return errNilPtr
}
*d = s
return nil
case *[]byte:
if d == nil {
return errNilPtr
}
*d = []byte(s)
return nil
case *RawBytes:
if d == nil {
return errNilPtr
}
*d = append((*d)[:0], s...)
return nil
}
case []byte:
switch d := dest.(type) {
case *string:
if d == nil {
return errNilPtr
}
*d = string(s)
return nil
case *interface{}:
if d == nil {
return errNilPtr
}
*d = cloneBytes(s)
return nil
case *[]byte:
if d == nil {
return errNilPtr
}
*d = cloneBytes(s)
return nil
case *RawBytes:
if d == nil {
return errNilPtr
}
*d = s
return nil
}
case time.Time:
switch d := dest.(type) {
case *time.Time:
*d = s
return nil
case *string:
*d = s.Format(time.RFC3339Nano)
return nil
case *[]byte:
if d == nil {
return errNilPtr
}
*d = []byte(s.Format(time.RFC3339Nano))
return nil
case *RawBytes:
if d == nil {
return errNilPtr
}
*d = s.AppendFormat((*d)[:0], time.RFC3339Nano)
return nil
}
case decimalDecompose:
switch d := dest.(type) {
case decimalCompose:
return d.Compose(s.Decompose(nil))
}
case nil:
switch d := dest.(type) {
case *interface{}:
if d == nil {
return errNilPtr
}
*d = nil
return nil
case *[]byte:
if d == nil {
return errNilPtr
}
*d = nil
return nil
case *RawBytes:
if d == nil {
return errNilPtr
}
*d = nil
return nil
}
// The driver is returning a cursor the client may iterate over.
case driver.Rows:
switch d := dest.(type) {
case *Rows:
if d == nil {
return errNilPtr
}
if rows == nil {
return errors.New("invalid context to convert cursor rows, missing parent *Rows")
}
rows.closemu.Lock()
*d = Rows{
dc: rows.dc,
releaseConn: func(error) {},
rowsi: s,
}
// Chain the cancel function.
parentCancel := rows.cancel
rows.cancel = func() {
// When Rows.cancel is called, the closemu will be locked as well.
// So we can access rs.lasterr.
d.close(rows.lasterr)
if parentCancel != nil {
parentCancel()
}
}
rows.closemu.Unlock()
return nil
}
}
var sv reflect.Value
switch d := dest.(type) {
case *string:
sv = reflect.ValueOf(src)
switch sv.Kind() {
case reflect.Bool,
reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
reflect.Float32, reflect.Float64:
*d = asString(src)
return nil
}
case *[]byte:
sv = reflect.ValueOf(src)
if b, ok := asBytes(nil, sv); ok {
*d = b
return nil
}
case *RawBytes:
sv = reflect.ValueOf(src)
if b, ok := asBytes([]byte(*d)[:0], sv); ok {
*d = RawBytes(b)
return nil
}
case *bool:
bv, err := driver.Bool.ConvertValue(src)
if err == nil {
*d = bv.(bool)
}
return err
case *interface{}:
*d = src
return nil
}
if scanner, ok := dest.(Scanner); ok {
return scanner.Scan(src)
}
dpv := reflect.ValueOf(dest)
if dpv.Kind() != reflect.Ptr {
return errors.New("destination not a pointer")
}
if dpv.IsNil() {
return errNilPtr
}
if !sv.IsValid() {
sv = reflect.ValueOf(src)
}
dv := reflect.Indirect(dpv)
if sv.IsValid() && sv.Type().AssignableTo(dv.Type()) {
switch b := src.(type) {
case []byte:
dv.Set(reflect.ValueOf(cloneBytes(b)))
default:
dv.Set(sv)
}
return nil
}
if dv.Kind() == sv.Kind() && sv.Type().ConvertibleTo(dv.Type()) {
dv.Set(sv.Convert(dv.Type()))
return nil
}
// The following conversions use a string value as an intermediate representation
// to convert between various numeric types.
//
// This also allows scanning into user defined types such as "type Int int64".
// For symmetry, also check for string destination types.
switch dv.Kind() {
case reflect.Ptr:
if src == nil {
dv.Set(reflect.Zero(dv.Type()))
return nil
}
dv.Set(reflect.New(dv.Type().Elem()))
return convertAssignRows(dv.Interface(), src, rows)
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
if src == nil {
return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
}
s := asString(src)
i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
if err != nil {
err = strconvErr(err)
return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
}
dv.SetInt(i64)
return nil
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
if src == nil {
return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
}
s := asString(src)
u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
if err != nil {
err = strconvErr(err)
return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
}
dv.SetUint(u64)
return nil
case reflect.Float32, reflect.Float64:
if src == nil {
return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
}
s := asString(src)
f64, err := strconv.ParseFloat(s, dv.Type().Bits())
if err != nil {
err = strconvErr(err)
return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
}
dv.SetFloat(f64)
return nil
case reflect.String:
if src == nil {
return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
}
switch v := src.(type) {
case string:
dv.SetString(v)
return nil
case []byte:
dv.SetString(string(v))
return nil
}
}
return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, dest)
}
func strconvErr(err error) error {
if ne, ok := err.(*strconv.NumError); ok {
return ne.Err
}
return err
}
func cloneBytes(b []byte) []byte {
if b == nil {
return nil
}
c := make([]byte, len(b))
copy(c, b)
return c
}
func asString(src interface{}) string {
switch v := src.(type) {
case string:
return v
case []byte:
return string(v)
}
rv := reflect.ValueOf(src)
switch rv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return strconv.FormatInt(rv.Int(), 10)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
return strconv.FormatUint(rv.Uint(), 10)
case reflect.Float64:
return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
case reflect.Float32:
return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
case reflect.Bool:
return strconv.FormatBool(rv.Bool())
}
return fmt.Sprintf("%v", src)
}
func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
switch rv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return strconv.AppendInt(buf, rv.Int(), 10), true
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
return strconv.AppendUint(buf, rv.Uint(), 10), true
case reflect.Float32:
return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
case reflect.Float64:
return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
case reflect.Bool:
return strconv.AppendBool(buf, rv.Bool()), true
case reflect.String:
s := rv.String()
return append(buf, s...), true
}
return
}
var valuerReflectType = reflect.TypeOf((*driver.Valuer)(nil)).Elem()
// callValuerValue returns vr.Value(), with one exception:
// If vr.Value is an auto-generated method on a pointer type and the
// pointer is nil, it would panic at runtime in the panicwrap
// method. Treat it like nil instead.
// Issue 8415.
//
// This is so people can implement driver.Value on value types and
// still use nil pointers to those types to mean nil/NULL, just like
// string/*string.
//
// This function is mirrored in the database/sql/driver package.
func callValuerValue(vr driver.Valuer) (v driver.Value, err error) {
if rv := reflect.ValueOf(vr); rv.Kind() == reflect.Ptr &&
rv.IsNil() &&
rv.Type().Elem().Implements(valuerReflectType) {
return nil, nil
}
return vr.Value()
}
// decimal composes or decomposes a decimal value to and from individual parts.
// There are four parts: a boolean negative flag, a form byte with three possible states
// (finite=0, infinite=1, NaN=2), a base-2 big-endian integer
// coefficient (also known as a significand) as a []byte, and an int32 exponent.
// These are composed into a final value as "decimal = (neg) (form=finite) coefficient * 10 ^ exponent".
// A zero length coefficient is a zero value.
// The big-endian integer coefficent stores the most significant byte first (at coefficent[0]).
// If the form is not finite the coefficient and exponent should be ignored.
// The negative parameter may be set to true for any form, although implementations are not required
// to respect the negative parameter in the non-finite form.
//
// Implementations may choose to set the negative parameter to true on a zero or NaN value,
// but implementations that do not differentiate between negative and positive
// zero or NaN values should ignore the negative parameter without error.
// If an implementation does not support Infinity it may be converted into a NaN without error.
// If a value is set that is larger than what is supported by an implementation,
// an error must be returned.
// Implementations must return an error if a NaN or Infinity is attempted to be set while neither
// are supported.
//
// NOTE(kardianos): This is an experimental interface. See https://golang.org/issue/30870
type decimal interface {
decimalDecompose
decimalCompose
}
type decimalDecompose interface {
// Decompose returns the internal decimal state in parts.
// If the provided buf has sufficient capacity, buf may be returned as the coefficient with
// the value set and length set as appropriate.
Decompose(buf []byte) (form byte, negative bool, coefficient []byte, exponent int32)
}
type decimalCompose interface {
// Compose sets the internal decimal value from parts. If the value cannot be
// represented then an error should be returned.
Compose(form byte, negative bool, coefficient []byte, exponent int32) error
}
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