/
load_file.go
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/
load_file.go
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// Copyright 2021 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package function
import (
"fmt"
"os"
"path/filepath"
"github.com/dolthub/go-mysql-server/sql"
"github.com/dolthub/go-mysql-server/sql/types"
)
type LoadFile struct {
fileName sql.Expression
}
var _ sql.FunctionExpression = (*LoadFile)(nil)
var _ sql.CollationCoercible = (*LoadFile)(nil)
// NewLoadFile returns a LoadFile object for the LOAD_FILE() function.
func NewLoadFile(fileName sql.Expression) sql.Expression {
return &LoadFile{
fileName: fileName,
}
}
// Description implements sql.FunctionExpression
func (l *LoadFile) Description() string {
return "returns a LoadFile object."
}
// Resolved implements sql.Expression.
func (l *LoadFile) Resolved() bool {
return l.fileName.Resolved()
}
// String implements sql.Expression.
func (l *LoadFile) String() string {
return fmt.Sprintf("%s(%s)", l.FunctionName(), l.fileName)
}
// Type implements sql.Expression.
func (l *LoadFile) Type() sql.Type {
return types.LongBlob
}
// CollationCoercibility implements the interface sql.CollationCoercible.
func (*LoadFile) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
return sql.Collation_binary, 5
}
// IsNullable implements sql.Expression.
func (l *LoadFile) IsNullable() bool {
return true
}
// TODO: Allow FILE privileges for GRANT
// Eval implements sql.Expression.
func (l *LoadFile) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
dir, err := ctx.Session.GetSessionVariable(ctx, "secure_file_priv")
if err != nil {
return "", err
}
// Read the file: Ensure it fits the max byte size
file, err := l.getFile(ctx, row, dir.(string))
if err != nil {
// If the file doesn't exist we swallow that error
if os.IsNotExist(err) {
return nil, nil
}
return nil, err
}
if file == nil {
return nil, nil
}
defer file.Close()
size, isTooBig, err := isFileTooBig(ctx, file)
if err != nil {
return nil, err
}
// According to the mysql spec we must return NULL if the file is too big.
if isTooBig {
return nil, nil
}
// Finally, read the file
data := make([]byte, size)
_, err = file.Read(data)
if err != nil {
return nil, err
}
return data, nil
}
// getFile returns the file handler for the passed in filename. The file must be in the secure_file_priv
// directory.
func (l *LoadFile) getFile(ctx *sql.Context, row sql.Row, secureFileDir string) (*os.File, error) {
fileName, err := l.fileName.Eval(ctx, row)
if err != nil {
return nil, err
}
// If the secure_file_priv directory is not set, just read the file from whatever directory it is in
// Otherwise determine whether the file is in the secure_file_priv directory.
if secureFileDir == "" {
return os.Open(fileName.(string))
}
// Open the two directories (secure_file_priv and the file dir) and validate they are the same.
sDir, err := os.Open(secureFileDir)
if err != nil {
return nil, err
}
sStat, err := sDir.Stat()
if err != nil {
return nil, err
}
ffDir, err := os.Open(filepath.Dir(fileName.(string)))
if err != nil {
return nil, err
}
fStat, err := ffDir.Stat()
if err != nil {
return nil, err
}
// If the two directories are not equivalent we return nil
if !os.SameFile(sStat, fStat) {
return nil, nil
}
return os.Open(fileName.(string))
}
// isFileTooBig return the current file size and whether or not it is larger than max_allowed_packet.
func isFileTooBig(ctx *sql.Context, file *os.File) (int64, bool, error) {
fi, err := file.Stat()
if err != nil {
return -1, false, err
}
val, err := ctx.Session.GetSessionVariable(ctx, "max_allowed_packet")
if err != nil {
return -1, false, err
}
return fi.Size(), fi.Size() > val.(int64), nil
}
// Children implements sql.Expression.
func (l *LoadFile) Children() []sql.Expression {
return []sql.Expression{l.fileName}
}
// WithChildren implements sql.Expression.
func (l *LoadFile) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(l, len(children), 1)
}
return NewLoadFile(children[0]), nil
}
// FunctionName implements sql.FunctionExpression.
func (l *LoadFile) FunctionName() string {
return "load_file"
}