forked from mirrors/gotosocial
121 lines
3.3 KiB
Go
121 lines
3.3 KiB
Go
package pgx
|
|
|
|
import (
|
|
"context"
|
|
"errors"
|
|
"io"
|
|
)
|
|
|
|
// LargeObjects is a structure used to access the large objects API. It is only valid within the transaction where it
|
|
// was created.
|
|
//
|
|
// For more details see: http://www.postgresql.org/docs/current/static/largeobjects.html
|
|
type LargeObjects struct {
|
|
tx Tx
|
|
}
|
|
|
|
type LargeObjectMode int32
|
|
|
|
const (
|
|
LargeObjectModeWrite LargeObjectMode = 0x20000
|
|
LargeObjectModeRead LargeObjectMode = 0x40000
|
|
)
|
|
|
|
// Create creates a new large object. If oid is zero, the server assigns an unused OID.
|
|
func (o *LargeObjects) Create(ctx context.Context, oid uint32) (uint32, error) {
|
|
err := o.tx.QueryRow(ctx, "select lo_create($1)", oid).Scan(&oid)
|
|
return oid, err
|
|
}
|
|
|
|
// Open opens an existing large object with the given mode. ctx will also be used for all operations on the opened large
|
|
// object.
|
|
func (o *LargeObjects) Open(ctx context.Context, oid uint32, mode LargeObjectMode) (*LargeObject, error) {
|
|
var fd int32
|
|
err := o.tx.QueryRow(ctx, "select lo_open($1, $2)", oid, mode).Scan(&fd)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return &LargeObject{fd: fd, tx: o.tx, ctx: ctx}, nil
|
|
}
|
|
|
|
// Unlink removes a large object from the database.
|
|
func (o *LargeObjects) Unlink(ctx context.Context, oid uint32) error {
|
|
var result int32
|
|
err := o.tx.QueryRow(ctx, "select lo_unlink($1)", oid).Scan(&result)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
if result != 1 {
|
|
return errors.New("failed to remove large object")
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// A LargeObject is a large object stored on the server. It is only valid within the transaction that it was initialized
|
|
// in. It uses the context it was initialized with for all operations. It implements these interfaces:
|
|
//
|
|
// io.Writer
|
|
// io.Reader
|
|
// io.Seeker
|
|
// io.Closer
|
|
type LargeObject struct {
|
|
ctx context.Context
|
|
tx Tx
|
|
fd int32
|
|
}
|
|
|
|
// Write writes p to the large object and returns the number of bytes written and an error if not all of p was written.
|
|
func (o *LargeObject) Write(p []byte) (int, error) {
|
|
var n int
|
|
err := o.tx.QueryRow(o.ctx, "select lowrite($1, $2)", o.fd, p).Scan(&n)
|
|
if err != nil {
|
|
return n, err
|
|
}
|
|
|
|
if n < 0 {
|
|
return 0, errors.New("failed to write to large object")
|
|
}
|
|
|
|
return n, nil
|
|
}
|
|
|
|
// Read reads up to len(p) bytes into p returning the number of bytes read.
|
|
func (o *LargeObject) Read(p []byte) (int, error) {
|
|
var res []byte
|
|
err := o.tx.QueryRow(o.ctx, "select loread($1, $2)", o.fd, len(p)).Scan(&res)
|
|
copy(p, res)
|
|
if err != nil {
|
|
return len(res), err
|
|
}
|
|
|
|
if len(res) < len(p) {
|
|
err = io.EOF
|
|
}
|
|
return len(res), err
|
|
}
|
|
|
|
// Seek moves the current location pointer to the new location specified by offset.
|
|
func (o *LargeObject) Seek(offset int64, whence int) (n int64, err error) {
|
|
err = o.tx.QueryRow(o.ctx, "select lo_lseek64($1, $2, $3)", o.fd, offset, whence).Scan(&n)
|
|
return n, err
|
|
}
|
|
|
|
// Tell returns the current read or write location of the large object descriptor.
|
|
func (o *LargeObject) Tell() (n int64, err error) {
|
|
err = o.tx.QueryRow(o.ctx, "select lo_tell64($1)", o.fd).Scan(&n)
|
|
return n, err
|
|
}
|
|
|
|
// Truncate the large object to size.
|
|
func (o *LargeObject) Truncate(size int64) (err error) {
|
|
_, err = o.tx.Exec(o.ctx, "select lo_truncate64($1, $2)", o.fd, size)
|
|
return err
|
|
}
|
|
|
|
// Close the large object descriptor.
|
|
func (o *LargeObject) Close() error {
|
|
_, err := o.tx.Exec(o.ctx, "select lo_close($1)", o.fd)
|
|
return err
|
|
}
|