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large_object.go
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large_object.go
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package pq
import (
"fmt"
"io"
"sync"
"github.com/flynn/go-sql"
"github.com/flynn/pq/oid"
)
type LargeObjects struct {
Has64 bool
mtx sync.Locker
fp *fastpath
}
const largeObjectFns = `select proname, oid from pg_catalog.pg_proc
where proname in (
'lo_open',
'lo_close',
'lo_create',
'lo_unlink',
'lo_lseek',
'lo_lseek64',
'lo_tell',
'lo_tell64',
'lo_truncate',
'lo_truncate64',
'loread',
'lowrite')
and pronamespace = (select oid from pg_catalog.pg_namespace where nspname = 'pg_catalog')`
func NewLargeObjects(tx *sql.Tx) (*LargeObjects, error) {
c, err := tx.Conn()
if err != nil {
return nil, err
}
c.Lock()
cn, ok := c.Conn.(*conn)
if !ok {
c.Unlock()
return nil, fmt.Errorf("pq: Expected driver.Conn to be *pq.conn, got %T", c.Conn)
}
if cn.fp == nil {
cn.fp = newFastpath(cn)
}
if _, exists := cn.fp.fns["lo_open"]; !exists {
c.Unlock()
res, err := tx.Query(largeObjectFns)
if err != nil {
return nil, err
}
if err := cn.fp.addFunctions(res); err != nil {
return nil, err
}
c.Lock()
}
lo := &LargeObjects{
mtx: c.Locker,
fp: cn.fp,
}
_, lo.Has64 = cn.fp.fns["lo_lseek64"]
c.Unlock()
return lo, nil
}
type LargeObjectMode int32
const (
LargeObjectModeWrite LargeObjectMode = 0x20000
LargeObjectModeRead LargeObjectMode = 0x40000
)
func (o *LargeObjects) Create(id oid.Oid) (oid.Oid, error) {
o.mtx.Lock()
defer o.mtx.Unlock()
newOid, err := fpInt32(o.fp.CallFn("lo_create", []fpArg{fpIntArg(int32(id))}))
return oid.Oid(newOid), err
}
func (o *LargeObjects) Open(oid oid.Oid, mode LargeObjectMode) (*LargeObject, error) {
o.mtx.Lock()
defer o.mtx.Unlock()
fd, err := fpInt32(o.fp.CallFn("lo_open", []fpArg{fpIntArg(int32(oid)), fpIntArg(int32(mode))}))
return &LargeObject{fd: fd, lo: o}, err
}
func (o *LargeObjects) Unlink(oid oid.Oid) error {
o.mtx.Lock()
defer o.mtx.Unlock()
_, err := o.fp.CallFn("lo_unlink", []fpArg{fpIntArg(int32(oid))})
return err
}
type LargeObject struct {
fd int32
lo *LargeObjects
}
func (o *LargeObject) Write(p []byte) (int, error) {
o.lo.mtx.Lock()
defer o.lo.mtx.Unlock()
n, err := fpInt32(o.lo.fp.CallFn("lowrite", []fpArg{fpIntArg(o.fd), p}))
return int(n), err
}
func (o *LargeObject) Read(p []byte) (int, error) {
o.lo.mtx.Lock()
defer o.lo.mtx.Unlock()
res, err := o.lo.fp.CallFn("loread", []fpArg{fpIntArg(o.fd), fpIntArg(int32(len(p)))})
if len(res) < len(p) {
err = io.EOF
}
return copy(p, res), err
}
func (o *LargeObject) Seek(offset int64, whence int) (n int64, err error) {
o.lo.mtx.Lock()
defer o.lo.mtx.Unlock()
if o.lo.Has64 {
n, err = fpInt64(o.lo.fp.CallFn("lo_lseek64", []fpArg{fpIntArg(o.fd), fpInt64Arg(offset), fpIntArg(int32(whence))}))
} else {
var n32 int32
n32, err = fpInt32(o.lo.fp.CallFn("lo_lseek", []fpArg{fpIntArg(o.fd), fpIntArg(int32(offset)), fpIntArg(int32(whence))}))
n = int64(n32)
}
return
}
func (o *LargeObject) Tell() (n int64, err error) {
o.lo.mtx.Lock()
defer o.lo.mtx.Unlock()
if o.lo.Has64 {
n, err = fpInt64(o.lo.fp.CallFn("lo_tell64", []fpArg{fpIntArg(o.fd)}))
} else {
var n32 int32
n32, err = fpInt32(o.lo.fp.CallFn("lo_tell", []fpArg{fpIntArg(o.fd)}))
n = int64(n32)
}
return
}
func (o *LargeObject) Truncate(size int64) (err error) {
o.lo.mtx.Lock()
defer o.lo.mtx.Unlock()
if o.lo.Has64 {
_, err = o.lo.fp.CallFn("lo_truncate64", []fpArg{fpIntArg(o.fd), fpInt64Arg(size)})
} else {
_, err = o.lo.fp.CallFn("lo_truncate", []fpArg{fpIntArg(o.fd), fpIntArg(int32(size))})
}
return
}
func (o *LargeObject) Close() error {
o.lo.mtx.Lock()
defer o.lo.mtx.Unlock()
_, err := o.lo.fp.CallFn("lo_close", []fpArg{fpIntArg(o.fd)})
return err
}