71 lines
1.7 KiB
Go
71 lines
1.7 KiB
Go
|
// Copyright 2010 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-GO file.
|
||
|
|
|
||
|
|
// Modifications Copyright 2020 The Libc 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 libc // import "modernc.org/libc"
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"os"
|
||
|
|
"sync"
|
||
|
|
"time"
|
||
|
|
"unsafe"
|
||
|
|
|
||
|
|
"golang.org/x/sys/unix"
|
||
|
|
"modernc.org/libc/errno"
|
||
|
|
"modernc.org/libc/fcntl"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Random number state.
|
||
|
|
// We generate random temporary file names so that there's a good
|
||
|
|
// chance the file doesn't exist yet - keeps the number of tries in
|
||
|
|
// TempFile to a minimum.
|
||
|
|
var randState uint32
|
||
|
|
var randStateMu sync.Mutex
|
||
|
|
|
||
|
|
func reseed() uint32 {
|
||
|
|
return uint32(time.Now().UnixNano() + int64(os.Getpid()))
|
||
|
|
}
|
||
|
|
|
||
|
|
func nextRandom(x uintptr) {
|
||
|
|
randStateMu.Lock()
|
||
|
|
r := randState
|
||
|
|
if r == 0 {
|
||
|
|
r = reseed()
|
||
|
|
}
|
||
|
|
r = r*1664525 + 1013904223 // constants from Numerical Recipes
|
||
|
|
randState = r
|
||
|
|
randStateMu.Unlock()
|
||
|
|
copy((*RawMem)(unsafe.Pointer(x))[:6:6], fmt.Sprintf("%06d", int(1e9+r%1e9)%1e6))
|
||
|
|
}
|
||
|
|
|
||
|
|
func tempFile(s, x uintptr, flags int32) (fd int, err error) {
|
||
|
|
const maxTry = 10000
|
||
|
|
nconflict := 0
|
||
|
|
flags |= int32(os.O_RDWR | os.O_CREATE | os.O_EXCL | unix.O_LARGEFILE)
|
||
|
|
for i := 0; i < maxTry; i++ {
|
||
|
|
nextRandom(x)
|
||
|
|
fdcwd := fcntl.AT_FDCWD
|
||
|
|
n, _, err := unix.Syscall6(unix.SYS_OPENAT, uintptr(fdcwd), s, uintptr(flags), 0600, 0, 0)
|
||
|
|
if err == 0 {
|
||
|
|
return int(n), nil
|
||
|
|
}
|
||
|
|
|
||
|
|
if err != errno.EEXIST {
|
||
|
|
return -1, err
|
||
|
|
}
|
||
|
|
|
||
|
|
if nconflict++; nconflict > 10 {
|
||
|
|
randStateMu.Lock()
|
||
|
|
randState = reseed()
|
||
|
|
nconflict = 0
|
||
|
|
randStateMu.Unlock()
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return -1, unix.Errno(errno.EEXIST)
|
||
|
|
}
|