ioutil_openbsd.go (1512B)
1 // Copyright 2010 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE-GO file. 4 5 // Modifications Copyright 2020 The Libc Authors. All rights reserved. 6 // Use of this source code is governed by a BSD-style 7 // license that can be found in the LICENSE file. 8 9 package libc // import "modernc.org/libc" 10 11 import ( 12 "fmt" 13 "os" 14 "sync" 15 "time" 16 "unsafe" 17 18 "golang.org/x/sys/unix" 19 ) 20 21 // Random number state. 22 // We generate random temporary file names so that there's a good 23 // chance the file doesn't exist yet - keeps the number of tries in 24 // TempFile to a minimum. 25 var randState uint32 26 var randStateMu sync.Mutex 27 28 func reseed() uint32 { 29 return uint32(time.Now().UnixNano() + int64(os.Getpid())) 30 } 31 32 func nextRandom(x uintptr) { 33 randStateMu.Lock() 34 r := randState 35 if r == 0 { 36 r = reseed() 37 } 38 r = r*1664525 + 1013904223 // constants from Numerical Recipes 39 randState = r 40 randStateMu.Unlock() 41 copy((*RawMem)(unsafe.Pointer(x))[:6:6], fmt.Sprintf("%06d", int(1e9+r%1e9)%1e6)) 42 } 43 44 func tempFile(s, x uintptr, _ int32) (fd int, err error) { 45 const maxTry = 10000 46 nconflict := 0 47 for i := 0; i < maxTry; i++ { 48 nextRandom(x) 49 if fd, err = unix.Open(GoString(s), os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600); err == nil { 50 return fd, nil 51 } 52 53 if !os.IsExist(err) { 54 return -1, err 55 } 56 57 if nconflict++; nconflict > 10 { 58 randStateMu.Lock() 59 randState = reseed() 60 nconflict = 0 61 randStateMu.Unlock() 62 } 63 } 64 return -1, err 65 }