1// Copyright 2020 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 file. 4 5package ld 6 7import ( 8 "syscall" 9 "unsafe" 10) 11 12// Implemented in the syscall package. 13// 14//go:linkname fcntl syscall.fcntl 15func fcntl(fd int, cmd int, arg int) (int, error) 16 17func (out *OutBuf) fallocate(size uint64) error { 18 stat, err := out.f.Stat() 19 if err != nil { 20 return err 21 } 22 // F_PEOFPOSMODE allocates from the end of the file, so we want the size difference. 23 // Apparently, it uses the end of the allocation, instead of the logical end of the 24 // file. 25 cursize := uint64(stat.Sys().(*syscall.Stat_t).Blocks * 512) // allocated size 26 if size <= cursize { 27 return nil 28 } 29 30 store := &syscall.Fstore_t{ 31 Flags: syscall.F_ALLOCATEALL, 32 Posmode: syscall.F_PEOFPOSMODE, 33 Offset: 0, 34 Length: int64(size - cursize), 35 } 36 37 _, err = fcntl(int(out.f.Fd()), syscall.F_PREALLOCATE, int(uintptr(unsafe.Pointer(store)))) 38 return err 39} 40 41func (out *OutBuf) purgeSignatureCache() { 42 // Apparently, the Darwin kernel may cache the code signature at mmap. 43 // When we mmap the output buffer, it doesn't have a code signature 44 // (as we haven't generated one). Invalidate the kernel cache now that 45 // we have generated the signature. See issue #42684. 46 msync(out.buf, syscall.MS_INVALIDATE) 47 // Best effort. Ignore error. 48} 49