| // Copyright 2020 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 file. | |
| package ld | |
| import ( | |
| "syscall" | |
| "unsafe" | |
| ) | |
| // Implemented in the syscall package. | |
| // | |
| //go:linkname fcntl syscall.fcntl | |
| func fcntl(fd int, cmd int, arg int) (int, error) | |
| func (out *OutBuf) fallocate(size uint64) error { | |
| stat, err := out.f.Stat() | |
| if err != nil { | |
| return err | |
| } | |
| // F_PEOFPOSMODE allocates from the end of the file, so we want the size difference. | |
| // Apparently, it uses the end of the allocation, instead of the logical end of the | |
| // file. | |
| cursize := uint64(stat.Sys().(*syscall.Stat_t).Blocks * 512) // allocated size | |
| if size <= cursize { | |
| return nil | |
| } | |
| store := &syscall.Fstore_t{ | |
| Flags: syscall.F_ALLOCATEALL, | |
| Posmode: syscall.F_PEOFPOSMODE, | |
| Offset: 0, | |
| Length: int64(size - cursize), | |
| } | |
| _, err = fcntl(int(out.f.Fd()), syscall.F_PREALLOCATE, int(uintptr(unsafe.Pointer(store)))) | |
| return err | |
| } | |
| func (out *OutBuf) purgeSignatureCache() { | |
| // Apparently, the Darwin kernel may cache the code signature at mmap. | |
| // When we mmap the output buffer, it doesn't have a code signature | |
| // (as we haven't generated one). Invalidate the kernel cache now that | |
| // we have generated the signature. See issue #42684. | |
| msync(out.buf, syscall.MS_INVALIDATE) | |
| // Best effort. Ignore error. | |
| } | |