mmap_unix.go RawHistoryFolder

1// SPDX-License-Identifier: MIT
2
3//go:build linux || darwin || freebsd || openbsd || netbsd || dragonfly
4
5package git
6
7import (
8	"os"
9	"syscall"
10)
11
12// mapFile maps a whole file read-only. The returned function unmaps it.
13func mapFile(f *os.File, size int64) ([]byte, func() error, error) {
14	if size <= 0 || int64(int(size)) != size {
15		return nil, nil, corrupt("%s: unusable size %d", f.Name(), size)
16	}
17	data, err := syscall.Mmap(int(f.Fd()), 0, int(size), syscall.PROT_READ, syscall.MAP_SHARED)
18	if err != nil {
19		return nil, nil, &os.PathError{Op: "mmap", Path: f.Name(), Err: err}
20	}
21	adviseRandom(data)
22	return data, func() error { return syscall.Munmap(data) }, nil
23}
24
25// fileIno returns the inode number of a stat result, 0 when unknown.
26func fileIno(fi os.FileInfo) uint64 {
27	if st, ok := fi.Sys().(*syscall.Stat_t); ok {
28		return uint64(st.Ino) //nolint:unconvert // the type differs per OS
29	}
30	return 0
31}