golang fallocate_test 代码
文件路径：/src/cmd/link/internal/ld/fallocate_test.go
/ 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.
/go:build darwin || linux
/ +build darwin linux
package ld
import (
"os"
"path/filepath"
"syscall"
"testing"
)
func TestFallocate(t *testing.T) {
dir := t.TempDir()
filename := filepath.Join(dir, "a.out")
out := NewOutBuf(nil)
err := out.Open(filename)
if err != nil {
t.Fatalf("Open file failed: %v", err)
}
defer out.Close()
/ Try fallocate first.
for {
err = out.fallocate(1 << 10)
if err == syscall.EOPNOTSUPP { / The underlying file system may not support fallocate
t.Skip("fallocate is not supported")
}
if err == syscall.EINTR {
continue / try again
}
if err != nil {
t.Fatalf("fallocate failed: %v", err)
}
break
}
/ Mmap 1 MiB initially, and grow to 2 and 3 MiB.
/ Check if the file size and disk usage is expected.
for _, sz := range []int64{1 << 20, 2 << 20, 3 << 20} {
err = out.Mmap(uint64(sz))
if err != nil {
t.Fatalf("Mmap failed: %v", err)
}
stat, err := os.Stat(filename)
if err != nil {
t.Fatalf("Stat failed: %v", err)
}
if got := stat.Size(); got != sz {
t.Errorf("unexpected file size: got %d, want %d", got, sz)
}
/ The number of blocks must be enough for the requested size.
/ We used to require an exact match, but it appears that
/ some file systems allocate a few extra blocks in some cases.
/ See issue #41127.
if got, want := stat.Sys().(*syscall.Stat_t).Blocks, (sz+511)/512; got < want {
t.Errorf("unexpected disk usage: got %d blocks, want at least %d", got, want)
}
out.munmap()
}
}