[Urgency] Error ctim value get from file.Stat().Sys().(*syscall.Stat_t)

[GoFreshMan]

linux version: 5.1.9-300.fc30.x86_64

linux dist: fedora 30

go version: go1.12.5 linux/amd64

[ ~/Rhizobium]$ stat README.md

 文件：README.md

 大小：461            块：8          IO 块：4096   普通文件

设备：805h/2053d      Inode：4199368     硬链接：1

权限：(0664/-rw-rw-r--)  Uid：( 1000/     dba)   Gid：( 1000/     dba)

环境：unconfined_u:object_r:user_home_t:s0

最近访问：2019-06-17 16:39:21.000000000 +0800 (last access)

最近更改：2019-06-18 10:40:27.000000000 +0800 (last change)

最近改动：2019-06-18 14:05:06.950815138 +0800 (last modified)

创建时间：2019-06-17 16:39:21.343782864 +0800 (create time)

In my go program:

package common

import (

"fmt"

"os"

"os/user"

"syscall"

"testing"

"time"

)

func TestGetFileState(t *testing.T) {

f, _ := os.Stat("/home/dba/Rhizobium/README.md")

x := GetFileState1(f)

fmt.Printf("%+v\n", f)

fmt.Printf("%+v", x)

}

func GetFileState1(info os.FileInfo) FileStat1 {

stat := info.Sys().(*syscall.Stat_t)

fileState := FileStat1{

Inode:   uint64(stat.Ino),

Device:  uint64(stat.Dev),

Name:    info.Name(),

Size:    info.Size(),

Mode:    info.Mode(),

CrtTime: time.Unix(int64(stat.Ctim.Sec), int64(stat.Ctim.Nsec)),

ModTime: time.Unix(stat.Mtim.Sec, stat.Mtim.Nsec),

AcsTime: time.Unix(stat.Atim.Sec, stat.Atim.Nsec),

isDir:   info.IsDir(),

}

groupPointer, _ := user.LookupGroupId(fmt.Sprintf("%d", stat.Gid))

fileState.userGroup = *groupPointer

userPointer, _ := user.LookupId(fmt.Sprintf("%d", stat.Uid))

fileState.user = *userPointer

return fileState

}

type FileStat1 struct {

Inode     uint64

Device    uint64

Name      string

Size      int64 // bytes

Mode      os.FileMode

CrtTime   time.Time // 创建时间

AcsTime   time.Time // 上次读取时间

ModTime   time.Time // 上次修改时间

isDir     bool

user      user.User

userGroup user.Group

}

output:

=== RUN   TestGetFileState

&{name:README.md size:461 mode:436 modTime:{wall:0 ext:63696422427 loc:0x638c00} sys:{Dev:2053 Ino:4199368 Nlink:1 Mode:33204 Uid:1000 Gid:1000 X__pad0:0 Rdev:0 Size:461 Blksize:4096 Blocks:8 Atim:{Sec:1560760761 Nsec:0} Mtim:{Sec:1560825627 Nsec:0} Ctim:{Sec:1560837906 Nsec:950815138} X__unused:[0 0 0]}}

{Inode:4199368 Device:2053 Name:README.md Size:461 Mode:-rw-rw-r-- CrtTime:2019-06-18 14:05:06.950815138 +0800 CST AcsTime:2019-06-17 16:39:21 +0800 CST ModTime:2019-06-18 10:40:27 +0800 CST isDir:false user:{Uid:1000 Gid:1000 Username:dba Name:dba HomeDir:/home/dba} userGroup:{Gid:1000 Name:dba}}--- PASS: TestGetFileState (0.00s)

PASS

ok  command-line-arguments 0.002s

Question:

why  file.Stat().Sys().(*syscall.Stat_t) get file create time is :

 Ctim:{Sec:1560837906 Nsec:950815138} === 2019-06-18 14:05:06.950815138 +0800 CST

access time is 

{Sec:1560760761 Nsec:0} ==== 2019-06-17 16:39:21 +0800

It seems the ctim and atime just on the contray

[David Finkel]

We'd have to know more about the history of that particular file on your system in order to provide more detailed information, but a couple things to note that probably help explaining your confusion:

• ctime is not the create time, it's the inode change time, so it gets updated whenever you change permissions, update the link-count (via a rename or  hardlink), or file-size change (among other things)
• atime may not be reliable. E.G. filesystems mounted with the "noatime" option won't ever generate a write to the inode on its own to update the atime of a file; and "relatime" will limit how often it updates the atime timestamp. 

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