golang中的time.Now的研究与hook

sudo apt install golang
mkdir test-go
cd test-go
go mod init test-go

package main

import "time"
import "fmt"

func main() {
        fmt.Println(time.Now())
}

go build .
./test-go

2023-05-03 20:10:11.703231839 +0800 CST m=+0.000657001

strace ./test-go  2>syscalls.txt
cat syscalls.txt

cat syscalls.txt | grep -v rt_sig | grep -v SIGURG | grep -v mmap\( | grep -v clone\(

execve("./test-go", ["./test-go"], 0x7ffe03de7c10 /* 29 vars */) = 0
arch_prctl(ARCH_SET_FS, 0x532db0)       = 0
sched_getaffinity(0, 8192, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]) = 32
openat(AT_FDCWD, "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", O_RDONLY) = 3
read(3, "2097152\n", 20)                = 8
close(3)                                = 0
sigaltstack(NULL, {ss_sp=NULL, ss_flags=SS_DISABLE, ss_size=0}) = 0
sigaltstack({ss_sp=0xc000004000, ss_flags=0, ss_size=32768}, NULL) = 0
gettid()                                = 1665715
futex(0xc000046548, FUTEX_WAKE_PRIVATE, 1) = 1
fcntl(0, F_GETFL)                       = 0x8402 (flags O_RDWR|O_APPEND|O_LARGEFILE)
futex(0xc000046948, FUTEX_WAKE_PRIVATE, 1) = 1
fcntl(1, F_GETFL)                       = 0x8402 (flags O_RDWR|O_APPEND|O_LARGEFILE)
fcntl(2, F_GETFL)                       = 0x8001 (flags O_WRONLY|O_LARGEFILE)
openat(AT_FDCWD, "/etc/localtime", O_RDONLY) = 3
read(3, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = 561
read(3, "", 4096)                       = 0
close(3)                                = 0
write(1, "2023-05-03 20:10:11.703231839 +0"..., 55) = 55
exit_group(0)                           = ?
+++ exited with 0 +++

git clone https://github.com/golang/go.git

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "gdbdebug", // 随便
            "type": "cppdbg", // c语言用cppdbg没毛病
            "request": "launch", // 不知道是啥
            "program": "${workspaceFolder}/build/${fileBasenameNoExtension}", // 每次debug运行的binary文件
            "args": [], // 程序的参数
            "stopAtEntry": false, // 是否停在main函数或者__start函数的首行
            "cwd": "${workspaceFolder}", // working directory
            "environment": [], // 环境变量
            "externalConsole": false, // 不启用外部Console (terminal)， 在linux里面启用会出现异常的错误
            "MIMode": "gdb", // 不知道是啥
            "miDebuggerPath": "gdb", // 不知道是啥
            "preLaunchTask": "Build", // 此项命名需要与tasks.json中的label项命名一致，编译程序使用
            "setupCommands": [ // 不知道是啥
                {
                    "description": "为 gdb 启用整齐打印",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ]
        }
    ]
}

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "Build", // 需与lauch.json中"preLaunchTask"项命名一致
            "type": "shell", // shell命令
            "command": "gcc", // 编译用的命令
            "args": [
              "${file}",
              "-g",
              "-o",
              "${workspaceFolder}/build/${fileBasenameNoExtension}" // 输出的目标binary
            ],
            "group": {
                "kind": "build",
                "isDefault": true
            },
            // Use the standard MS compiler pattern to detect errors, warnings and infos
            "problemMatcher": [
                "$gcc"
            ]
        }
    ]
}

#include "stdio.h"

int main(void) {
    printf("hello world!\n");
    return 0;
}

#include <sys/time.h>

// int gettimeofday(struct timeval *tv, struct timezone *tz);

// The tv argument is a struct timeval (as specified in <sys/time.h>):
struct timeval
{
    time_t tv_sec;       /* seconds */
    suseconds_t tv_usec; /* microseconds */
};

// and gives the number of seconds and microseconds since the Epoch (see time(2)).

// The tz argument is a struct timezone:

struct timezone
{
    int tz_minuteswest; /* minutes west of Greenwich */
    int tz_dsttime;     /* type of DST correction */
};
// If either tv or tz is NULL, the corresponding structure is not set or returned.  (However, compilation warnings will result if tv is NULL.)

#include "stdio.h"
#include <sys/time.h>

int main(void)
{
    struct timeval tv;
    
    gettimeofday(&tv, NULL);

    printf("Is is %ld now\n", tv.tv_sec);
    return 0;
}

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "gdbdebug", // 随便
            "type": "cppdbg", // c语言用cppdbg没毛病
            "request": "launch", // 不知道是啥
            "program": "${workspaceFolder}/build/${fileBasenameNoExtension}", // 每次debug运行的binary文件
            "args": [], // 程序的参数
            "stopAtEntry": false, // 是否停在main函数或者__start函数的首行
            "cwd": "${workspaceFolder}", // working directory
            "externalConsole": false, // 不启用外部Console (terminal)， 在linux里面启用会出现异常的错误
            "MIMode": "gdb", 
            "miDebuggerPath": "gdb",
            "preLaunchTask": "buildAndSetGlibc", // 此项命名需要与tasks.json中的label项命名一致，编译程序使用
            "setupCommands": [ // gdb启动时的命令
                {
                    "description": "为 gdb 启用整齐打印",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                },
            ]
        }
    ]
}

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "buildAndSetGlibc", 
            "type": "shell", 
            "command": "/bin/bash",
            "args": [
                "setGlibc.sh"
            ],
        }
    ]
}

gcc test.c -o build/test -g
patchelf --replace-needed libc.so.6 /glibc/x64/2.35/lib/libc.so.6 build/test
patchelf --set-interpreter /glibc/x64/2.35/lib/ld-linux-x86-64.so.2 build/test

/* Sleep for a given number of seconds.  POSIX.1 version.
   Copyright (C) 1991-2022 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
#include <sys/param.h>


/* Make the process sleep for SECONDS seconds, or until a signal arrives
   and is not ignored.  The function returns the number of seconds less
   than SECONDS which it actually slept (zero if it slept the full time).
   If a signal handler does a `longjmp' or modifies the handling of the
   SIGALRM signal while inside `sleep' call, the handling of the SIGALRM
   signal afterwards is undefined.  There is no return value to indicate
   error, but if `sleep' returns SECONDS, it probably didn't work.  */
unsigned int
__sleep (unsigned int seconds)
{
  int save_errno = errno;
  printf("you are sleeping....\n"); // 加一句哈哈哈
  const unsigned int max
    = (unsigned int) (((unsigned long int) (~((time_t) 0))) >> 1);
  struct timespec ts = { 0, 0 };
  do
    {
      if (sizeof (ts.tv_sec) <= sizeof (seconds))
        {
          /* Since SECONDS is unsigned assigning the value to .tv_sec can
             overflow it.  In this case we have to wait in steps.  */
          ts.tv_sec += MIN (seconds, max);
          seconds -= (unsigned int) ts.tv_sec;
        }
      else
        {
          ts.tv_sec = (time_t) seconds;
          seconds = 0;
        }

      if (__nanosleep (&ts, &ts) < 0)
        /* We were interrupted.
           Return the number of (whole) seconds we have not yet slept.  */
        return seconds + ts.tv_sec;
    }
  while (seconds > 0);

  __set_errno (save_errno);

  return 0;
}
weak_alias (__sleep, sleep)

#include "time.h"
#include "stdio.h"


int main(void)
{
    // struct timeval tv;
    // gettimeofday(&tv, NULL);
    sleep(1);
    // printf("Is is %ld now\n", tv.tv_sec);
    // printf("Is is %ld now\n", tv.tv_usec);
    printf("Hello world!\n");
    return 0;
}

[root@test ~]# timedatectl set-time "2018-01-22 23:29"
Failed to set time: Automatic time synchronization is enabled
[root@test ~]# timedatectl set-ntp 0
[root@test ~]# timedatectl set-time "2018-01-22 23:29"
[root@test ~]# timedatectl set-ntp 1
[root@test ~]# timedatectl set-time "2018-01-22 23:29"
Failed to set time: Automatic time synchronization is enabled
[root@test ~]#