coreutils5.0 uname命令和源码分析

  uname   /* 默认输出内核名。和uname -s一样 */

  -a, --all  /* 按以下顺序打印所有信息 */
  -s  /* 打印内核名称 */
  -n  /* 打印主机名 */
  -r  /* 打印内核版本发行号 */
  -v  /* 打印内核版本 */
  -m  /* 打印机器硬件名称 */
  -p  /* 打印CPU类型 */
  -i  /* 打印硬件平台 */
  -o   /* 打印操作系统 */

/* uname -- print system information

   Copyright 1989, 1992, 1993, 1996, 1997, 1999, 2000, 2001, 2002 Free
   Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Written by David MacKenzie <djm@gnu.ai.mit.edu> */

#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/utsname.h>
#include <getopt.h>

#if HAVE_SYSINFO && HAVE_SYS_SYSTEMINFO_H
# include <sys/systeminfo.h>
#endif

#if HAVE_SYSCTL && HAVE_SYS_SYSCTL_H
# include <sys/param.h> /* needed for OpenBSD 3.0 */
# include <sys/sysctl.h>
# ifdef HW_MODEL
#  ifdef HW_MACHINE_ARCH
/* E.g., FreeBSD 4.5, NetBSD 1.5.2 */
#   define UNAME_HARDWARE_PLATFORM HW_MODEL
#   define UNAME_PROCESSOR HW_MACHINE_ARCH
#  else
/* E.g., OpenBSD 3.0 */
#   define UNAME_PROCESSOR HW_MODEL
#  endif
# endif
#endif

#include "system.h"
#include "error.h"
#include "closeout.h"

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "uname"

#define AUTHORS "David MacKenzie"

/* 用于修改toprint的值 */
/* 内核名称 */
#define PRINT_KERNEL_NAME 1

/* 主机名 */
#define PRINT_NODENAME 2

/* 内核发行号 */
#define PRINT_KERNEL_RELEASE 4

/* 内核版本 */
#define PRINT_KERNEL_VERSION 8

/* 硬件名 */
#define PRINT_MACHINE 16

/* CPU类型 */
#define PRINT_PROCESSOR 32

/* 硬件平台  */
#define PRINT_HARDWARE_PLATFORM 64

/* 操作系统  */
#define PRINT_OPERATING_SYSTEM 128

/* 保存程序名 = argv[0] */
char *program_name;

/* 长选项结构体 */
static struct option const long_options[] =
{
  {"all", no_argument, NULL, 'a'}, /* "长选项名称"，"选项：no_argument代表该长选项无需参数"，"元素三为NULL时，getopt将直接返回元素四，不为空时参数三将保存元素4" */
  {"kernel-name", no_argument, NULL, 's'},
  {"sysname", no_argument, NULL, 's'},	/* 即将弃用，该源码是5.0，不知道9.0是否以弃用.  */
  {"nodename", no_argument, NULL, 'n'},
  {"kernel-release", no_argument, NULL, 'r'},
  {"release", no_argument, NULL, 'r'},  /* 即将弃用，该源码是5.0，不知道9.0是否以弃用.  */
  {"kernel-version", no_argument, NULL, 'v'},
  {"machine", no_argument, NULL, 'm'},
  {"processor", no_argument, NULL, 'p'},
  {"hardware-platform", no_argument, NULL, 'i'},
  {"operating-system", no_argument, NULL, 'o'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0} /* 没有参数时返回0 */
};

/* 传入的命令行参数的错误函数，传入不支持的参数就调用该函数 */
void
usage (int status)
{
  if (status != 0)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
	     program_name);
  else
    {
      /* 调用错误函数时，提示该命令用法，命令没有参数时将和-s一样 */
      printf (_("Usage: %s [OPTION]...\n"), program_name);
      fputs (_("\
Print certain system information.  With no OPTION, same as -s.\n\
\n\
  /* 按以下顺序打印所有信息 */
  -a, --all                print all information, in the following order:\n\
  /* 打印内核名称 */
  -s, --kernel-name        print the kernel name\n\
  /* 打印主机名 */
  -n, --nodename           print the network node hostname\n\
  /* 打印内核版本发行号 */
  -r, --kernel-release     print the kernel release\n\
"), stdout);
      fputs (_("\
  /* 打印内核版本 */
  -v, --kernel-version     print the kernel version\n\
  /* 打印机器硬件名称 */
  -m, --machine            print the machine hardware name\n\
  /* 打印CPU类型 */
  -p, --processor          print the processor type\n\
  /* 打印硬件平台 */
  -i, --hardware-platform  print the hardware platform\n\
  /* 打印操作系统 */
  -o, --operating-system   print the operating system\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    }
  exit (status);
}

/* Print ELEMENT, preceded by a space if something has already been
   printed.  */

static void
print_element (char const *element)
{
  static int printed;
  if (printed++)
    putchar (' ');
  fputs (element, stdout);
}

int
main (int argc, char **argv)
{
  int c;
  static char const unknown[] = "unknown";

  /* Mask indicating which elements to print. */
  /* 指示要打印哪些元素的掩码(最后用该值判断用户需要输出什么信息) */
  unsigned toprint = 0;

  /* 程序初始化 */
  program_name = argv[0];  /* 程序名 */
  setlocale (LC_ALL, "");  /* 获取系统编码、地区代码等信息 */
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);
  
  atexit (close_stdout);/* 出口函数 */

  /* 解析命令行参数 */
  while ((c = getopt_long (argc, argv, "asnrvmpio", long_options, NULL)) != -1) /* c保存用户传入的参数 */
    {
      /* 判断用户传入的函数来修改toprint的值 */
      switch (c)  
	{
	case 0:
	  break;

	case 'a':
	  toprint = -1;
	  break;

   /* 内核名称，值=1 */
	case 's':
	  toprint |= PRINT_KERNEL_NAME;
	  break;

   /* 主机名称，值=2 */
	case 'n':
	  toprint |= PRINT_NODENAME;
	  break;

   /* 内核发行号，值=4 */
	case 'r':
	  toprint |= PRINT_KERNEL_RELEASE;
	  break;

   /* 内核版本，值=8 */
	case 'v':
	  toprint |= PRINT_KERNEL_VERSION;
	  break;

   /* 硬件名，值=16 */
	case 'm':
	  toprint |= PRINT_MACHINE;
	  break;

   /* CPU类型，值=32 */
	case 'p':
	  toprint |= PRINT_PROCESSOR;
	  break;

   /* 硬件平台，值=64 */
	case 'i':
	  toprint |= PRINT_HARDWARE_PLATFORM;
	  break;

   /* 操作系统，值=128 */
	case 'o':
	  toprint |= PRINT_OPERATING_SYSTEM;
	  break;

   /* 在system.h内定义 在这case内会exit退出程序 */
	case_GETOPT_HELP_CHAR;

   /* 在system.h内定义 在这case内会exit退出程序 */
	case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);

	default:
	  usage (EXIT_FAILURE);  /* 如果以上case都没有触发的话，调用usage帮助函数，退出程序，EXIT_FAILURE的值为1，定义在stdlib */
	}
    }

  /* getopt调用的次数不等于main传入的参数就报错。用来测试传入的参数是否全部都getopt成功。因为每次调用一次getopt都会使optind +1 */
  if (optind != argc)
    usage (EXIT_FAILURE);

  /* 不带参数默认转成内核名称 */
  if (toprint == 0)
    toprint = PRINT_KERNEL_NAME;

  /* 参数值==1 | 2 | 4 | 8 | 16 进入该if */
  if (toprint
       & (PRINT_KERNEL_NAME | PRINT_NODENAME | PRINT_KERNEL_RELEASE
	  | PRINT_KERNEL_VERSION | PRINT_MACHINE))
    {
      struct utsname name;  /* 获取系统相关信息的结构体 */

      if (uname (&name) == -1)  /* 填充ustname结构 */
	error (EXIT_FAILURE, errno, _("cannot get system name"));  /* 无法获取系统名称 */

      if (toprint & PRINT_KERNEL_NAME)
	print_element (name.sysname);
      if (toprint & PRINT_NODENAME)
	print_element (name.nodename);
      if (toprint & PRINT_KERNEL_RELEASE)
	print_element (name.release);
      if (toprint & PRINT_KERNEL_VERSION)
	print_element (name.version);
      if (toprint & PRINT_MACHINE)
	print_element (name.machine);
    }

  /* 参数值==32 */
  if (toprint & PRINT_PROCESSOR)
    {
      char const *element = unknown;
#if HAVE_SYSINFO && defined SI_ARCHITECTURE
      {
	static char processor[257];
	if (0 <= sysinfo (SI_ARCHITECTURE, processor, sizeof processor))
	  element = processor;
      }
#endif
#ifdef UNAME_PROCESSOR
      if (element == unknown)
	{
	  static char processor[257];
	  size_t s = sizeof processor;
	  static int mib[] = { CTL_HW, UNAME_PROCESSOR };
	  if (sysctl (mib, 2, processor, &s, 0, 0) >= 0)
	    element = processor;
	}
#endif
      print_element (element);
    }

  /* 参数值==64 */
  if (toprint & PRINT_HARDWARE_PLATFORM)
    {
      char const *element = unknown;
#if HAVE_SYSINFO && defined SI_PLATFORM
      {
	static char hardware_platform[257];
	if (0 <= sysinfo (SI_PLATFORM,
			  hardware_platform, sizeof hardware_platform))
	  element = hardware_platform;
      }
#endif
#ifdef UNAME_HARDWARE_PLATFORM
      if (element == unknown)
	{
	  static char hardware_platform[257];
	  size_t s = sizeof hardware_platform;
	  static int mib[] = { CTL_HW, UNAME_HARDWARE_PLATFORM };
	  if (sysctl (mib, 2, hardware_platform, &s, 0, 0) >= 0)
	    element = hardware_platform;
	}
#endif
      print_element (element);
    }

  /* 参数值==128 */
  if (toprint & PRINT_OPERATING_SYSTEM)
    print_element (HOST_OPERATING_SYSTEM);

  putchar ('\n');

  exit (EXIT_SUCCESS);
}

用getopt_long解析用户传入参数后并保存在toprint，调用uname填充ustname结构体，判断torint输出对应的信息

问1：-a = -1时是怎么输出所有。是不是-1在&别的常量时if判断为true所以能输出所有。

因为发现5.0和新的源码差距太大了，所以man shuf翻到最下面查看了我linux的coreutils是8.32，所以去看8.32了，这个问题等8.32的时候在解决了