刚刚看完了rmdir.c，当然这个程序调用了系统调用rmdir，这是我刚刚看的，其实coreutil的很多程序都调用了系统调用，将来看起来肯定更顺利了。
具体这个程序来说，在删除上级目录的时候做了比较多的判断，我没有完全去跟踪，都是一些字符串的操作。
/* rmdir -- remove directories
Copyright (C) 90, 91, 1995-2002, 2004, 2005, 2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Options:
-p, --parent Remove any parent dirs that are explicitly mentioned
in an argument, if they become empty after the
argument file is removed.
David MacKenzie */
//包含头文件
#include
#include
#include
#include
#include "system.h"
#include "error.h"
#include "quotearg.h"
/* The official name of this program (e.g., no `g' prefix). */
#define PROGRAM_NAME "rmdir"//定义宏
#define AUTHORS "David MacKenzie"//定义宏
/* The name this program was run with. */
char *program_name;//声明全局字符指针变量，只分配一个指针的空间而已
/* If true, remove empty parent directories. */
static bool remove_empty_parents;//暂且不管它的作用，语法的意思是，声明一个全局布尔变量，其值保存在一个静态区，传说中的全局变量^_^
/* If true, don't treat failure to remove a nonempty directory
as an error. */
static bool ignore_fail_on_non_empty;//暂且不管它的作用，语法的意思是，声明一个全局布尔变量，其值保存在一个静态区，传说中的全局变量^_^
/* If true, output a diagnostic for every directory processed. */
static bool verbose;//暂且不管它的作用，语法的意思是，声明一个全局布尔变量，其值保存在一个静态区，传说中的全局变量^_^
/* For long options that have no equivalent short option, use a
non-character as a pseudo short option, starting with CHAR_MAX + 1. */
enum
{
IGNORE_FAIL_ON_NON_EMPTY_OPTION = CHAR_MAX + 1
};//初始化一个枚举类型的变量
static struct option const longopts[] =
{
/* Don't name this `--force' because it's not close enough in meaning
to e.g. rm's -f option. */
{"ignore-fail-on-non-empty", no_argument, NULL,
IGNORE_FAIL_ON_NON_EMPTY_OPTION},
{"path", no_argument, NULL, 'p'}, /* Deprecated. */
{"parents", no_argument, NULL, 'p'},
{"verbose", no_argument, NULL, 'v'},
{GETOPT_HELP_OPTION_DECL},
{GETOPT_VERSION_OPTION_DECL},
{NULL, 0, NULL, 0}
};//初始化一个option类型的结构体数组，还是用来处理命令行选项
/* Return true if ERROR_NUMBER is one of the values associated
with a failed rmdir due to non-empty target directory. */
static bool
errno_rmdir_non_empty (int error_number)
{
return (error_number == RMDIR_ERRNO_NOT_EMPTY);
}//这个函数让人惊叹其简洁^_^ ，作用是将形参和RMDIR_ERRNO_NOT_EMPTY进行比较，返回比较后的结果，返回值是个布尔类型值
/* Remove any empty parent directories of DIR.
If DIR contains slash characters, at least one of them
(beginning with the rightmost) is replaced with a NUL byte.
Return true if successful. */
static bool
remove_parents (char *dir)//函数定义部分，接受一个字符指针变量的形参
{
char *slash;//声明一个字符指针类型的局部变量
bool ok = true;//初始化局部布尔类型变量ok为真
strip_trailing_slashes (dir);
while (1)
{
slash = strrchr (dir, '/');//slash指向dir这个字符串中的最后一个/，如果dir中没有/，则退出while循环
if (slash == NULL)
break;
/* Remove any characters after the slash, skipping any extra
slashes in a row. */
while (slash > dir && *slash == '/')
--slash;
slash[1] = 0;
/* Give a diagnostic for each attempted removal if --verbose. */
if (verbose)
error (0, 0, _("removing directory, %s"), dir);
ok = (rmdir (dir) == 0);//调用rmdir删除后是否成功的状态保存在ok里
if (!ok)//如果rmdir不成功，则判断是否忽略
{
/* Stop quietly if --ignore-fail-on-non-empty. */
if (ignore_fail_on_non_empty
&& errno_rmdir_non_empty (errno))
{
ok = true;
}
else
{
error (0, errno, "%s", quotearg_colon (dir));
}
break;
}
}
return ok;
}
void
usage (int status)//帮助函数
{
if (status != EXIT_SUCCESS)
fprintf (stderr, _("Try `%s --help' for more information.\n"),
program_name);
else
{
printf (_("Usage: %s [OPTION]... DIRECTORY...\n"), program_name);
fputs (_("\
Remove the DIRECTORY(ies), if they are empty.\n\
\n\
--ignore-fail-on-non-empty\n\
ignore each failure that is solely because a directory\n\
is non-empty\n\
"), stdout);
fputs (_("\
-p, --parents Remove DIRECTORY and its ancestors. E.g., `rmdir -p a/b/c' is\n\
similar to `rmdir a/b/c a/b a'.\n\
-v, --verbose output a diagnostic for every directory processed\n\
"), stdout);
fputs (HELP_OPTION_DESCRIPTION, stdout);
fputs (VERSION_OPTION_DESCRIPTION, stdout);
printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
}
exit (status);
}
int
main (int argc, char **argv)
{
//声明main函数里的变量
bool ok = true;
int optc;
initialize_main (&argc, &argv);
program_name = argv[0];
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
atexit (close_stdout);
remove_empty_parents = false;//初始化全局变量
while ((optc = getopt_long (argc, argv, "pv", longopts, NULL)) != -1)
{//解析命令行选项，根据选项，设置全局变量的值
switch (optc)
{
case 'p':
remove_empty_parents = true;
break;
case IGNORE_FAIL_ON_NON_EMPTY_OPTION:
ignore_fail_on_non_empty = true;
break;
case 'v':
verbose = true;
break;
case_GETOPT_HELP_CHAR;
case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
default:
usage (EXIT_FAILURE);
}
}
if (optind == argc)//此程序需要命令行参数
{
error (0, 0, _("missing operand"));
usage (EXIT_FAILURE);
}
for (; optind < argc; ++optind)
{//在这个for循环里，处理每一个命令行参数，也就是删除每一个列出来的目录
char *dir = argv[optind];
/* Give a diagnostic for each attempted removal if --verbose. */
if (verbose)
error (0, 0, _("removing directory, %s"), dir);
if (rmdir (dir) != 0)//如果调用rmdir删除dir不成功，则执行下面的代码，判断是否忽略非空的目录，采取措施
{
if (ignore_fail_on_non_empty
&& errno_rmdir_non_empty (errno))
continue;//如果满足上面的条件，直接跳到下一个for循环，否则打印错误，并将ok的值设置为假
error (0, errno, "%s", quotearg_colon (dir));
ok = false;
}
else if (remove_empty_parents)//否则，如果成功删除了dir，并且remove_empty_parents的值为真，则执行:
{
ok &= remove_parents (dir);//先调用remove_parents删除dir，然后用ok的值和函数的返回值进行并
}
}
exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);//main函数退出
}
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