C编程-Stat系统调用-错误 [英] C Programming - Stat system call - Error

问题描述

我是C语言的新手，但是尝试了一些系统调用.

I'm new to C but trying some system calls.

我正在编写一个程序，它遍历目录中的所有文件并打印当前文件名和大小.我可以让程序打印文件名，但是在执行stat系统调用时出错.

I'm writing program that iterates through all files in a directory and prints the current file name and size. I can get the program to print the file name but it errors when I preform the stat system call.

下面是一些代码:

while (dptr = readdir(dirp)) { 
            if (stat(dptr->d_name, &buf) != 0) {
                //Always does this and it does print the file name
                printf("Error on when getting size of %s \n", dptr->d_name);
            } else {
                //Never gets here
                printf("%u", buf.st_size);
              }         
}

我有这样描述的结构:

struct stat buf;
struct dirent *dptr;
DIR *dirp;

如果我更改:

if (stat(dptr->d_name, &buf) != 0)

到

if (stat(dptr->d_name, &buf) != [EACCES])

它仍然进入循环，这使我认为它无法读取文件名，但可以在错误语句中毫无问题地将其打印出来.

It still goes into the loop which makes me think it can't read the file name but it's printing it in the error statement without a problem.

有人可以指出我正确的方向吗?谢谢！

Can someone point me in the right direction? Thanks!

Аркадий

推荐答案

首先，如果遇到错误，则stat()返回-1，而不是实际的错误代码.错误代码将在errno中设置.打印错误的一种简单方法是使用perror().

First, stat() returns -1 if an error is encountered, not the actual error code. The error code will be set in errno. An easy way to print the error is to use perror().

第二，dptr-> d_name仅提供文件的相对文件名，而不提供完整文件名.要获取完整的文件名，必须从相对文件名和目录名生成它.

Second, dptr->d_name only provides a relative filename of the file and not the full filename. To obtain the full filename, you must generate it from the relative filename and the directory name.

这里是一个例子:

int cwdloop(void)
{
   DIR           * dirp;
   struct stat     buff;
   struct dirent * dptr;
   char            filename[1024];
   char            dirname[1024];

   if (!(getcwd(dirname, 1024)))
   {
       perror("getcwd");
       return(1);
   };

   dirp = opendir(dirname);
   if (!(dirp))
   {
      perror("opendir()");
      return(1);
   };

   while ((dptr = readdir(dirp)))
   {
      snprintf(filename, 1024, "%s/%s", dirname, dptr->d_name);
      if (stat(filename, &buff) != 0)
      {
         perror("stat()");
         return(1);
      } else {
         printf("size: %u\n", (unsigned)buff.st_size);
      };
   };

   closedir(dirp);

   return(0);
}

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