c - 编写简单的 du clone。获取子目录中文件大小的随机值。

Question

我正在尝试编写一个基本程序来汇总当前目录和所有子目录中所有文件的文件大小。我认为这将是一个很好的练习。我正在尝试为此使用基本递归。这是我目前所拥有的:

#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <dirent.h>
#include <string.h>

long totalbytes = 0;

long dirsize(const char* directory, int verbose)
{
  struct dirent *de;
  struct stat s;
  DIR * dir; 
  //long total_items = 0;
  long filesize = 0;

  dir = opendir(directory);
  if (dir == NULL)
  {
     printf("Failed to open %s.\n", directory);
     return -1;
  }

  while ((de = readdir (dir)) != NULL)
  {
    stat(de->d_name, &s);
  if (S_ISLNK(s.st_mode)) 
  {
    printf("links are ignored.\n");
  }
  if (de->d_type == DT_REG)
  {
    filesize = 0; //be sure to reset this each time to avoid inaccuracy
    stat(de->d_name, &s); // get file info into our s structure
    if (verbose) 
    {
      printf("%s/%s : %ld bytes (%f MB)\n", directory, de->d_name, s.st_size, (float) s.st_size / 1024 / 1024);
    }
    filesize = s.st_size; //put file size into filesize variable
    totalbytes += filesize; //increment totalbytes
  }
  if (de->d_type == DT_DIR && strcmp(de->d_name, ".") != 0 && strcmp(de->d_name, "..") != 0)
  {
    char pathname[PATH_MAX];
    sprintf(pathname, "%s/%s", directory, de->d_name);
    dirsize(pathname, verbose); //recursion: keep looping until no more subdirs remain
    }
  }
  closedir(dir);
  return totalbytes;
}

long compute_size(const char* directory, int verbose)
{
  long space = dirsize(directory, verbose);
  return space;
}

int main(int argc, char* argv[])
{
  if (argc != 2)
  {
    printf("Usage: dirsize DIRECTORY\n");
return -1;
  }

  int verbose = 1; //show or hide individual computations

  long space = compute_size(argv[1], verbose);
  if (space != -1)
  {
    float space_mb = (float) space / 1024 / 1024;
    printf("space occupied: %ld bytes\n", space);
    printf("(%f MB)\n", space_mb);
  }
  return 0;
}

这是我的程序输出(我还包括子目录的 ls)

08:35 PM@~/tmp$ ./dirsize .
./dirsize : 8369 bytes (0.007981 MB)
./diskstat.c : 1430 bytes (0.001364 MB)
./diskstat : 7993 bytes (0.007623 MB)
./ftw.c : 491 bytes (0.000468 MB)
./a.out : 8044 bytes (0.007671 MB)
./arrays.sh : 212 bytes (0.000202 MB)
./fileread/timestamp : 0 bytes (0.000000 MB)
./fileread/timestamp.c : 0 bytes (0.000000 MB)
./fileread/a.out : 8044 bytes (0.007671 MB)
./fileread/build.prop : 8044 bytes (0.007671 MB)
./fileread/read.c : 4096 bytes (0.003906 MB)
./fileread/read : 454656 bytes (0.433594 MB)
./local.fstab : 76 bytes (0.000072 MB)
./dirsize.c : 1857 bytes (0.001771 MB)
./echo.sh : 223 bytes (0.000213 MB)
./TEAMS.sh : 605 bytes (0.000577 MB)
space occupied: 504140 bytes
(0.480785 MB)
08:35 PM@~/tmp$ ls -l fileread/
total 40
-rwxr-xr-x 1 raidzero raidzero 8132 Dec 28 10:39 a.out
-rw-r--r-- 1 raidzero raidzero 2346 Dec 28 10:09 build.prop
-rwxr-xr-x 1 raidzero raidzero 8384 Dec 29 13:57 read
-rw-r--r-- 1 raidzero raidzero 1150 Dec 28 10:16 read.c
-rwxr-xr-x 1 raidzero raidzero 8132 Dec 29 13:57 timestamp
-rw-r--r-- 1 raidzero raidzero  659 Dec 28 10:39 timestamp.c
08:35 PM@~/tmp$

以我有限的经验，获取随机数据是内存分配不当的标志，但 stat 结构中的 st_size 是一个 long int..？

Answer 1

de->d_name 只有文件名 - 它不包含指向它的路径。例如，您正在统计 ./timestamp 而不是 ./fileread/timestamp。您可以构建文件的完整路径，使用 chdir() 随时输入目录(如果您处于多线程环境中则不安全，并且如果目录被移动则可能很脆弱当你在其中时 - fchdir() 对回到更高的目录非常有帮助)，或者(在最近的 unixen 上)使用 openat()/fstat()遍历目录的函数。

请注意，如果您检查过 stat 的错误返回，您会注意到这一点。始终检查那些错误返回。