dir_walk_example.c

/*************************************************************************
    > File Name: dir_walk_example.c
    > Author: VOID_133
    > A small program demos the process "ls -R", potential buggy
    > Mail: ################### 
    > Created Time: Mon 09 May 2016 09:24:56 PM CST
 ************************************************************************/
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/file.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<dirent.h>
#include<fcntl.h>
#include<errno.h>


#define MAX_PATH 2048
struct stat fs_stat;

void usage();
void get_size(char *filename);

int main(int argc, char *argv[])
{
    if(argc < 2)
    {
        usage();
    }
    else
    {
        while(--argc > 0)
            get_size(*++argv);
    }
}

void dir_walk(char *dir, void (*fsz)(char *))
{
    char file_name[MAX_PATH];
    DIR *dfd;
    struct dirent* pentry;
    printf("entering %s...\n", dir);
    if((dfd = opendir(dir)) == NULL)
    {
        perror("opendir");
        //exit(errno);
    }
    else
    {
        while((pentry = readdir(dfd)) != NULL)
        {
            if(!strcmp(pentry->d_name, ".") || !strcmp(pentry->d_name, ".."))
            {
                printf("%8ld %s\n", 0, pentry->d_name);
                continue;
            }
            if(strlen(dir) + strlen(pentry->d_name) + 2 > MAX_PATH)
            {
                fprintf(stderr, "dir_walk name %s/%s is too long", dir, pentry->d_name);
            }
            if(!strcmp(dir,"/"))
                sprintf(file_name, "/%s", pentry->d_name);
            else
                sprintf(file_name, "%s/%s", dir, pentry->d_name);
            fsz(file_name);
        }
        closedir(dfd);
    }
    return ;
}

void get_size(char *file_name)
{
    int retval = 0xdeadbeef;
    retval = lstat(file_name, &fs_stat);
    if(retval < 0)
        perror("stat");
    else
    {
        mode_t mode = fs_stat.st_mode;
        if(((mode & S_IFMT) == S_IFDIR) && ((mode & S_IFMT) != S_IFLNK))
        {
            dir_walk(file_name, get_size);
        }
        else
        {
            printf("%8ld %s\n", fs_stat.st_size, file_name);
        }
    }
}

void usage()
{
    printf("Usage: myls directory_name\n");
}