Unix-Linux編程實踐教程——pwd

//
// Created by Eddie on 2020/3/16.
//

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <cstdlib>
#include <cstring>
#include <zconf.h>

ino_t get_inode(char * fname){
    struct stat info;
    if(stat(fname, &info) == -1){
        fprintf(stderr, "Cannot stat");
        perror(fname);
        exit(1);
    }
    return info.st_ino;
}

void inum_to_name(ino_t inode_to_find, char* namebuf, int buflen)
{
    DIR * dir_ptr;
    struct dirent * direntp;
    dir_ptr = opendir(".");
    if(dir_ptr == NULL){
        perror(".");
        exit(1);
    }

    while((direntp = readdir(dir_ptr)) != NULL){//why while?
        if(direntp->d_ino == inode_to_find){
            strncpy(namebuf, direntp->d_name, buflen);
            namebuf[buflen-1] = '\0';
            closedir(dir_ptr);
            return;
        }
    }
    fprintf(stderr, "%d\n", inode_to_find);
    return;
}

void printpathto(ino_t this_inode)
{
    ino_t my_inode;
    char its_name[BUFSIZ];
    if(get_inode(".") != this_inode){
        inum_to_name(this_inode, its_name, BUFSIZ);
        chdir("..");
        my_inode = get_inode(".");
        printpathto(my_inode);
        printf("/%s", its_name);
    }
}

int main(){
    printpathto(get_inode("."));
    putchar('\n');
    return 0;
}

爲啥要cd到上層目錄去找當前目錄的name呢。因爲當前目錄在當前目錄只是.，是沒有名字的。

爲啥註釋行是while一直想不明白，返回去看了下目錄那塊，發現確實是while，代碼手敲一遍確實不一樣，有些細節不會忽略。