pwd的實現

print?#include <string.h>  
#include <stdlib.h>  
#include <dirent.h>  
#include <sys/types.h>  
#include <sys/stat.h>  
 
ino_t get_inode(char *); 
void printpathto(ino_t); 
void inum_to_name(ino_t, char *, int); 
 
int main() 
{ 
    printpathto(get_inode(".")); 
    printf("\n"); 
    return 0; 
} 
 
void printpathto(ino_t this_inode) 
{ 
    ino_t my_inode; 
    char its_name[BUFSIZ]; 
    if (get_inode("..") != this_inode) 
    {    
        chdir(".."); 
        inum_to_name(this_inode, its_name, BUFSIZ); 
        my_inode = get_inode("."); 
        printpathto(my_inode); 
        printf("/%s", its_name); 
    }    
 
} 
 
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) 
        if (direntp->d_ino == inode_to_find) 
        {    
            strncpy(namebuf, direntp->d_name, buflen); 
            namebuf[buflen-1] = '\0'; 
            closedir(dir_ptr); 
            return; 
        } 
    fprintf(stderr, "error looking for inum %d\n", inode_to_find); 
    exit(1); 
} 
 
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; 
} 

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

ino_t get_inode(char *);
void printpathto(ino_t);
void inum_to_name(ino_t, char *, int);

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

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

}

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)
        if (direntp->d_ino == inode_to_find)
        {  
            strncpy(namebuf, direntp->d_name, buflen);
            namebuf[buflen-1] = '\0';
            closedir(dir_ptr);
            return;
        }
    fprintf(stderr, "error looking for inum %d\n", inode_to_find);
    exit(1);
}

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;
}