directory listing C (using dirent and stat)

Question

Im making a directory listing application that prints a directory listing just like the ’ls’ and ’dir’ commands in Linux and Windows respec- tively.

my function: prints a listing of all files in the directory specified by path.

this is my code so far:

#include "ls.h"

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

// Use this function to display the files. DO NOT CHANGE IT.
void _printLine(unsigned int size, unsigned int sizeOnDisk, const char* name)
{
    printf("%010u   %010u   %s\n", size, sizeOnDisk, name);
}

// Assume this to be the maximum length of a file name returned by readdir
#define MAX_FILE_NAME_LENGTH 255

int list(const char* path)
{
    (void) path;
    struct dirent *dent;
    struct stat s;
    DIR *dir;
    dir = opendir(".");
    if (!dir){
        perror("opendir");
        return -1;
    }

    errno = 0;
    while ((dent = readdir(dir)) != NULL){
        _printLine(s.st_size, s.st_blocks*512, dent->d_name);
    }
    closedir(dir);

    return 0;
}

Im trying to pass the "size" of the file and "size on disk" to the print function(using stat), while also passing the name of the file (using dirent). But i can't figure out how to implement this right, or if it is even possible?

Comment: avoid creating functions (or variables) with names that start with an underscore. Such names are generally reserved for use by “the implementation”. Yes, there are caveats and qualifications to this rule, but the headline version is simple and safe. — Jonathan Leffler, Mar 18 '22 at 11:37
What problem are you having? Is the code not compiling? Is it crashing? — Chris Turner, Mar 18 '22 at 11:40

score 2 · Accepted Answer · answered Mar 18 '22 at 12:40

You never called stat?

$ gcc -Wall ls.c 
$ ./a.out .
0000000160   0000000000   .
0000000608   0000000000   ..
0000000947   0000004096   ls.c
0000000811   0000004096   read.c
0000049840   0000053248   a.out
$ ls -l 
total 120
-rwxr-xr-x  1 anicolao  wheel  49840 Mar 18 08:39 a.out
-rw-r--r--  1 anicolao  wheel    947 Mar 18 08:39 ls.c
-rw-r--r--  1 anicolao  wheel    811 Mar 17 17:58 read.c
$ cat ls.c

//#include "ls.h"

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

// Use this function to display the files. DO NOT CHANGE IT.
void _printLine(unsigned int size, unsigned int sizeOnDisk, const char* name)
{
    printf("%010u   %010u   %s\n", size, sizeOnDisk, name);
}

// Assume this to be the maximum length of a file name returned by readdir
#define MAX_FILE_NAME_LENGTH 255

int list(const char* path)
{
    (void) path;
    struct dirent *dent;
    struct stat s;
    DIR *dir;
    dir = opendir(".");
    if (!dir){
        perror("opendir");
        return -1;
    }

    errno = 0;
    while ((dent = readdir(dir)) != NULL){
        stat(dent->d_name, &s);
        _printLine(s.st_size, s.st_blocks*512, dent->d_name);
    }
    closedir(dir);

    return 0;
}

int main(int argc, char **argv) {
    return list(argv[1]);
}

There is also missing error checking, but I think the missing call will get you going.

directory listing C (using dirent and stat)

1 Answers1