C opening and reading directories - c

Question

So im trying to write a program in C that works like the ls command from Linux,
for the moment i've been capable of listing the files and directories inside my Current working directory, but i don't seem to be capable of doing the same for directories that are not my CWD, do i need to change it before i start listing it? or does the function opendir() work for any directory?
It has to work like ls -li from Linux but i got the printing stuff handled.
In general my program looks like this (obvsly it has more things):
void function(char *directory_to_list){
DIR *d;
struct dirent *dirp;
struct stat filestat;
if ( (d = opendir(directory_to_list)) == NULL){
//print error
}
while ( ( dirp = readdir(d) ) != NULL){
//here i call the stat() function for every entry to get various information
if (stat(dirp->d_name, &filestat) == -1){
continue;
}
//various prints
}
closedir(d);
}
EDIT: The command would be -> ls -li [-dir] so if you dont get any dir you just list your CWD.
EDIT2: No error is being returned it just does nothing, it opens the directory just fine but doenst list anything so i guess the stat call is not being done well, also added the line for how i call stat().

Answer 1

Here is a working version. Pay special attention that you do not overflow the buffer. you'll have to do some significant error checking to make this secure:
#include <stdio.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
int function(char *);
int main(void)
{
function("/tmp");
return 0;
}
int function(char *path)
{
DIR *dir;
struct dirent *dentry;
struct stat filestat;
char *giantbuffer = malloc(sizeof(char) * ((PATH_MAX * 2 ) + 1) );
if ( ( dir = opendir(path) ) )
{
dentry = readdir(dir);
while ( dentry )
{
sprintf(giantbuffer, "%s/%s", path, dentry->d_name);
printf("%s ", giantbuffer);
if (stat(giantbuffer, &filestat) == 0)
printf("%zu\n", filestat.st_size);
dentry = readdir(dir);
}
closedir(dir);
}
else
return -1;
return 0;
}