Print readdir() and stat() info for each directory argument

print_readdir.c

/* For each argument, this program prints each file name in that directory plus
 * the file type. Type 0 is unknown.
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/dir.h>
#include <sys/stat.h>
#include <unistd.h>

void print_readdir(char * const dir_name) {
  DIR *dir = opendir(dir_name);
  if (dir == NULL) {
    fprintf(stderr, "Can't open directory: %s\n", dir_name);
    return;
  }

  struct dirent *dir_info;
  while ((dir_info = readdir(dir)) != NULL) {
    // First, print the readdir() file type.
    printf("%s: readdir_d_type=%d", dir_info->d_name, dir_info->d_type);
    // Second, for comparison, print some stat() file types.
    struct stat stat_info;
    if (stat(dir_info->d_name, &stat_info) != -1) {
      printf(" stat_is_reg=%d stat_is_dir=%d", S_ISREG(stat_info.st_mode), S_ISDIR(stat_info.st_mode));
    }
    printf("\n");
  }
  closedir(dir);
}

int main(int argc, char * const argv[]) {
  // If there are no arguments, use the $PWD.
  if (argc <= 1) {
    print_readdir(".");
    return 0;
  }

  // If there are arguments, print the readdir info for each argument, assuming
  // it is a directory.
  for (int i = 1; i < argc; i++) {
    print_readdir(argv[i]);
    if (i + 1 < argc) {
      printf("\n");
    }
  }
  return 0;
}