C Lang - Struct Array and Segmentation fault (core dumped)

Question

I have written a simple code to read a directory then sort the files by last modified time,but the following code will crash because Segmentation fault (core dumped)，（occur when try to access the lsf[0] and lsf[1] ），how to solve the problem，please help，thanks：

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

typedef struct {
  char *name;
  unsigned long lasted;
} sort_file;

char *make_path(char *path) {
  char *endp = path + strlen(path);
  *endp++ = '/';
  return endp;
}

int main(int arc, char **argv) {

  const char *n_dir = "/home/psycho/Pictures";
  char *dir_name = strdup(n_dir);

  char *endp = make_path(dir_name);

  DIR *dir;
  struct dirent *ent;
  struct stat attr;

  int size = 150;
  int count = 0;
  sort_file **lsf = malloc(size * sizeof(sort_file *));
  printf("[Logging] : %d => %d  \n", sizeof(sort_file), sizeof(sort_file *));
  if ((dir = opendir(n_dir)) != NULL) {
    while ((ent = readdir(dir)) != NULL) {

      if (ent->d_name[0] == '.') {
        continue;
      } else if (ent->d_type == DT_DIR) {
        strcpy(endp, ent->d_name);
        stat(dir_name, &attr);

        lsf[count] = malloc(sizeof(sort_file));
        lsf[count]->lasted = (unsigned long)attr.st_mtime;
        lsf[count]->name = malloc((strlen(ent->d_name) )* sizeof(char));

        sprintf(lsf[count]->name, "%s", ent->d_name);
        printf("[Logging] : --- %lu --- %d --- %s  \n", lsf[count]->lasted,
               count, lsf[count]->name);


        count++;

      }
    }
    closedir(dir);

  } else {
    return 0;
  }

  while (count--) {
    printf("[Logging] : --- %lu --- %d --- %s  \n", lsf[count]->lasted, count,
           lsf[count]->name);
  }
  return 0;
}

Answer 1

This code includes some memory panics, depend on different compilers different errors may occur.

1. In make_path , endp is pointing to last character of dir_name ( '\\0' ) and is trying to change it from '\\0' to '/' without inserting the string trailing char ( '\\0' ) at the end and realloc one more character for dir_name
2. In main , const char *n_dir = "/home/psycho/Pictures"; do not need to be defined as pointer because length is known at compile time. In fact it should be changed to: const char n_dir[] = "/home/psycho/Pictures";
3. In main , endp is not allocated at all so strcpy(endp, ent->d_name); copies to restricted memory spaces
4. In main , lsf[count]->name = malloc((strlen(ent->d_name) )* sizeof(char)); should allocate one more unit because of trailing '\\0' : lsf[count]->name = malloc((strlen(ent->d_name) + 1 )* sizeof(char));

At last I noticed a logical error: if (ent->d_name[0] == '.') { ... makes program to skip ' . ', ' .. ', and all other directories starting with ' . ' (Linux hidden folders). You can use 0 == (strcmp(ent->d_name, ".") * strcmp(ent->d_name, ".."))