closedir() causes changes in existing list's nodes

This is a simplified code of my function:

myList* listFilesInDirectory(char* path) {
    DIR* dir = opendir(path);
    myList* list = createList();
    struct dirent* entry;

    while ((entry = readdir(dir)) != NULL) {
        myNode* node = createNode(entry->d_name);
        addToList(list, node);
    }
    closedir(dir);
    return list;
}

that I use in main function:

myList* sourceFiles = listFilesInDirectory("source/");
myList* destFiles = listFilesInDirectory("dest/");

The problem is that second invocation of function changes elements of list that was returned in first invocation. Elements of sourceFiles become changed after listFilesInDirectory("dest/"); is called.

But when I remove a closedir(dir) from function body, then everything works correctly and elements of sourceFiles are not changed.

I prepared a simple program https://pastebin.com/9pTYmpm2 so you can see what happens. Example result:

As you see, SourceFiles content 1 and SourceFiles content 2 are different. The first was printed before listFilesInDirectory("dest/") was invoked, and the second was printed after. But if I remove closedir(dir) from function all works correctly:

What is going on here? Why does it happen? How to prevent it? Should I not use closedir() in my programs?

The problem seems to be that you are creating your node with the name straight from entry->d_name. But entry is stack allocated struct which will become invalid once your exit listFilesInDirectory.

An easy fix:

while ((entry = readdir(dir)) != NULL) {
        myNode* node = createNode(strdup(entry->d_name));
        addToList(list, node);
}

But I suggest you check the return values of everything: opendir, closedir, as well as strdup.