"retsize <= sizeInWords" in mbstowcs in dirent.h on Windows - c++

Question

Background information:
I'm building a file tree in windows using dirent.h (project requirement) on VS2013. I got dirent.h from here. I crash at runtime with a debug assertion failed ("retsize <= sizeInWords") from crt\crtw32\mbstowcs.c, line 283.
To test dirent.h, I used
void printDir(std::string dir, std::string tab)
{
DIR* d = opendir(dir.c_str());
dirent* ent = nullptr;
while (ent = readdir(d)) {
if (ent->d_name[0] != '.') {
std::cout << tab << ent->d_name << std::endl;
if (ent->d_type == DT_DIR) {
printDir(dir + "/" + ent->d_name, tab + " ");
}
}
}
}
which worked (called from main as printDir(".", ""))
so to build my tree I have:
struct Dirf {
std::string getFullPath() {
if (out) {
return out->getFullPath() + "/" + ent.d_name;
}
else return ent.d_name;
}
Dirf(DIR* dir, Dirf* parent = nullptr)
: out(parent)
{
if (dir) {
dirent* d = readdir(dir);
if (d) {
ent = *d;
if (dir) {
next = std::make_shared<Dirf>(dir, parent);
}
if (ent.d_type == DT_DIR) {
DIR* inDir = opendir(getFullPath().c_str());
in = std::make_shared<Dirf>(inDir, this);
closedir(inDir);
}
}
}
}
private:
typedef std::shared_ptr<Dirf> point;
friend std::string to_string(Dirf, std::string);
dirent ent;
Dirf* out; // parent to this; in->out == this, out->in == this;
point in, // in != null iff car.d_type == DT_DIR
next; // next entry in the dir
};
std::string to_string(Dirf, std::string tab = "");
However, calling Dirf(opendir(".")) fails with the debug assertion described above

Answer 1

While composing the question, I figured out the answer: I forgot to check for "." and ".." in Dirf's constructor (I remembered to do it in my test case). Adding
while (d && d->d_name[0] == '.') { // skip '..' and '.'
d = readdir(dir);
}
after dirent* d = readdir(dir) made the error go away.