How can i get all files from disk?

Question

I have to create a vector of all files on my disk, starting from root ("C:/"). I used filesystem library and recursive_directory_iterator, however program throws filesystem::filesystem_error when it reaches some of system directories which only the system has access to.

#include <filesystem>
#include <iostream>
#include <vector>

using namespace std;
namespace fs = std::filesystem;

vector<fs::path> get_all_files_from_disk(fs::path path,vector<fs::path>* all_files = NULL) {
    if (all_files == NULL)
        all_files = new vector<fs::path>();
    try {
        for (auto dir : fs::directory_iterator(path)) {         
                if (dir.is_directory())
                    *all_files = get_all_files_from_disk(dir, all_files);
                else
                    all_files->push_back(dir.path());
        }
    }
    catch (fs::filesystem_error e) {
        cout << "error";
    }
    return *all_files;
}

vector<fs::path> getAllFilesFromDisk(fs::path path) {
    vector<fs::path> all_files;
    for (auto dir : fs::recursive_directory_iterator(path)) {
        if (!dir.is_directory())
            all_files.push_back(dir.path());
    };
    return all_files;
};

int main() {
    setlocale(LC_ALL, "");
    fs::path path("C:/");
    vector<fs::path> a = get_all_files_from_disk(path);
    vector<fs::path> b = getAllFilesFromDisk(path);
}

The first algorithm doesn't crash, but executes really long time (it executed at about 40 minutes), however when output displaying all elements of vector is empty for some reason, with no-root directories it works fine. The second one crashes because of the reason stated in the beginning.

:( Could you help please?

Answer 1

There may be the problem that the underlying filesystem denies you the permission to read certain directories (like for example special system directories).

That my be the reason that you iterator fails.

If you read about the std::filesystem::recursive_directory_iterator in the CPP reference here, then you can see in the description of the constructor no 5, that you can set a flag to ignore unaccessable directories. Please read here about the flag skip_permission_denied

Still it will run some time, because of many many many directories is you start from root. Please Switch optimizations on.

Example code:

#include <filesystem>
#include <iostream>
#include <vector>

using namespace std;
namespace fs = std::filesystem;

vector<fs::path> getAllFilesFromDisk(fs::path path) {
    vector<fs::path> all_files;
    for (auto dir : fs::recursive_directory_iterator(path, fs::directory_options::skip_permission_denied)) {
        if (!dir.is_directory())
            all_files.push_back(dir.path());
    };
    return all_files;
};

int main() {
    setlocale(LC_ALL, "");
    fs::path path("C:/");
    vector<fs::path> b = getAllFilesFromDisk(path);
}