How do I handle symbolic links when using `directory_iterator`?

Question

Ryan McCombe · Accepted Answer

Handling symbolic links (symlinks) in a directory can be important depending on whether you want to follow them or treat them as distinct entries. The std::filesystem::directory_iterator provides methods to check if an entry is a symlink.

Here's how to identify and handle symbolic links:

1#include <filesystem>
2#include <iostream>
3
4namespace fs = std::filesystem;
5
6int main() {
7  fs::directory_iterator start{R"(c:\test)"};
8  fs::directory_iterator end{};
9
10  for (auto iter{start}; iter != end; ++iter) {
11    std::cout << iter->path().string();
12    if (iter->is_symlink()) { 
13      std::cout << " (Symbolic Link)";
14    }
15    std::cout << '\n';
16  }
17}

1c:\test\file1.txt
2c:\test\symlink (Symbolic Link)
3c:\test\directory

Following Symbolic Links:

If you want to follow symbolic links and access the target they point to, you can use std::filesystem::read_symlink():

1#include <filesystem>
2#include <iostream>
3
4namespace fs = std::filesystem;
5
6int main() {
7  fs::directory_iterator start{R"(c:\test)"};
8  fs::directory_iterator end{};
9
10  for (auto iter{start}; iter != end; ++iter) {
11    std::cout << iter->path().string();
12    if (iter->is_symlink()) {
13      auto target = fs::read_symlink(iter->path());  
14      std::cout << " -> " << target.string();
15    }
16    std::cout << '\n';
17  }
18}

1c:\test\file1.txt
2c:\test\symlink -> c:\actual\path\to\file
3c:\test\directory

Key Considerations:

Security: Be cautious when following symlinks as they can point to unexpected locations, potentially leading to security issues.
Recursion: When using std::filesystem::recursive_directory_iterator, symlinks can cause infinite loops if they point back to an ancestor directory. Handle this by tracking visited directories or limiting recursion depth.

Ignoring Symbolic Links:

If you prefer to ignore symlinks, simply skip them in your iteration:

1#include <filesystem>
2#include <iostream>
3
4namespace fs = std::filesystem;
5
6int main() {
7  fs::directory_iterator start{R"(c:\test)"};
8  fs::directory_iterator end{};
9
10  for (auto iter{start}; iter != end; ++iter) {
11    if (iter->is_symlink()) {
12      continue; 
13    }
14    std::cout << iter->path().string() << '\n';
15  }
16}

By understanding how to handle symbolic links, you can decide whether to follow them, log their targets, or ignore them based on your application's needs.

Directory Iterators

Handle Symbolic Links During Directory Iteration

Following Symbolic Links:

Key Considerations:

Ignoring Symbolic Links:

Directory Iterators

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