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Subject: [Bug libstdc++/99533] New: "operation not permitted" error on
 recursive_directory_iterator despite skip_permission_denied
Date: Wed, 10 Mar 2021 23:04:55 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99533

            Bug ID: 99533
           Summary: "operation not permitted" error on
                    recursive_directory_iterator despite
                    skip_permission_denied
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ssh at pobox dot com
  Target Milestone: ---

On POSIX filesystem backend type systems the
std::filesystem::recursive_directory_iterator throws a filesystem_error
exception with "operation not permitted" when the opendir/readdir call retu=
rns
EPERM instead of EACCES even if
std::filesystem::directory_options::skip_permission_denied is set.

Given the following code:

#include <iostream>
#include <filesystem>

int main(int argc, char* argv[])
{
    fs::path dir{"."};
    if(argc =3D=3D 2) {
        dir =3D fs::u8path(argv[1]);
    }

    int totalDirs =3D 0;
    int totalFiles =3D 0;
    try {
        for(const auto& de : fs::recursive_directory_iterator(dir,
fs::directory_options::skip_permission_denied)) {
            if(de.is_regular_file()) {
                ++totalFiles;
            }
            else if(de.is_directory()) {
                ++totalDirs;
            }
        }
    }
    catch(fs::filesystem_error fe) {
        std::cerr << "Error: " << fe.what() << std::endl;
        exit(1);
    }
    std::cout << totalFiles << " files in " << totalDirs << " directories" =
<<
std::endl;
    return 0;
}

This fails for example on macOS when called on the user home directory with:

Error: filesystem error: cannot increment recursive directory iterator:
Operation not permitted

This is due to System Integrity Protection (since macOS 10.14) on the
"/Users/<user>/Library/Application Support/MobileSync" folder leading to EP=
ERM.

On Linux, called with / it stops when hitting for example a
"/proc/1/task/1/cwd", resulting in EPERM too.

I don't have examples from other POSIX systems, but I would say handling on=
ly
EACCES  for the skip_permission_denied option is not enough.=