[Bug libstdc++/99533] New: "operation not permitted" error on recursive_directory_iterator despite skip_permission_denied

[ssh at pobox dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99533

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 returns
EPERM instead of EACCES even if
std::filesystem::directory_options::skip_permission_denied is set.

Given the following code:

#include 
#include 

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

int totalDirs = 0;
int totalFiles = 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//Library/Application Support/MobileSync" folder leading to EPERM.

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 only
EACCES  for the skip_permission_denied option is not enough.

[Bug libstdc++/99533] "operation not permitted" error on recursive_directory_iterator despite skip_permission_denied

[ssh at pobox dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99533

--- Comment #5 from Steffen Schuemann  ---
Thank you for looking into this and sorry for the namespace issue, I was to
greedy when deleting the preprocessor parts that switched between my
implementation and std::filesystem.

First of all, I'm with you in thinking the macOS issue is more of an os
problem, but knowing the chances that this gets fixed on Apples side,
especially for anything older than Big Sur, I hoped that a fix/workaround on
GCC/LLVM side would be a much better chance. Thanks for the changes, I'll try
to test macOS later this day. 

And thank you for pointing out that the situation under Linux is in fact not
the same. You are right. Sadly I was fooled to believe it is, while comparing
the behavior with my implementation but after some debugging the reason mine
iterates through /proc/1/task/1/cwd without an error is actually a bug on my
side. So I have to thank you for helping me find that one.

So to recap: EPERM issue is indeed macOS only, not Linux!