Boost C++ Libraries: Ticket #6821: recursive_directory_iterator: increment fails with 'access denied'

attachment set

Sun, 22 Apr 2012 18:54:37 GMT

attachment → fs_bug.cpp

source code

attachment set

Fri, 27 Apr 2012 15:29:52 GMT

attachment → diff.txt

Fri, 27 Apr 2012 15:31:42 GMT

Attached is a proposed one line code change that will fix the issue described without changing or introducing functionality.

The diff is created from operations.cpp, trunk rev 78220.

attachment set

Wed, 02 May 2012 17:52:31 GMT

attachment → access_denied.patch

svn patch file

status changed

Beman Dawes — Mon, 28 May 2012 12:44:13 GMT

status new → assigned

You suggestion of adding an option to treat permission denied as an empty directory seems to me to be the best resolution, since the desired behavior is very application dependent.

I've implemented and tested that for Windows, and am satisfied with the results. This work has been stashed until 1.50.0 is out the door, when I'll resume work on it.

Thanks,

--Beman

Wed, 29 Aug 2012 03:11:42 GMT

The proposed fix only addresses when the first entry is a directory and returns an access denied code. The POSIX code handles this situation nicely with the iterator being set to EOF. However, if there are more entries you get an internal error.

Here is the test directory structure I used to reproduce this as user anonymous:

drwxrwxr-x 5 anonymous anonymous 4096 Aug 28 20:45 ./
drwxrwxr-x 8 anonymous anonymous 4096 Aug 28 20:14 ../
drwx------ 2 root      root      4096 Aug 28 15:30 root_noaccess/
drwxrwxr-x 2 root      anonymous 4096 Aug 28 15:28 root_subdir/
drwxrwxr-x 2 anonymous anonymous 4096 Aug 28 20:14 xfiles/

#include <boost/config/warning_disable.hpp>
#include <boost/filesystem.hpp>
#include <iostream>
#include <iterator>
using namespace std;
int main(int argc, char* argv[]) {
	boost::system::error_code dir_error;
	for ( boost::filesystem::recursive_directory_iterator end, dir(".", dir_error); dir != end; dir.increment(dir_error) ) {
		if (dir_error.value()) {
			cerr << "Error accessing file: " << dir_error.message() << endl;
		}else{
			cout << dir->path() << endl;
		}
	}
	return 0;
}

Output:

anonymous@ubuntu:~/perm_test$ ./test_perms
"./root_noaccess"
Error accessing file: Permission denied
***** Internal Program Error - assertion (m_imp.get()) failed in boost::filesystem::directory_entry& boost::filesystem::directory_iterator::dereference() const:
/usr/local/include/boost/filesystem/operations.hpp(714): attempt to dereference end iterator
Aborted (core dumped)

The expected outcome would be for the iterator to continue on to root_subdir since the program has no access to the directory "./root_noaccess".

Wed, 29 Aug 2012 13:05:38 GMT

Found ticket #5403 that has more details and a workaround for the problems with increment.

Claudio Bley — Mon, 25 Mar 2013 16:27:14 GMT

Actually, this is a regression in regard to v2.

In v2 you could use no_push() in order to skip a directory after an error occurred.

With v3, the directory_iterator at the top of the stack is invalid (ie. an end iterator) if an error occurs. So, you cannot dereference it, and you cannot use any other method (e.g. no_push) on it, otherwise std::abort will be called.

Simple fix: just don't push an end iterator to m_stack.

--- C:\Users\Claudio\src\boost.svn\boost\filesystem\operations.hpp      2012-07-24 08:43:28 +0200
+++ boost\filesystem\operations.hpp     2013-03-25 17:21:39 +0100
@@ -791,9 +791,11 @@
             m_stack.push(directory_iterator(m_stack.top()->path()));
           else
           {
-            m_stack.push(directory_iterator(m_stack.top()->path(), *ec));
+            directory_iterator next = directory_iterator(m_stack.top()->path(), *ec);
             if (*ec)
               return;
+            else
+              m_stack.push(next);
           }
           if (m_stack.top() != directory_iterator())
           {

version, severity changed

rose.branston@… — Wed, 21 May 2014 12:00:08 GMT

version Boost 1.49.0 → Boost 1.55.0
severity Problem → Showstopper

I have encountered the same problem on ubuntu except I don't get the "Permission Denied" message or an exception thrown, it just aborts.

status changed; resolution set

Beman Dawes — Tue, 22 Jul 2014 15:49:16 GMT

status assigned → closed
resolution → fixed

recursive_directory_iterator::increment implementation code has been reorganized, adding an invariant that progress is always made even if an error is reported by exception or error_code. Thanks to Claudio Bley for his pull request, which was incorporated into the reorganized code.

Tickets 5403 and 6821 have been closed. Please open a new issue and supply test cases if you continue to experience problems.