#643 _wstat64i32 fails on path ending with slash, causing failure in the filesystem library

[Qrox]

Hello,

The experimental filesystem library is failiing for my project, and from what I can gather, it's caused by _wstat64i32 not correctly handling paths ending with slash. Patch #34 fixed failure of stat & wstat when the path ends with a slash, however _wstat64i32 etc were not fixed. The current implementation of std::experimental::filesystem uses _wstat to retrieve path status, which is a macro which expands to _wstat64i32. This in turn causes the filesystem library to fail, e.g., create_directories can fail because the call is_directory will fail and return false for the parent directories (which ends with slash).

[niXman]

Patch #34

What are you talking about?

[Qrox]

Sorry, I mean https://sourceforge.net/p/mingw-w64/patches/34/

[niXman]

Done for master:
https://sourceforge.net/p/mingw-w64/mingw-w64/ci/32ec57d19d9678f0be7c4ecb2b251dba10d860e6/

[Jonathan Wakely]

The fix looks wrong, it means that _stat("regular_file/", &buf) will resolve to "regular_file" but a trailing slash should only be valid on a directory. Stripping the slash unconditionally is wrong.

A better fix would be to append "." to the path, so that something ending in a slash is treated as a directory, but that won't work because of https://sourceforge.net/p/mingw-w64/bugs/782/

[Jonathan Wakely]

I take it back, on Windows "regular_file/" is the same path as "regular_file" so stripping the slash is fine, and works consistently with the expected behaviour on the OS.

I was foolishly expecting Windows to have sane pathname handling, but I was wrong.

[Jonathan Wakely]

This seems to have been fixed for _stat and _wstat but not for _wstat64. Is that intentional?

[Jonathan Wakely]

ping?

[Jonathan Yong]

I don't think it is intentional, is this still happening?

[Jonathan Wakely]

I see it with 7.0.0 which includes the fixes for this issue (but only _stat and _wstat), did _wstat64 change for 8.0.0?

[Sundaram Ramaswamy]

@nixmann I can still reproduce the issue; stat() errors out on a directory path with trailing slash with -D_FILE_OFFSET_BITS=64.

$ cat test.cpp
#include <cassert>
#include <sys/stat.h>

int main() {
  struct stat s;
  assert(stat("C:/Windows/", &s) == 0);
}

$ g++ -std=c++11 -D_FILE_OFFSET_BITS=64 && a.exe
Assertion failed: stat("C:/Windows/", &s) == 0, file test.cpp, line 6

Should we reopen this or do I open a new bug?

Toolchain Version: MinGW x86_64-12.2.0-release-posix-seh-rt_v10-rev0