Can't create directory and file like "D:/Logs/log.txt"

[fanghtao]

platform: windows
file: os-inl.h
line: 538
if (!subdir.empty() && !path_exists(subdir) && !mkdir_(subdir)) {
return false; // return error if failed creating dir
}
this code will return false when create subdir = "D:/"
std::shared_ptrspdlog::logger logger = spdlog::daily_logger_mt("log", "/Logs/log.txt") ---- create directory succeed
std::shared_ptrspdlog::logger logger = spdlog::daily_logger_mt("log", "D:/Logs/log.txt") ---- can't create directory

[tt4g]

It may have something to do with the fact that the Windows path separator is \ and some Windows APIs do not support /.

-"D:/Logs/log.txt"
+"D:\\Logs\\log.txt"

[fanghtao]

Thank you for your response but it's not a problem of windows path separator.

std::shared_ptrspdlog::logger logger = spdlog::daily_logger_mt("Log", "D:\\Logs\\log.txt");
file: os-inl.h
line: 538
if (!subdir.empty() && !path_exists(subdir) && !mkdir_(subdir)) {
return false; // return error if failed creating dir
}
this code will return false when create subdir = "D:" (not "D:/" or "D:\\")

[gabime]

Could be a permissions problem.

[fanghtao]

I'm sure it's not a permissions problem becasuse spdlog::daily_logger_mt("Log", "\\Logs\\log.txt") is ok and in fact they are the same path on my computer.

file: os-inl.h
line: 536

• auto subdir = path.substr(0, token_pos); this code will create "D:" but it's not a directory
  +auto subdir = path.substr(0, token_pos + 1);

[tt4g]

auto subdir = path.substr(0, token_pos); this code will create "D:" but it's not a directory
+auto subdir = path.substr(0, token_pos + 1);

This fix causes a problem on UNIX-like systems.

The problem should be considered that _stat() called in path_exists() fails when only the drive letter character D: is passed.

spdlog/include/spdlog/details/os-inl.h

Lines 538 to 540 in 238c9ff

	if (!subdir.empty() && !path_exists(subdir) && !mkdir_(subdir)) {
	return false; // return error if failed creating dir
	}

spdlog/include/spdlog/details/os-inl.h

Lines 178 to 190 in 238c9ff

	SPDLOG_INLINE bool path_exists(const filename_t &filename) SPDLOG_NOEXCEPT {
	#ifdef _WIN32
	struct _stat buffer;
	#ifdef SPDLOG_WCHAR_FILENAMES
	return (::_wstat(filename.c_str(), &buffer) == 0);
	#else
	return (::_stat(filename.c_str(), &buffer) == 0);
	#endif
	#else // common linux/unix all have the stat system call
	struct stat buffer;
	return (::stat(filename.c_str(), &buffer) == 0);
	#endif
	}

Can you try to complete \ when filename is a drive letter character and see if it works?
If it works, could you send the PR.

[fanghtao]

[tt4g]

Since the Windows drive letter specification is one of A-Z, can't we fix this with a hack that if _stat() fails and the next condition is met, then _stat() again with the \ character added?

• 2 characters
• First character is a-zA-Z.
• Last character is :

[fanghtao]

I don't know what effect this will have on UNIX-like systems, but _stat("D:/") and _mkdir("D:/") or _stat("D:/XX/") and _mkdir("D:/XX/") works on Windows.
maybe we can do like this:

#ifdef _WIN32
auto subdir = path.substr(0, token_pos + 1);
#else
auto subdir = path.substr(0, token_pos);
#endif // _WIN32

[tt4g]

The behavior when a path is a symbolic link differs depending on whether or not a trailing slash is used.
This may affect Windows as well, since recent Windows OS supports symbolic links.

• directory - Trailing slashes on symbolic links to directories - Unix & Linux Stack Exchange
• Under linux / unix, how to discover if a directory is a link using c++? - Stack Overflow

[tt4g]

You must also consider the case where a log file is to be created directly under the drive (e.g. D:\log.txt).
In that case, only "D:" is passed to create_dir(), so your fix cannot cover this pattern.

spdlog/include/spdlog/details/os-inl.h

Lines 547 to 555 in 238c9ff

	// Return directory name from given path or empty string
	// "abc/file" => "abc"
	// "abc/" => "abc"
	// "abc" => ""
	// "abc///" => "abc//"
	SPDLOG_INLINE filename_t dir_name(const filename_t &path) {
	auto pos = path.find_last_of(folder_seps_filename);
	return pos != filename_t::npos ? path.substr(0, pos) : filename_t{};
	}

[fanghtao]

Thank you for your patient reply and answer. But it's a real problem when I use spdlog to create log files and I need to manually create the parent directory.

[tt4g]

Please try adding to the workaround I came up with: #3079 (comment)

[gabime]

@fanghtao So what was the fix ??

[fanghtao]

@gabime Thank you for your fix