How to combine the working directory with a user specified file (w or w/o path) to get the up-dir of the file

at the moment I'm writing a kind of lib, which gets from outside the file name 'sFilename'. With it data were written to a file it will be created, data were append to an existing file with data, data were updated in an existing file with data or the data were read from an existing data.

The user of the application with my lib should get as much as possible on information about errors of file handling.

For this purpose I code a method FileExists(...) which uses _stat() to determine if a file exists or not and a method "bool checkPermission(std::string sFilename, CFile::EOpenmode iOpenmode)" which gives back a bool if the specified file (sFilename) with the iOpenmode (Read, Write, Readwrite) have the permission to be read, written or read and written.

This method works with _stat(sFilename.c_str(), &buf) too and gives the desired information of the file back in buf.

Before checking any file I want to check if the directory containing the specified file has the desired permissions and for that I want to use the checkPermission method [works with _stat()] for the directory!

Now the problem: how can I determine easyly the containing directory? If the user just give a filename "test.txt" the file will be created or read in working directory. So its easy to get the up-directory. Its the same like the working directory. (And there its simple to use checkPermission to get detailed information about the directory).

But what about when the user not only give the file name? For exaample "....\test.txt" or "dir1\dir2\test.txt". How to combine the working directory with a specific path to gain the up-directory of the file and then to check the permissions?

Phew, I hope a开发者_如何学JAVAll is clear and it was'nt too long ;-)

Rumo

I'd suggest using the Boost FileSystem library at www.boost.org. In particular, check out the path class, which has methods such as make_absolute and parent_path.

This is Windows example code GetFileNameFromHandle to show you how to get the path from a HANDLE. I think it is what you are looking for.

http://msdn.microsoft.com/en-us/library/aa366789%28v=vs.85%29.aspx

I found out that _stat() and _access() doesn't really works for the permissions of the directories. See this stackoverflow page.

With _stat() you can't use ".\" to get information about the current directory. But _access() at least can check if a directory exists as well ".\" or "..\".

In conclusion I use _access() to check the existence of a directory and _stat() to check the permissions of an existing file. If a file should be created I'll check it by doing.

And by the way ;-) I don't need to combine working directory with the user specified file because I can use the specified file alone in _access() to determine if directory exists.

Rumo