|Subject:||Re: symlink.c for Windows|
|Date:||Mon, 9 Sep 2013 21:57:34 +0400|
> From: Dmitry Selyutin <address@hidden>
> Date: Mon, 9 Sep 2013 02:27:13 +0400
>Caveat: I'm not a gnulib developer or maintainer, so what's below in
> Sorry for the long absence, there are lot of other things to be done. Still
> I'm trying to participate, though, as I can. Recently I've found that there
> is no symlink function for Windows, though Windows has CreateSymbolicLink
> function. I've tried to implement my own. I don't know C or C++ really
> well, but fix seemed to be trivial enough. MinGW doesn't support symlinks,
> though reports success.
no way reflects the opinions of the project about your contribution.
That said, please allow me a few comments.
First, I think having 'symlink' is just a small part of support for
symbolic links. Functions such as 'lstat' (a real one, not an alias
of 'stat'), 'stat' that reports about the target of the symlink, and
'readlink' are also needed. Unlike with 'symlink', where the Windows
implementation is simple, 'readlink' (and to some degree 'stat') are
not, because there's no easy-to-use API on Windows that allows to find
the target of a symlink.
In addition, some other library functions, like 'access' and 'chmod',
need to resolve symlinks internally, because the Windows APIs used by
these functions report the attributes of the symlink, not of its
IMO, having just 'symlink' without all the rest will provide a very
incomplete support for symbolic links.
A couple of comments to your code:
I don't understand: if the code you wrote is not for MinGW, then for
> +# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
> +# include <windows.h>
> +# if defined __MINGW32__
> +/* MinGW does not support symlinks. */
what Windows development environment is it, and how does that
environment support symlinks, if it doesn't have the 'symlink'
The test of the trailing backslash will not do what you want in a
> + /* Reject trailing slashes on non-directories. */
> + if ((len1 && (file1[len1 - 1] == '/' || file1[len1 - 1] == '\\'))
> + || (len2 && (file2[len2 - 1] == '/' || file2[len2 - 1] == '\\')))
Windows locale that uses DBCS character sets, because there the second
byte of a two-byte character can be a backslash, even though the
character is some CJK character, not a directory separator. The
result will be that the function will reject a perfectly valid file
This doesn't allow creation of symbolic links to non-existent
> + if (stat (file1, &st) == 0 && S_ISDIR (st.st_mode))
> + errno = EPERM;
directories, which is a subtlety Posix programs might not expect
(because Posix platforms don't distinguish between symlinks to
directories and non-directories).
Thanks again for working on this.
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