Re: [PATCH/RFC 1/4] cleanup_path: force forward slashes on Windows

[Junio C Hamano <gitster@pobox.com>]

"Delilah Ashley Wu via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> All existing callers of
> `cleanup_path()` pass `char *` anyways, so this change is compatible.

Not just compatible ;-).  If there is a caller that wants
cleanup_path() not to munge what it passes, this change will
introduce a bug for them.  Have you made sure that none of these
callers mind that backslashes are converted into forward slashes?

> The next patch, config: test home and xdg files in `list --global`, will
> assert that the XDG config path uses forward slashes.

The path to the leaf-level blobs is always slash separated in the
index, a tree object sorts an entry that points at a subtree as if
its path component has terminating slash, etc., and only when these
paths are externalized, they are converted to filesystem dependent
hierarchy separator (by system call like creat(2) even on platforms
like Windows whose filesystem uses backslashes as the pathname
separator).  Canonicalizing end-user supplied path early at a
central place does make sense.

> -static const char *cleanup_path(const char *path)
> +static char *cleanup_path(char *path)
>  {
>  	/* Clean it up */
> -	if (skip_prefix(path, "./", &path)) {
> +	if (skip_prefix(path, "./", (const char **)&path))
>  		while (*path == '/')
>  			path++;
> -	}

Hmph, the need for cast is a bit annoying, but more importantly, why
don't we have to worry about leading ".\\\\" instead of ".////"?
Shouldn't we be stripping backslashes the same way on Windows?

> +#ifdef GIT_WINDOWS_NATIVE
> +	convert_slashes(path);
> +#endif

In other words, why do it here, not _before_ the loop that says "If
the path begins with dot (i.e. the thing is relative to the current
directory) followed by a directory separator, remove it together
with any extra directory separators that come immediately after it"?

>  	return path;
>  }