[m-rev.] for review: library changes for `mmc --make' on Windows

[Fergus Henderson]

On 15-Jun-2003, Simon Taylor <stayl at cs.mu.OZ.AU> wrote:
> 
> Library changes required to make the compiler work on Windows
> without Cygwin.  (Compiler changes to come separately).
...
> library/io.m:
...
> 	Add io.file_id for use by dir.foldl2 to detect
> 	symlink loops. This is a bit low level, so it's
> 	not included in the user documentation.
...
> +% Can we retrieve inodes on this system.
> +:- type file_id
> +	---> file_id(device :: int, inode :: int).
> +
> +io__file_id(FileName, Result) -->
> +	( { have_file_ids } ->
> +		io__file_id_2(FileName, Status, Msg, Device, Inode),
> +		( { Status = 1 } ->
> +			{ Result = ok(file_id(Device, Inode)) }
> +		;
> +			{ Result = error(io_error(Msg)) }
> +		)
> +	;
> +		{ Result = error(
> +	make_io_error("io.file_id not implemented on this platform")) }
> +	).
> +
> +:- pred io__file_id_2(string, int, string, int, int,
> +		io__state, io__state).
> +:- mode io__file_id_2(in, out, out, out, out, di, uo) is det.
> +
> +:- pragma foreign_proc("C",
> +	io__file_id_2(FileName::in, Status::out, Msg::out,
> +		Device::out, Inode::out, IO0::di, IO::uo),
> +	[will_not_call_mercury, promise_pure, tabled_for_io, thread_safe],
> +"{
> +#ifdef MR_HAVE_STAT
> +	struct stat s;
> +	if (stat(FileName, &s) == 0) {
> +		Device = s.st_dev;
> +		Inode = s.st_ino;

This code assumes that a dev_t and an ino_t are integral types
that will fit into a Mercury int.  This assumption is false,
and results in a compilation error on mars with lcc, where
dev_t is a struct type (because it is 64 bits and lcc has no
64-bit integral type).

Probably the best fix is to use a foreign_type instead.
The foreign type would have to be defined carefully using appropriate
#ifdefs, because on non-Posix systems dev_t and ino_t might not exist.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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