[mercury-users] Convert posix__fd to io__stream

[Fergus Henderson]

On 08-Feb-2006, Ondrej Bojar <obo at cuni.cz> wrote:
> What is the correct way of redirecting io__write to a file descriptor 
> and read_term to read from a file descriptor?

In library/io.m, there is a C function mercury_open():

	MercuryFilePtr
	mercury_open(const char *filename, const char *openmode)
	{
	    MercuryFilePtr  mf;
	    FILE            *f;

	    f = fopen(filename, openmode);
	    if (f == NULL) {
		return NULL;
	    }
	    mf = MR_GC_NEW(MercuryFile);
	    MR_mercuryfile_init(f, 1, mf);
	    return mf;
	}

You need something very similar, but using fdopen() instead of fopen().
Call this say mercury_open_fd().

	MercuryFilePtr
	mercury_open_fd(int fd, const char *openmode)
	{
	    MercuryFilePtr  mf;
	    FILE            *f;

	    f = fdopen(fd, openmode);
	    if (f == NULL) {
		return NULL;
	    }
	    mf = MR_GC_NEW(MercuryFile);
	    MR_mercuryfile_init(f, 1, mf);
	    return mf;
	}

Then you need to make copies of all the callers (io__open_input,
io__open_output, and io__do_open_text, or the binary versions)
but modified to call mercury_open_fd() instead of mercury_open().

-- 
Fergus Henderson                    |  "I have always known that the pursuit
                                    |  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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