Re: GCC 3.2 replacement for streammarker?

[Steve Greenland <steveg@moregruel.net>]

On 27-Oct-02, 10:20 (CST), "Steve M. Robbins" <steven.robbins@videotron.ca> wrote: 
> [Bear in mind, however, that this code dates from 10 years ago,
> and was developed when stdio was a lot more standard, apparently.
> They took a lot of liberties with poking about in the FILE structure]

10 years ago was 3 years after the ANSI/ISO C standard was released, And
FILE has always[1] been an opaque type. No excuse. As I'm sure you know.

> Sadly, geomview is too general: it accepts input from many different
> sources including over the net from a remote machine, the tty, a
> pipe from another process, a memory buffer, or a bona-fide disk file.
> 
> In a perfect world, it needs to occasionally seek backwards on
> any of those sources.

Then it needs to do its own buffering. 

With no errorchecking, or even a compile test:

#include <stdio.h>
#include <stdlib.h>

static int dobuf = 0;
static char *buf=NULL;
static char *bp = NULL;
static size_t l = 0;

void add_to_buf(int c) {
	l++;
	buf = realloc(buf, l));
	buf[l-1] = (char) c;
}

int my_fgetc(FILE *foo) {
	int c;
	if (bp) {
		if (*bp != '\0') {
			c = (int) *bp++;	
		} else {
			bp == NULL;
		}
	} else {
		c = fgetc(foo);
		if (dobuf) {
			add_to_buf(c);
		}
	}
	return c;
}

my_setmark() {
	dobuf = 1;
}

my_freemark() {
	free(buf);
	bp = NULL;
	l = 0;
}

my_rewind() {	
	bp = buf;
}
	

(No, I wouldn't code it this way for real. But it's sure as hell better
than mucking about in FILE *).

Steve

[1] Or at least since I started C programming in 1987, which is just
like "always" in Internet time. I think even K&R 1 said not to muck
around in FILE.

-- 
Steve Greenland

    The irony is that Bill Gates claims to be making a stable operating
    system and Linus Torvalds claims to be trying to take over the
    world.       -- seen on the net