fmtstr.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 * The authors of this software are Rob Pike and Ken Thompson.
 *              Copyright (c) 2002 by Lucent Technologies.
 * Permission to use, copy, modify, and distribute this software for any
 * purpose without fee is hereby granted, provided that this entire notice
 * is included in all copies of any software which is or includes a copy
 * or modification of this software and in all copies of the supporting
 * documentation for such software.
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
 */
#include <stdarg.h>
#include <string.h>
#include <stdlib.h>
#include "utf.h"
#include "fmt.h"
#include "fmtdef.h"

static int
fmtStrFlush(Fmt *f)
{
	char *s;
	int n;

	n = (int)f->farg;
	n += 256;
	f->farg = (void*)n;
	s = (char*)f->start;
	f->start = realloc(s, n);
	if(f->start == nil){
		f->start = s;
		return 0;
	}
	f->to = (char*)f->start + ((char*)f->to - s);
	f->stop = (char*)f->start + n - 1;
	return 1;
}

int
fmtstrinit(Fmt *f)
{
	int n;

	f->runes = 0;
	n = 32;
	f->start = malloc(n);
	if(f->start == nil)
		return -1;
	f->to = f->start;
	f->stop = (char*)f->start + n - 1;
	f->flush = fmtStrFlush;
	f->farg = (void*)n;
	f->nfmt = 0;
	return 0;
}

char*
fmtstrflush(Fmt *f)
{
	*(char*)f->to = '\0';
	f->to = f->start;
	return (char*)f->start;
}