/* * pANS stdio -- freopen */#include "iolib.h"/* * Open the named file with the given mode, using the given FILE * Legal modes are given below, `additional characters may follow these sequences': * r rb		open to read * w wb		open to write, truncating * a ab		open to write positioned at eof, creating if non-existant * r+ r+b rb+	open to read and write, creating if non-existant * w+ w+b wb+	open to read and write, truncating * a+ a+b ab+	open to read and write, positioned at eof, creating if non-existant. */FILE *freopen(const char *name, const char *mode, FILE *f){	int m; 	if(f->state!=CLOSED){		fclose(f);/* premature; fall through and see what happens *//*		f->state=OPEN; */	} 	m = *mode++;	if(m == 0)		return NULL;	if(*mode == 'b')		mode++;	switch(m){	default:		return NULL;	case 'r':		f->fd=open(name, (*mode == '+'? ORDWR: OREAD));		break;	case 'w':		f->fd=create(name, (*mode == '+'? ORDWR: OWRITE), 0666);		break;	case 'a':		m = (*mode == '+'? ORDWR: OWRITE);		f->fd=open(name, m);		if(f->fd<0)			f->fd=create(name, m, 0666);		seek(f->fd, 0LL, 2);		break;	} 	if(f->fd==-1)		return NULL;	f->flags=(mode[0]=='a')? APPEND : 0;	f->state=OPEN;	f->buf=0;	f->rp=0;	f->wp=0;	f->lp=0;	return f;}