/* * 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){	if(f->state!=CLOSED) fclose(f);	if(mode[1]=='+' || mode[2]=='+'){		if(mode[0]=='w') f->fd=create(name, 2, 0666);		else{			f->fd=open(name, 2);			if(mode[0]=='a'){				if(f->fd<0)					f->fd=create(name, 2, 0666);				if(f->fd>=0)					seek(f->fd, 0L, 2);			}		}	}	else{		switch(mode[0]){		default: return NULL;		case 'r':			f->fd=open(name, 0);			break;		case 'w':			f->fd=create(name, 1, 0666);			break;		case 'a':			f->fd=open(name, 1);			if(f->fd==-1)				f->fd=create(name, 1, 0666);			seek(f->fd, 0L, 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;}