#include <u.h>#include <libc.h>#include <gio.h> RWLock giolock;ReadWriter *gio_filedes[256];uchar gio_filedes_st[256]; intgetnext(void){	int i;	for(i = 0; i < 256; i++)		if(gio_filedes_st[i] == 0)			break;	if(i == 256)		return -1;	return i;} ReadWriter*getrdstruct(int fd){	ReadWriter *rval;	rlock(&giolock);	if(gio_filedes_st[fd] != 1){		runlock(&giolock);		return nil;	}	rval = gio_filedes[fd];	runlock(&giolock);	return rval;} intgopen(ReadWriter* rd, void *aux){	int pfd;	ReadWriter *buf; 	wlock(&giolock);	pfd = getnext();	if(pfd == -1){		wunlock(&giolock);		return -1;	}	buf = malloc(sizeof(ReadWriter));	if(buf == nil)		exits("bad malloc");	memcpy(buf, rd, sizeof(ReadWriter));	buf->aux = aux;	buf->offset = 0;	if(buf->open != nil){		if((buf->open(buf)) != 0){			buf->close(buf);			free(buf);			wunlock(&giolock);			return -1;		}	}	gio_filedes[pfd] = buf;	gio_filedes_st[pfd] = 1;	wunlock(&giolock);	return pfd;} intgclose(int fd){	ReadWriter *bf;	int rval = 0; 	if(gio_filedes_st[fd] == 0)		return -1;	wlock(&giolock);	bf = gio_filedes[fd];	if(bf->close != nil)		rval = bf->close(bf);	free(bf);	gio_filedes_st[fd] = 0;	gio_filedes[fd] = nil;	wunlock(&giolock);	return rval;}