apm.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

estrdupn(char *s, int n)
{
	int l;
	char *t;

	l = strlen(s);
	if(l > n)
		l = n;
	t = emalloc(l+1);
	memmove(t, s, l);
	t[l] = '\0';
	setmalloctag(t, getcallerpc(&s));
	return t;
}

enum {
	Qroot = 0,
	Qevent,
	Qbattery,
	Qctl,
};

static void rootread(Req*);
static void eventread(Req*);
static void ctlread(Req*);
static void ctlwrite(Req*);
static void batteryread(Req*);

typedef struct Dfile Dfile;
struct Dfile {
	Qid qid;
	char *name;
	ulong mode;
	void (*read)(Req*);
	void (*write)(Req*);
};

Dfile dfile[] = {
	{ {Qroot,0,QTDIR},		"/",		DMDIR|0555,	rootread,		nil, },
	{ {Qevent},		"event",	0444,		eventread,	nil, },
	{ {Qbattery},	"battery",	0444,		batteryread,	nil, },
	{ {Qctl},		"ctl",		0666,		ctlread,		ctlwrite, },
};

static int
fillstat(uvlong path, Dir *d, int doalloc)
{
	int i;

	for(i=0; i<nelem(dfile); i++)
		if(path==dfile[i].qid.path)
			break;
	if(i==nelem(dfile))
		return -1;

	memset(d, 0, sizeof *d);
	d->uid = doalloc ? estrdup("apm") : "apm";
	d->gid = doalloc ? estrdup("apm") : "apm";
	d->length = 0;
	d->name = doalloc ? estrdup(dfile[i].name) : dfile[i].name;
	d->mode = dfile[i].mode;
	d->atime = d->mtime = time(0);
	d->qid = dfile[i].qid;
	return 0;
}

static char*
fswalk1(Fid *fid, char *name, Qid *qid)
{
	int i;

	if(strcmp(name, "..")==0){
		*qid = dfile[0].qid;
		fid->qid = *qid;
		return nil;
	}

	for(i=1; i<nelem(dfile); i++){	/* i=1: 0 is root dir */
		if(strcmp(dfile[i].name, name)==0){
			*qid = dfile[i].qid;
			fid->qid = *qid;
			return nil;
		}
	}
	return "file does not exist";
}

static void
fsopen(Req *r)
{
	switch((ulong)r->fid->qid.path){
	case Qroot:
		r->fid->aux = (void*)0;
		respond(r, nil);
		return;

	case Qevent:
	case Qbattery:
		if(r->ifcall.mode == OREAD){
			respond(r, nil);
			return;
		}
		break;

	case Qctl:
		if((r->ifcall.mode&~(OTRUNC|OREAD|OWRITE|ORDWR)) == 0){
			respond(r, nil);
			return;
		}
		break;
	}
	respond(r, "permission denied");
	return;
}

static void
fsstat(Req *r)
{
	fillstat(r->fid->qid.path, &r->d, 1);
	respond(r, nil);
}

static void
fsread(Req *r)
{
	dfile[r->fid->qid.path].read(r);
}

static void
fswrite(Req *r)
{
	dfile[r->fid->qid.path].write(r);
}

static void
rootread(Req *r)
{
	int n;
	uvlong offset;
	char *p, *ep;
	Dir d;

	if(r->ifcall.offset == 0)
		offset = 0;
	else
		offset = (uvlong)r->fid->aux;

	p = r->ofcall.data;
	ep = r->ofcall.data+r->ifcall.count;

	if(offset == 0)		/* skip root */
		offset = 1;
	for(; p+2 < ep; p+=n){
		if(fillstat(offset, &d, 0) < 0)
			break;
		n = convD2M(&d, (uchar*)p, ep-p);
		if(n <= BIT16SZ)
			break;
		offset++;
	}
	r->fid->aux = (void*)offset;
	r->ofcall.count = p - r->ofcall.data;
	respond(r, nil);
}

static void
batteryread(Req *r)
{
	char buf[Mbattery*80], *ep, *p;
	int i;

	apmgetpowerstatus(&apm, DevAll);

	p = buf;
	ep = buf+sizeof buf;
	*p = '\0';	/* could be no batteries */
	for(i=0; i<apm.nbattery && i<Mbattery; i++)
		p += snprint(p, ep-p, "%s %d %d\n",
			batterystatus(apm.battery[i].status),
			apm.battery[i].percent, apm.battery[i].time);
	
	readstr(r, buf);
	respond(r, nil);
}

int
iscmd(char *p, char *cmd)
{
	int l;

	l = strlen(cmd);
	return strncmp(p, cmd, l)==0 && p[l]=='\0' || p[l]==' ' || p[l]=='\t';
}

char*
skip(char *p, char *cmd)
{
	p += strlen(cmd);
	while(*p==' ' || *p=='\t')
		p++;
	return p;
}

static void
respondx(Req *r, int c)
{
	char err[ERRMAX];

	if(c == 0)
		respond(r, nil);
	else{
		rerrstr(err, sizeof err);
		respond(r, err);
	}
}

/*
 * we don't do suspend because it messes up the
 * cycle counter as well as the pcmcia ethernet cards.
 */
static void
ctlwrite(Req *r)
{
	char buf[80], *p, *q;
	int dev;
	long count;

	count = r->ifcall.count;
	if(count > sizeof(buf)-1)
		count = sizeof(buf)-1;
	memmove(buf, r->ifcall.data, count);
	buf[count] = '\0';

	if(count && buf[count-1] == '\n'){
		--count;
		buf[count] = '\0';
	}

	q = buf;
	p = strchr(q, ' ');
	if(p==nil)
		p = q+strlen(q);
	else
		*p++ = '\0';

	if(strcmp(q, "")==0 || strcmp(q, "system")==0)
		dev = DevAll;
	else if(strcmp(q, "display")==0)
		dev = DevDisplay;
	else if(strcmp(q, "storage")==0)
		dev = DevStorage;
	else if(strcmp(q, "lpt")==0)
		dev = DevLpt;
	else if(strcmp(q, "eia")==0)
		dev = DevEia;
	else if(strcmp(q, "network")==0)
		dev = DevNetwork;
	else if(strcmp(q, "pcmcia")==0)
		dev = DevPCMCIA;
	else{
		respond(r, "unknown device");
		return;
	}

	if(strcmp(p, "enable")==0)
		respondx(r, apmsetpowermgmt(&apm, dev, EnablePowerMgmt));
	else if(strcmp(p, "disable")==0)
		respondx(r, apmsetpowermgmt(&apm, dev, DisablePowerMgmt));
	else if(strcmp(p, "standby")==0)
		respondx(r, apmsetpowerstate(&apm, dev, PowerStandby));
	else if(strcmp(p, "on")==0)
		respondx(r, apmsetpowerstate(&apm, dev, PowerEnabled));
/*
	else if(strcmp(p, "off")==0)
		respondx(r, apmsetpowerstate(&apm, dev, PowerOff));
*/
	else if(strcmp(p, "suspend")==0)
		respondx(r, apmsetpowerstate(&apm, dev, PowerSuspend));
	else
		respond(r, "unknown verb");
}

static int
statusline(char *buf, int nbuf, char *name, int dev)
{
	int s;
	char *state;

	state = "unknown";
	if((s = apmgetpowerstate(&apm, dev)) >= 0)
		state = powerstate(s);
	return snprint(buf, nbuf, "%s %s\n", name, state);
}

static void
ctlread(Req *r)
{
	char buf[256+7*50], *ep, *p;

	p = buf;
	ep = buf+sizeof buf;

	p += snprint(p, ep-p, "ac %s\n", acstatus(apm.acstatus));
	p += snprint(p, ep-p, "capabilities");
	if(apm.capabilities & CapStandby) 
		p += snprint(p, ep-p, " standby");
	if(apm.capabilities & CapSuspend) 
		p += snprint(p, ep-p, " suspend");
	if(apm.capabilities & CapSlowCpu)
		p += snprint(p, ep-p, " slowcpu");
	p += snprint(p, ep-p, "\n");

	p += statusline(p, ep-p, "system", DevAll);
	p += statusline(p, ep-p, "display", DevDisplay);
	p += statusline(p, ep-p, "storage", DevStorage);
	p += statusline(p, ep-p, "lpt", DevLpt);
	p += statusline(p, ep-p, "eia", DevEia|All);
	p += statusline(p, ep-p, "network", DevNetwork|All);
	p += statusline(p, ep-p, "pcmcia", DevPCMCIA|All);
	USED(p);

	readstr(r, buf);
	respond(r, nil);
}

enum {
	STACK = 16384,
};

Channel *creq;
Channel *cflush;
Channel *cevent;
Req *rlist, **tailp;
int rp, wp;
int nopoll;
char eventq[32][80];

static void
flushthread(void*)
{
	Req *r, *or, **rq;

	threadsetname("flushthread");
	while(r = recvp(cflush)){
		or = r->oldreq;
		for(rq=&rlist; *rq; rq=&(*rq)->aux){
			if(*rq == or){
				*rq = or->aux;
				if(tailp==&or->aux)
					tailp = rq;
				respond(or, "interrupted");
				break;
			}
		}
		respond(r, nil);
	}
}

static void
answerany(void)
{
	char *buf;
	int l, m;
	Req *r;

	if(rlist==nil || rp==wp)
		return;

	while(rlist && rp != wp){
		r = rlist;
		rlist = r->aux;
		if(rlist==nil)
			tailp = &rlist;

		l = 0;
		buf = r->ofcall.data;
		m = r->ifcall.count;
		while(rp != wp){
			if(l+strlen(eventq[rp]) <= m){
				strcpy(buf+l, eventq[rp]);
				l += strlen(buf+l);
			}else if(l==0){
				strncpy(buf, eventq[rp], m-1);
				buf[m-1] = '\0';
				l += m;
			}else
				break;
			rp++;
			if(rp == nelem(eventq))
				rp = 0;
		}
		r->ofcall.count = l;
		respond(r, nil);
	}
}

static void
eventwatch(void*)
{
	int e, s;

	threadsetname("eventwatch");
	for(;;){
		s = 0;
		while((e = apmgetevent(&apm)) >= 0){
			sendul(cevent, e);
			s = 1;
		}
		if(s)
			sendul(cevent, -1);
		if(sleep(750) < 0)
			break;
	}
}

static void
eventthread(void*)
{
	int e;

	threadsetname("eventthread");
	for(;;){
		while((e = recvul(cevent)) >= 0){
			snprint(eventq[wp], sizeof(eventq[wp])-1, "%s", apmevent(e));
			strcat(eventq[wp], "\n");
			wp++;
			if(wp==nelem(eventq))
				wp = 0;
			if(wp+1==rp || (wp+1==nelem(eventq) && rp==0))
				break;
		}
		answerany();
	}
}

static void
eventproc(void*)
{
	Req *r;

	threadsetname("eventproc");

	creq = chancreate(sizeof(Req*), 0);
	cevent = chancreate(sizeof(ulong), 0);
	cflush = chancreate(sizeof(Req*), 0);

	tailp = &rlist;
	if(!nopoll)
		proccreate(eventwatch, nil, STACK);
	threadcreate(eventthread, nil, STACK);
	threadcreate(flushthread, nil, STACK);

	while(r = recvp(creq)){
		*tailp = r;
		r->aux = nil;
		tailp = &r->aux;
		answerany();
	}
}

static void
fsflush(Req *r)
{
	sendp(cflush, r);
}

static void
eventread(Req *r)
{
	sendp(creq, r);
}

static void
fsattach(Req *r)
{
	char *spec;
	static int first = 1;

	spec = r->ifcall.aname;

	if(first){
		first = 0;
		proccreate(eventproc, nil, STACK);
	}

	if(spec && spec[0]){
		respond(r, "invalid attach specifier");
		return;
	}
	r->fid->qid = dfile[0].qid;
	r->ofcall.qid = dfile[0].qid;
	respond(r, nil);
}

Srv fs = {
.attach=	fsattach,
.walk1=	fswalk1,
.open=	fsopen,
.read=	fsread,
.write=	fswrite,
.stat=	fsstat,
.flush=	fsflush,
};

void
usage(void)
{
	fprint(2, "usage: aux/apm [-ADPi] [-d /dev/apm] [-m /mnt/apm] [-s service]\n");
	exits("usage");
}

void
threadmain(int argc, char **argv)
{
	char *dev, *mtpt, *srv;

	dev = nil;
	mtpt = "/mnt/apm";
	srv = nil;
	ARGBEGIN{
	case 'A':
		apmdebug = 1;
		break;
	case 'D':
		chatty9p = 1;
		break;
	case 'P':
		nopoll = 1;
		break;
	case 'd':
		dev = EARGF(usage());
		break;
	case 'i':
		fs.nopipe++;
		fs.infd = 0;
		fs.outfd = 1;
		mtpt = nil;
		break;
	case 'm':
		mtpt = EARGF(usage());
		break;
	case 's':
		srv = EARGF(usage());
		break;
	}ARGEND

	if(dev == nil){
		if((apm.fd = open("/dev/apm", ORDWR)) < 0
		&& (apm.fd = open("#P/apm", ORDWR)) < 0){
			fprint(2, "open %s: %r\n", dev);
			threadexitsall("open");
		}
	} else if((apm.fd = open(dev, ORDWR)) < 0){
		fprint(2, "open %s: %r\n", dev);
		threadexitsall("open");
	}

	if(apmversion(&apm) < 0){
		fprint(2, "cannot get apm version: %r\n");
		threadexitsall("apmversion");
	}

	if(apm.verhi < 1 || (apm.verhi==1 && apm.verlo < 2)){
		fprint(2, "apm version %d.%d not supported\n", apm.verhi, apm.verlo);
		threadexitsall("apmversion");
	}

	if(apmgetcapabilities(&apm) < 0)
		fprint(2, "warning: cannot read apm capabilities: %r\n");

	apminstallationcheck(&apm);
	apmcpuidle(&apm);

	rfork(RFNOTEG);
	threadpostmountsrv(&fs, srv, mtpt, MREPL);
}