give up on the drive letter business.  let sdctl tell us about controllers,
and assume that each controler provides a contiguous set of drives.

Reference: /n/atom/patch/applied2013/scuzzdevs
Date: Sat Oct 19 05:00:07 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/scuzz/scuzz.c	Sat Oct 19 04:58:38 2013
+++ /sys/src/cmd/scuzz/scuzz.c	Sat Oct 19 04:58:41 2013
@@ -2340,45 +2340,53 @@
 	return 0;
 }
 
-static long
-cmdprobe(ScsiReq *rp, int argc, char *argv[])
+static void
+probectlr(char *ctlr)
 {
 	char buf[32];
+	int i;
 	ScsiReq scsireq;
-	char *ctlr, *unit;
+
+	memset(&scsireq, 0, sizeof scsireq);
+	for(i = 0; i < 0x15; i++){
+		snprint(buf, sizeof buf, "/dev/%s%x", ctlr, i);
+		if(access(buf, OREAD) == -1)
+			return;
+		if(SRopenraw(&scsireq, buf) == -1)
+			continue;
+		SRreqsense(&scsireq);
+		switch(scsireq.status){
+		case STok:
+		case Status_SD:
+			Bprint(&bout, "%s: ", buf);
+			cmdinquiry(&scsireq, 0, 0);
+			break;
+		}
+		SRclose(&scsireq);
+	}
+}
+
+static long
+cmdprobe(ScsiReq *rp, int argc, char *argv[])
+{
+	char buf[1025], *s, *p, *f[3];
+	int fd, l;
 
 	USED(argc, argv);
 	rp->status = STok;
-	scsireq.flags = 0;
-
-	for(ctlr="CDEFGHIJ0123456789abcdef"; *ctlr; ctlr++) {
-		/*
-		 * I can guess how many units you have.
-		 * SATA controllers can have more than two drives each.
-		 */
-		if(*ctlr >= 'C' && *ctlr <= 'D')
-			unit = "01";
-		else if((*ctlr >= '0' && *ctlr <= '9')
-		     || (*ctlr >= 'a' && *ctlr <= 'f'))
-			unit = "0123456789abcdef";	/* allow wide scsi */
-		else
-			unit = "01234567";
 
-		for(; *unit; unit++){
-			sprint(buf, "/dev/sd%c%c", *ctlr, *unit);
-			if(SRopenraw(&scsireq, buf) == -1)
+	fd = open("#S/sdctl", OREAD);
+	if((l = read(fd, buf, 1024)) > 0){
+		s = buf;
+		s[l] = 0;
+		for(; p = strchr(s, '\n'); s = p + 1){
+			*p = 0;
+			if(tokenize(s, f, nelem(f)) < 1)
 				continue;
-			SRreqsense(&scsireq);
-			switch(scsireq.status){
-			case STok:
-			case Status_SD:
-				Bprint(&bout, "%s: ", buf);
-				cmdinquiry(&scsireq, 0, 0);
-				break;
-			}
-			SRclose(&scsireq);
+			probectlr(f[0]);
 		}
 	}
+	close(fd);
 	return 0;
 }