From 17c219fd6f018b21d39de2623c533be2f507008e Mon Sep 17 00:00:00 2001
From: Warner Losh <imp@FreeBSD.org>
Date: Sat, 29 Aug 2020 04:30:12 +0000
Subject: [PATCH] Move to using sbuf for some sysctl in newbus

Convert two different sysctl to using sbuf. First, for all the default
sysctls we implement for each device driver that's attached. This is a
pure sbuf conversion.

Second, convert sysctl_devices to fill its buffer with sbuf rather
than a hand-rolled crappy thing I wrote years ago.

Reviewed by: cem, markj
Differential Revision: https://reviews.freebsd.org/D26206
---
 sys/kern/subr_bus.c | 68 +++++++++++++++++----------------------------
 1 file changed, 26 insertions(+), 42 deletions(-)

diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index 503e73ff59b0..e6abb1779a69 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -260,36 +260,33 @@ enum {
 static int
 device_sysctl_handler(SYSCTL_HANDLER_ARGS)
 {
+	struct sbuf sb;
 	device_t dev = (device_t)arg1;
-	const char *value;
-	char *buf;
 	int error;
 
-	buf = NULL;
+	sbuf_new_for_sysctl(&sb, NULL, 1024, req);
 	switch (arg2) {
 	case DEVICE_SYSCTL_DESC:
-		value = dev->desc ? dev->desc : "";
+		sbuf_cpy(&sb, dev->desc ? dev->desc : "");
 		break;
 	case DEVICE_SYSCTL_DRIVER:
-		value = dev->driver ? dev->driver->name : "";
+		sbuf_cpy(&sb, dev->driver ? dev->driver->name : "");
 		break;
 	case DEVICE_SYSCTL_LOCATION:
-		value = buf = malloc(1024, M_BUS, M_WAITOK | M_ZERO);
-		bus_child_location_str(dev, buf, 1024);
+		bus_child_location_sb(dev, &sb);
 		break;
 	case DEVICE_SYSCTL_PNPINFO:
-		value = buf = malloc(1024, M_BUS, M_WAITOK | M_ZERO);
-		bus_child_pnpinfo_str(dev, buf, 1024);
+		bus_child_pnpinfo_sb(dev, &sb);
 		break;
 	case DEVICE_SYSCTL_PARENT:
-		value = dev->parent ? dev->parent->nameunit : "";
+		sbuf_cpy(&sb, dev->parent ? dev->parent->nameunit : "");
 		break;
 	default:
+		sbuf_delete(&sb);
 		return (EINVAL);
 	}
-	error = SYSCTL_OUT_STR(req, value);
-	if (buf != NULL)
-		free(buf, M_BUS);
+	error = sbuf_finish(&sb);
+	sbuf_delete(&sb);
 	return (error);
 }
 
@@ -5464,13 +5461,13 @@ SYSCTL_PROC(_hw_bus, OID_AUTO, info, CTLTYPE_STRUCT | CTLFLAG_RD |
 static int
 sysctl_devices(SYSCTL_HANDLER_ARGS)
 {
+	struct sbuf		sb;
 	int			*name = (int *)arg1;
 	u_int			namelen = arg2;
 	int			index;
 	device_t		dev;
 	struct u_device		*udev;
 	int			error;
-	char			*walker, *ep;
 
 	if (namelen != 2)
 		return (EINVAL);
@@ -5501,34 +5498,21 @@ sysctl_devices(SYSCTL_HANDLER_ARGS)
 	udev->dv_devflags = dev->devflags;
 	udev->dv_flags = dev->flags;
 	udev->dv_state = dev->state;
-	walker = udev->dv_fields;
-	ep = walker + sizeof(udev->dv_fields);
-#define CP(src)						\
-	if ((src) == NULL)				\
-		*walker++ = '\0';			\
-	else {						\
-		strlcpy(walker, (src), ep - walker);	\
-		walker += strlen(walker) + 1;		\
-	}						\
-	if (walker >= ep)				\
-		break;
-
-	do {
-		CP(dev->nameunit);
-		CP(dev->desc);
-		CP(dev->driver != NULL ? dev->driver->name : NULL);
-		bus_child_pnpinfo_str(dev, walker, ep - walker);
-		walker += strlen(walker) + 1;
-		if (walker >= ep)
-			break;
-		bus_child_location_str(dev, walker, ep - walker);
-		walker += strlen(walker) + 1;
-		if (walker >= ep)
-			break;
-		*walker++ = '\0';
-	} while (0);
-#undef CP
-	error = SYSCTL_OUT(req, udev, sizeof(*udev));
+	sbuf_new(&sb, udev->dv_fields, sizeof(udev->dv_fields), SBUF_FIXEDLEN);
+	sbuf_cat(&sb, dev->nameunit);
+	sbuf_putc(&sb, '\0');
+	sbuf_cat(&sb, dev->desc);
+	sbuf_putc(&sb, '\0');
+	sbuf_cat(&sb, dev->driver != NULL ? dev->driver->name : '\0');
+	sbuf_putc(&sb, '\0');
+	bus_child_pnpinfo_sb(dev, &sb);
+	sbuf_putc(&sb, '\0');
+	bus_child_location_sb(dev, &sb);
+	sbuf_putc(&sb, '\0');
+	error = sbuf_finish(&sb);
+	if (error == 0)
+		error = SYSCTL_OUT(req, udev, sizeof(*udev));
+	sbuf_delete(&sb);
 	free(udev, M_BUS);
 	return (error);
 }