Get rid of setgid kmem for systat, and while being there, fix some bugs

and compiler warnings.
The data for network statistics are still obtained via the kvm interface
if systat was started with the needed privileges, otherwise sysctls are
used. The reason for this is that with really many open sockets, the
sysctl method is probably slower, but it systat -netstat is probably not
really usable in either mode under these conditions.

Approved by:	rwatson

1 files changed, 95 insertions, 1 deletions

diff --git a/usr.bin/systat/fetch.c b/usr.bin/systat/fetch.c
index ff69ac5..94ef619 100644
--- a/usr.bin/systat/fetch.c
+++ b/usr.bin/systat/fetch.c
@@ -29,6 +29,8 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
+ *
+ * $FreeBSD$
  */
 
 #ifndef lint
@@ -36,6 +38,13 @@ static char sccsid[] = "@(#)fetch.c	8.1 (Berkeley) 6/6/93";
 #endif /* not lint */
 
 #include <sys/types.h>
+#include <sys/sysctl.h>
+
+#include <errno.h>
+#include <err.h>
+#include <string.h>
+#include <stdlib.h>
+
 #include "systat.h"
 #include "extern.h"
 
@@ -46,9 +55,94 @@ kvm_ckread(a, b, l)
 {
 	if (kvm_read(kd, (u_long)a, b, l) != l) {
 		if (verbose)
-			error("error reading kmem at %x\n", a);
+			error("error reading kmem at %x", a);
 		return (0);
 	}
 	else
 		return (1);
 }
+
+void getsysctl(name, ptr, len)
+	char *name;
+	void *ptr;
+	size_t len;
+{
+	int err;
+	size_t nlen = len;
+	if ((err = sysctlbyname(name, ptr, &nlen, NULL, 0)) != 0) {
+		error("sysctl(%s...) failed: %s", name, 
+		    strerror(errno));
+	}
+	if (nlen != len) {
+		error("sysctl(%s...) expected %d, got %d", name, 
+		    len, nlen);
+    }
+}
+
+/*
+ * Read sysctl data with variable size. Try some times (with increasing 
+ * buffers), fail if still too small.
+ * This is needed sysctls with possibly raplidly increasing data sizes,
+ * but imposes little overhead in the case of constant sizes.
+ * Returns NULL on error, or a pointer to freshly malloc()'ed memory that holds
+ * the requested data.
+ * If szp is not NULL, the size of the returned data will be written into *szp.
+ */
+
+/* Some defines: Number of tries. */
+#define SD_NTRIES  10
+/* Percent of over-allocation (initial) */
+#define SD_MARGIN  10 
+/* 
+ * Factor for over-allocation in percent (the margin is increased by this on
+ * any failed try).
+ */
+#define SD_FACTOR  50
+/* Maximum supported MIB depth */
+#define SD_MAXMIB  16
+
+char *
+sysctl_dynread(n, szp)
+	char *n;
+	size_t *szp;
+{
+	char   *rv = NULL;
+	int    mib[SD_MAXMIB];
+	size_t mibsz = SD_MAXMIB;
+	size_t mrg = SD_MARGIN;
+	size_t sz;
+	int i;
+
+	/* cache the MIB */
+	if (sysctlnametomib(n, mib, &mibsz) == -1) {
+		if (errno == ENOMEM) {
+			error("XXX: SD_MAXMIB too small, please bump!");
+		}
+		return NULL;
+	}
+	for (i = 0; i < SD_NTRIES; i++) {
+		/* get needed buffer size */
+		if (sysctl(mib, mibsz, NULL, &sz, NULL, 0) == -1)
+			break;
+		sz += sz * mrg / 100;
+		if ((rv = (char *)malloc(sz)) == NULL) {
+			error("Out of memory!");
+			return NULL;
+		}
+		if (sysctl(mib, mibsz, rv, &sz, NULL, 0) == -1) {
+			free(rv);
+			rv = NULL;
+			if (errno == ENOMEM) {
+				mrg += mrg * SD_FACTOR / 100;
+			} else
+				break;
+		} else {
+			/* success */
+			if (szp != NULL)
+				*szp = sz;
+			break;
+		}
+	}
+
+	return rv;
+}