Fix compiler warnings in iostat

Raise WARNS from 1 to 6 (the default)
Fix warnings:
* Use C99 designated initializers for structs, and initialize all fields
* Mark global variables as static
* Mark unused function arguments
* Be careful about signed/unsigned comparisons

Reviewed by:	eadler
MFC after:	4 weeks
Sponsored by:	Spectra Logic Corp
Differential Revision:	https://reviews.freebsd.org/D5328

2 files changed, 25 insertions, 24 deletions

diff --git a/usr.sbin/iostat/Makefile b/usr.sbin/iostat/Makefile
index dfbf69d..4d74fe1 100644
--- a/usr.sbin/iostat/Makefile
+++ b/usr.sbin/iostat/Makefile
@@ -6,6 +6,4 @@ MAN=	iostat.8
 
 LIBADD=	devstat kvm m
 
-WARNS?=	1
-
 .include <bsd.prog.mk>
diff --git a/usr.sbin/iostat/iostat.c b/usr.sbin/iostat/iostat.c
index 170ce0d..7610a7f 100644
--- a/usr.sbin/iostat/iostat.c
+++ b/usr.sbin/iostat/iostat.c
@@ -117,30 +117,34 @@
 #include <termios.h>
 #include <unistd.h>
 
-struct nlist namelist[] = {
+static struct nlist namelist[] = {
 #define X_TTY_NIN	0
-	{ "_tty_nin" },
+	{ .n_name = "_tty_nin",
+	  .n_type = 0, .n_other = 0, .n_desc = 0, .n_value = 0 },
 #define X_TTY_NOUT	1
-	{ "_tty_nout" },
+	{ .n_name = "_tty_nout",
+	  .n_type = 0, .n_other = 0, .n_desc = 0, .n_value = 0 },
 #define X_BOOTTIME	2
-	{ "_boottime" },
+	{ .n_name = "_boottime",
+	  .n_type = 0, .n_other = 0, .n_desc = 0, .n_value = 0 },
 #define X_END		2
-	{ NULL },
+	{ .n_name = NULL,
+	  .n_type = 0, .n_other = 0, .n_desc = 0, .n_value = 0 },
 };
 
 #define	IOSTAT_DEFAULT_ROWS	20	/* Traditional default `wrows' */
 
-struct statinfo cur, last;
-int num_devices;
-struct device_selection *dev_select;
-int maxshowdevs;
-volatile sig_atomic_t headercount;
-volatile sig_atomic_t wresized;		/* Tty resized, when non-zero. */
-volatile sig_atomic_t alarm_rang;
-volatile sig_atomic_t return_requested;
-unsigned short wrows;			/* Current number of tty rows. */
-int dflag = 0, Iflag = 0, Cflag = 0, Tflag = 0, oflag = 0, Kflag = 0;
-int xflag = 0, zflag = 0;
+static struct statinfo cur, last;
+static int num_devices;
+static struct device_selection *dev_select;
+static int maxshowdevs;
+static volatile sig_atomic_t headercount;
+static volatile sig_atomic_t wresized;	/* Tty resized, when non-zero. */
+static volatile sig_atomic_t alarm_rang;
+static volatile sig_atomic_t return_requested;
+static unsigned short wrows;		/* Current number of tty rows. */
+static int dflag = 0, Iflag = 0, Cflag = 0, Tflag = 0, oflag = 0, Kflag = 0;
+static int xflag = 0, zflag = 0;
 
 /* local function declarations */
 static void usage(void);
@@ -650,7 +654,7 @@ main(int argc, char **argv)
  * Force a header to be prepended to the next output.
  */
 void
-needhdr(int signo)
+needhdr(int signo __unused)
 {
 
 	headercount = 1;
@@ -662,7 +666,7 @@ needhdr(int signo)
  * prepended to the next output.
  */
 void
-needresize(int signo)
+needresize(int signo __unused)
 {
 
 	wresized = 1;
@@ -673,7 +677,7 @@ needresize(int signo)
  * Record the alarm so the main loop can break its sleep
  */
 void
-alarm_clock(int signo)
+alarm_clock(int signo __unused)
 {
 	alarm_rang = 1;
 }
@@ -682,7 +686,7 @@ alarm_clock(int signo)
  * Request that the main loop exit soon
  */
 void
-needreturn(int signo)
+needreturn(int signo __unused)
 {
 	return_requested = 1;
 }
@@ -998,8 +1002,7 @@ readvar(kvm_t *kd, const char *name, int nlid, void *ptr, size_t len)
 			warnx("kvm_read(%s): %s", namelist[nlid].n_name,
 			    kvm_geterr(kd));
 			return (1);
-		}
-		if (nbytes != len) {
+		} else if ((size_t)nbytes != len) {
 			warnx("kvm_read(%s): expected %zu bytes, got %zd bytes",
 			      namelist[nlid].n_name, len, nbytes);
 			return (1);