Use appropriate includes
Fix char vs pointer type mismatch
Use more parenthesis to silence warnings about correct code

Index: quotatool.c
--- quotatool.c.orig
+++ quotatool.c
@@ -49,7 +49,8 @@ static const char rcsid[] =
 #include <stdlib.h>
 #include <string.h>
 #include <sys/param.h>
-#include <sys/errno.h>
+#include <errno.h>
+#include <unistd.h>
 #include <ufs/ufs/quota.h>
 #include <pwd.h>
 #include <grp.h>
@@ -235,10 +236,10 @@ do_test()
 	printf("    f_ig %d\n", f_ig);
 	printf("    v_bh %lu\n", v_bh);
 	printf("    v_bs %lu\n", v_bs);
-	printf("    v_bg %lu\n", v_bg);
+	printf("    v_bg %lld\n", (long long)v_bg);
 	printf("    v_ih %lu\n", v_ih);
 	printf("    v_is %lu\n", v_is);
-	printf("    v_ig %lu\n", v_ig);
+	printf("    v_ig %lld\n", (long long)v_ig);
 
 	return;
 }
@@ -267,11 +268,11 @@ convert_block(p_block)
 	char	*p_block;
 {
 	u_long	value = 0;
-	char	unit = NULL;
+	char	unit = '\0';
 	u_long	r_blocks;
 
 	if (sscanf(p_block, "%lu%c", &value, &unit) != 2) {
-		if (unit == NULL)
+		if (unit == '\0')
 			unit = 'k';
 	}
 
@@ -299,11 +300,11 @@ convert_time(p_time)
 	char	*p_time;
 {
 	u_long	value = 0;
-	char	unit = NULL;
+	char	unit = '\0';
 	time_t	r_time;
 
 	if (sscanf(p_time, "%ld%c", &value, &unit) != 2) {
-		if (unit == NULL)
+		if (unit == '\0')
 			unit = 'd';
 	}
 
@@ -350,7 +351,7 @@ valid_fs(fsname)
 {
 	struct fstab *fs;
 	
-	if (fs = getfsfile(fsname)) {
+	if ((fs = getfsfile(fsname))) {
 		if (!strstr(fs->fs_mntops, m_qtype[f_group])) {
 			fprintf(stderr, "%s : %s does not have quotas enabled.\n", m_proc[f_mode], fsname);
 			exit(1);