Calculate the string length of a u_long at compile-time, instead of using a

hardcoded value.

1 files changed, 17 insertions, 5 deletions

diff --git a/lib/libc/rpc/netname.c b/lib/libc/rpc/netname.c
index 58b7e45..cec14df 100644
--- a/lib/libc/rpc/netname.c
+++ b/lib/libc/rpc/netname.c
@@ -49,10 +49,11 @@ static char sccsid[] = "@(#)netname.c 1.8 91/03/11 Copyr 1986 Sun Micro";
 #include <rpcsvc/ypclnt.h>
 #endif
 #include <ctype.h>
+#include <limits.h>
+#include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
-#include <stdio.h>
+#include <unistd.h>
 
 #ifndef MAXHOSTNAMELEN
 #define MAXHOSTNAMELEN 256
@@ -61,6 +62,19 @@ static char sccsid[] = "@(#)netname.c 1.8 91/03/11 Copyr 1986 Sun Micro";
 #define NGROUPS 16
 #endif
 
+#define TYPE_BIT(type)  (sizeof (type) * CHAR_BIT)
+
+#define TYPE_SIGNED(type) (((type) -1) < 0)
+
+/*
+** 302 / 1000 is log10(2.0) rounded up.
+** Subtract one for the sign bit if the type is signed;
+** add one for integer division truncation;
+** add one more for a minus sign if the type is signed.
+*/
+#define INT_STRLEN_MAXIMUM(type) \
+    ((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + 1 + TYPE_SIGNED(type))
+
 static char *OPSYS = "unix";
 
 /*
@@ -92,15 +106,13 @@ user2netname(netname, uid, domain)
 {
 	char *dfltdom;
 
-#define MAXIPRINT	(20)	/* max length of printed integer */
-
 	if (domain == NULL) {
 		if (_rpc_get_default_domain(&dfltdom) != 0) {
 			return (0);
 		}
 		domain = dfltdom;
 	}
-	if (strlen(domain) + 1 + MAXIPRINT + 1 + strlen(OPSYS) > MAXNETNAMELEN) {
+	if (strlen(domain) + 1 + INT_STRLEN_MAXIMUM(u_long) + 1 + strlen(OPSYS) > MAXNETNAMELEN) {
 		return (0);
 	}
 	(void) sprintf(netname, "%s.%ld@%s", OPSYS, (u_long)uid, domain);