Add macros to determine the length of an integer type in string form.

Adapted from answer #6 in:
https://stackoverflow.com/questions/10536207/ansi-c-maximum-number-of-characters-printing-a-decimal-int

include/sudo_util.h

@@ -136,6 +136,10 @@
 #define sudo_isset(_a, _i)	((_a)[(_i) / NBBY] & (1<<((_i) % NBBY)))
 #define sudo_isclr(_a, _i)	(((_a)[(_i) / NBBY] & (1<<((_i) % NBBY))) == 0)
 
+/* Macros to determine the length of a type in string form. */
+#define STRLEN_MAX_UNSIGNED(t)	(((sizeof(t) * 8 * 1233) >> 12) + 1)
+#define STRLEN_MAX_SIGNED(t)	(STRLEN_MAX_UNSIGNED(t) + ((sizeof(t) == 8) ? 0 : 1))
+
 /* sudo_parseln() flags */
 #define PARSELN_COMM_BOL	0x01	/* comments only at beginning of line */
 #define PARSELN_CONT_IGN	0x02	/* ignore line continuation char */

lib/eventlog/eventlog.c

@@ -84,7 +84,7 @@ new_logline(int event_type, int flags, struct eventlog_args *args,
     const struct eventlog_config *evl_conf = eventlog_getconf();
     const char *iolog_file;
     const char *tty, *tsid = NULL;
-    char exit_str[(((sizeof(int) * 8) + 2) / 3) + 2];
+    char exit_str[STRLEN_MAX_SIGNED(int) + 1];
     char sessid[7], offsetstr[64] = "";
     size_t i;
     debug_decl(new_logline, SUDO_DEBUG_UTIL);

lib/iolog/iolog_timing.c

@@ -88,7 +88,7 @@ char *
 iolog_parse_delay(const char *cp, struct timespec *delay,
     const char *decimal_point)
 {
-    char numbuf[(((sizeof(long long) * 8) + 2) / 3) + 2];
+    char numbuf[STRLEN_MAX_SIGNED(long long) + 1];
     const char *errstr, *ep;
     long long llval;
     size_t len;

lib/util/json.c

@@ -318,7 +318,7 @@ sudo_json_add_value_int(struct json_container *jsonc, const char *name,
     struct json_value *value, bool as_object)
 {
     struct json_container saved_container = *jsonc;
-    char numbuf[(((sizeof(long long) * 8) + 2) / 3) + 2];
+    char numbuf[STRLEN_MAX_SIGNED(long long) + 1];
     debug_decl(sudo_json_add_value, SUDO_DEBUG_UTIL);
 
     /* Add comma if we are continuing an object/array. */

lib/util/lbuf.c

@@ -302,7 +302,7 @@ sudo_lbuf_append_v1(struct sudo_lbuf *lbuf, const char * restrict fmt, ...)
 		num_end++;
 	    if (num_end[0] == '$' && num_end[1] == 's' && num_end > num_start) {
 		/* Convert the numeric part to an integer */
-		char numbuf[(((sizeof(int) * 8) + 2) / 3) + 2];
+		char numbuf[STRLEN_MAX_SIGNED(int) + 1];
 		len = (unsigned int)(num_end - num_start);
 		if (len >= sizeof(numbuf)) {
 		    errno = EINVAL;

lib/util/sudo_debug.c

@@ -112,7 +112,7 @@ struct sudo_debug_instance {
 static struct sudo_debug_instance *sudo_debug_instances[SUDO_DEBUG_INSTANCE_MAX];
 static int sudo_debug_last_instance = -1;
 
-static char sudo_debug_pidstr[(((sizeof(int) * 8) + 2) / 3) + 3];
+static char sudo_debug_pidstr[STRLEN_MAX_SIGNED(int) + 3];
 static size_t sudo_debug_pidlen;
 
 #define round_nfds(_n)	(((_n) + (4 * NBBY) - 1) & ~((4 * NBBY) - 1))

plugins/sudoers/cvtsudoers_ldif.c

@@ -658,7 +658,7 @@ print_userspec_ldif(FILE *fp, const struct sudoers_parse_tree *parse_tree,
 	    print_cmndspec_ldif(fp, parse_tree, cs, &next, &priv->defaults);
 
 	    if (conf->sudo_order != 0) {
-		char numbuf[(((sizeof(conf->sudo_order) * 8) + 2) / 3) + 2];
+		char numbuf[STRLEN_MAX_UNSIGNED(conf->sudo_order) + 1];
 		if (conf->order_max != 0 && conf->sudo_order > conf->order_max) {
 		    sudo_fatalx(U_("too many sudoers entries, maximum %u"),
 			conf->order_padding);

plugins/sudoers/display.c

@@ -228,7 +228,7 @@ display_cmndspec_long(const struct sudoers_parse_tree *parse_tree,
 	if (cs->runcwd != NULL)
 	    sudo_lbuf_append(lbuf, "    Cwd: %s\n", cs->runcwd);
 	if (cs->timeout > 0) {
-	    char numbuf[(((sizeof(int) * 8) + 2) / 3) + 2];
+	    char numbuf[STRLEN_MAX_SIGNED(int) + 1];
 	    (void)snprintf(numbuf, sizeof(numbuf), "%d", cs->timeout);
 	    sudo_lbuf_append(lbuf, "    Timeout: %s\n", numbuf);
 	}

plugins/sudoers/fmtsudoers.c

@@ -255,7 +255,7 @@ sudoers_format_cmndspec(struct sudo_lbuf *lbuf,
     if (cs->runcwd != NULL && FIELD_CHANGED(prev_cs, cs, runcwd))
 	sudo_lbuf_append(lbuf, "CWD=%s ", cs->runcwd);
     if (cs->timeout > 0 && FIELD_CHANGED(prev_cs, cs, timeout)) {
-	char numbuf[(((sizeof(int) * 8) + 2) / 3) + 2];
+	char numbuf[STRLEN_MAX_SIGNED(int) + 1];
 	(void)snprintf(numbuf, sizeof(numbuf), "%d", cs->timeout);
 	sudo_lbuf_append(lbuf, "TIMEOUT=%s ", numbuf);
     }

plugins/sudoers/logging.c

@@ -399,7 +399,7 @@ log_failure(const struct sudoers_context *ctx, unsigned int status,
 static char *
 fmt_authfail_message(unsigned int tries)
 {
-    char numbuf[(((sizeof(int) * 8) + 2) / 3) + 2];
+    char numbuf[STRLEN_MAX_UNSIGNED(unsigned int) + 1];
     char *dst, *dst_end, *ret = NULL;
     const char *src;
     size_t len;

src/exec_preload.c

@@ -76,7 +76,7 @@ fmtstr(sudo_alloc_fn_t alloc_fn, sudo_free_fn_t free_fn, const char * restrict o
 		fmt += 2;
 		continue;
 	    case 'd': {
-		char numbuf[(((sizeof(int) * 8) + 2) / 3) + 2];
+		char numbuf[STRLEN_MAX_SIGNED(int) + 1];
 		len = (size_t)snprintf(numbuf, sizeof(numbuf), "%d",
 		    va_arg(ap, int));
 		if (len >= sizeof(numbuf)) {

src/limits.c

@@ -681,8 +681,8 @@ serialize_rlimits(char **info, size_t info_max)
     for (idx = 0; idx < nitems(saved_limits); idx++) {
 	const struct saved_limit *lim = &saved_limits[idx];
 	const struct rlimit *rl = &lim->oldlimit;
-	char curlim[(((sizeof(long long) * 8) + 2) / 3) + 2];
-	char maxlim[(((sizeof(long long) * 8) + 2) / 3) + 2];
+	char curlim[STRLEN_MAX_UNSIGNED(unsigned long long) + 1];
+	char maxlim[STRLEN_MAX_UNSIGNED(unsigned long long) + 1];
 
 	if (!lim->saved)
 	    continue;