recent changes

util.c

@@ -4,8 +4,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
-#include <time.h>
-#include <fcntl.h>
+#include <stdint.h>
 
 /* ----------------------------- strbuf ------------------------------ */
 
@@ -25,9 +24,15 @@ void sb_free(strbuf *s) {
 
 int sb_append(strbuf *s, const char *data, size_t n) {
   if (n == 0) return 0;
-  if (s->len + n + 1 > s->cap) {
-    size_t ncap = s->cap ? s->cap * 2 : 64;
-    while (ncap < s->len + n + 1) ncap *= 2;
+  if (!data) return -1;
+  if (n > SIZE_MAX - s->len - 1) return -1;
+  size_t need = s->len + n + 1;
+  if (need > s->cap) {
+    size_t ncap = s->cap ? s->cap : 64;
+    while (ncap < need) {
+      if (ncap > SIZE_MAX / 2) { ncap = need; break; }
+      ncap *= 2;
+    }
     char *nb = (char *)realloc(s->buf, ncap);
     if (!nb) return -1;
     s->buf = nb;
@@ -40,6 +45,7 @@ int sb_append(strbuf *s, const char *data, size_t n) {
 }
 
 int sb_append_str(strbuf *s, const char *str) {
+  if (!str) return 0;
   return sb_append(s, str, strlen(str));
 }