Add stralloc_readyplus_tuned, fix overflow on stralloc_readyplus

2 files changed, 14 insertions, 1 deletions

diff --git a/src/include/skalibs/stralloc.h b/src/include/skalibs/stralloc.h
index b5f89ca..9572251 100644
--- a/src/include/skalibs/stralloc.h
+++ b/src/include/skalibs/stralloc.h
@@ -18,8 +18,9 @@ struct stralloc_s
 extern stralloc const stralloc_zero ;
 
 extern int stralloc_ready_tuned (stralloc *, size_t, size_t, size_t, size_t) ;
+extern int stralloc_readyplus_tuned (stralloc *, size_t, size_t, size_t, size_t) ;
 #define stralloc_ready(sa, n) stralloc_ready_tuned(sa, (n), 8, 1, 8)
-#define stralloc_readyplus(sa, n) stralloc_ready(sa, (sa)->len + (n))
+#define stralloc_readyplus(sa, n) stralloc_readyplus_tuned(sa, (n), 8, 1, 8)
 extern void stralloc_free (stralloc *) ;
 extern int stralloc_shrink (stralloc *) ;
 extern int stralloc_copyb (stralloc *, char const *, size_t) ;
diff --git a/src/libstddjb/stralloc_readyplus_tuned.c b/src/libstddjb/stralloc_readyplus_tuned.c
new file mode 100644
index 0000000..f00813f
--- /dev/null
+++ b/src/libstddjb/stralloc_readyplus_tuned.c
@@ -0,0 +1,12 @@
+/* ISC license. */
+
+#include <errno.h>
+#include <skalibs/stralloc.h>
+
+int stralloc_readyplus_tuned (stralloc *sa, size_t n, size_t base, size_t a, size_t b)
+{
+  size_t newlen = sa->len + n ;
+  return newlen < sa->len ?
+    (errno = ERANGE, 0) :
+    stralloc_ready_tuned(sa, newlen, base, a, b) ;
+}