t7800: readlink may not be available

diff --git a/git-compat-util.h b/git-compat-util.h
index af5af226807ed2da5a2630d258aac14953811dd4..061e33c7749dc496e1f5e78aabdfd4c6f1e82736 100644 (file)
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -96,6 +96,14 @@
 #define unsigned_add_overflows(a, b) \
     ((b) > maximum_unsigned_value_of_type(a) - (a))
 
+/*
+ * Returns true if the multiplication of "a" and "b" will
+ * overflow. The types of "a" and "b" must match and must be unsigned.
+ * Note that this macro evaluates "a" twice!
+ */
+#define unsigned_mult_overflows(a, b) \
+    ((a) && (b) > maximum_unsigned_value_of_type(a) / (a))
+
 #ifdef __GNUC__
 #define TYPEOF(x) (__typeof__(x))
 #else
@@ -698,6 +706,32 @@ extern void release_pack_memory(size_t);
 typedef void (*try_to_free_t)(size_t);
 extern try_to_free_t set_try_to_free_routine(try_to_free_t);
 
+static inline size_t st_add(size_t a, size_t b)
+{
+       if (unsigned_add_overflows(a, b))
+               die("size_t overflow: %"PRIuMAX" + %"PRIuMAX,
+                   (uintmax_t)a, (uintmax_t)b);
+       return a + b;
+}
+#define st_add3(a,b,c)   st_add((a),st_add((b),(c)))
+#define st_add4(a,b,c,d) st_add((a),st_add3((b),(c),(d)))
+
+static inline size_t st_mult(size_t a, size_t b)
+{
+       if (unsigned_mult_overflows(a, b))
+               die("size_t overflow: %"PRIuMAX" * %"PRIuMAX,
+                   (uintmax_t)a, (uintmax_t)b);
+       return a * b;
+}
+
+static inline size_t st_sub(size_t a, size_t b)
+{
+       if (a < b)
+               die("size_t underflow: %"PRIuMAX" - %"PRIuMAX,
+                   (uintmax_t)a, (uintmax_t)b);
+       return a - b;
+}
+
 #ifdef HAVE_ALLOCA_H
 # include <alloca.h>
 # define xalloca(size)      (alloca(size))