#define _FILE_OFFSET_BITS 64
+
+/* Derived from Linux "Features Test Macro" header
+ * Convenience macros to test the versions of gcc (or
+ * a compatible compiler).
+ * Use them like this:
+ * #if GIT_GNUC_PREREQ (2,8)
+ * ... code requiring gcc 2.8 or later ...
+ * #endif
+*/
+#if defined(__GNUC__) && defined(__GNUC_MINOR__)
+# define GIT_GNUC_PREREQ(maj, min) \
+ ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
+#else
+ #define GIT_GNUC_PREREQ(maj, min) 0
+#endif
+
+
#ifndef FLEX_ARRAY
/*
* See if our compiler is known to support flexible array members.
#endif
#endif
-#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
+
+/*
+ * BUILD_ASSERT_OR_ZERO - assert a build-time dependency, as an expression.
+ * @cond: the compile-time condition which must be true.
+ *
+ * Your compile will fail if the condition isn't true, or can't be evaluated
+ * by the compiler. This can be used in an expression: its value is "0".
+ *
+ * Example:
+ * #define foo_to_char(foo) \
+ * ((char *)(foo) \
+ * + BUILD_ASSERT_OR_ZERO(offsetof(struct foo, string) == 0))
+ */
+#define BUILD_ASSERT_OR_ZERO(cond) \
+ (sizeof(char [1 - 2*!(cond)]) - 1)
+
+#if GIT_GNUC_PREREQ(3, 1)
+ /* &arr[0] degrades to a pointer: a different type from an array */
+# define BARF_UNLESS_AN_ARRAY(arr) \
+ BUILD_ASSERT_OR_ZERO(!__builtin_types_compatible_p(__typeof__(arr), \
+ __typeof__(&(arr)[0])))
+#else
+# define BARF_UNLESS_AN_ARRAY(arr) 0
+#endif
+/*
+ * ARRAY_SIZE - get the number of elements in a visible array
+ * <at> x: the array whose size you want.
+ *
+ * This does not work on pointers, or arrays declared as [], or
+ * function parameters. With correct compiler support, such usage
+ * will cause a build error (see the build_assert_or_zero macro).
+ */
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]) + BARF_UNLESS_AN_ARRAY(x))
+
#define bitsizeof(x) (CHAR_BIT * sizeof(x))
#define maximum_signed_value_of_type(a) \
#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
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))
extern void *xrealloc(void *ptr, size_t size);
extern void *xcalloc(size_t nmemb, size_t size);
extern void *xmmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);
+extern void *xmmap_gently(void *start, size_t length, int prot, int flags, int fd, off_t offset);
extern ssize_t xread(int fd, void *buf, size_t len);
extern ssize_t xwrite(int fd, const void *buf, size_t len);
extern ssize_t xpread(int fd, void *buf, size_t len, off_t offset);