git-compat-util: introduce more size_t helpers
We will use them in the next commit. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin committed
Nov 2, 2021 at 15:46 UTC
e2ffeae3f6795939e1af9f8e2b5fa151343eec66
1 file changed
+25
git-compat-util.h
+25
@@ -113,6 +113,14 @@
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#define unsigned_mult_overflows(a, b) \
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((a) && (b) > maximum_unsigned_value_of_type(a) / (a))
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+/*
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+ * Returns true if the left shift of "a" by "shift" bits will
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+ * overflow. The type of "a" must be unsigned.
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+ */
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+#define unsigned_left_shift_overflows(a, shift) \
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+ ((shift) < bitsizeof(a) && \
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+ (a) > maximum_unsigned_value_of_type(a) >> (shift))
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+
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#ifdef __GNUC__
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#define TYPEOF(x) (__typeof__(x))
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#else
@@ -859,6 +867,23 @@ static inline size_t st_sub(size_t a, size_t b)
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return a - b;
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}
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+static inline size_t st_left_shift(size_t a, unsigned shift)
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+{
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+ if (unsigned_left_shift_overflows(a, shift))
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+ die("size_t overflow: %"PRIuMAX" << %u",
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+ (uintmax_t)a, shift);
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+ return a << shift;
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+}
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+
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+static inline unsigned long cast_size_t_to_ulong(size_t a)
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+{
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+ if (a != (unsigned long)a)
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+ die("object too large to read on this platform: %"
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+ PRIuMAX" is cut off to %lu",
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+ (uintmax_t)a, (unsigned long)a);
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+ return (unsigned long)a;
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+}
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+
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#ifdef HAVE_ALLOCA_H
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# include <alloca.h>
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# define xalloca(size) (alloca(size))