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do not depend on signed integer overflow
Signed integer overflow is not defined in C, so do not depend on it. This fixes a problem with GCC 4.4.0 and -O3 where the optimizer would consider "consumed_bytes > consumed_bytes + bytes" as a constant expression, and never execute the die()-call. Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com> Acked-by: Nicolas Pitre <nico@fluxnic.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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@ -161,7 +161,7 @@ static void use(int bytes)
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input_offset += bytes;
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/* make sure off_t is sufficiently large not to wrap */
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if (consumed_bytes > consumed_bytes + bytes)
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if (signed_add_overflows(consumed_bytes, bytes))
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die("pack too large for current definition of off_t");
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consumed_bytes += bytes;
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}
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@ -431,7 +431,7 @@ static int write_one(struct sha1file *f,
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written_list[nr_written++] = &e->idx;
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/* make sure off_t is sufficiently large not to wrap */
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if (*offset > *offset + size)
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if (signed_add_overflows(*offset, size))
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die("pack too large for current definition of off_t");
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*offset += size;
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return 1;
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@ -83,7 +83,7 @@ static void use(int bytes)
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offset += bytes;
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/* make sure off_t is sufficiently large not to wrap */
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if (consumed_bytes > consumed_bytes + bytes)
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if (signed_add_overflows(consumed_bytes, bytes))
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die("pack too large for current definition of off_t");
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consumed_bytes += bytes;
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}
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@ -28,6 +28,18 @@
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#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
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#define bitsizeof(x) (CHAR_BIT * sizeof(x))
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#define maximum_signed_value_of_type(a) \
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(INTMAX_MAX >> (bitsizeof(intmax_t) - bitsizeof(a)))
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/*
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* Signed integer overflow is undefined in C, so here's a helper macro
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* to detect if the sum of two integers will overflow.
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*
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* Requires: a >= 0, typeof(a) equals typeof(b)
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*/
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#define signed_add_overflows(a, b) \
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((b) > maximum_signed_value_of_type(a) - (a))
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#ifdef __GNUC__
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#define TYPEOF(x) (__typeof__(x))
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#else
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