sha1_file.c: avoid gcc signed overflow warnings
With the recent gcc, we get: sha1_file.c: In check_packed_git_: sha1_file.c:527: warning: assuming signed overflow does not occur when assuming that (X + c) < X is always false sha1_file.c:527: warning: assuming signed overflow does not occur when assuming that (X + c) < X is always false for a piece of code that tries to make sure that off_t is large enough to hold more than 2^32 offset. The test tried to make sure these do not wrap-around: /* make sure we can deal with large pack offsets */ off_t x = 0x7fffffffUL, y = 0xffffffffUL; if (x > (x + 1) || y > (y + 1)) { but gcc assumes it can do whatever optimization it wants for a signed overflow (undefined behaviour) and warns about this construct. Follow Linus's suggestion to check sizeof(off_t) instead to work around the problem. Signed-off-by: Junio C Hamano <gitster@pobox.com>
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sha1_file.c
16
sha1_file.c
@ -521,13 +521,15 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
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munmap(idx_map, idx_size);
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return error("wrong index v2 file size in %s", path);
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}
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if (idx_size != min_size) {
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/* make sure we can deal with large pack offsets */
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off_t x = 0x7fffffffUL, y = 0xffffffffUL;
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if (x > (x + 1) || y > (y + 1)) {
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munmap(idx_map, idx_size);
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return error("pack too large for current definition of off_t in %s", path);
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}
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if (idx_size != min_size &&
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/*
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* make sure we can deal with large pack offsets.
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* 31-bit signed offset won't be enough, neither
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* 32-bit unsigned one will be.
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*/
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(sizeof(off_t) <= 4)) {
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munmap(idx_map, idx_size);
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return error("pack too large for current definition of off_t in %s", path);
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}
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}
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