[PATCH 1/2] avoid shifting signed integers 31 bits
- From
Jeff King <peff@peff.net>
- Date
- Dec 29, 2015, 06:35 UTC
- Message-ID
- <20151229063545.GA30340@sigill.intra.peff.net>
- In-Reply-To
- <20151229063449.GA28755@sigill.intra.peff.net>
We sometimes use 32-bit unsigned integers as bit-fields. It's fine to access the MSB, because it's unsigned. However, doing so as "1 << 31" is wrong, because the constant "1" is a signed int, and we shift into the sign bit, causing undefined behavior.
We can fix this by using "1U" as the constant.
Signed-off-by: Jeff King <peff@peff.net> --- builtin/receive-pack.c | 2 +- diff.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c index ca38131..2b3b746 100644 --- a/builtin/receive-pack.c +++ b/builtin/receive-pack.c @@ -1618,7 +1618,7 @@ static void prepare_shallow_update(struct command *commands, continue; si->need_reachability_test[i]++; for (k = 0; k < 32; k++) - if (si->used_shallow[i][j] & (1 << k)) + if (si->used_shallow[i][j] & (1U << k)) si->shallow_ref[j * 32 + k]++; } diff --git a/diff.h b/diff.h index f7208ad..893f446 100644 --- a/diff.h +++ b/diff.h @@ -91,7 +91,7 @@ typedef struct strbuf *(*diff_prefix_fn_t)(struct diff_options *opt, void *data) #define DIFF_OPT_DIRSTAT_BY_LINE (1 << 28) #define DIFF_OPT_FUNCCONTEXT (1 << 29) #define DIFF_OPT_PICKAXE_IGNORE_CASE (1 << 30) -#define DIFF_OPT_DEFAULT_FOLLOW_RENAMES (1 << 31) +#define DIFF_OPT_DEFAULT_FOLLOW_RENAMES (1U << 31) #define DIFF_OPT_TST(opts, flag) ((opts)->flags & DIFF_OPT_##flag) #define DIFF_OPT_TOUCHED(opts, flag) ((opts)->touched_flags & DIFF_OPT_##flag)
-- 2.7.0.rc2.368.g1cbb535