From 887d0eee6bab35847253181b32e78ff707010ccd Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Fri, 2 Oct 2020 10:17:27 -0700 Subject: Export of internal Abseil changes -- d6e582e21ceec768aa72e857c10ba80cad2f2202 by Abseil Team : adds bounds-checking for the second range in absl::c_mismatch The API for the two-range absl::c_mismatch is misleading as it doesn't check the bounds of the second range against the first one. This commit cleans up the internals of the overload to make sure that buggy calls are not exploitable; non-buggy calls are unaffected. This is consistent with both C++14's two-range std::mismatch and C++20's std::ranges::mismatch (see http://wg21.link/mismatch). PiperOrigin-RevId: 335050236 GitOrigin-RevId: d6e582e21ceec768aa72e857c10ba80cad2f2202 Change-Id: I77e0d030adf35c09069ceab5ea67efdf09377390 --- absl/algorithm/container.h | 39 +++++++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 10 deletions(-) (limited to 'absl/algorithm/container.h') diff --git a/absl/algorithm/container.h b/absl/algorithm/container.h index 5c033571..7778ab17 100644 --- a/absl/algorithm/container.h +++ b/absl/algorithm/container.h @@ -340,24 +340,43 @@ container_algorithm_internal::ContainerDifferenceType c_count_if( // c_mismatch() // // Container-based version of the `std::mismatch()` function to -// return the first element where two ordered containers differ. +// return the first element where two ordered containers differ. Applies `==` to +// the first N elements of `c1` and `c2`, where N = min(size(c1), size(c2)). template container_algorithm_internal::ContainerIterPairType c_mismatch(C1& c1, C2& c2) { - return std::mismatch(container_algorithm_internal::c_begin(c1), - container_algorithm_internal::c_end(c1), - container_algorithm_internal::c_begin(c2)); + auto first1 = container_algorithm_internal::c_begin(c1); + auto last1 = container_algorithm_internal::c_end(c1); + auto first2 = container_algorithm_internal::c_begin(c2); + auto last2 = container_algorithm_internal::c_end(c2); + + for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) { + if (*first1 != *first2) { + break; + } + } + + return std::make_pair(first1, first2); } // Overload of c_mismatch() for using a predicate evaluation other than `==` as -// the function's test condition. +// the function's test condition. Applies `pred`to the first N elements of `c1` +// and `c2`, where N = min(size(c1), size(c2)). template container_algorithm_internal::ContainerIterPairType -c_mismatch(C1& c1, C2& c2, BinaryPredicate&& pred) { - return std::mismatch(container_algorithm_internal::c_begin(c1), - container_algorithm_internal::c_end(c1), - container_algorithm_internal::c_begin(c2), - std::forward(pred)); +c_mismatch(C1& c1, C2& c2, BinaryPredicate pred) { + auto first1 = container_algorithm_internal::c_begin(c1); + auto last1 = container_algorithm_internal::c_end(c1); + auto first2 = container_algorithm_internal::c_begin(c2); + auto last2 = container_algorithm_internal::c_end(c2); + + for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) { + if (!pred(*first1, *first2)) { + break; + } + } + + return std::make_pair(first1, first2); } // c_equal() -- cgit v1.2.3