From c7ed7187203ca0b348a0bb8a355b01332c446101 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Fri, 20 Aug 2021 18:11:14 +0200 Subject: [PATCH] macro: handle overflow in ALIGN_TO() somewhat reasonably The helper call rounds up to next multiple of specified boundary. If one passes a very large value as first argument, then there might not be a next multiple. So far we ignored that. Let's handle this now and return SIZE_MAX in this case, as special indicator that we reached the end. Of course, IRL this should not happen. With this new change we at least do something somewhat reasonable, leaving it to the caller to handle it further. --- src/basic/macro.h | 14 ++++++++++++++ src/test/test-macro.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 47 insertions(+) diff --git a/src/basic/macro.h b/src/basic/macro.h index 280f3028643..6977a1ddd94 100644 --- a/src/basic/macro.h +++ b/src/basic/macro.h @@ -146,6 +146,20 @@ #define ALIGN8_PTR(p) ((void*) ALIGN8((unsigned long) (p))) static inline size_t ALIGN_TO(size_t l, size_t ali) { + /* Check that alignment is exponent of 2 */ +#if SIZE_MAX == UINT_MAX + assert(__builtin_popcount(ali) == 1); +#elif SIZE_MAX == ULONG_MAX + assert(__builtin_popcountl(ali) == 1); +#elif SIZE_MAX == ULONGLONG_MAX + assert(__builtin_popcountll(ali) == 1); +#else +#error "Unexpected size_t" +#endif + + if (l > SIZE_MAX - (ali - 1)) + return SIZE_MAX; /* indicate overflow */ + return ((l + ali - 1) & ~(ali - 1)); } diff --git a/src/test/test-macro.c b/src/test/test-macro.c index 5c0007cb5be..428f3b952ae 100644 --- a/src/test/test-macro.c +++ b/src/test/test-macro.c @@ -295,6 +295,38 @@ static void test_foreach_pointer(void) { assert(k == 11); } +static void test_align_to(void) { + log_info("/* %s */", __func__); + + assert_se(ALIGN_TO(0, 1) == 0); + assert_se(ALIGN_TO(1, 1) == 1); + assert_se(ALIGN_TO(2, 1) == 2); + assert_se(ALIGN_TO(3, 1) == 3); + assert_se(ALIGN_TO(4, 1) == 4); + assert_se(ALIGN_TO(SIZE_MAX-1, 1) == SIZE_MAX-1); + assert_se(ALIGN_TO(SIZE_MAX, 1) == SIZE_MAX); + + assert_se(ALIGN_TO(0, 2) == 0); + assert_se(ALIGN_TO(1, 2) == 2); + assert_se(ALIGN_TO(2, 2) == 2); + assert_se(ALIGN_TO(3, 2) == 4); + assert_se(ALIGN_TO(4, 2) == 4); + assert_se(ALIGN_TO(SIZE_MAX-3, 2) == SIZE_MAX-3); + assert_se(ALIGN_TO(SIZE_MAX-2, 2) == SIZE_MAX-1); + assert_se(ALIGN_TO(SIZE_MAX-1, 2) == SIZE_MAX-1); + assert_se(ALIGN_TO(SIZE_MAX, 2) == SIZE_MAX); /* overflow */ + + assert_se(ALIGN_TO(0, 4) == 0); + assert_se(ALIGN_TO(1, 4) == 4); + assert_se(ALIGN_TO(2, 4) == 4); + assert_se(ALIGN_TO(3, 4) == 4); + assert_se(ALIGN_TO(4, 4) == 4); + assert_se(ALIGN_TO(SIZE_MAX-3, 4) == SIZE_MAX-3); + assert_se(ALIGN_TO(SIZE_MAX-2, 4) == SIZE_MAX); /* overflow */ + assert_se(ALIGN_TO(SIZE_MAX-1, 4) == SIZE_MAX); /* overflow */ + assert_se(ALIGN_TO(SIZE_MAX, 4) == SIZE_MAX); /* overflow */ +} + int main(int argc, char *argv[]) { test_setup_logging(LOG_INFO); @@ -305,6 +337,7 @@ int main(int argc, char *argv[]) { test_in_set(); test_foreach_pointer(); test_ptr_to_int(); + test_align_to(); return 0; } -- 2.47.3