From f7b573b4e96f3cf421dc92063b11121da2370e46 Mon Sep 17 00:00:00 2001 From: David Carlier Date: Wed, 29 Aug 2018 21:04:32 +0100 Subject: [PATCH] Support fixed address mmap without replacement Reapply changes for Zend fixed mapping but only for FreeBSD. Other BSD might expose some day a similar flag (private for OpenBSD for the moment for example). The Linux's part could be brought back but not before 7.4, at this time, distributions with kernel > 4.17 will be more widely available. --- Zend/zend_alloc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/Zend/zend_alloc.c b/Zend/zend_alloc.c index 11691d83775..302f9e72815 100644 --- a/Zend/zend_alloc.c +++ b/Zend/zend_alloc.c @@ -423,11 +423,15 @@ static void *zend_mm_mmap_fixed(void *addr, size_t size) #ifdef _WIN32 return VirtualAlloc(addr, size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE); #else + int flags = MAP_PRIVATE | MAP_ANON; +#if defined(MAP_EXCL) + flags |= MAP_FIXED | MAP_EXCL; +#endif /* MAP_FIXED leads to discarding of the old mapping, so it can't be used. */ - void *ptr = mmap(addr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON /*| MAP_POPULATE | MAP_HUGETLB*/, -1, 0); + void *ptr = mmap(addr, size, PROT_READ | PROT_WRITE, flags /*| MAP_POPULATE | MAP_HUGETLB*/, -1, 0); if (ptr == MAP_FAILED) { -#if ZEND_MM_ERROR +#if ZEND_MM_ERROR && !defined(MAP_EXCL) fprintf(stderr, "\nmmap() failed: [%d] %s\n", errno, strerror(errno)); #endif return NULL;