From a8096e30f4d08f2b90cc147b44b414191de6155f Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Fri, 13 Aug 2021 10:38:22 +1200 Subject: [PATCH] Make EXEC_BACKEND more convenient on macOS. It's hard to disable ASLR on current macOS releases, for testing with -DEXEC_BACKEND. You could already set the environment variable PG_SHMEM_ADDR to something not likely to collide with mappings created earlier in process startup. Let's also provide a default value that works on current releases and architectures, for developer convenience. As noted in the pre-existing comment, this is a horrible hack, but -DEXEC_BACKEND is only used by Unix-based PostgreSQL developers for testing some otherwise Windows-only code paths, so it seems excusable. Back-patch to all supported branches. Reviewed-by: Tom Lane Discussion: https://postgr.es/m/20210806032944.m4tz7j2w47mant26%40alap3.anarazel.de --- src/backend/port/sysv_shmem.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c index 968506dd51..3267648c95 100644 --- a/src/backend/port/sysv_shmem.c +++ b/src/backend/port/sysv_shmem.c @@ -142,6 +142,16 @@ InternalIpcMemoryCreate(IpcMemoryKey memKey, Size size) if (pg_shmem_addr) requestedAddress = (void *) strtoul(pg_shmem_addr, NULL, 0); + else + { +#if defined(__darwin__) && SIZEOF_VOID_P == 8 + /* + * Provide a default value that is believed to avoid problems with + * ASLR on the current macOS release. + */ + requestedAddress = (void *) 0x80000000000; +#endif + } } #endif