From 6242c6a690ce8e18aad711103902bfff00cc2757 Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Wed, 4 Jul 2018 12:40:25 -0400 Subject: [PATCH] darwin: Don't use sbrk This patch gets rid of this warning on macOS: CXX main.o /Users/simark/src/binutils-gdb/gdb/main.c:492:27: error: 'sbrk' is deprecated [-Werror,-Wdeprecated-declarations] lim_at_start = (char *) sbrk (0); ^ /usr/include/unistd.h:585:1: note: 'sbrk' has been explicitly marked deprecated here __deprecated __WATCHOS_PROHIBITED __TVOS_PROHIBITED ^ /usr/include/sys/cdefs.h:176:37: note: expanded from macro '__deprecated' #define __deprecated __attribute__((deprecated)) ^ sbrk on macOS is not useful for our purposes, since sbrk(0) always returns the same value. From what I read, brk/sbrk on macOS is just an emulation, it always returns a pointer in a 4MB section reserved for that. So instead of letting users use "maint set per-command space on" and print silly results, I think we should just disable that feature for this platform (as we do for platforms that don't have sbrk). I defined a HAVE_USEFUL_SBRK macro and used that instead of HAVE_SBRK. gdb/ChangeLog: * common/common-defs.h (HAVE_USEFUL_SBRK): Define. * main.c: Use HAVE_USEFUL_SBRK instead of HAVE_SBRK. * maint.c: Likewise. * top.c: Likewise. --- gdb/ChangeLog | 7 +++++++ gdb/common/common-defs.h | 9 +++++++++ gdb/main.c | 2 +- gdb/maint.c | 4 ++-- gdb/top.c | 2 +- 5 files changed, 20 insertions(+), 4 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index cc097557946..d2319c06d52 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,10 @@ +2018-07-04 Simon Marchi + + * common/common-defs.h (HAVE_USEFUL_SBRK): Define. + * main.c: Use HAVE_USEFUL_SBRK instead of HAVE_SBRK. + * maint.c: Likewise. + * top.c: Likewise. + 2018-07-04 Joel Brobecker * NEWS: Create a new section for the next release branch. diff --git a/gdb/common/common-defs.h b/gdb/common/common-defs.h index eb0ec214926..80f1ff4f560 100644 --- a/gdb/common/common-defs.h +++ b/gdb/common/common-defs.h @@ -105,4 +105,13 @@ /* String containing the current directory (what getwd would return). */ extern char *current_directory; +/* sbrk on macOS is not useful for our purposes, since sbrk(0) always + returns the same value. brk/sbrk on macOS is just an emulation + that always returns a pointer to a 4MB section reserved for + that. */ + +#if defined (HAVE_SBRK) && !__APPLE__ +#define HAVE_USEFUL_SBRK 1 +#endif + #endif /* COMMON_DEFS_H */ diff --git a/gdb/main.c b/gdb/main.c index 9694af24269..e925128a426 100644 --- a/gdb/main.c +++ b/gdb/main.c @@ -487,7 +487,7 @@ captured_main_1 (struct captured_main_args *context) int save_auto_load; struct objfile *objfile; -#ifdef HAVE_SBRK +#ifdef HAVE_USEFUL_SBRK /* Set this before constructing scoped_command_stats. */ lim_at_start = (char *) sbrk (0); #endif diff --git a/gdb/maint.c b/gdb/maint.c index a8a1fcbc299..5d4701cfacc 100644 --- a/gdb/maint.c +++ b/gdb/maint.c @@ -828,7 +828,7 @@ scoped_command_stats::~scoped_command_stats () if (m_space_enabled && per_command_space) { -#ifdef HAVE_SBRK +#ifdef HAVE_USEFUL_SBRK char *lim = (char *) sbrk (0); long space_now = lim - lim_at_start; @@ -866,7 +866,7 @@ scoped_command_stats::scoped_command_stats (bool msg_type) { if (!m_msg_type || per_command_space) { -#ifdef HAVE_SBRK +#ifdef HAVE_USEFUL_SBRK char *lim = (char *) sbrk (0); m_start_space = lim - lim_at_start; m_space_enabled = 1; diff --git a/gdb/top.c b/gdb/top.c index fdef3e0d0bf..de1a335e40a 100644 --- a/gdb/top.c +++ b/gdb/top.c @@ -171,7 +171,7 @@ int remote_timeout = 2; int remote_debug = 0; /* Sbrk location on entry to main. Used for statistics only. */ -#ifdef HAVE_SBRK +#ifdef HAVE_USEFUL_SBRK char *lim_at_start; #endif -- 2.30.2