* Re: Warning in lib/stdlib.c
2024-12-21 13:10 Warning in lib/stdlib.c Eli Zaretskii
@ 2024-12-27 0:38 ` Paul Eggert
2024-12-27 3:24 ` Stefan Kangas
0 siblings, 1 reply; 3+ messages in thread
From: Paul Eggert @ 2024-12-27 0:38 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: emacs-devel
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On 2024-12-21 05:10, Eli Zaretskii wrote:
> stdlib.c:20: warning: "_GL_STDLIB_INLINE" redefined
That's a violation of the C standard and so should be fixed.
The real culprit here is that Emacs config.h includes <stdlib.h>. It's
generally not a good idea for config.h to include headers like
<stdlib.h>, as that's brittle (as shown here).
I adjusted Gnulib to work around this particular problem and merged that
into Emacs. However, the culprit may cause other lurking issues so I
also installed the attached patches to Emacs so that config.h no longer
includes <stdlib.h>.
In <https://bugs.gnu.org/52455#21> I just now proposed removing
no-longer-working code that attempts to support unexec on macOS. That
would have simplified the attached patches.
It would also simplify things to remove the HYBRID_MALLOC code but I
don't know whether that stuff is still used.
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From a51642ba5fad891239552fe7e746fa160e3f88ea Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 23 Dec 2024 14:03:06 -0800
Subject: [PATCH 1/2] Let Gnulib deal with MB_CUR_MAX
Recent Gnulib should work around the Android NDK 16
MB_CUR_MAX bug, so Emacs no longer needs to worry about it.
* configure.ac (gl_STDLIB_H):
Remove, to stop overriding Gnulib.
* configure.ac (__ctype_get_mb_cur_max)
(emacs_cv_broken_mb_cur_max, REPLACEMENT_MB_CUR_MAX):
* src/conf_post.h (MB_CUR_MAX):
Remove, as Gnulib does this now.
---
configure.ac | 33 ---------------------------------
src/conf_post.h | 10 ----------
2 files changed, 43 deletions(-)
diff --git a/configure.ac b/configure.ac
index 18cbb42b0ef..bfef9cd294d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1615,10 +1615,6 @@ AC_DEFUN
AC_DEFUN([gt_TYPE_WINT_T],
[GNULIBHEADERS_OVERRIDE_WINT_T=0
AC_SUBST([GNULIBHEADERS_OVERRIDE_WINT_T])])
-# Emacs does not need precise checks for the Solaris 10 MB_CUR_MAX bug.
-AC_DEFUN_ONCE([gl_STDLIB_H],
- [AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
- gl_NEXT_HEADERS([stdlib.h])])
# Emacs does not need to check for off64_t.
AC_DEFUN([gl_TYPE_OFF64_T],
[HAVE_OFF64_T=1
@@ -7646,35 +7642,6 @@ AC_DEFUN
AC_SUBST([WINDOW_SYSTEM_OBJ])
-# Some systems have MB_CUR_MAX defined to a call to
-# __ctype_get_mb_cur_max, but do not have __ctype_get_mb_cur_max in
-# libc. Check for that situation and define MB_CUR_MAX to something
-# sane.
-
-AC_CHECK_FUNC([__ctype_get_mb_cur_max])
-
-AC_CACHE_CHECK([whether MB_CUR_MAX is defined to function that won't link],
- [emacs_cv_broken_mb_cur_max],
- [AC_EGREP_CPP(__ctype_get_mb_cur_max, [
-#include <stdlib.h>
-#ifndef MB_CUR_MAX
-#define MB_CUR_MAX -1
-#endif
-static int foo = MB_CUR_MAX;
-], [AS_IF([test "$ac_cv_func___ctype_get_mb_cur_max" = "yes"],
- [emacs_cv_broken_mb_cur_max=no],
- [emacs_cv_broken_mb_cur_max=yes])],
- [emacs_cv_broken_mb_cur_max=no])])
-
-AS_IF([test "$emacs_cv_broken_mb_cur_max" = "yes"],
- # Define this to 4, which is right for Android.
- [AS_CASE([$opsys], [android],
- [AC_DEFINE([REPLACEMENT_MB_CUR_MAX], [4],
- [Define to MB_CUR_MAX if stdlib.h is broken.])],
- [AC_MSG_ERROR([MB_CUR_MAX does not work on your system.
-Please modify configure.ac to set an appropriate value, then
-send your change to bug-gnu-emacs@gnu.org])])])
-
AH_TOP([/* GNU Emacs site configuration template file.
Copyright (C) 1988-2024 Free Software Foundation, Inc.
diff --git a/src/conf_post.h b/src/conf_post.h
index 9d3f5711bef..6aa2c901cc7 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -462,16 +462,6 @@ #define VFORK() vfork ()
# define UNINIT /* empty */
#endif
-/* MB_CUR_MAX is often broken on systems which copy-paste LLVM
- headers, so replace its definition with a working one if
- necessary. */
-
-#ifdef REPLACEMENT_MB_CUR_MAX
-#include <stdlib.h>
-#undef MB_CUR_MAX
-#define MB_CUR_MAX REPLACEMENT_MB_CUR_MAX
-#endif /* REPLACEMENT_MB_CUR_MAX */
-
/* Emacs does not need glibc strftime behavior for AM and PM
indicators. */
#define REQUIRE_GNUISH_STRFTIME_AM_PM false
--
2.45.2
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From 577714e3fe722625236ce060f53b5d76f7933454 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 26 Dec 2024 15:44:34 -0800
Subject: [PATCH 2/2] =?UTF-8?q?Don=E2=80=99t=20include=20stdlib.h=20from?=
=?UTF-8?q?=20conf=5Fpost.h?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
This is brittle, as evinced by the recent problem with lib/stdlib.c.
* src/conf_post.h: Move potential inclusion of stdlib.h and
redefinitions of malloc, free, realloc, aligned_alloc, and calloc
from here ...
* src/lisp.h: ... to here. Do not redefine the symbols
if UNEXMACOS_C is defined.
* src/unexmacosx.c: Do not undef malloc, realloc, free.
(UNEXMACOS_C): New symbol, to prevent lisp.h from defining them.
---
src/conf_post.h | 49 ------------------------------------------------
src/gmalloc.c | 2 +-
src/lisp.h | 35 ++++++++++++++++++++++++++++++++++
src/unexmacosx.c | 7 +------
4 files changed, 37 insertions(+), 56 deletions(-)
diff --git a/src/conf_post.h b/src/conf_post.h
index 6aa2c901cc7..e204a85b973 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -93,55 +93,6 @@ Copyright (C) 1988, 1993-1994, 1999-2002, 2004-2024 Free Software
# define ADDRESS_SANITIZER false
#endif
-#ifdef emacs
-/* We include stdlib.h here, because Gnulib's stdlib.h might redirect
- 'free' to its replacement, and we want to avoid that in unexec
- builds. Including it here will render its inclusion after config.h
- a no-op. */
-# if (defined DARWIN_OS && defined HAVE_UNEXEC) || defined HYBRID_MALLOC
-# include <stdlib.h>
-# endif
-#endif
-
-#if defined DARWIN_OS && defined emacs && defined HAVE_UNEXEC
-# undef malloc
-# define malloc unexec_malloc
-# undef realloc
-# define realloc unexec_realloc
-# undef free
-# define free unexec_free
-
-extern void *unexec_malloc (size_t);
-extern void *unexec_realloc (void *, size_t);
-extern void unexec_free (void *);
-
-#endif
-
-/* If HYBRID_MALLOC is defined (e.g., on Cygwin), emacs will use
- gmalloc before dumping and the system malloc after dumping.
- hybrid_malloc and friends, defined in gmalloc.c, are wrappers that
- accomplish this. */
-#ifdef HYBRID_MALLOC
-#ifdef emacs
-#undef malloc
-#define malloc hybrid_malloc
-#undef realloc
-#define realloc hybrid_realloc
-#undef aligned_alloc
-#define aligned_alloc hybrid_aligned_alloc
-#undef calloc
-#define calloc hybrid_calloc
-#undef free
-#define free hybrid_free
-
-extern void *hybrid_malloc (size_t);
-extern void *hybrid_calloc (size_t, size_t);
-extern void hybrid_free (void *);
-extern void *hybrid_aligned_alloc (size_t, size_t);
-extern void *hybrid_realloc (void *, size_t);
-#endif /* emacs */
-#endif /* HYBRID_MALLOC */
-
/* We have to go this route, rather than the old hpux9 approach of
renaming the functions via macros. The system's stdlib.h has fully
prototyped declarations, which yields a conflicting definition of
diff --git a/src/gmalloc.c b/src/gmalloc.c
index 1faf6506167..d6c5d351925 100644
--- a/src/gmalloc.c
+++ b/src/gmalloc.c
@@ -62,7 +62,7 @@ #define USE_PTHREAD
grealloc... via the macros that follow). The dumped emacs,
however, will use the system malloc, realloc.... In other source
files, malloc, realloc... are renamed hybrid_malloc,
- hybrid_realloc... via macros in conf_post.h. hybrid_malloc and
+ hybrid_realloc... via macros in lisp.h. hybrid_malloc and
friends are wrapper functions defined later in this file. */
#undef malloc
#undef realloc
diff --git a/src/lisp.h b/src/lisp.h
index bf6b023fc2a..f3566ad2973 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -4930,10 +4930,45 @@ #define safe_calln(...) \
/* Defined in unexmacosx.c. */
#if defined DARWIN_OS && defined HAVE_UNEXEC
+/* Redirect calls to malloc, realloc and free to a macOS zone memory allocator.
+ FIXME: Either also redirect unexec_aligned_alloc and unexec_calloc,
+ or fix this comment to explain why those two redirections are not needed. */
extern void unexec_init_emacs_zone (void);
extern void *unexec_malloc (size_t);
extern void *unexec_realloc (void *, size_t);
extern void unexec_free (void *);
+# ifndef UNEXMACOSX_C
+# include <stdlib.h>
+# undef malloc
+# undef realloc
+# undef free
+# define malloc unexec_malloc
+# define realloc unexec_realloc
+# define free unexec_free
+# endif
+#endif
+
+/* Defined in gmalloc.c. */
+#ifdef HYBRID_MALLOC
+/* Redirect calls to malloc and friends to a hybrid allocator that
+ uses gmalloc before dumping and the system malloc after dumping.
+ This can be useful on Cygwin, for example. */
+extern void *hybrid_aligned_alloc (size_t, size_t);
+extern void *hybrid_calloc (size_t, size_t);
+extern void *hybrid_malloc (size_t);
+extern void *hybrid_realloc (void *, size_t);
+extern void hybrid_free (void *);
+# include <stdlib.h>
+# undef aligned_alloc
+# undef calloc
+# undef malloc
+# undef realloc
+# undef free
+# define aligned_alloc hybrid_aligned_alloc
+# define calloc hybrid_calloc
+# define malloc hybrid_malloc
+# define realloc hybrid_realloc
+# define free hybrid_free
#endif
/* The definition of Lisp_Module_Function depends on emacs-module.h,
diff --git a/src/unexmacosx.c b/src/unexmacosx.c
index 7b2326441b4..d6c7686607f 100644
--- a/src/unexmacosx.c
+++ b/src/unexmacosx.c
@@ -87,15 +87,10 @@
#include <config.h>
-/* Although <config.h> redefines malloc to unexec_malloc, etc., this
- file wants stdlib.h to declare the originals. */
-#undef malloc
-#undef realloc
-#undef free
-
#include <stdlib.h>
#include "unexec.h"
+#define UNEXMACOSX_C /* Tell lisp.h we want the system malloc, etc. */
#include "lisp.h"
#include "sysstdio.h"
--
2.45.2
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