* [patch v3] aligned_alloc: conform to C17
@ 2023-03-21 4:47 DJ Delorie
2023-03-21 17:28 ` Florian Weimer
0 siblings, 1 reply; 6+ messages in thread
From: DJ Delorie @ 2023-03-21 4:47 UTC (permalink / raw)
To: libc-alpha
Changes from V2:
* Simplified debug_malloc (else propogating "check needed" everywhere*
*made it excessively messy, and technically difficult).
* Added a test case.
* Removed new DSO symbols.
References:
https://patchwork.sourceware.org/project/glibc/patch/33ec9e0c1e587813b90e8aa771c2c8e6e379dd48.camel@posteo.net/
https://sourceware.org/bugzilla/show_bug.cgi?id=20137
https://sourceware.org/pipermail/libc-alpha/2023-February/145858.html
The memory.texi portion matches Martin's proposed patch.
man page portion, quoted to avoid CI/CD issues (I can send an official
patch separately after the glibc patch is applied):
> diff --git a/man3/posix_memalign.3 b/man3/posix_memalign.3
> index f5d6618b7..a73ff0421 100644
> --- a/man3/posix_memalign.3
> +++ b/man3/posix_memalign.3
> @@ -91,9 +91,8 @@ The function
> is the same as
> .BR memalign (),
> except for the added restriction that
> -.I size
> -should be a multiple of
> -.IR alignment .
> +.I alignment
> +must be a power of two.
> .PP
> The obsolete function
> .BR valloc ()
From 7139d1e689032249e6de223b3867c6b802c37ea1 Mon Sep 17 00:00:00 2001
From: DJ Delorie <dj@redhat.com>
Date: Tue, 21 Mar 2023 00:46:43 -0400
Subject: aligned_alloc: conform to C17
This patch adds the strict checking for power-of-two alignments
in aligned_alloc(), and updates the manual accordingly.
diff --git a/malloc/Makefile b/malloc/Makefile
index dfb51d344c..691714fb52 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -43,10 +43,12 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
tst-tcfree1 tst-tcfree2 tst-tcfree3 \
tst-safe-linking \
tst-mallocalign1 \
+ tst-aligned-alloc \
tests-static := \
tst-interpose-static-nothread \
- tst-interpose-static-thread
+ tst-interpose-static-thread \
+ tst-aligned-alloc-static
# Test for the malloc_set_state symbol removed in glibc 2.25.
ifeq ($(have-GLIBC_2.23)$(build-shared),yesyes)
diff --git a/malloc/malloc-debug.c b/malloc/malloc-debug.c
index 3867d15698..da9d2340d3 100644
--- a/malloc/malloc-debug.c
+++ b/malloc/malloc-debug.c
@@ -299,7 +299,14 @@ __debug_memalign (size_t alignment, size_t bytes)
return _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0));
}
strong_alias (__debug_memalign, memalign)
-strong_alias (__debug_memalign, aligned_alloc)
+static void *
+__debug_aligned_alloc (size_t alignment, size_t bytes)
+{
+ if (!powerof2 (alignment) || alignment == 0)
+ return NULL;
+ return _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0));
+}
+strong_alias (__debug_aligned_alloc, aligned_alloc)
static void *
__debug_pvalloc (size_t bytes)
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 76c50e3f58..101d257287 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3509,6 +3509,26 @@ __libc_memalign (size_t alignment, size_t bytes)
void *address = RETURN_ADDRESS (0);
return _mid_memalign (alignment, bytes, address);
}
+libc_hidden_def (__libc_memalign)
+
+/* For ISO C11. */
+static void *
+__libc_aligned_alloc (size_t alignment, size_t bytes)
+{
+ if (!__malloc_initialized)
+ ptmalloc_init ();
+
+ /* Similar to memalign, but ISO C17 requires an error for invalid
+ alignments. Valid alignments are non-negative powers of two. */
+ if (!powerof2 (alignment) || alignment == 0)
+ {
+ __set_errno (EINVAL);
+ return 0;
+ }
+
+ void *address = RETURN_ADDRESS (0);
+ return _mid_memalign (alignment, bytes, address);
+}
static void *
_mid_memalign (size_t alignment, size_t bytes, void *address)
@@ -3567,9 +3587,6 @@ _mid_memalign (size_t alignment, size_t bytes, void *address)
ar_ptr == arena_for_chunk (mem2chunk (p)));
return tag_new_usable (p);
}
-/* For ISO C11. */
-weak_alias (__libc_memalign, aligned_alloc)
-libc_hidden_def (__libc_memalign)
void *
__libc_valloc (size_t bytes)
@@ -5903,6 +5920,7 @@ weak_alias (__libc_mallinfo, mallinfo)
strong_alias (__libc_mallinfo2, __mallinfo2)
weak_alias (__libc_mallinfo2, mallinfo2)
strong_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
+weak_alias (__libc_aligned_alloc, aligned_alloc)
weak_alias (__malloc_stats, malloc_stats)
weak_alias (__malloc_usable_size, malloc_usable_size)
diff --git a/malloc/tst-aligned-alloc-static.c b/malloc/tst-aligned-alloc-static.c
new file mode 100644
index 0000000000..d504473094
--- /dev/null
+++ b/malloc/tst-aligned-alloc-static.c
@@ -0,0 +1 @@
+#include "tst-aligned-alloc.c"
diff --git a/malloc/tst-aligned-alloc.c b/malloc/tst-aligned-alloc.c
new file mode 100644
index 0000000000..d6739376d4
--- /dev/null
+++ b/malloc/tst-aligned-alloc.c
@@ -0,0 +1,56 @@
+/* Copyright (C) 2023 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <malloc.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libc-diag.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+ void *p1;
+ void *p2;
+ void *p3;
+
+ errno = 0;
+
+ p1 = aligned_alloc (64, 64);
+
+ if (p1 == NULL)
+ FAIL_EXIT1 ("aligned_alloc(64, 64) failed");
+
+ p2 = aligned_alloc (65, 64);
+
+ if (p2 != NULL)
+ FAIL_EXIT1 ("aligned_alloc(65, 64) did not fail");
+
+ p3 = aligned_alloc (0, 64);
+
+ if (p3 != NULL)
+ FAIL_EXIT1 ("aligned_alloc(0, 64) did not fail");
+
+ free (p1);
+ return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
diff --git a/manual/memory.texi b/manual/memory.texi
index 9d3398a326..8952ff2bfa 100644
--- a/manual/memory.texi
+++ b/manual/memory.texi
@@ -995,7 +995,7 @@ power of two than that, use @code{aligned_alloc} or @code{posix_memalign}.
@c Alias to memalign.
The @code{aligned_alloc} function allocates a block of @var{size} bytes whose
address is a multiple of @var{alignment}. The @var{alignment} must be a
-power of two and @var{size} must be a multiple of @var{alignment}.
+power of two.
The @code{aligned_alloc} function returns a null pointer on error and sets
@code{errno} to one of the following values:
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch v3] aligned_alloc: conform to C17
2023-03-21 4:47 [patch v3] aligned_alloc: conform to C17 DJ Delorie
@ 2023-03-21 17:28 ` Florian Weimer
2023-03-21 17:47 ` DJ Delorie
2023-03-21 20:21 ` DJ Delorie
0 siblings, 2 replies; 6+ messages in thread
From: Florian Weimer @ 2023-03-21 17:28 UTC (permalink / raw)
To: DJ Delorie via Libc-alpha; +Cc: DJ Delorie
* DJ Delorie via Libc-alpha:
> +/* For ISO C11. */
> +static void *
> +__libc_aligned_alloc (size_t alignment, size_t bytes)
> +{
> +weak_alias (__libc_aligned_alloc, aligned_alloc)
I'm surprised that this even compiles. This sort of makes the
function static and gives it external linkage.
Is anything calling __libc_aligned_alloc?
Perhaps you could use this?
static void *
weak_function
aligned_alloc (size_t alignment, size_t bytes)
{
Assuming that there are no internal callers.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch v3] aligned_alloc: conform to C17
2023-03-21 17:28 ` Florian Weimer
@ 2023-03-21 17:47 ` DJ Delorie
2023-03-21 19:08 ` Florian Weimer
2023-03-21 20:21 ` DJ Delorie
1 sibling, 1 reply; 6+ messages in thread
From: DJ Delorie @ 2023-03-21 17:47 UTC (permalink / raw)
To: Florian Weimer; +Cc: libc-alpha
Florian Weimer <fw@deneb.enyo.de> writes:
> I'm surprised that this even compiles. This sort of makes the
> function static and gives it external linkage.
It almost does the same thing as your example, but follows the
internal/external paradigm we've been using for all the other functions.
(in your example, just drop the "static", then it's the same)
And yes, it took Carlos and I a while to go through all this linkage
stuff to make sure we understood it.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch v3] aligned_alloc: conform to C17
2023-03-21 17:47 ` DJ Delorie
@ 2023-03-21 19:08 ` Florian Weimer
0 siblings, 0 replies; 6+ messages in thread
From: Florian Weimer @ 2023-03-21 19:08 UTC (permalink / raw)
To: DJ Delorie; +Cc: libc-alpha
* DJ Delorie:
> Florian Weimer <fw@deneb.enyo.de> writes:
>> I'm surprised that this even compiles. This sort of makes the
>> function static and gives it external linkage.
>
> It almost does the same thing as your example, but follows the
> internal/external paradigm we've been using for all the other functions.
>
> (in your example, just drop the "static", then it's the same)
>
> And yes, it took Carlos and I a while to go through all this linkage
> stuff to make sure we understood it.
Yeah, the static was wrong. I think you should avoid the alias if
there aren't any internal calls.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch v3] aligned_alloc: conform to C17
2023-03-21 17:28 ` Florian Weimer
2023-03-21 17:47 ` DJ Delorie
@ 2023-03-21 20:21 ` DJ Delorie
2023-03-21 20:43 ` Florian Weimer
1 sibling, 1 reply; 6+ messages in thread
From: DJ Delorie @ 2023-03-21 20:21 UTC (permalink / raw)
To: Florian Weimer; +Cc: libc-alpha
Florian Weimer <fw@deneb.enyo.de> writes:
> Perhaps you could use this?
One other difference that isn't obvious in the patch...
the weak alias for aligned_alloc is inside a conditional:
#if IS_IN (libc)
. . .
weak_alias (__libc_aligned_alloc, aligned_alloc)
. . .
#endif
I don't know what, if anything uses malloc.c without being in glibc, but
if such a thing existed, it would break if aligned_alloc weren't inside
this conditional.
Or the conditional could be removed?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch v3] aligned_alloc: conform to C17
2023-03-21 20:21 ` DJ Delorie
@ 2023-03-21 20:43 ` Florian Weimer
0 siblings, 0 replies; 6+ messages in thread
From: Florian Weimer @ 2023-03-21 20:43 UTC (permalink / raw)
To: DJ Delorie; +Cc: libc-alpha
* DJ Delorie:
> Florian Weimer <fw@deneb.enyo.de> writes:
>> Perhaps you could use this?
>
> One other difference that isn't obvious in the patch...
>
> the weak alias for aligned_alloc is inside a conditional:
>
> #if IS_IN (libc)
> . . .
> weak_alias (__libc_aligned_alloc, aligned_alloc)
> . . .
> #endif
>
> I don't know what, if anything uses malloc.c without being in glibc, but
> if such a thing existed, it would break if aligned_alloc weren't inside
> this conditional.
>
> Or the conditional could be removed?
Siddhesh added it for libc_malloc_debug, it has !IS_IN (libc).
Surely we want libc_malloc_debug to keep defining aligned_alloc,
so this shouldn't be conditional on IS_IN (libc).
^ permalink raw reply [flat|nested] 6+ messages in thread
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2023-03-21 4:47 [patch v3] aligned_alloc: conform to C17 DJ Delorie
2023-03-21 17:28 ` Florian Weimer
2023-03-21 17:47 ` DJ Delorie
2023-03-21 19:08 ` Florian Weimer
2023-03-21 20:21 ` DJ Delorie
2023-03-21 20:43 ` Florian Weimer
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