References: https://patchwork.sourceware.org/project/glibc/patch/33ec9e0c1e587813b90e8aa771c2c8e6e379dd48.camel@xxxxxxxxxx/ 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 4767e0e764e1a7a5ef01e303f503036379dd42c5 Mon Sep 17 00:00:00 2001 From: DJ Delorie <dj@xxxxxxxxxx> Date: Thu, 16 Mar 2023 01:33:41 -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/Versions b/malloc/Versions index c763395c6d..28f41a94f3 100644 --- a/malloc/Versions +++ b/malloc/Versions @@ -67,6 +67,9 @@ libc { GLIBC_2.33 { mallinfo2; } + GLIBC_2.38 { + __libc_aligned_alloc; + } GLIBC_PRIVATE { # Internal startup hook for libpthread. __libc_malloc_pthread_startup; diff --git a/malloc/malloc-debug.c b/malloc/malloc-debug.c index 3867d15698..4d2ec04a1a 100644 --- a/malloc/malloc-debug.c +++ b/malloc/malloc-debug.c @@ -268,7 +268,8 @@ __debug_realloc (void *oldmem, size_t bytes) strong_alias (__debug_realloc, realloc) static void * -_debug_mid_memalign (size_t alignment, size_t bytes, const void *address) +_debug_mid_memalign (size_t alignment, size_t bytes, const void *address, + int check_alignment) { void *(*hook) (size_t, size_t, const void *) = atomic_forced_read (__memalign_hook); @@ -281,9 +282,15 @@ _debug_mid_memalign (size_t alignment, size_t bytes, const void *address) if ((!__is_malloc_debug_enabled (MALLOC_MCHECK_HOOK) || !memalign_mcheck_before (alignment, &bytes, &victim))) { - victim = (__is_malloc_debug_enabled (MALLOC_CHECK_HOOK) - ? memalign_check (alignment, bytes) - : __libc_memalign (alignment, bytes)); + if (check_alignment && !powerof2 (alignment)) + { + __set_errno (EINVAL); + victim = NULL; + } + else + victim = (__is_malloc_debug_enabled (MALLOC_CHECK_HOOK) + ? memalign_check (alignment, bytes) + : __libc_memalign (alignment, bytes)); } if (__is_malloc_debug_enabled (MALLOC_MCHECK_HOOK) && victim != NULL) victim = memalign_mcheck_after (victim, alignment, orig_bytes); @@ -296,10 +303,15 @@ _debug_mid_memalign (size_t alignment, size_t bytes, const void *address) static void * __debug_memalign (size_t alignment, size_t bytes) { - return _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0)); + return _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0), 0); } strong_alias (__debug_memalign, memalign) -strong_alias (__debug_memalign, aligned_alloc) +static void * +__debug_aligned_alloc (size_t alignment, size_t bytes) +{ + return _debug_mid_memalign (alignment, bytes, RETURN_ADDRESS (0), 1); +} +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..09619ed168 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -656,6 +656,9 @@ libc_hidden_proto (__libc_realloc) void* __libc_memalign(size_t, size_t); libc_hidden_proto (__libc_memalign) +void * __libc_aligned_alloc (size_t alignment, size_t bytes); +libc_hidden_proto (__libc_aligned_alloc) + /* valloc(size_t n); Equivalent to memalign(pagesize, n), where pagesize is the page @@ -3509,6 +3512,27 @@ __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. */ +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)) + { + __set_errno (EINVAL); + return 0; + } + + void *address = RETURN_ADDRESS (0); + return _mid_memalign (alignment, bytes, address); +} +libc_hidden_def (__libc_aligned_alloc) static void * _mid_memalign (size_t alignment, size_t bytes, void *address) @@ -3567,9 +3591,6 @@ _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 +5924,7 @@ 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/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:
