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GET /api/patches/2195772/?format=api
{ "id": 2195772, "url": "http://patchwork.ozlabs.org/api/patches/2195772/?format=api", "web_url": "http://patchwork.ozlabs.org/project/glibc/patch/20260211201815.82913-3-eggert@cs.ucla.edu/", "project": { "id": 41, "url": "http://patchwork.ozlabs.org/api/projects/41/?format=api", "name": "GNU C Library", "link_name": "glibc", "list_id": "libc-alpha.sourceware.org", "list_email": "libc-alpha@sourceware.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260211201815.82913-3-eggert@cs.ucla.edu>", "list_archive_url": null, "date": "2026-02-11T20:17:35", "name": "[v2,2/4] Document malloc alignment", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "7c4ef2f024f3d9d7293277229fb2e9c1deb867af", "submitter": { "id": 4434, "url": "http://patchwork.ozlabs.org/api/people/4434/?format=api", "name": "Paul Eggert", "email": "eggert@CS.UCLA.EDU" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/glibc/patch/20260211201815.82913-3-eggert@cs.ucla.edu/mbox/", "series": [ { "id": 491904, "url": "http://patchwork.ozlabs.org/api/series/491904/?format=api", "web_url": "http://patchwork.ozlabs.org/project/glibc/list/?series=491904", "date": "2026-02-11T20:17:33", "name": "malloc doc fixes for alignment", "version": 2, "mbox": "http://patchwork.ozlabs.org/series/491904/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2195772/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2195772/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<libc-alpha-bounces~incoming=patchwork.ozlabs.org@sourceware.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "libc-alpha@sourceware.org" ], "Delivered-To": [ "patchwork-incoming@legolas.ozlabs.org", "libc-alpha@sourceware.org" ], "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=cs.ucla.edu header.i=@cs.ucla.edu header.a=rsa-sha256\n header.s=9D0B346E-2AEB-11ED-9476-E14B719DCE6C header.b=XeKatL5X;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=sourceware.org\n (client-ip=2620:52:6:3111::32; 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a=rsa-sha256; d=sourceware.org; s=key; t=1770841113; cv=none;\n b=SC0wxzjJIIZodXFkA4ViG1yGoH9eqGeL/NY681ik9kpZZ09ar6ZhbLHGs0WVUJHkwbcwCLLb2XOQYfHXUhUyU25Yc1NiXNGIe3lii5K2qT0gLh0boBDHcE0LkzRE/kQ+cKhj6YPqP4xIa6O5UkP6UR1maZGiPU13m4KdJQJ1aYw=", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1770841113; c=relaxed/simple;\n bh=hAocleQ2PNLQGkM+rA1xPuM1B1YEzftAexrGNT2Yv84=;\n h=DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version;\n b=TlvnIckVvbescT4H2UUQMarDsx6dp9+jKjqICKUam6E5viEfw9urR+McvbbDXwluxXsOB7DM3HgWtbUSptSzF1QBWDV7LzEV4PaorGMRdz22+0dDL9wwjv+uiKf1pVfYkxLnULEK8aUeeSWtQ/WC/ebOfRapyM4XhWwvkiqMonM=", "ARC-Authentication-Results": "i=1; server2.sourceware.org", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=cs.ucla.edu;\n s=9D0B346E-2AEB-11ED-9476-E14B719DCE6C; t=1770841112;\n bh=y/xRklcdfZ6re3EXhKrYXhwRoq18O5CsAiEZB1IssP4=;\n h=From:To:Date:Message-ID:MIME-Version;\n b=XeKatL5XTsLuOi2b75hMCp4N+527CUuZUug+x0wxd8B6HVgPB9SBSc/iclr1byzBt\n PC8LkTvtrSbzeKJl+rGW1PSzDIiDG27SiWWbBWQ/l+d/90Gf7oLQJ/KUwGS9pc4Lwh\n U0m5+wHLYEPDokRwmPfPpDaPxHHNsBoK7x793vFzQT+cBvg5sE7Yd4fh2ANn0o2br9\n APptg2H9Hi4Dq+Mct7Tumv2kAYOL54HmFdJtHv+pXNyRz9/Iu3r44I52SFm0p7MM8C\n /8SivD6wgr+CJVAFftNpmwEpkQpB3VhvXcgtyopTf3xYFcD98m7/JRu4wPjA2pajHU\n u8uzfK7gZOYOQ==", "X-Virus-Scanned": "amavis at mail.cs.ucla.edu", "From": "Paul Eggert <eggert@cs.ucla.edu>", "To": "libc-alpha@sourceware.org", "Cc": "Paul Eggert <eggert@cs.ucla.edu>", "Subject": "[PATCH v2 2/4] Document malloc alignment", "Date": "Wed, 11 Feb 2026 12:17:35 -0800", "Message-ID": "<20260211201815.82913-3-eggert@cs.ucla.edu>", "X-Mailer": "git-send-email 2.51.0", "In-Reply-To": "<20260211201815.82913-1-eggert@cs.ucla.edu>", "References": "<20260211201815.82913-1-eggert@cs.ucla.edu>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "quoted-printable", "X-BeenThere": "libc-alpha@sourceware.org", "X-Mailman-Version": "2.1.30", "Precedence": "list", "List-Id": "Libc-alpha mailing list <libc-alpha.sourceware.org>", "List-Unsubscribe": "<https://sourceware.org/mailman/options/libc-alpha>,\n <mailto:libc-alpha-request@sourceware.org?subject=unsubscribe>", "List-Archive": "<https://sourceware.org/pipermail/libc-alpha/>", "List-Post": "<mailto:libc-alpha@sourceware.org>", "List-Help": "<mailto:libc-alpha-request@sourceware.org?subject=help>", "List-Subscribe": "<https://sourceware.org/mailman/listinfo/libc-alpha>,\n <mailto:libc-alpha-request@sourceware.org?subject=subscribe>", "Errors-To": "libc-alpha-bounces~incoming=patchwork.ozlabs.org@sourceware.org" }, "content": "* manual/memory.texi (Malloc Examples, Changing Block Size)\n(Allocating Cleared Space):\nDocument the alignment of the returned value.\n---\n manual/memory.texi | 24 ++++++++++++++++++++----\n 1 file changed, 20 insertions(+), 4 deletions(-)", "diff": "diff --git a/manual/memory.texi b/manual/memory.texi\nindex f85e8ef26d..dab2592ac3 100644\n--- a/manual/memory.texi\n+++ b/manual/memory.texi\n@@ -652,10 +652,11 @@ savestring (const char *ptr, size_t len)\n @end group\n @end smallexample\n \n-The block that @code{malloc} gives you is guaranteed to be aligned so\n-that it can hold any type of data. On @gnusystems{}, the address is\n-always a multiple of eight on 32-bit systems, and a multiple of 16 on\n-64-bit systems. Only rarely is any higher boundary (such as a page\n+In @theglibc{}, the block that @code{malloc} gives you is guaranteed\n+to be aligned so that its address is a multiple of\n+@code{alignof (max_align_t)}, so that it can hold object types\n+with any fundamental alignment and without stricter alignment specifiers.\n+Only rarely is any higher boundary (such as a page\n boundary) necessary; for those cases, use @code{aligned_alloc} or\n @code{posix_memalign} (@pxref{Aligned Memory Blocks}).\n \n@@ -677,6 +678,11 @@ returns a non-null pointer to a newly allocated size-zero block;\n other implementations may return @code{NULL} instead.\n POSIX and the ISO C standard allow both behaviors.\n \n+@item\n+In implementations other than @theglibc{}, a non-null pointer returned\n+by @code{malloc (@var{size})} is guaranteed to be aligned only for\n+fundamentally-aligned objects of size at most @code{max (@var{size}, 1)}.\n+\n @item\n In @theglibc{}, a failed @code{malloc} call sets @code{errno},\n but ISO C does not require this and non-POSIX implementations\n@@ -866,6 +872,10 @@ Otherwise, if @var{newsize} is zero\n Otherwise, if @code{realloc} cannot reallocate the requested size\n it returns @code{NULL} and sets @code{errno}; the original block\n is left undisturbed.\n+\n+Any non-null pointer returned by @code{realloc} satisfies the same\n+alignment restrictions as a similar pointer returned by @code{malloc}\n+with the same size.\n @end deftypefun\n \n @deftypefun {void *} reallocarray (void *@var{ptr}, size_t @var{nmemb}, size_t @var{size})\n@@ -980,6 +990,12 @@ is declared in @file{stdlib.h}.\n This function allocates a block long enough to contain a vector of\n @var{count} elements, each of size @var{eltsize}. Its contents are\n cleared to zero before @code{calloc} returns.\n+\n+In @theglibc{}, the vector is aligned the same way that @code{malloc}\n+aligns its returned values. In other implementations, it is merely\n+aligned suitably for any array of fundamentally-aligned elements each\n+with size at most @code{max (@var{size}, 1)}.\n+\n @end deftypefun\n \n You could define @code{calloc} as follows:\n", "prefixes": [ "v2", "2/4" ] }