From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.4 Received: from second.openwall.net (second.openwall.net [193.110.157.125]) by inbox.vuxu.org (Postfix) with SMTP id BD62621646 for ; Mon, 6 May 2024 16:50:48 +0200 (CEST) Received: (qmail 3845 invoked by uid 550); 6 May 2024 14:50:44 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 3789 invoked from network); 6 May 2024 14:50:43 -0000 Date: Mon, 6 May 2024 10:50:57 -0400 From: Rich Felker To: Tony Ambardar Cc: musl@lists.openwall.com Message-ID: <20240506145056.GG10433@brightrain.aerifal.cx> References: <20240421153640.379015-1-Tony.Ambardar@gmail.com> <20240423234355.2414567-1-Tony.Ambardar@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240423234355.2414567-1-Tony.Ambardar@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] [PATCH v2] add renameat2 linux syscall wrapper On Tue, Apr 23, 2024 at 04:43:55PM -0700, Tony Ambardar wrote: > This syscall is available since Linux 3.15 and also implemented in glibc > from version 2.28. It is commonly used in filesystem or security contexts. > > Constants RENAME_NOREPLACE, RENAME_EXCHANGE, RENAME_WHITEOUT are guarded by > _GNU_SOURCE as with glibc. > > Signed-off-by: Tony Ambardar > --- > v1 -> v2: > * align related constants > * drop 'int' from 'unsigned int' > * add fallback to SYS_renameat where applicable > --- > include/stdio.h | 7 +++++++ > src/linux/renameat2.c | 12 ++++++++++++ > 2 files changed, 19 insertions(+) > create mode 100644 src/linux/renameat2.c > > diff --git a/include/stdio.h b/include/stdio.h > index cb858618..4ea4c170 100644 > --- a/include/stdio.h > +++ b/include/stdio.h > @@ -158,6 +158,13 @@ char *ctermid(char *); > #define L_ctermid 20 > #endif > > +#if defined(_GNU_SOURCE) > +#define RENAME_NOREPLACE (1 << 0) > +#define RENAME_EXCHANGE (1 << 1) > +#define RENAME_WHITEOUT (1 << 2) > + > +int renameat2(int, const char *, int, const char *, unsigned); > +#endif > > #if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) \ > || defined(_BSD_SOURCE) > diff --git a/src/linux/renameat2.c b/src/linux/renameat2.c > new file mode 100644 > index 00000000..48ee8d53 > --- /dev/null > +++ b/src/linux/renameat2.c > @@ -0,0 +1,12 @@ > +#define _GNU_SOURCE > +#include > +#include "syscall.h" > + > +int renameat2(int oldfd, const char *old, int newfd, const char *new, unsigned flags) > +{ > + int r = __syscall(SYS_renameat2, oldfd, old, newfd, new, flags); > +#ifdef SYS_renameat > + if (r==-ENOSYS && !flags) r = __syscall(SYS_renameat, oldfd, old, newfd, new); > +#endif > + return __syscall_ret(r); > +} > -- > 2.34.1 If flags is 0, the SYS_renameat syscall is semantically equivalent to the SYS_renameat2 one, so it would be better to just unconditionally do that first rather than failing and falling back. Rich