Re: [eudev] [PATCH] use #pragma once for header files

[Anthony G. Basile]

On 12/5/17 1:28 PM, Marcus Folkesson wrote:
> Hi Anthony,
>
> On Tue, Dec 05, 2017 at 01:15:59PM -0500, Anthony G. Basile wrote:
>> On 12/4/17 6:34 AM, Marcus Folkesson wrote:
>>> Some headerfiles are missing "#pragma once" or corresponding
>>> "#ifndef..." which may result in build error if multiple source files
>>> include the same file.
>>>
>>> Add "#pragma once" for concerned files.
>>>
>>> Signed-off-by: Marcus Folkesson <marcus.folkesson@×××××.com>
>>> ---
>>>  src/mtd_probe/mtd_probe.h | 2 ++
>>>  src/scsi_id/scsi.h        | 2 ++
>>>  src/scsi_id/scsi_id.h     | 2 ++
>>>  src/shared/device-nodes.h | 2 ++
>>>  src/shared/fileio.h       | 2 ++
>>>  src/shared/path-util.h    | 2 ++
>>>  src/shared/siphash24.h    | 3 +++
>>>  src/shared/socket-util.h  | 2 ++
>>>  src/udev/udevadm-util.h   | 2 ++
>>>  9 files changed, 19 insertions(+)
>>>
>>> diff --git a/src/mtd_probe/mtd_probe.h b/src/mtd_probe/mtd_probe.h
>>> index e048a0122..caea5c269 100644
>>> --- a/src/mtd_probe/mtd_probe.h
>>> +++ b/src/mtd_probe/mtd_probe.h
>>> @@ -17,6 +17,8 @@
>>>   * Boston, MA  02110-1301  USA
>>>   */
>>>
>>> +#pragma once
>>> +
>>>  #include <mtd/mtd-user.h>
>>>
>>>  #include "macro.h"
>>> diff --git a/src/scsi_id/scsi.h b/src/scsi_id/scsi.h
>>> index c423cac57..3f99ae772 100644
>>> --- a/src/scsi_id/scsi.h
>>> +++ b/src/scsi_id/scsi.h
>>> @@ -10,6 +10,8 @@
>>>   *        Free Software Foundation version 2 of the License.
>>>   */
>>>
>>> +#pragma once
>>> +
>>>  #include <scsi/scsi.h>
>>>
>>>  struct scsi_ioctl_command {
>>> diff --git a/src/scsi_id/scsi_id.h b/src/scsi_id/scsi_id.h
>>> index 648b5ce42..141b116a8 100644
>>> --- a/src/scsi_id/scsi_id.h
>>> +++ b/src/scsi_id/scsi_id.h
>>> @@ -15,6 +15,8 @@
>>>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>>>   */
>>>
>>> +#pragma once
>>> +
>>>  #define MAX_PATH_LEN 512
>>>
>>>  /*
>>> diff --git a/src/shared/device-nodes.h b/src/shared/device-nodes.h
>>> index d27ac0906..5df53e8c0 100644
>>> --- a/src/shared/device-nodes.h
>>> +++ b/src/shared/device-nodes.h
>>> @@ -17,5 +17,7 @@
>>>    along with systemd; If not, see <http://www.gnu.org/licenses/>.
>>>  ***/
>>>
>>> +#pragma once
>>> +
>>>  int encode_devnode_name(const char *str, char *str_enc, size_t len);
>>>  int whitelisted_char_for_devnode(char c, const char *additional);
>>> diff --git a/src/shared/fileio.h b/src/shared/fileio.h
>>> index 641bf0230..7beed2eb8 100644
>>> --- a/src/shared/fileio.h
>>> +++ b/src/shared/fileio.h
>>> @@ -17,6 +17,8 @@
>>>    along with systemd; If not, see <http://www.gnu.org/licenses/>.
>>>  ***/
>>>
>>> +#pragma once
>>> +
>>>  #include <stddef.h>
>>>  #include <stdio.h>
>>>
>>> diff --git a/src/shared/path-util.h b/src/shared/path-util.h
>>> index 0123c2609..1d15d4c0f 100644
>>> --- a/src/shared/path-util.h
>>> +++ b/src/shared/path-util.h
>>> @@ -17,6 +17,8 @@
>>>    along with systemd; If not, see <http://www.gnu.org/licenses/>.
>>>  ***/
>>>
>>> +#pragma once
>>> +
>>>  #include <stdbool.h>
>>>
>>>  #include "macro.h"
>>> diff --git a/src/shared/siphash24.h b/src/shared/siphash24.h
>>> index 3253c179b..c2c19b437 100644
>>> --- a/src/shared/siphash24.h
>>> +++ b/src/shared/siphash24.h
>>> @@ -1,3 +1,6 @@
>>> +
>>> +#pragma once
>>> +
>>>  #include <inttypes.h>
>>>  #include <sys/types.h>
>>>
>>> diff --git a/src/shared/socket-util.h b/src/shared/socket-util.h
>>> index 2daa3279f..52b8dff66 100644
>>> --- a/src/shared/socket-util.h
>>> +++ b/src/shared/socket-util.h
>>> @@ -17,6 +17,8 @@
>>>    along with systemd; If not, see <http://www.gnu.org/licenses/>.
>>>  ***/
>>>
>>> +#pragma once
>>> +
>>>  #include <sys/socket.h>
>>>  #include <netinet/in.h>
>>>  #include <sys/un.h>
>>> diff --git a/src/udev/udevadm-util.h b/src/udev/udevadm-util.h
>>> index dba651fdd..37e4fe836 100644
>>> --- a/src/udev/udevadm-util.h
>>> +++ b/src/udev/udevadm-util.h
>>> @@ -15,6 +15,8 @@
>>>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>>>   */
>>>
>>> +#pragma once
>>> +
>>>  #include "udev.h"
>>>
>>>  struct udev_device *find_device(struct udev *udev,
>>>
>>
>> I know we have some clang users.  Does #pragma work for clang?
>>
> Actually I don't know. But #pragma is used for most of the headers already:
>
> [19:21:38]marcus@little:~/git/eudev$ git grep pragma
> src/shared/conf-files.h:21:#pragma once
> src/shared/def.h:20:#pragma once
> src/shared/dev-setup.h:20:#pragma once
> src/shared/formats-util.h:1:#pragma once
> src/shared/hashmap.h:3:#pragma once
> src/shared/label.h:20:#pragma once
> src/shared/list.h:3:#pragma once
> src/shared/log.h:20:#pragma once
> src/shared/macro.h:20:#pragma once
> src/shared/mempool.h:3:#pragma once
> src/shared/missing.h:20:#pragma once
> src/shared/mkdir.h:20:#pragma once
> src/shared/process-util.h:1:#pragma once
> src/shared/random-util.h:1:#pragma once
> src/shared/selinux-util.h:20:#pragma once
> src/shared/set.h:3:#pragma once
> src/shared/smack-util.h:22:#pragma once
> src/shared/strbuf.h:20:#pragma once
> src/shared/strv.h:20:#pragma once
> src/shared/strxcpyx.h:20:#pragma once
> src/shared/sysctl-util.h:3:#pragma once
> src/shared/terminal-util.h:1:#pragma once
> src/shared/time-util.h:20:#pragma once
> src/shared/udev-util.h:20:#pragma once
> src/shared/utf8.h:20:#pragma once
> src/shared/util.h:20:#pragma once
> src/shared/virt.h:20:#pragma once
> src/udev/udev.h:19:#pragma once
>
> Only a few headers in src/libudev/ is using the #ifndef-#define-#endif
> what I can tell.
>
> Maybe I should convert those to #pragma instead to keep it uniform.
>
>
> Best regards
> Marcus Folkesson


Yeah let's switch everything to #pragma and get rid of the ifndefs. 
clang does respect gcc's #pragma's.  See

http://clang.llvm.org/docs/UsersManual.html#controlling-diagnostics-via-pragmas

I think a single commit in which you sqaush your previous commit
together with removing the ifndefs would be best.  The commit message
could be something like "consistenlty use #pragma to avoid double
inclusion of headers" or similar.

-- 
Anthony G. Basile, Ph.D.
Gentoo Linux Developer [Hardened]
E-Mail    : basile@××××××××××.net
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