Re: [PATCH mtd-utils] include sys/sysmacros.h for major/minor/makedev

Re: [PATCH mtd-utils] include sys/sysmacros.h for major/minor/makedev

[Brian Norris]

+ man-page and glibc folks

On Sat, Apr 16, 2016 at 10:30:45PM -0400, Mike Frysinger wrote:
> These functions have always been defined in sys/sysmacros.h under
> Linux C libraries.  For some, including sys/types.h implicitly
> includes that as well, but glibc wants to deprecate that, and some
> others already have.  Include the header explicitly for the funcs.
> 
> Signed-off-by: Mike Frysinger <vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>

Patch looks fine to me, thanks. Pushed to mtd-utils.git.

But I don't see this change documented anywhere. (Helpfully, I do see
the change from your other patch -- _BSD_SOURCE -> _DEFAULT_SOURCE --
documented though!) Should the man-pages project be updated? I see the
latest makedev(5) still recommends #include <sys/types.h>.

Brian

> ---
>  include/common.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/common.h b/include/common.h
> index fb0ca83..8cb3142 100644
> --- a/include/common.h
> +++ b/include/common.h
> @@ -28,6 +28,7 @@
>  #include <errno.h>
>  #include <features.h>
>  #include <inttypes.h>
> +#include <sys/sysmacros.h>
>  #include "version.h"
>  
>  #ifndef PROGRAM_NAME
> -- 
> 2.7.4
> 
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Re: [PATCH mtd-utils] include sys/sysmacros.h for major/minor/makedev

[Mike Frysinger]

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On 18 Apr 2016 09:39, Brian Norris wrote:
> On Sat, Apr 16, 2016 at 10:30:45PM -0400, Mike Frysinger wrote:
> > These functions have always been defined in sys/sysmacros.h under
> > Linux C libraries.  For some, including sys/types.h implicitly
> > includes that as well, but glibc wants to deprecate that, and some
> > others already have.  Include the header explicitly for the funcs.
> > 
> > Signed-off-by: Mike Frysinger <vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
> 
> Patch looks fine to me, thanks. Pushed to mtd-utils.git.
> 
> But I don't see this change documented anywhere. (Helpfully, I do see
> the change from your other patch -- _BSD_SOURCE -> _DEFAULT_SOURCE --
> documented though!) Should the man-pages project be updated? I see the
> latest makedev(5) still recommends #include <sys/types.h>.

glibc hasn't moved forward (yet).  we should update the man pages now
though to mention sys/sysmacros.h.
-mike

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[PATCH] makedev(3): point people at sys/sysmacros.h

[Mike Frysinger]

Defining these functions via sys/types.h violates POSIX namespace
requirements, so we want to disentangle it from that header.  Since
glibc has basically always used this header, update the docs to have
people include that instead.

Signed-off-by: Mike Frysinger <vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
---
 man3/makedev.3 | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/man3/makedev.3 b/man3/makedev.3
index f91f4b5..3d26d15 100644
--- a/man3/makedev.3
+++ b/man3/makedev.3
@@ -28,23 +28,13 @@
 makedev, major, minor \- manage a device number
 .SH SYNOPSIS
 .nf
-.B #include <sys/types.h>
+.B #include <sys/sysmacros.h>
 
 .BI "dev_t makedev(unsigned int " maj ", unsigned int " min );
 
 .BI "unsigned int major(dev_t " dev );
 .BI "unsigned int minor(dev_t " dev );
 .fi
-.sp
-.BR makedev (),
-.BR major (),
-.BR minor ():
-.nf
-    Since glibc 2.19:
-        _DEFAULT_SOURCE
-    In glibc up to and including 2.19:
-        _BSD_SOURCE
-.fi
 .SH DESCRIPTION
 A device ID consists of two parts:
 a major ID, identifying the class of the device,
@@ -90,7 +80,9 @@ and
 .BR minor ()
 functions are not specified in POSIX.1,
 but are present on many other systems.
-.\" The BSDs, HP-UX, Solaris, AIX, Irix
+.\" The BSDs, HP-UX, Solaris, AIX, Irix.
+.\" The header location is inconsistent:
+.\" Could be sys/mkdev.h, sys/sysmacros.h, or sys/types.h.
 .SH NOTES
 These interfaces are defined as macros.
 Since glibc 2.3.3,
-- 
2.7.4

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Re: [PATCH] makedev(3): point people at sys/sysmacros.h

[Michael Kerrisk (man-pages)]

Hi Mike,

I don't object to the patch, but...

On 04/19/2016 06:52 AM, Mike Frysinger wrote:
> Defining these functions via sys/types.h violates POSIX namespace
> requirements, 

What do the previous lines mean? Violate namespace requirements how?

Cheers,

Michael


> so we want to disentangle it from that header.  Since
> glibc has basically always used this header, update the docs to have
> people include that instead.
>
> Signed-off-by: Mike Frysinger <vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
> ---
>  man3/makedev.3 | 16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
> 
> diff --git a/man3/makedev.3 b/man3/makedev.3
> index f91f4b5..3d26d15 100644
> --- a/man3/makedev.3
> +++ b/man3/makedev.3
> @@ -28,23 +28,13 @@
>  makedev, major, minor \- manage a device number
>  .SH SYNOPSIS
>  .nf
> -.B #include <sys/types.h>
> +.B #include <sys/sysmacros.h>
>  
>  .BI "dev_t makedev(unsigned int " maj ", unsigned int " min );
>  
>  .BI "unsigned int major(dev_t " dev );
>  .BI "unsigned int minor(dev_t " dev );
>  .fi
> -.sp
> -.BR makedev (),
> -.BR major (),
> -.BR minor ():
> -.nf
> -    Since glibc 2.19:
> -        _DEFAULT_SOURCE
> -    In glibc up to and including 2.19:
> -        _BSD_SOURCE
> -.fi
>  .SH DESCRIPTION
>  A device ID consists of two parts:
>  a major ID, identifying the class of the device,
> @@ -90,7 +80,9 @@ and
>  .BR minor ()
>  functions are not specified in POSIX.1,
>  but are present on many other systems.
> -.\" The BSDs, HP-UX, Solaris, AIX, Irix
> +.\" The BSDs, HP-UX, Solaris, AIX, Irix.
> +.\" The header location is inconsistent:
> +.\" Could be sys/mkdev.h, sys/sysmacros.h, or sys/types.h.
>  .SH NOTES
>  These interfaces are defined as macros.
>  Since glibc 2.3.3,
> 


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Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: [PATCH] makedev(3): point people at sys/sysmacros.h

[Zack Weinberg]

On Wed, Apr 20, 2016 at 7:31 AM, Michael Kerrisk (man-pages)
<mtk.manpages@gmail.com> wrote:
> On 04/19/2016 06:52 AM, Mike Frysinger wrote:
>> Defining these functions via sys/types.h violates POSIX namespace
>> requirements,
>
> What do the previous lines mean? Violate namespace requirements how?

I think it's technically not true that they violate POSIX namespace
requirements, since they're only defined in the non-conforming modes.

The reason I originally proposed the change is that libstdc++
force-enables _GNU_SOURCE, which means people writing in C++ _can't_
avoid these nonstandard macros by using a strict conformance mode.

zw

Re: [PATCH] makedev(3): point people at sys/sysmacros.h

[Michael Kerrisk (man-pages)]

On 04/20/2016 01:47 PM, Zack Weinberg wrote:
> On Wed, Apr 20, 2016 at 7:31 AM, Michael Kerrisk (man-pages)
> <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> On 04/19/2016 06:52 AM, Mike Frysinger wrote:
>>> Defining these functions via sys/types.h violates POSIX namespace
>>> requirements,
>>
>> What do the previous lines mean? Violate namespace requirements how?
> 
> I think it's technically not true that they violate POSIX namespace
> requirements, since they're only defined in the non-conforming modes.
> 
> The reason I originally proposed the change is that libstdc++
> force-enables _GNU_SOURCE, which means people writing in C++ _can't_
> avoid these nonstandard macros by using a strict conformance mode.

Thanks for the explanation, Zack. I applied Mike's patch.

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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