[PATCH v2] Remove several implicit function declarations

[PATCH v2] Remove several implicit function declarations

[Arjun Shankar]

During configure, several ioctl checks omit the corresponding include
and a pwritev2 check uses the wrong feature test macro.
This commit fixes the same.

Signed-off-by: Arjun Shankar <arjun@redhat.com>
---
We ran into these when trying to port Fedora to modern C:

https://fedoraproject.org/wiki/Changes/PortingToModernC
https://fedoraproject.org/wiki/Toolchain/PortingToModernC

v2 notes: Removed the changes to unicrash.c;
          it was already fixed by 5ead2de386d879
---
 m4/package_libcdev.m4 | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
index bb1ab49c..f987aa4a 100644
--- a/m4/package_libcdev.m4
+++ b/m4/package_libcdev.m4
@@ -117,6 +117,7 @@ AC_DEFUN([AC_HAVE_FIEMAP],
 #define _GNU_SOURCE
 #include <linux/fs.h>
 #include <linux/fiemap.h>
+#include <sys/ioctl.h>
 	]], [[
 struct fiemap *fiemap;
 ioctl(0, FS_IOC_FIEMAP, (unsigned long)fiemap);
@@ -153,7 +154,7 @@ AC_DEFUN([AC_HAVE_PWRITEV2],
   [ AC_MSG_CHECKING([for pwritev2])
     AC_LINK_IFELSE(
     [	AC_LANG_PROGRAM([[
-#define _BSD_SOURCE
+#define _GNU_SOURCE
 #include <sys/uio.h>
 	]], [[
 pwritev2(0, 0, 0, 0, 0);
@@ -454,6 +455,7 @@ AC_DEFUN([AC_HAVE_SG_IO],
     AC_COMPILE_IFELSE(
     [	AC_LANG_PROGRAM([[
 #include <scsi/sg.h>
+#include <sys/ioctl.h>
 	]], [[
 struct sg_io_hdr hdr;
 ioctl(0, SG_IO, &hdr);
@@ -471,7 +473,8 @@ AC_DEFUN([AC_HAVE_HDIO_GETGEO],
   [ AC_MSG_CHECKING([for struct hd_geometry ])
     AC_COMPILE_IFELSE(
     [	AC_LANG_PROGRAM([[
-#include <linux/hdreg.h>,
+#include <linux/hdreg.h>
+#include <sys/ioctl.h>
 	]], [[
 struct hd_geometry hdr;
 ioctl(0, HDIO_GETGEO, &hdr);
-- 
2.38.1

Re: [PATCH v2] Remove several implicit function declarations

[Darrick J. Wong]

On Wed, Feb 08, 2023 at 03:34:16PM +0100, Arjun Shankar wrote:
> During configure, several ioctl checks omit the corresponding include
> and a pwritev2 check uses the wrong feature test macro.
> This commit fixes the same.
> 
> Signed-off-by: Arjun Shankar <arjun@redhat.com>
> ---
> We ran into these when trying to port Fedora to modern C:
> 
> https://fedoraproject.org/wiki/Changes/PortingToModernC
> https://fedoraproject.org/wiki/Toolchain/PortingToModernC
> 
> v2 notes: Removed the changes to unicrash.c;
>           it was already fixed by 5ead2de386d879
> ---
>  m4/package_libcdev.m4 | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
> index bb1ab49c..f987aa4a 100644
> --- a/m4/package_libcdev.m4
> +++ b/m4/package_libcdev.m4
> @@ -117,6 +117,7 @@ AC_DEFUN([AC_HAVE_FIEMAP],
>  #define _GNU_SOURCE
>  #include <linux/fs.h>
>  #include <linux/fiemap.h>
> +#include <sys/ioctl.h>
>  	]], [[
>  struct fiemap *fiemap;
>  ioctl(0, FS_IOC_FIEMAP, (unsigned long)fiemap);
> @@ -153,7 +154,7 @@ AC_DEFUN([AC_HAVE_PWRITEV2],
>    [ AC_MSG_CHECKING([for pwritev2])
>      AC_LINK_IFELSE(
>      [	AC_LANG_PROGRAM([[
> -#define _BSD_SOURCE
> +#define _GNU_SOURCE

Could you update the pwritev2 manpage to document that _GNU_SOURCE is
the feature test macro for pwritev2?

>  #include <sys/uio.h>
>  	]], [[
>  pwritev2(0, 0, 0, 0, 0);
> @@ -454,6 +455,7 @@ AC_DEFUN([AC_HAVE_SG_IO],
>      AC_COMPILE_IFELSE(
>      [	AC_LANG_PROGRAM([[
>  #include <scsi/sg.h>
> +#include <sys/ioctl.h>
>  	]], [[
>  struct sg_io_hdr hdr;
>  ioctl(0, SG_IO, &hdr);
> @@ -471,7 +473,8 @@ AC_DEFUN([AC_HAVE_HDIO_GETGEO],
>    [ AC_MSG_CHECKING([for struct hd_geometry ])
>      AC_COMPILE_IFELSE(
>      [	AC_LANG_PROGRAM([[
> -#include <linux/hdreg.h>,

Gosh, how did that ever work with the trailing comma??

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> +#include <linux/hdreg.h>
> +#include <sys/ioctl.h>
>  	]], [[
>  struct hd_geometry hdr;
>  ioctl(0, HDIO_GETGEO, &hdr);
> -- 
> 2.38.1
> 

Re: [PATCH v2] Remove several implicit function declarations

[Arjun Shankar]

On Wed, Feb 8, 2023 at 5:43 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Wed, Feb 08, 2023 at 03:34:16PM +0100, Arjun Shankar wrote:
> > During configure, several ioctl checks omit the corresponding include
> > and a pwritev2 check uses the wrong feature test macro.
> > This commit fixes the same.
> >
> > Signed-off-by: Arjun Shankar <arjun@redhat.com>
> > ---
> > We ran into these when trying to port Fedora to modern C:
> >
> > https://fedoraproject.org/wiki/Changes/PortingToModernC
> > https://fedoraproject.org/wiki/Toolchain/PortingToModernC
> >
> > v2 notes: Removed the changes to unicrash.c;
> >           it was already fixed by 5ead2de386d879
> > ---
> >  m4/package_libcdev.m4 | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
> > index bb1ab49c..f987aa4a 100644
> > --- a/m4/package_libcdev.m4
> > +++ b/m4/package_libcdev.m4
> > @@ -117,6 +117,7 @@ AC_DEFUN([AC_HAVE_FIEMAP],
> >  #define _GNU_SOURCE
> >  #include <linux/fs.h>
> >  #include <linux/fiemap.h>
> > +#include <sys/ioctl.h>
> >       ]], [[
> >  struct fiemap *fiemap;
> >  ioctl(0, FS_IOC_FIEMAP, (unsigned long)fiemap);
> > @@ -153,7 +154,7 @@ AC_DEFUN([AC_HAVE_PWRITEV2],
> >    [ AC_MSG_CHECKING([for pwritev2])
> >      AC_LINK_IFELSE(
> >      [        AC_LANG_PROGRAM([[
> > -#define _BSD_SOURCE
> > +#define _GNU_SOURCE
>
> Could you update the pwritev2 manpage to document that _GNU_SOURCE is
> the feature test macro for pwritev2?

Thanks for pointing this out. I'm making a note to get this done. In
addition, there's a chance that pwritev2 might be made available under
_DEFAULT_SOURCE in future versions of glibc. Either way, current
versions of glibc do make this function available under _GNU_SOURCE
and that needs to be documented.

> >  #include <sys/uio.h>
> >       ]], [[
> >  pwritev2(0, 0, 0, 0, 0);
> > @@ -454,6 +455,7 @@ AC_DEFUN([AC_HAVE_SG_IO],
> >      AC_COMPILE_IFELSE(
> >      [        AC_LANG_PROGRAM([[
> >  #include <scsi/sg.h>
> > +#include <sys/ioctl.h>
> >       ]], [[
> >  struct sg_io_hdr hdr;
> >  ioctl(0, SG_IO, &hdr);
> > @@ -471,7 +473,8 @@ AC_DEFUN([AC_HAVE_HDIO_GETGEO],
> >    [ AC_MSG_CHECKING([for struct hd_geometry ])
> >      AC_COMPILE_IFELSE(
> >      [        AC_LANG_PROGRAM([[
> > -#include <linux/hdreg.h>,
>
> Gosh, how did that ever work with the trailing comma??

That surprised me as well. cpp seems to complain about it but is fine
with it for some reason.

> Reviewed-by: Darrick J. Wong <djwong@kernel.org>

Thanks for the review!