[v3] eudev: generate hwdb.bin at system startup

From: Carlos Santos <casantos@datacom.ind.br>

Programs that use libudev (e.g. lsusb, from usbutils) need the hwdb.bin
file to work properly.

If BR2_PACKAGE_EUDEV_ENABLE_HWDB is selected then the eudev installation
populates /etc/udev/hwdb.d/ but does not genarete /etc/udev/hwdb.bin. It
must be created running "udevadm hwdb --update" on the target device but
this does not work with a read-only /etc, so we need these changes:

- Add the BR2_PACKAGE_EUDEV_HWDB_BIN_PATH config, allowing the user to
  set the location of hwdb.bin.
- Patch the configuration script, allowing to set the hwdb.bin path by
  means of an environment variable (udevhwdbbinpath).
- Pass the value set in BR2_PACKAGE_EUDEV_HWDB_BIN_PATH to the configure
  script by means of the udevhwdbbinpath variable.
- Make the S10udev init script run "udevadm hwdb --update" to recreate
  hwdb.bin or print an error message if the operation fails (e.g. no
  write permission on the filesystem).

Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
Tested-by: Matt Weber <matthew.weber@rockwellcollins.com>
---
Changes v1->v2
- Incorporate fixes and improvements provided by Matt Weber
Changes v2->v3
- Make HWDB_BIN_PATH depend on ENABLE_HWDB, as pointed by Matt Weber.

Note: there was a discussion via email and on IRC, with suggetsions to
prebuild hwdb.bin at build time and to add a /etc/defaults/udev cfg file
instead patching S10udev (like in the recent S01logging suggested
updates). I like both suggestions but I'd prefer to implement them in
subsequent patches rather, since they woud require additional changes
(e.g. adding eudev as a host tool).
---
 package/eudev/Config.in | 10 ++++++++++
 package/eudev/S10udev   |  8 +++++++-
 package/eudev/eudev.mk  | 11 ++++++++++-
 3 files changed, 27 insertions(+), 2 deletions(-)

Carlos,

On Tue, Oct 16, 2018 at 12:02 PM Carlos Santos <casantos@datacom.com.br> wrote:
>
> From: Carlos Santos <casantos@datacom.ind.br>
>
> Programs that use libudev (e.g. lsusb, from usbutils) need the hwdb.bin
> file to work properly.
>
> If BR2_PACKAGE_EUDEV_ENABLE_HWDB is selected then the eudev installation
> populates /etc/udev/hwdb.d/ but does not genarete /etc/udev/hwdb.bin. It
> must be created running "udevadm hwdb --update" on the target device but
> this does not work with a read-only /etc, so we need these changes:
>
> - Add the BR2_PACKAGE_EUDEV_HWDB_BIN_PATH config, allowing the user to
>   set the location of hwdb.bin.
> - Patch the configuration script, allowing to set the hwdb.bin path by
>   means of an environment variable (udevhwdbbinpath).
> - Pass the value set in BR2_PACKAGE_EUDEV_HWDB_BIN_PATH to the configure
>   script by means of the udevhwdbbinpath variable.
> - Make the S10udev init script run "udevadm hwdb --update" to recreate
>   hwdb.bin or print an error message if the operation fails (e.g. no
>   write permission on the filesystem).
>
> Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
> Tested-by: Matt Weber <matthew.weber@rockwellcollins.com>
> ---
> Changes v1->v2
> - Incorporate fixes and improvements provided by Matt Weber
> Changes v2->v3
> - Make HWDB_BIN_PATH depend on ENABLE_HWDB, as pointed by Matt Weber.
>
> Note: there was a discussion via email and on IRC, with suggetsions to
> prebuild hwdb.bin at build time and to add a /etc/defaults/udev cfg file
> instead patching S10udev (like in the recent S01logging suggested
> updates). I like both suggestions but I'd prefer to implement them in
> subsequent patches rather, since they woud require additional changes
> (e.g. adding eudev as a host tool).
> ---
>  package/eudev/Config.in | 10 ++++++++++
>  package/eudev/S10udev   |  8 +++++++-
>  package/eudev/eudev.mk  | 11 ++++++++++-
>  3 files changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/package/eudev/Config.in b/package/eudev/Config.in
> index 2220265a55..0ee5390dfb 100644
> --- a/package/eudev/Config.in
> +++ b/package/eudev/Config.in
> @@ -32,6 +32,16 @@ config BR2_PACKAGE_EUDEV_ENABLE_HWDB
>         help
>           Enables hardware database installation to /etc/udev/hwdb.d
>
> +config BR2_PACKAGE_EUDEV_HWDB_BIN_PATH
> +       string "hwdb.bin path"
> +       depends on BR2_PACKAGE_EUDEV_ENABLE_HWDB
> +       default "/etc/udev/hwdb.bin"
> +       help
> +         Location of the hwdb.bin file, which is re-generated at system
> +         startup. The default is /etc/udev/hwdb.bin but you may want to
> +         move it elsewhere (e.g. /var/run/udev/hwdb.bin) if /etc is in
> +         a read-only filesystem.
> +
>  endif
>
>  comment "eudev needs eudev /dev management"
> diff --git a/package/eudev/S10udev b/package/eudev/S10udev
> index 4e799d6507..08aca82dd9 100755
> --- a/package/eudev/S10udev
> +++ b/package/eudev/S10udev
> @@ -21,14 +21,20 @@ UDEV_CONFIG=/etc/udev/udev.conf
>  test -r $UDEV_CONFIG || exit 6
>  . $UDEV_CONFIG
>
> +UDEV_HWDB_BIN=%%UDEV_HWDB_BIN%%
> +
>  case "$1" in
>      start)
>          printf "Populating %s using udev: " "${udev_root:-/dev}"
>          [ -e /proc/sys/kernel/hotplug ] && printf '\000\000\000\000' > /proc/sys/kernel/hotplug
>          /sbin/udevd -d || { echo "FAIL"; exit 1; }
> +        echo "done"
>          udevadm trigger --type=subsystems --action=add
>          udevadm trigger --type=devices --action=add
> -        udevadm settle --timeout=30 || echo "udevadm settle failed"
> +        udevadm settle --timeout=30 || { echo "udevadm settle failed" && exit 1; }
> +        echo "done"
> +        printf "Compiling hardware database information $UDEV_HWDB_BIN: "
> +        udevadm hwdb --update || { echo "FAIL" && exit 1; }
>          echo "done"
>          ;;
>      stop)
> diff --git a/package/eudev/eudev.mk b/package/eudev/eudev.mk
> index 11dc93762b..e4fc7c884c 100644
> --- a/package/eudev/eudev.mk
> +++ b/package/eudev/eudev.mk
> @@ -33,6 +33,12 @@ endif
>
>  ifeq ($(BR2_PACKAGE_EUDEV_ENABLE_HWDB),y)
>  EUDEV_CONF_OPTS += --enable-hwdb
> +define EUDEV_POST_PATCH
> +       $(SED) 's,$${udevconfdir}/hwdb.bin,$${udevhwdbbinpath:-$${udevconfdir}/hwdb.bin},' \
> +               $(@D)/configure
> +endef
> +EUDEV_POST_PATCH_HOOKS += EUDEV_POST_PATCH
> +EUDEV_CONF_ENV += udevhwdbbinpath=$(BR2_PACKAGE_EUDEV_HWDB_BIN_PATH)

I believe BR2_PACKAGE_EUDEV_HWDB_BIN_PATH needs a qstrip?

>  else
>  EUDEV_CONF_OPTS += --disable-hwdb
>  endif
> @@ -45,7 +51,10 @@ EUDEV_CONF_OPTS += --disable-selinux
>  endif
>
>  define EUDEV_INSTALL_INIT_SYSV
> -       $(INSTALL) -D -m 0755 package/eudev/S10udev $(TARGET_DIR)/etc/init.d/S10udev
> +       $(INSTALL) -D -m 0755 package/eudev/S10udev \
> +               $(TARGET_DIR)/etc/init.d/S10udev
> +       $(SED) 's,%%UDEV_HWDB_BIN%%,$(BR2_PACKAGE_EUDEV_HWDB_BIN_PATH),' \
> +               $(TARGET_DIR)/etc/init.d/S10udev
>  endef
>
>  # Required by default rules for input devices
> --
> 2.14.4
>

Matt

> From: "Matthew Weber" <matthew.weber@rockwellcollins.com>
> To: "DATACOM" <casantos@datacom.com.br>
> Cc: "buildroot" <buildroot@buildroot.org>, "Bernd Kuhls" <bernd.kuhls@t-online.de>, "Eric Le Bihan"
> <eric.le.bihan.dev@free.fr>, "Yann Morin" <yann.morin.1998@free.fr>, "Carlos Santos" <casantos@datacom.ind.br>
> Sent: Monday, October 29, 2018 11:11:17 AM
> Subject: Re: [PATCH v3] eudev: generate hwdb.bin at system startup

> Carlos,
> 
> On Tue, Oct 16, 2018 at 12:02 PM Carlos Santos <casantos@datacom.com.br> wrote:
>>
>> From: Carlos Santos <casantos@datacom.ind.br>
[...]
>>  ifeq ($(BR2_PACKAGE_EUDEV_ENABLE_HWDB),y)
>>  EUDEV_CONF_OPTS += --enable-hwdb
>> +define EUDEV_POST_PATCH
>> +       $(SED)
>> 's,$${udevconfdir}/hwdb.bin,$${udevhwdbbinpath:-$${udevconfdir}/hwdb.bin},' \
>> +               $(@D)/configure
>> +endef
>> +EUDEV_POST_PATCH_HOOKS += EUDEV_POST_PATCH
>> +EUDEV_CONF_ENV += udevhwdbbinpath=$(BR2_PACKAGE_EUDEV_HWDB_BIN_PATH)
> 
> I believe BR2_PACKAGE_EUDEV_HWDB_BIN_PATH needs a qstrip?

Not really, since the quotes are properly handled and may even be even
required in the unlikely situation of BR2_PACKAGE_EUDEV_HWDB_BIN_PATH
containing white spaces.

On Mon, Oct 29, 2018 at 9:34 AM Carlos Santos <casantos@datacom.com.br> wrote:
>
> > From: "Matthew Weber" <matthew.weber@rockwellcollins.com>
> > To: "DATACOM" <casantos@datacom.com.br>
> > Cc: "buildroot" <buildroot@buildroot.org>, "Bernd Kuhls" <bernd.kuhls@t-online.de>, "Eric Le Bihan"
> > <eric.le.bihan.dev@free.fr>, "Yann Morin" <yann.morin.1998@free.fr>, "Carlos Santos" <casantos@datacom.ind.br>
> > Sent: Monday, October 29, 2018 11:11:17 AM
> > Subject: Re: [PATCH v3] eudev: generate hwdb.bin at system startup
>
> > Carlos,
> >
> > On Tue, Oct 16, 2018 at 12:02 PM Carlos Santos <casantos@datacom.com.br> wrote:
> >>
> >> From: Carlos Santos <casantos@datacom.ind.br>
> [...]
> >>  ifeq ($(BR2_PACKAGE_EUDEV_ENABLE_HWDB),y)
> >>  EUDEV_CONF_OPTS += --enable-hwdb
> >> +define EUDEV_POST_PATCH
> >> +       $(SED)
> >> 's,$${udevconfdir}/hwdb.bin,$${udevhwdbbinpath:-$${udevconfdir}/hwdb.bin},' \
> >> +               $(@D)/configure
> >> +endef
> >> +EUDEV_POST_PATCH_HOOKS += EUDEV_POST_PATCH
> >> +EUDEV_CONF_ENV += udevhwdbbinpath=$(BR2_PACKAGE_EUDEV_HWDB_BIN_PATH)
> >
> > I believe BR2_PACKAGE_EUDEV_HWDB_BIN_PATH needs a qstrip?
>
> Not really, since the quotes are properly handled and may even be even
> required in the unlikely situation of BR2_PACKAGE_EUDEV_HWDB_BIN_PATH
> containing white spaces.
>
> --
> Carlos Santos (Casantos) - DATACOM, P&D
> “Marched towards the enemy, spear upright, armed with the certainty
> that only the ignorant can have.” — Epitaph of a volunteer

Reviewed-by: Matt Weber <matthew.weber@rockwellcollins.com>