[Buildroot] [PATCH 3/5] package/pseudo: wrap the real pseudo with a wrapper

[Arnout Vandecappelle]

On 08-11-16 23:18, Yann E. MORIN wrote:
> Running pseudo is more involved than running fakeroot. In the transition
> from using fakeroot, we just did not account for the extra requirements.
> 
> First, we explicitly tell pseudo where it is, otherwise it tries to
> guess. Its guess is correct, but it prints a warning, which is not nice.
> 
> Second, we tell it where to find the passwd and group files in case it
> has to emulate access to them. We currently do not use that feature, but
> better safe than sorry.
> 
> Third, pseudo spawns a background daemon, and talks to it (when fakeroot
> would emulate the state all in the current process' state, pseudo uses
> the daemon to coordinate the state across multiple processes). We are
> not much interested in the daemon lingering around, so we just tell it
> to terminate as soon as the last clients quits (this can take up to one
> second).
> 
> Fourth and last, pseudo always stores its internal database when
> exiting, and reloads it when spawned. The database is by default stored
> in a sub-directory of the prefix it was installed in, but this is
> impractical for us. We want the database to be specific to the one
> config dir we are building, so we store the database in a (hidden)
> sub-dir of the build dir, thus ensuring it is never shared with another
> build. That directory is hidden (starts with a dot) because we consider
> that to be our internal state that we do not want to expose to the user.
> 
> The wrapper has to be relocatable, so we avoid using hard-coded paths
> in there: we derive those paths fom the runtime path of pseudo. However,
                                  ^^^ Gah, I missed one :-P

> the build directory $(BUILD_DIR) is not available in the environment
> (we do not export it because it conflicts with some buildsystems).
> Instead, we use $(BASE_DIR) which is exported.
> 
> Finally, when relocated, the wrapper would not be used in the Buildroot
> environment, so may not have access to TARGET_DIR or BASE_DIR, unless
> the user sets them. If he does not, we still want the wrapper to be
> working (to avoid the warning about the prefix, and to exit the daemon
> asap); thus we leave the passwd and localstatedir variable alone if we
> don't have what it needs to set them, rather than set them to incorrect
> values.
> 
> Signed-off-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
> Cc: Gaël PORTAY <gael.portay at savoirfairelinux.com>
> Cc: Patrick Keroulas <patrick.keroulas at savoirfairelinux.com>
> Cc: Erico Nunes <nunes.erico at gmail.com>
> Cc: Julien BOIBESSOT <julien.boibessot at free.fr>
> Cc: Arnout Vandecappelle <arnout at mind.be>

Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout at mind.be>

 Regards,
 Arnout

> 
> ---
> Changes v1 -> v2:
>   - do not use a variable, but use a wrapper
> ---
>  package/pseudo/pseudo-wrapper | 12 ++++++++++++
>  package/pseudo/pseudo.mk      |  6 ++++++
>  2 files changed, 18 insertions(+)
>  create mode 100644 package/pseudo/pseudo-wrapper
> 
> diff --git a/package/pseudo/pseudo-wrapper b/package/pseudo/pseudo-wrapper
> new file mode 100644
> index 0000000..feaa7fc
> --- /dev/null
> +++ b/package/pseudo/pseudo-wrapper
> @@ -0,0 +1,12 @@
> +#!/bin/sh
> +
> +export PSEUDO_PREFIX="$(dirname "${0%/*}")"
> +export PSEUDO_OPTS="-t0"
> +if [ -n "${TARGET_DIR}" ]; then
> +    export PSEUDO_PASSWD="${TARGET_DIR}"
> +fi
> +if [ -n "${BASE_DIR}" ]; then
> +    export PSEUDO_LOCALSTATEDIR="${BASE_DIR}/build/.pseudodb"
> +fi
> +
> +exec "${0%-wrapper}" "${@}"
> diff --git a/package/pseudo/pseudo.mk b/package/pseudo/pseudo.mk
> index 4be5154..474eae2 100644
> --- a/package/pseudo/pseudo.mk
> +++ b/package/pseudo/pseudo.mk
> @@ -26,6 +26,12 @@ HOST_PSEUDO_CONF_OPTS = \
>  	--libdir=$(HOST_DIR)/usr/lib \
>  	--with-sqlite=$(HOST_DIR)/usr
>  
> +define HOST_PSEUDO_INSTALL_WRAPPER
> +	$(INSTALL) -D -m 0755 $(HOST_PSEUDO_PKGDIR)/pseudo-wrapper \
> +		$(HOST_DIR)/usr/bin/pseudo-wrapper
> +endef
> +HOST_PSEUDO_POST_INSTALL_HOOKS += HOST_PSEUDO_INSTALL_WRAPPER
> +
>  define HOST_PSEUDO_FAKEROOT_SYMLINK
>  	ln -sf pseudo $(HOST_DIR)/usr/bin/fakeroot
>  endef
> 

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF