Re: [PATCH iproute2-next v2] arpd: create /var/lib/arpd on first use

[Ratheesh Kannoth <rkannoth@marvell.com>]

On 2024-03-17 at 14:31:24, Max Gautier (mg@max.gautier.name) wrote:
> The motivation is to build distributions packages without /var to go
> towards stateless systems, see link below (TL;DR: provisionning anything
> outside of /usr on boot).
>
> We only try do create the database directory when it's in the default
> location, and assume its parent (/var/lib in the usual case) exists.
>
> Links: https://0pointer.net/blog/projects/stateless.html
> Signed-off-by: Max Gautier <mg@max.gautier.name>
> ---
>  Makefile    |  2 +-
>  misc/arpd.c | 12 +++++++++++-
>  2 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 8024d45e..2b2c3dec 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -42,6 +42,7 @@ DEFINES+=-DCONF_USR_DIR=\"$(CONF_USR_DIR)\" \
>           -DCONF_ETC_DIR=\"$(CONF_ETC_DIR)\" \
>           -DNETNS_RUN_DIR=\"$(NETNS_RUN_DIR)\" \
>           -DNETNS_ETC_DIR=\"$(NETNS_ETC_DIR)\" \
> +         -DARPDDIR=\"$(ARPDDIR)\" \
>           -DCONF_COLOR=$(CONF_COLOR)
>
>  #options for AX.25
> @@ -104,7 +105,6 @@ config.mk:
>  install: all
>  	install -m 0755 -d $(DESTDIR)$(SBINDIR)
>  	install -m 0755 -d $(DESTDIR)$(CONF_USR_DIR)
> -	install -m 0755 -d $(DESTDIR)$(ARPDDIR)
>  	install -m 0755 -d $(DESTDIR)$(HDRDIR)
>  	@for i in $(SUBDIRS);  do $(MAKE) -C $$i install; done
>  	install -m 0644 $(shell find etc/iproute2 -maxdepth 1 -type f) $(DESTDIR)$(CONF_USR_DIR)
> diff --git a/misc/arpd.c b/misc/arpd.c
> index 1ef837c6..a64888aa 100644
> --- a/misc/arpd.c
> +++ b/misc/arpd.c
> @@ -19,6 +19,7 @@
>  #include <fcntl.h>
>  #include <sys/uio.h>
>  #include <sys/socket.h>
> +#include <sys/stat.h>
>  #include <sys/time.h>
>  #include <time.h>
>  #include <signal.h>
> @@ -35,7 +36,8 @@
>  #include "rt_names.h"
>
>  DB	*dbase;
> -char	*dbname = "/var/lib/arpd/arpd.db";
> +char const	default_dbname[] = ARPDDIR "/arpd.db";
> +char const	*dbname = default_dbname;
>
>  int	ifnum;
>  int	*ifvec;
> @@ -668,6 +670,14 @@ int main(int argc, char **argv)
>  		}
>  	}
>
> +	if (strcmp(default_dbname, dbname) == 0
> +			&& mkdir(ARPDDIR, 0755) != 0
> +			&& errno != EEXIST
why do you need errno != EEXIST case ? mkdir() will return error in this case as well.
> +			) {
> +		perror("create_db_dir");
> +		exit(-1);
> +	}
> +
>  	dbase = dbopen(dbname, O_CREAT|O_RDWR, 0644, DB_HASH, NULL);
>  	if (dbase == NULL) {
>  		perror("db_open");
> --
> 2.44.0
>