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

Le 17 mars 2024 17:03:32 GMT+01:00, Meiyong Yu [off-list ref] a écrit :

quoted

On Mar 17, 2024, at 17:04, Max Gautier [off-list ref] 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 <redacted>
---
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
+            ) {
+        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

if (strcmp(default_dbname, dbname) == 0

Do you consider when the input dbname is relative path, for example: ../../var/lib/arpd/arpd.db, anther example: //var//lib//arpd//arpd.db

I don't. IMO this is a corner case which isn't worth doing path normalization.
Symlinks are not considered either.