sysctl: fix compatibility with procps sysctl

Busybox sysctl is incompatible with procps when '.' appears in
directory name, mostly happens with VLANs.

        busybox syntax (since 2008): net.ipv4.conf.eth0.100.mc_forwarding
         procps syntax (since 2002): net.ipv4.conf.eth0/100.mc_forwarding
                 (supported by both: net/ipv4/conf/eth0.100/mc_forwarding)

Use procps syntax for output; for input, allow both.

function                                             old     new   delta
sysctl_dots_to_slashes                                86     143     +57
sysctl_act_on_setting                                443     453     +10
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 67/0)               Total: 67 bytes

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/procps/sysctl.c b/procps/sysctl.c
index 5303460f93b82f2631773463cd91e521dd2572a9..6d77185caec8ef5b2c6887b2a1df85f749acab13 100644 (file)
--- a/procps/sysctl.c
+++ b/procps/sysctl.c
@@ -56,9 +56,32 @@ enum {
 
 static void sysctl_dots_to_slashes(char *name)
 {
-       char *cptr, *last_good, *end;
+       char *cptr, *last_good, *end, *slash;
        char end_ch;
 
+       end = strchrnul(name, '=');
+
+       slash = strchrnul(name, '/');
+       if (slash < end
+        && strchrnul(name, '.') < slash
+       ) {
+               /* There are both dots and slashes, and 1st dot is
+                * before 1st slash.
+                * (IOW: not raw, unmangled a/b/c.d format)
+                *
+                * procps supports this syntax for names with dots:
+                *  net.ipv4.conf.eth0/100.mc_forwarding
+                * (dots and slashes are simply swapped)
+                */
+               while (end != name) {
+                       end--;
+                       if (*end == '.') *end = '/';
+                       else if (*end == '/') *end = '.';
+               }
+               return;
+       }
+       /* else: use our old behavior: */
+
        /* Convert minimum number of '.' to '/' so that
         * we end up with existing file's name.
         *
@@ -77,7 +100,6 @@ static void sysctl_dots_to_slashes(char *name)
         *
         * To set up testing: modprobe 8021q; vconfig add eth0 100
         */
-       end = strchrnul(name, '=');
        end_ch = *end;
        *end = '.'; /* trick the loop into trying full name too */
 
@@ -114,6 +136,8 @@ static int sysctl_act_on_setting(char *setting)
        while (*cptr) {
                if (*cptr == '/')
                        *cptr = '.';
+               else if (*cptr == '.')
+                       *cptr = '/';
                cptr++;
        }