sysctl: fix bug 3894 (by Kryzhanovskyy Maksym)

function                                             old     new   delta
sysctl_dots_to_slashes                                 -      47     +47
sysctl_write_setting                                 310     298     -12
sysctl_read_setting                                  296     284     -12
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/2 up/down: 47/-24)             Total: 23 bytes

1 files changed, 23 insertions, 4 deletions

diff --git a/procps/sysctl.c b/procps/sysctl.c
index 79f0074c9..18caa2c11 100644
--- a/procps/sysctl.c
+++ b/procps/sysctl.c
@@ -20,6 +20,7 @@ static int sysctl_read_setting(const char *setting);
 static int sysctl_write_setting(const char *setting);
 static int sysctl_display_all(const char *path);
 static int sysctl_preload_file_and_exit(const char *filename);
+static void sysctl_dots_to_slashes(char *name);
 
 static const char ETC_SYSCTL_CONF[] ALIGN1 = "/etc/sysctl.conf";
 static const char PROC_SYS[] ALIGN1 = "/proc/sys/";
@@ -143,8 +144,7 @@ static int sysctl_write_setting(const char *setting)
         tmpname = xasprintf("%s%.*s", PROC_SYS, (int)(equals - name), name);
         outname = xstrdup(tmpname + strlen_PROC_SYS);
 
-        while ((cptr = strchr(tmpname, '.')) != NULL)
-                *cptr = '/';
+        sysctl_dots_to_slashes(tmpname);
 
         while ((cptr = strchr(outname, '/')) != NULL)
                 *cptr = '.';
@@ -198,8 +198,8 @@ static int sysctl_read_setting(const char *name)
         tmpname = concat_path_file(PROC_SYS, name);
         outname = xstrdup(tmpname + strlen_PROC_SYS);
 
-        while ((cptr = strchr(tmpname, '.')) != NULL)
-                *cptr = '/';
+        sysctl_dots_to_slashes(tmpname);
+
         while ((cptr = strchr(outname, '/')) != NULL)
                 *cptr = '.';
 
@@ -266,3 +266,22 @@ static int sysctl_display_all(const char *path)
 
         return retval;
 } /* end sysctl_display_all() */
+
+static void sysctl_dots_to_slashes(char *name)
+{
+        char *cptr = name;
+
+        /* Example from bug 3894:
+         * net.ipv4.conf.eth0.100.mc_forwarding ->
+         * net/ipv4/conf/eth0.100/mc_forwarding */
+        while (*cptr != '\0') {
+                if (*cptr == '.') {
+                        *cptr = '\0';
+                        if (access(name, F_OK) == 0)
+                                *cptr = '/';
+                        else
+                                *cptr = '.';
+                }
+                cptr++;
+        }
+} /* end sysctl_dots_to_slashes() */