libcgroup: Introduce the new namespace keyword

This patch introduces a new keywork NAMESPACE which allow cgroups
to be created starting from a certain point as mentioned by the
administrator. This is provided via the configuration file.

Newer APIs will use this feature.

Changes from v1:
1. Attempted to fix the indentation
2. Change a variable name

Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>

4 files changed, 79 insertions, 7 deletions

diff --git a/src/config.c b/src/config.c
index 130fac1..7435795 100644
--- a/src/config.c
+++ b/src/config.c
@@ -59,8 +59,11 @@ extern int yyparse(void);
  * cgroup_table_index -> Where in the cgroup_table we are.
  */
 static struct cg_mount_table_s config_mount_table[CG_CONTROLLER_MAX];
+static struct cg_mount_table_s config_namespace_table[CG_CONTROLLER_MAX];
 static int config_table_index;
+static int namespace_table_index;
 static pthread_rwlock_t config_table_lock = PTHREAD_RWLOCK_INITIALIZER;
+static pthread_rwlock_t namespace_table_lock = PTHREAD_RWLOCK_INITIALIZER;
 static struct cgroup config_cgroup_table[MAX_CGROUPS];
 int cgroup_table_index;
 
@@ -352,6 +355,36 @@ void cgroup_config_cleanup_mount_table(void)
 }
 
 /*
+ * The moment we have found the controller's information
+ * insert it into the config_mount_table.
+ */
+int cgroup_config_insert_into_namespace_table(char *name, char *nspath)
+{
+	if (namespace_table_index >= CG_CONTROLLER_MAX)
+		return 0;
+
+	pthread_rwlock_wrlock(&namespace_table_lock);
+
+	strcpy(config_namespace_table[namespace_table_index].name, name);
+	strcpy(config_namespace_table[namespace_table_index].path, nspath);
+	namespace_table_index++;
+
+	pthread_rwlock_unlock(&namespace_table_lock);
+	free(name);
+	free(nspath);
+	return 1;
+}
+
+/*
+ * Cleanup all the data from the config_mount_table
+ */
+void cgroup_config_cleanup_namespace_table(void)
+{
+	memset(&config_namespace_table, 0,
+			sizeof(struct cg_mount_table_s) * CG_CONTROLLER_MAX);
+}
+
+/*
  * Start mounting the mount table.
  */
 int cgroup_config_mount_fs()
diff --git a/src/lex.l b/src/lex.l
index 817b6b6..6291b55 100644
--- a/src/lex.l
+++ b/src/lex.l
@@ -23,11 +23,12 @@ int line_no = 1;
 [ \t]	{/* DO NOTHING */}
 ^#.*[ \t]*  {/* Comments */}
 ^\*.*[ \t]* {/* Comments */}
-"mount"	{return MOUNT;}
-"task"	{return TASK;}
-"admin"	{return ADMIN;}
-"perm"	{return PERM;}
-"group"	{return GROUP;}
+"mount"		{return MOUNT;}
+"task"		{return TASK;}
+"admin"		{return ADMIN;}
+"perm"		{return PERM;}
+"group"		{return GROUP;}
+"namespace"	{return NAMESPACE;}
 [a-zA-Z0-9_\-\/\.]+ {yylval.name = strdup(yytext); return ID;}
 .	{return yytext[0];}
 %%
diff --git a/src/libcgroup-internal.h b/src/libcgroup-internal.h
index 8ceb73e..81a7b98 100644
--- a/src/libcgroup-internal.h
+++ b/src/libcgroup-internal.h
@@ -125,6 +125,7 @@ int cgroup_config_parse_controller_options(char *controller, char *name_value);
 int cgroup_config_group_task_perm(char *perm_type, char *value);
 int cgroup_config_group_admin_perm(char *perm_type, char *value);
 int cgroup_config_insert_into_mount_table(char *name, char *mount_point);
+int cgroup_config_insert_into_namespace_table(char *name, char *mount_point);
 void cgroup_config_cleanup_mount_table(void);
 __END_DECLS
 
diff --git a/src/parse.y b/src/parse.y
index 32a3c74..47abee6 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -37,7 +37,7 @@ int yywrap(void)
 
 %}
 
-%token ID MOUNT GROUP PERM TASK ADMIN
+%token ID MOUNT GROUP PERM TASK ADMIN NAMESPACE
 
 %union {
 	char *name;
@@ -47,6 +47,7 @@ int yywrap(void)
 %type <name> ID namevalue_conf
 %type <val> mountvalue_conf mount task_namevalue_conf admin_namevalue_conf
 %type <val> admin_conf task_conf task_or_admin group_conf group start
+%type <val> namespace namespace_conf
 %start start
 %%
 
@@ -58,7 +59,11 @@ start   : start group
 	{
 		$$ = $1;
 	}
-        |
+        | start namespace
+	{
+		$$ = $1;
+	}
+	|
 	{
 		$$ = 1;
 	}
@@ -266,5 +271,37 @@ mount   :       MOUNT '{' mountvalue_conf '}'
 	}
         ;
 
+namespace_conf
+        :       ID '=' ID ';'
+	{
+		if (!cgroup_config_insert_into_namespace_table($1, $3)) {
+			cgroup_config_cleanup_namespace_table();
+			$$ = 0;
+			return $$;
+		}
+		$$ = 1;
+	}
+        |       namespace_conf ID '=' ID ';'
+	{
+		if (!cgroup_config_insert_into_namespace_table($2, $4)) {
+			cgroup_config_cleanup_namespace_table();
+			$$ = 0;
+			return $$;
+		}
+		$$ = 1;
+	}
+        ;
+
+namespace   :       NAMESPACE '{' namespace_conf '}'
+	{
+		$$ = $3;
+		if (!$$) {
+			fprintf(stderr, "parsing failed at line number %d\n",
+				line_no);
+			$$ = 0;
+			return $$;
+		}
+	}
+        ;
 
 %%