Add dlns_get and add dlns_create2

Need one interface to get dlns, and can set default parent for new namespace. add dlns_create2 interface which caller can create namespace without inherit
from default namespace.

test: creat2 without flags
Signed-off-by: Nhuanghuijin <huanghuijin@huawei.com>

libc-test/src/functionalext/dlns/dlns_dlopen.c

@@ -220,6 +220,55 @@ void dlopen_ns_0500(void)
     dlclose(handle);
 }
 
+/**
+ * @tc.name      : dlns_get_0100
+ * @tc.desc      : Gets an existing namespace handle.
+ * @tc.level     : Level 1
+ */
+void dlns_get_0100(void)
+{
+    Dl_namespace dlns;
+    dlns_init(&dlns, "dlns_get_0100");
+    dlns_create(&dlns, NULL);
+    dlns_get("dlns_get_0100", &dlns);
+    EXPECT_EQ("dlns_get_0100", strcmp(dlns.name, "dlns_get_0100"), 0);
+}
+
+/**
+ * @tc.name      : dlns_get_0200
+ * @tc.desc      : Gets the current namespace handle when name=NULL.
+ * @tc.level     : Level 1
+ */
+void dlns_get_0200(void)
+{
+    Dl_namespace dlns;
+    dlns_get(NULL, &dlns);
+    EXPECT_EQ("dlns_get_0200", strcmp(dlns.name, "default"), 0);
+}
+
+/**
+ * @tc.name      : dlns_get_0300
+ * @tc.desc      : Call dlns_get when dlns=NULL.
+ * @tc.level     : Level 2
+ */
+void dlns_get_0300(void)
+{
+    dlns_get(NULL, NULL);
+    EXPECT_EQ("dlns_get_0300", dlns_get(NULL, NULL), EINVAL);
+}
+
+/**
+ * @tc.name      : dlns_get_0400
+ * @tc.desc      : Gets a namespace handle that does not exist.
+ * @tc.level     : Level 2
+ */
+void dlns_get_0400(void)
+{
+    Dl_namespace dlns;
+    dlns_init(&dlns, "dlns_get_0400");
+    EXPECT_EQ("dlns_get_0400", dlns_get("dlns_get_0400", &dlns), ENOKEY);
+}
+
 TEST_FUN G_Fun_Array[] = {
     dlopen_0100,
     dlopen_0200,
@@ -235,6 +284,10 @@ TEST_FUN G_Fun_Array[] = {
     dlopen_ns_0300,
     dlopen_ns_0400,
     dlopen_ns_0500,
+    dlns_get_0100,
+    dlns_get_0200,
+    dlns_get_0300,
+    dlns_get_0400,
 };
 
 int main(void)

porting/linux/user/include/dlfcn.h

@@ -20,6 +20,11 @@ extern "C" {
 
 #define RTLD_DI_LINKMAP 2
 
+
+/* create flags for dlns_create */
+#define CREATE_INHERIT_DEFAULT 0x1
+#define CREATE_INHERIT_CURRENT 0x2
+
 int    dlclose(void *);
 char  *dlerror(void);
 void  *dlopen(const char *, int);
@@ -33,17 +38,28 @@ typedef struct {
 
 /**
   * @brief Initialize a namespace structure for operating namespaces through related functional interfaces.
-  * @param Dl_namespace * Carry the naming information of the namespace.
+  * @param Dl_namespace * namespace handle.
   * @param char * namespace name.
   * @return void.
   * @retval none.
   */
 void dlns_init(Dl_namespace *, const char *);
 
+/**
+  * @brief Gets the current namespace handle, or verifies that the given name namespace exists.
+  * @param char * Namespace name.Gets the current caller namespace handle when name is null.
+  * @param Dl_namespace * namespace handle.
+  * @return return 0 on success,fail other values.
+  * @retval
+  *    EINVAL(22) Invalid argument.
+  *    ENOKEY(126) Required key not available.
+  */
+int dlns_get(const char *, Dl_namespace *);
+
 /**
   * @brief open dso in given namespace which has own lib search paths, when namespace is null, it's same to dlopen().
   *        avoid using "default" as namespace, which is the default namespace.
-  * @param Dl_namespace * Carry the naming information of the namespace.
+  * @param Dl_namespace * namespace handle.
   * @param char * the name of the so file you want to open.
   * @param int open file mode.
   *    -- RTLD_LAZY.
@@ -61,7 +77,7 @@ void *dlopen_ns(Dl_namespace *, const char *, int);
   * @brief create the namespace and set lib search paths of namespace,
   *        the paths should be splited by ':'. When namespace already exist,return error.
   *        avoid using "default" as namespace, which is the default namespace.
-  * @param Dl_namespace * namespace information.
+  * @param Dl_namespace * namespace handle.
   * @param char * lib path library that can be specified.
   * @return return 0 on success,fail other values.
   * @retval
@@ -71,6 +87,20 @@ void *dlopen_ns(Dl_namespace *, const char *, int);
   */
 int dlns_create(Dl_namespace *, const char *);
 
+/**
+  * @brief create the namespace and set lib search paths of namespace,
+  *        like dlns_create, except can use flags to set parent ns.
+  * @param Dl_namespace * namespace handle.
+  * @param char * lib path library that can be specified.
+  * #param int flags for create namespace, CREATE_INHERIT_CURRENT or CREATE_INHERIT_DEFAULT.
+  * @return return 0 on success,fail other values.
+  * @retval
+  *    EINVAL(22) Invalid argument.
+  *    EEXIST(17) File exists.
+  *    ENOMEM(12) Out of memory.
+  */
+int dlns_create2(Dl_namespace *, const char *, int);
+
 /**
   * @brief make one namespace inherit another, and so it can use shared libs by the inherited one.
   *        param1: namespace, param2: inherited namespace, param3: shared libs.

porting/linux/user/ldso/README.md

@@ -15,4 +15,4 @@ There are two ways to use the linker namespace:
 
 ### Usage example
 
-Test usages show some examples of using the linker namespace. The file <ld-musl-namespace.ini> in current directory is configures for test. The file <libc-test/src/functional/dlopen_ns.c> gives usages of how apis and configures work.
+Test usages show some examples of using the linker namespace. The file <ld-musl-namespace-arm.ini> or <ld-musl-namespace-aarch64.ini> in config directory is configures for test. The file <libc-test/src/functionalext/dlns/> gives usages of how apis and configures work.

porting/linux/user/ldso/dynlink.c

@@ -2636,6 +2636,36 @@ void dlns_init(Dl_namespace *dlns, const char *name)
 	LD_LOGI("dlns_init dlns->name:%s .\n", dlns->name);
 }
 
+int dlns_get(const char *name, Dl_namespace *dlns)
+{
+	if (!dlns) {
+		LD_LOGW("dlns_get dlns is null.\n");
+		return EINVAL;
+	}
+	int ret = 0;
+	ns_t *ns = NULL;
+	pthread_rwlock_rdlock(&lock);
+	if (!name) {
+		struct dso *caller;
+		const void *caller_addr = __builtin_return_address(0);
+		caller = (struct dso *)addr2dso((size_t)caller_addr);
+		ns = ((caller && caller->namespace) ? caller->namespace : get_default_ns());
+		(void)snprintf(dlns->name, sizeof dlns->name, ns->ns_name);
+		LD_LOGI("dlns_get name is null, current dlns dlns->name:%s.\n", dlns->name);
+	} else {
+		ns = find_ns_by_name(name);
+		if (ns) {
+			(void)snprintf(dlns->name, sizeof dlns->name, ns->ns_name);
+			LD_LOGI("dlns_get found ns, current dlns dlns->name:%s.\n", dlns->name);
+		} else {
+			LD_LOGI("dlns_get not found ns! name:%s.\n", name);
+			ret = ENOKEY;
+		}
+	}
+	pthread_rwlock_unlock(&lock);
+	return ret;
+}
+
 void *dlopen_ns(Dl_namespace *dlns, const char *file, int mode)
 {
 	const void *caller_addr = __builtin_return_address(0);
@@ -2643,7 +2673,7 @@ void *dlopen_ns(Dl_namespace *dlns, const char *file, int mode)
 	return dlopen_impl(file, mode, dlns->name, caller_addr, NULL);
 }
 
-int dlns_create(Dl_namespace *dlns, const char *lib_path)
+int dlns_create2(Dl_namespace *dlns, const char *lib_path, int flags)
 {
 	if (!dlns) {
 		LD_LOGW("dlns_create dlns is null.\n");
@@ -2668,7 +2698,20 @@ int dlns_create(Dl_namespace *dlns, const char *lib_path)
 	ns_add_dso(ns, get_default_ns()->ns_dsos->dsos[0]); /* add main app to this namespace*/
 	nslist_add_ns(ns); /* add ns to list*/
 	ns_set_lib_paths(ns, lib_path);
-	ns_add_inherit(ns, get_default_ns(), NULL);
+
+	if ((flags & CREATE_INHERIT_DEFAULT) != 0) {
+		ns_add_inherit(ns, get_default_ns(), NULL);
+	}
+
+	if ((flags & CREATE_INHERIT_CURRENT) != 0) {
+		struct dso *caller;
+		const void *caller_addr = __builtin_return_address(0);
+		caller = (struct dso *)addr2dso((size_t)caller_addr);
+		if (caller && caller->namespace) {
+			ns_add_inherit(ns, caller->namespace, NULL);
+		}
+	}
+
 	LD_LOGI("dlns_create :"
 			"ns: %p ,"
 			"ns_name: %s ,"
@@ -2680,6 +2723,11 @@ int dlns_create(Dl_namespace *dlns, const char *lib_path)
 	return 0;
 }
 
+int dlns_create(Dl_namespace *dlns, const char *lib_path)
+{
+	return dlns_create2(dlns, lib_path, CREATE_INHERIT_DEFAULT);
+}
+
 int dlns_inherit(Dl_namespace *dlns, Dl_namespace *inherited, const char *shared_libs)
 {
 	if (!dlns || !inherited) {