!250 add namespace create interface for musl

Merge pull request !250 from hhj/dlns-inf

musl_src.gni

@@ -1832,6 +1832,7 @@ musl_src_porting_file = [
   "include/sys/sysinfo.h",
   "src/internal/dynlink.h",
   "include/unistd.h",
+  "include/dlfcn.h",
   "src/internal/pthread_impl.h",
   "src/internal/syscall.h",
   "src/legacy/ulimit.c",

porting/linux/user/include/dlfcn.h

+#ifndef	_DLFCN_H
+#define	_DLFCN_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <features.h>
+
+#define RTLD_LAZY   1
+#define RTLD_NOW    2
+#define RTLD_NOLOAD 4
+#define RTLD_NODELETE 4096
+#define RTLD_GLOBAL 256
+#define RTLD_LOCAL  0
+
+#define RTLD_NEXT    ((void *)-1)
+#define RTLD_DEFAULT ((void *)0)
+
+#define RTLD_DI_LINKMAP 2
+
+int    dlclose(void *);
+char  *dlerror(void);
+void  *dlopen(const char *, int);
+void  *dlsym(void *__restrict, const char *__restrict);
+
+/* namespace apis */
+typedef const char* Dl_namespace;
+
+void dlns_init(Dl_namespace *, const char *);
+
+/* open dso in given namespace which has own lib search paths
+ * when namespace is null, it's same to dlopen() 
+ * void to use "default" as namespace, which is the default namespace*/
+void *dlopen_ns(Dl_namespace *, const char *, int);
+
+/* create the namespace and set lib search paths of namespace,
+ * the paths should be splited by ':'. When namespace already exist, 
+ * return error */
+int dlns_create(Dl_namespace *, const char *);
+
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+typedef struct {
+	const char *dli_fname;
+	void *dli_fbase;
+	const char *dli_sname;
+	void *dli_saddr;
+} Dl_info;
+int dladdr(const void *, Dl_info *);
+int dlinfo(void *, int, void *);
+#endif
+
+#if _REDIR_TIME64
+__REDIR(dlsym, __dlsym_time64);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

porting/linux/user/ldso/dynlink.c

@@ -1083,7 +1083,7 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
 					sys_path = "";
 				}
 			}
-			if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
+			if (!sys_path) sys_path = strdup("/lib:/usr/local/lib:/usr/lib");
 			fd = path_open(name, sys_path, buf, sizeof buf);
 		}
 		pathname = buf;
@@ -2427,3 +2427,46 @@ static void error(const char *fmt, ...)
 	__dl_vseterr(fmt, ap);
 	va_end(ap);
 }
+void dlns_init(Dl_namespace *ns, const char *name)
+{
+	*ns = name;
+}
+
+void *dlopen_ns(Dl_namespace *ns, const char *file, int mode)
+{
+	if (!ns) return NULL;
+
+	return dlopen(file, mode);
+}
+
+int dlns_create(Dl_namespace *ns,const char *search_path)
+{
+	int sys_length = 0;
+	int search_length =  0;
+	char * new_path = NULL;
+
+	if (!search_path || !ns) return EINVAL;
+
+	sys_length = strlen(sys_path);
+	search_length = strlen(search_path);
+
+	if (search_path[0] != ':'){
+		sys_length += search_length + 1;
+	} else  {
+		sys_length += search_length;
+	}
+
+	new_path = malloc(sys_length + 1);
+	if (!new_path) return ENOMEM;
+
+	strcat(new_path, sys_path);
+	if (search_path[0] != ':') {
+		strcat(new_path, ":");
+	}
+	strcat(new_path, search_path);
+
+	free(sys_path);
+	sys_path = new_path;
+
+	return 0;
+}