LocalSocketAddress(String name, Namespace namespace)
第二個 argument : namespace ，決定 name 的真正位置 (path)。LocalSocketAddress.Namespace :
public enum Namespace {
/** A socket in the Linux abstract namespace */
ABSTRACT(0),
/**
* A socket in the Android reserved namespace in /dev/socket.
* Only the init process may create a socket here.
*/
RESERVED(1),
/**
* A socket named with a normal filesystem path.
*/
FILESYSTEM(2);
/** The id matches with a #define in include/cutils/sockets.h */
private int id;
Namespace (int id) {
this.id = id;
}
可以知道，follow 一般 linux 的用法，要用 LocalSocketAddress.Namespace.FILESYSTEM。這樣才會完全依照 name 的內容來解析。
至於 另一個 LocalSocketAddress 的生成函數：
public LocalSocketAddress(String name) {
this(name,Namespace.ABSTRACT);
}
不指定的時候，用 ABSTRACT。至於每個 namespace 的真正位置，在 system/core/libcutils/sock_local_client.c:
int socket_make_sockaddr_un(const char *name, int namespaceId,
struct sockaddr_un *p_addr, socklen_t *alen)
{
memset (p_addr, 0, sizeof (*p_addr));
size_t namelen;
switch (namespaceId) {
case ANDROID_SOCKET_NAMESPACE_ABSTRACT:
#ifdef HAVE_LINUX_LOCAL_SOCKET_NAMESPACE
namelen = strlen(name);
// Test with length +1 for the *initial* '\0'.
if ((namelen + 1) > sizeof(p_addr->sun_path)) {
goto error;
}
/*
* Note: The path in this case is *not* supposed to be
* '\0'-terminated. ("man 7 unix" for the gory details.)
*/
p_addr->sun_path[0] = 0;
memcpy(p_addr->sun_path + 1, name, namelen);
#else /*HAVE_LINUX_LOCAL_SOCKET_NAMESPACE*/
/* this OS doesn't have the Linux abstract namespace */
namelen = strlen(name) + strlen(FILESYSTEM_SOCKET_PREFIX);
/* unix_path_max appears to be missing on linux */
if (namelen > sizeof(*p_addr)
- offsetof(struct sockaddr_un, sun_path) - 1) {
goto error;
}
strcpy(p_addr->sun_path, FILESYSTEM_SOCKET_PREFIX);
strcat(p_addr->sun_path, name);
#endif /*HAVE_LINUX_LOCAL_SOCKET_NAMESPACE*/
break;
case ANDROID_SOCKET_NAMESPACE_RESERVED:
namelen = strlen(name) + strlen(ANDROID_RESERVED_SOCKET_PREFIX);
/* unix_path_max appears to be missing on linux */
if (namelen > sizeof(*p_addr)
- offsetof(struct sockaddr_un, sun_path) - 1) {
goto error;
}
strcpy(p_addr->sun_path, ANDROID_RESERVED_SOCKET_PREFIX);
strcat(p_addr->sun_path, name);
break;
case ANDROID_SOCKET_NAMESPACE_FILESYSTEM:
namelen = strlen(name);
/* unix_path_max appears to be missing on linux */
if (namelen > sizeof(*p_addr)
- offsetof(struct sockaddr_un, sun_path) - 1) {
goto error;
}
strcpy(p_addr->sun_path, name);
break;
default:
// invalid namespace id
return -1;
}
p_addr->sun_family = AF_LOCAL;
*alen = namelen + offsetof(struct sockaddr_un, sun_path) + 1;
return 0;
error:
return -1;
}
有點複雜，還要去查 core/libcutils/socket_local.h
#define FILESYSTEM_SOCKET_PREFIX "/tmp/"
#define ANDROID_RESERVED_SOCKET_PREFIX "/dev/socket/"
* 如果沒有注意這個，在 connect 的時候，會有 connection denied 的 error。
ref:
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