Fix accept4 (socketcall 18) unimplemented issue causing Go applications to fail

fs/fd.c

@@ -226,21 +226,6 @@ void fdtable_do_cloexec(struct fdtable *table) {
     unlock(&table->lock);
 }
 
-#define F_DUPFD_ 0
-#define F_GETFD_ 1
-#define F_SETFD_ 2
-#define F_GETFL_ 3
-#define F_SETFL_ 4
-
-#define F_GETLK_ 5
-#define F_SETLK_ 6
-#define F_SETLKW_ 7
-#define F_GETLK64_ 12
-#define F_SETLK64_ 13
-#define F_SETLKW64_ 14
-
-#define F_DUPFD_CLOEXEC_ 1030
-
 dword_t sys_dup(fd_t f) {
     STRACE("dup(%d)", f);
     struct fd *fd = f_get(f);

fs/fd.h

@@ -124,6 +124,21 @@ struct dir_entry {
     char name[NAME_MAX + 1];
 };
 
+#define F_DUPFD_ 0
+#define F_GETFD_ 1
+#define F_SETFD_ 2
+#define F_GETFL_ 3
+#define F_SETFL_ 4
+
+#define F_GETLK_ 5
+#define F_SETLK_ 6
+#define F_SETLKW_ 7
+#define F_GETLK64_ 12
+#define F_SETLK64_ 13
+#define F_SETLKW64_ 14
+
+#define F_DUPFD_CLOEXEC_ 1030
+
 #define LSEEK_SET 0
 #define LSEEK_CUR 1
 #define LSEEK_END 2

fs/sock.c

@@ -450,6 +450,21 @@ int_t sys_accept(fd_t sock_fd, addr_t sockaddr_addr, addr_t sockaddr_len_addr) {
     return client_f;
 }
 
+int_t sys_accept4(fd_t sock_fd, addr_t sockaddr_addr, addr_t sockaddr_len_addr, int_t flags) {
+    if (flags & ~(SOCK_NONBLOCK_ | SOCK_CLOEXEC_))
+        return _EINVAL;
+    fd_t client = sys_accept(sock_fd, sockaddr_addr, sockaddr_len_addr);
+    if (client < 0)
+        return client;
+    if (flags & SOCK_NONBLOCK_) {
+        int_t old = sys_fcntl(client, F_GETFL_, 0);
+        sys_fcntl(client, F_SETFL_, old | O_NONBLOCK_);
+    }
+    if (flags & SOCK_CLOEXEC_)
+        sys_fcntl(client, F_SETFD_, 1);
+    return client;
+}
+
 static void copy_unix_name(char *sockaddr, dword_t *sockaddr_len, struct fd *sock) {
     struct sockaddr_ *fake_addr = (void *) sockaddr;
     fake_addr->family = PF_LOCAL_;
@@ -1214,7 +1229,7 @@ static struct socket_call {
     {(syscall_t) sys_getsockopt, 5},
     {(syscall_t) sys_sendmsg, 3},
     {(syscall_t) sys_recvmsg, 3},
-    {NULL}, // accept4
+    {(syscall_t) sys_accept4, 4},
     {NULL}, // recvmmsg
     {(syscall_t) sys_sendmmsg, 4},
 };

fs/sock.h

@@ -16,6 +16,7 @@ int_t sys_bind(fd_t sock_fd, addr_t sockaddr_addr, uint_t sockaddr_len);
 int_t sys_connect(fd_t sock_fd, addr_t sockaddr_addr, uint_t sockaddr_len);
 int_t sys_listen(fd_t sock_fd, int_t backlog);
 int_t sys_accept(fd_t sock_fd, addr_t sockaddr_addr, addr_t sockaddr_len_addr);
+int_t sys_accept4(fd_t sock_fd, addr_t sockaddr_addr, addr_t sockaddr_len_addr, int_t flags);
 int_t sys_getsockname(fd_t sock_fd, addr_t sockaddr_addr, addr_t sockaddr_len_addr);
 int_t sys_getpeername(fd_t sock_fd, addr_t sockaddr_addr, addr_t sockaddr_len_addr);
 int_t sys_socketpair(dword_t domain, dword_t type, dword_t protocol, addr_t sockets_addr);

tests/e2e/accept4/expected.txt

@@ -0,0 +1 @@
+accept4 ok

tests/e2e/accept4/test.sh

@@ -0,0 +1,21 @@
+python3 -c "
+import socket, ctypes, ctypes.util, threading, time
+
+libc = ctypes.CDLL(ctypes.util.find_library('c'), use_errno=True)
+s = socket.socket()
+s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+s.bind(('127.0.0.1', 19999))
+s.listen(1)
+
+def connect():
+    time.sleep(0.3)
+    c = socket.socket()
+    c.connect(('127.0.0.1', 19999))
+
+threading.Thread(target=connect).start()
+
+args = (ctypes.c_ulong * 4)(s.fileno(), 0, 0, 0)
+result = libc.syscall(102, 18, args)
+err = ctypes.get_errno()
+print('accept4 ok' if result > 0 else 'accept4 failed errno=' + str(err))
+"