add systemd helper (#58)

* add systemd helper

socket/CMakeLists.txt

@@ -53,7 +53,7 @@ if (SC_BUILD_TEST)
                     -Wl,--wrap=setsockopt,--wrap=listen,--wrap=fcntl,--wrap=socket
                     -Wl,--wrap=inet_ntop,--wrap=send,--wrap=recv,--wrap=connect
                     -Wl,--wrap=write,--wrap=read,--wrap=epoll_ctl,--wrap=getsockopt
-                    -Wl,--wrap=epoll_wait,--wrap=getsockname)
+                    -Wl,--wrap=epoll_wait,--wrap=getsockname,--wrap=sendmsg)
         endif ()
     endif ()
 

socket/sc_sock.c

@@ -104,9 +104,14 @@ int sc_sock_cleanup()
     return rc != 0 ? -1 : 0;
 }
 
+int sc_sock_notify_systemd(const char *msg)
+{
+    return -1;
+}
 
 #else
     #include <arpa/inet.h>
+    #include <assert.h>
     #include <netdb.h>
     #include <netinet/in.h>
     #include <netinet/tcp.h>
@@ -122,6 +127,51 @@ int sc_sock_cleanup()
     #define SC_EINPROGRESS EINPROGRESS
     #define SC_EINTR       EINTR
 
+int sc_sock_notify_systemd(const char *msg)
+{
+    assert(msg != NULL);
+
+    int fd, rc;
+    const char *s;
+    struct sockaddr_un addr = {.sun_family = AF_UNIX};
+    struct iovec iovec = {.iov_base = (char *) msg, .iov_len = strlen(msg)};
+    struct msghdr msghdr = {.msg_name = &addr,
+            .msg_iov = &iovec,
+            .msg_iovlen = 1};
+
+    s = getenv("NOTIFY_SOCKET");
+    if (!s) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if ((s[0] != '@' && s[0] != '/') || s[1] == '\0') {
+        errno = EINVAL;
+        return -1;
+    }
+
+    fd = socket(AF_UNIX, SOCK_DGRAM, 0);
+    if (fd < 0) {
+        return -1;
+    }
+
+    strncpy(addr.sun_path, s, sizeof(addr.sun_path) - 1);
+    if (addr.sun_path[0] == '@') {
+        addr.sun_path[0] = '\0';
+    }
+
+    msghdr.msg_namelen = offsetof(struct sockaddr_un, sun_path) + strlen(s);
+    if (msghdr.msg_namelen > sizeof(struct sockaddr_un)) {
+        msghdr.msg_namelen = sizeof(struct sockaddr_un);
+    }
+
+    rc = sendmsg(fd, &msghdr, MSG_NOSIGNAL);
+
+    close(fd);
+
+    return rc < 0 ? -1 : 0;
+}
+
 int sc_sock_startup()
 {
     return 0;
@@ -748,7 +798,6 @@ void sc_sock_print(struct sc_sock *sock, char *buf, size_t len)
     snprintf(buf, len, "Local(%s), Remote(%s) ", l, r);
 }
 
-
 const char *sc_sock_pipe_err(struct sc_sock_pipe *pipe)
 {
     return pipe->err;

socket/sc_sock.h

@@ -245,6 +245,19 @@ const char *sc_sock_remote_str(struct sc_sock *sock, char *buf, size_t len);
 void sc_sock_print(struct sc_sock *sock, char *buf, size_t len);
 
 
+/**
+ * Linux only. Helper function make your application a daemon with systemd.
+ * e.g
+ * sc_sock_notify_systemd("READY=1\n");           // Tell systemd app started
+ * sc_sock_notify_systemd("STATUS=doing work\n"); // Tell systemd app doing sth
+ * sc_sock_notify_systemd("STOPPING=1\n")       ; // Tell systemd app will stop
+ *
+ * @param msg msg with systemd protocol format
+ * @return    '0' on success, negative on error, errno will be set.
+ */
+int sc_sock_notify_systemd(const char *msg);
+
+
 struct sc_sock_pipe
 {
     struct sc_sock_fd fdt;

socket/sock_test.c

@@ -732,6 +732,17 @@ int __wrap_connect(int fd, const struct sockaddr *addr, socklen_t len)
     return __real_connect(fd, addr, len);
 }
 
+int success_sendmsg = 0;
+ssize_t __real_sendmsg(int fd, const struct msghdr *message, int flags);
+ssize_t __wrap_sendmsg(int fd, const struct msghdr *message, int flags)
+{
+    if (success_sendmsg) {
+        return 0;
+    }
+
+    return __real_sendmsg(fd, message, flags);
+}
+
 int fail_send = INT32_MAX;
 int fail_send_err = 0;
 int fail_send_errno = 0;
@@ -1337,6 +1348,29 @@ void sock_fail_test3()
     assert(sc_sock_finish_connect(&client) != 0);
     fail_getsockopt = 0;
     sc_sock_term(&client);
+
+    assert(sc_sock_notify_systemd("test") == -1);
+    setenv("NOTIFY_SOCKET", "x", 1);
+    assert(sc_sock_notify_systemd("test") == -1);
+    setenv("NOTIFY_SOCKET", "/", 1);
+    assert(sc_sock_notify_systemd("test") == -1);
+    setenv("NOTIFY_SOCKET", "@", 1);
+    assert(sc_sock_notify_systemd("test") == -1);
+
+    setenv("NOTIFY_SOCKET", "/tmp/x", 1);
+    fail_socket = 1;
+    assert(sc_sock_notify_systemd("test") == -1);
+    fail_socket = 0;
+    setenv("NOTIFY_SOCKET", "@tmp/x", 1);
+    assert(sc_sock_notify_systemd("test") == -1);
+    setenv("NOTIFY_SOCKET", "@tmp/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 1);
+    assert(sc_sock_notify_systemd("test") == -1);
+
+    success_sendmsg = 1;
+    setenv("NOTIFY_SOCKET", "/tmp/x", 1);
+    assert(sc_sock_notify_systemd("test") == 0);
+    success_sendmsg = 0;
+    unsetenv("NOTIFY_SOCKET");
 }
 
 #else