From b87d7a8b402894ef8dfbb0af73a8eaef02660021 Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Mon, 2 Aug 2021 21:56:39 +0200
Subject: [PATCH] glib-aux: add nm_sd_notify() helper

Reimplements systemd's sd_notify(). We want to notify, but we don't
want to link with libsystemd.
---
 src/libnm-glib-aux/nm-io-utils.c | 48 ++++++++++++++++++++++++++++++++
 src/libnm-glib-aux/nm-io-utils.h |  2 ++
 2 files changed, 50 insertions(+)

diff --git a/src/libnm-glib-aux/nm-io-utils.c b/src/libnm-glib-aux/nm-io-utils.c
index a1e642cbaa..85a81f69bc 100644
--- a/src/libnm-glib-aux/nm-io-utils.c
+++ b/src/libnm-glib-aux/nm-io-utils.c
@@ -675,3 +675,51 @@ nm_io_sockaddr_un_set(struct sockaddr_un *ret, NMOptionBool is_abstract, const c
      * calculated the same. */
     return (nm_offsetof(struct sockaddr_un, sun_path) + 1) + l;
 }
+
+/*****************************************************************************/
+
+/* taken from systemd's sd_notify(). */
+int
+nm_sd_notify(const char *state)
+{
+    struct sockaddr_un sockaddr;
+    struct iovec       iovec;
+    struct msghdr      msghdr = {
+        .msg_iov    = &iovec,
+        .msg_iovlen = 1,
+        .msg_name   = &sockaddr,
+    };
+    nm_auto_close int fd = -1;
+    const char *      e;
+    int               r;
+
+    if (!state)
+        g_return_val_if_reached(-EINVAL);
+
+    e = getenv("NOTIFY_SOCKET");
+    if (!e)
+        return 0;
+
+    r = nm_io_sockaddr_un_set(&sockaddr, NM_OPTION_BOOL_DEFAULT, e);
+    if (r < 0)
+        return r;
+    msghdr.msg_namelen = r;
+
+    fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
+    if (fd < 0)
+        return -NM_ERRNO_NATIVE(errno);
+
+    /* systemd calls here fd_set_sndbuf(fd, SNDBUF_SIZE) .We don't bother. */
+
+    iovec = (struct iovec){
+        .iov_base = (gpointer) state,
+        .iov_len  = strlen(state),
+    };
+
+    /* systemd sends ucred, if geteuid()/getegid() does not match getuid()/getgid(). We don't bother. */
+
+    if (sendmsg(fd, &msghdr, MSG_NOSIGNAL) < 0)
+        return -NM_ERRNO_NATIVE(errno);
+
+    return 0;
+}
diff --git a/src/libnm-glib-aux/nm-io-utils.h b/src/libnm-glib-aux/nm-io-utils.h
index 34d2c183e3..479d0e5100 100644
--- a/src/libnm-glib-aux/nm-io-utils.h
+++ b/src/libnm-glib-aux/nm-io-utils.h
@@ -75,4 +75,6 @@ struct sockaddr_un;
 
 int nm_io_sockaddr_un_set(struct sockaddr_un *ret, NMOptionBool is_abstract, const char *path);
 
+int nm_sd_notify(const char *state);
+
 #endif /* __NM_IO_UTILS_H__ */