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From 1743102a92479834c8e17b20697129e05b7c8313 Mon Sep 17 00:00:00 2001
From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Thu, 4 Jul 2024 14:10:10 +0200
Subject: [PATCH 40/56] tools: Import stand-alone sd_notify() implementation
from systemd
... in order to avoid linking against the whole of libsystemd.
Only minimal changes to the upstream copy, to function as a drop-in
replacement for sd_notify() and as a header-only library.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Christian Lindig <christian.lindig@cloud.com>
master commit: 78510f3a1522f2856330ffa429e0e35f8aab4277
master date: 2024-05-23 15:04:40 +0100
master commit: 78510f3a1522f2856330ffa429e0e35f8aab4277
master date: 2024-05-23 15:04:40 +0100
---
tools/include/xen-sd-notify.h | 98 +++++++++++++++++++++++++++++++++++
1 file changed, 98 insertions(+)
create mode 100644 tools/include/xen-sd-notify.h
diff --git a/tools/include/xen-sd-notify.h b/tools/include/xen-sd-notify.h
new file mode 100644
index 0000000000..28c9b20f15
--- /dev/null
+++ b/tools/include/xen-sd-notify.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: MIT-0 */
+
+/*
+ * Implement the systemd notify protocol without external dependencies.
+ * Supports both readiness notification on startup and on reloading,
+ * according to the protocol defined at:
+ * https://www.freedesktop.org/software/systemd/man/latest/sd_notify.html
+ * This protocol is guaranteed to be stable as per:
+ * https://systemd.io/PORTABILITY_AND_STABILITY/
+ *
+ * Differences from the upstream copy:
+ * - Rename/rework as a drop-in replacement for systemd/sd-daemon.h
+ * - Only take the subset Xen cares about
+ * - Respect -Wdeclaration-after-statement
+ */
+
+#ifndef XEN_SD_NOTIFY
+#define XEN_SD_NOTIFY
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+static inline void xen_sd_closep(int *fd) {
+ if (!fd || *fd < 0)
+ return;
+
+ close(*fd);
+ *fd = -1;
+}
+
+static inline int xen_sd_notify(const char *message) {
+ union sockaddr_union {
+ struct sockaddr sa;
+ struct sockaddr_un sun;
+ } socket_addr = {
+ .sun.sun_family = AF_UNIX,
+ };
+ size_t path_length, message_length;
+ ssize_t written;
+ const char *socket_path;
+ int __attribute__((cleanup(xen_sd_closep))) fd = -1;
+
+ /* Verify the argument first */
+ if (!message)
+ return -EINVAL;
+
+ message_length = strlen(message);
+ if (message_length == 0)
+ return -EINVAL;
+
+ /* If the variable is not set, the protocol is a noop */
+ socket_path = getenv("NOTIFY_SOCKET");
+ if (!socket_path)
+ return 0; /* Not set? Nothing to do */
+
+ /* Only AF_UNIX is supported, with path or abstract sockets */
+ if (socket_path[0] != '/' && socket_path[0] != '@')
+ return -EAFNOSUPPORT;
+
+ path_length = strlen(socket_path);
+ /* Ensure there is room for NUL byte */
+ if (path_length >= sizeof(socket_addr.sun.sun_path))
+ return -E2BIG;
+
+ memcpy(socket_addr.sun.sun_path, socket_path, path_length);
+
+ /* Support for abstract socket */
+ if (socket_addr.sun.sun_path[0] == '@')
+ socket_addr.sun.sun_path[0] = 0;
+
+ fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
+ if (fd < 0)
+ return -errno;
+
+ if (connect(fd, &socket_addr.sa, offsetof(struct sockaddr_un, sun_path) + path_length) != 0)
+ return -errno;
+
+ written = write(fd, message, message_length);
+ if (written != (ssize_t) message_length)
+ return written < 0 ? -errno : -EPROTO;
+
+ return 1; /* Notified! */
+}
+
+static inline int sd_notify(int unset_environment, const char *message) {
+ int r = xen_sd_notify(message);
+
+ if (unset_environment)
+ unsetenv("NOTIFY_SOCKET");
+
+ return r;
+}
+
+#endif /* XEN_SD_NOTIFY */
--
2.45.2
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