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/* SPDX-License-Identifier: MIT-0 */
/* Lightly modified from the sd_notify manpage. */
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
int
systemd_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;
int fd = -1;
const char *socket_path;
/* 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) {
close(fd);
return -errno;
}
ssize_t written = write(fd, message, message_length);
if (written != (ssize_t) message_length) {
close(fd);
return written < 0 ? -errno : -EPROTO;
}
return 1; /* Notified! */
}
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