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https://github.com/xen-project/xen.git
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Andrew Cooper
78510f3a15
... 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>
99 lines
2.5 KiB
C
99 lines
2.5 KiB
C
/* SPDX-License-Identifier: MIT-0 */
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/*
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* Implement the systemd notify protocol without external dependencies.
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* Supports both readiness notification on startup and on reloading,
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* according to the protocol defined at:
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* https://www.freedesktop.org/software/systemd/man/latest/sd_notify.html
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* This protocol is guaranteed to be stable as per:
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* https://systemd.io/PORTABILITY_AND_STABILITY/
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*
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* Differences from the upstream copy:
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* - Rename/rework as a drop-in replacement for systemd/sd-daemon.h
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* - Only take the subset Xen cares about
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* - Respect -Wdeclaration-after-statement
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*/
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#ifndef XEN_SD_NOTIFY
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#define XEN_SD_NOTIFY
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#include <errno.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <unistd.h>
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static inline void xen_sd_closep(int *fd) {
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if (!fd || *fd < 0)
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return;
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close(*fd);
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*fd = -1;
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}
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static inline int xen_sd_notify(const char *message) {
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union sockaddr_union {
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struct sockaddr sa;
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struct sockaddr_un sun;
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} socket_addr = {
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.sun.sun_family = AF_UNIX,
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};
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size_t path_length, message_length;
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ssize_t written;
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const char *socket_path;
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int __attribute__((cleanup(xen_sd_closep))) fd = -1;
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/* Verify the argument first */
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if (!message)
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return -EINVAL;
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message_length = strlen(message);
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if (message_length == 0)
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return -EINVAL;
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/* If the variable is not set, the protocol is a noop */
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socket_path = getenv("NOTIFY_SOCKET");
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if (!socket_path)
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return 0; /* Not set? Nothing to do */
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/* Only AF_UNIX is supported, with path or abstract sockets */
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if (socket_path[0] != '/' && socket_path[0] != '@')
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return -EAFNOSUPPORT;
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path_length = strlen(socket_path);
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/* Ensure there is room for NUL byte */
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if (path_length >= sizeof(socket_addr.sun.sun_path))
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return -E2BIG;
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memcpy(socket_addr.sun.sun_path, socket_path, path_length);
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/* Support for abstract socket */
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if (socket_addr.sun.sun_path[0] == '@')
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socket_addr.sun.sun_path[0] = 0;
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fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
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if (fd < 0)
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return -errno;
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if (connect(fd, &socket_addr.sa, offsetof(struct sockaddr_un, sun_path) + path_length) != 0)
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return -errno;
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written = write(fd, message, message_length);
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if (written != (ssize_t) message_length)
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return written < 0 ? -errno : -EPROTO;
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return 1; /* Notified! */
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}
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static inline int sd_notify(int unset_environment, const char *message) {
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int r = xen_sd_notify(message);
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if (unset_environment)
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unsetenv("NOTIFY_SOCKET");
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return r;
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}
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#endif /* XEN_SD_NOTIFY */
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