[Xen-changelog] [xen master] cxenstored: add support for systemd active sockets

[patchbot@xxxxxxx]

commit 5e82217e34c38f07d286bd57029db47e6590350f
Author:     Luis R. Rodriguez <mcgrof@xxxxxxxx>
AuthorDate: Thu Jul 17 16:28:13 2014 -0700
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Thu Jul 24 16:23:20 2014 +0100

    cxenstored: add support for systemd active sockets
    
    This adds systemd socket activation support for the C xenstored.
    Active sockets enable xenstored to be loaded only if required by a system
    onto which Xen is installed on. Socket activation is handled by
    systemd, once a port for a service which claims a socket is used
    systemd will start the required services for it, on demand. For more
    details on socket activation refer to Lennart's socket-activation
    post regarding this [0].
    
    Right now this code adds a no-op for this functionality, leaving the
    enablement to be done later once systemd is properly hooked into
    the build system. The socket activation is ordered in aligment with
    the socket activation order passed on to systemd.
    
    [0] http://0pointer.de/blog/projects/socket-activation2.html
    
    Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 tools/xenstore/xenstored_core.c |  104 ++++++++++++++++++++++++++++++++++++++-
 1 files changed, 103 insertions(+), 1 deletions(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 47f0722..7f72f68 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -40,6 +40,7 @@
 #include <signal.h>
 #include <assert.h>
 #include <setjmp.h>
+#include <config.h>
 
 #include "utils.h"
 #include "list.h"
@@ -54,6 +55,16 @@
 
 #include "hashtable.h"
 
+#ifndef NO_SOCKETS
+#if defined(HAVE_SYSTEMD)
+#define XEN_SYSTEMD_ENABLED 1
+#endif
+#endif
+
+#if defined(XEN_SYSTEMD_ENABLED)
+#include <systemd/sd-daemon.h>
+#endif
+
 extern xc_evtchn *xce_handle; /* in xenstored_domain.c */
 static int xce_pollfd_idx = -1;
 static struct pollfd *fds;
@@ -1714,6 +1725,75 @@ static int destroy_fd(void *_fd)
        return 0;
 }
 
+#if defined(XEN_SYSTEMD_ENABLED)
+/* Will work regardless of the order systemd gives them to us */
+static int xs_get_sd_fd(const char *connect_to)
+{
+       int fd = SD_LISTEN_FDS_START;
+       int r;
+
+       while (fd <= SD_LISTEN_FDS_START + 1) {
+               r = sd_is_socket_unix(fd, SOCK_STREAM, 1, connect_to, 0);
+               if (r > 0)
+                       return fd;
+               fd++;
+       }
+
+       return -EBADR;
+}
+
+static int xs_validate_active_socket(const char *connect_to)
+{
+       if ((strcmp("/var/run/xenstored/socket_ro", connect_to) != 0) &&
+           (strcmp("/var/run/xenstored/socket", connect_to) != 0)) {
+               sd_notifyf(0, "STATUS=unexpected socket: %s\n"
+                          "ERRNO=%i",
+                          connect_to,
+                          EBADR);
+               return -EBADR;
+       }
+
+       return xs_get_sd_fd(connect_to);
+}
+
+static void xen_claim_active_sockets(int **psock, int **pro_sock)
+{
+       int *sock, *ro_sock;
+       const char *soc_str = xs_daemon_socket();
+       const char *soc_str_ro = xs_daemon_socket_ro();
+       int n;
+
+       n = sd_listen_fds(0);
+       if (n <= 0) {
+               sd_notifyf(0, "STATUS=Failed to get any active sockets: %s\n"
+                          "ERRNO=%i",
+                          strerror(errno),
+                          errno);
+               barf_perror("sd_listen_fds() failed\n");
+       } else if (n > 2) {
+               fprintf(stderr, SD_ERR "Expected 2 fds but given %d\n", n);
+               sd_notifyf(0, "STATUS=Mismatch on number (2): %s\n"
+                          "ERRNO=%d",
+                          strerror(EBADR),
+                          EBADR);
+               barf_perror("sd_listen_fds() gave too many fds\n");
+       }
+
+       *psock = sock = talloc(talloc_autofree_context(), int);
+       *sock = xs_validate_active_socket(soc_str);
+       if (*sock <= 0)
+               barf_perror("%s", soc_str);
+
+       *pro_sock = ro_sock = talloc(talloc_autofree_context(), int);
+       *ro_sock = xs_validate_active_socket(soc_str_ro);
+       if (*ro_sock <= 0)
+               barf_perror("%s", soc_str_ro);
+
+       talloc_set_destructor(sock, destroy_fd);
+       talloc_set_destructor(ro_sock, destroy_fd);
+}
+#endif
+
 static void init_sockets(int **psock, int **pro_sock)
 {
        struct sockaddr_un addr;
@@ -1884,6 +1964,15 @@ int main(int argc, char *argv[])
        if (optind != argc)
                barf("%s: No arguments desired", argv[0]);
 
+#if defined(XEN_SYSTEMD_ENABLED)
+       if (sd_booted()) {
+               dofork = false;
+               if (pidfile)
+                       barf("%s: PID file not needed on systemd", argv[0]);
+               pidfile = NULL;
+       }
+#endif
+
        reopen_log();
 
        /* make sure xenstored directories exist */
@@ -1905,7 +1994,13 @@ int main(int argc, char *argv[])
        /* Don't kill us with SIGPIPE. */
        signal(SIGPIPE, SIG_IGN);
 
-       init_sockets(&sock, &ro_sock);
+#if defined(XEN_SYSTEMD_ENABLED)
+       if (sd_booted())
+               xen_claim_active_sockets(&sock, &ro_sock);
+       else
+#endif
+               init_sockets(&sock, &ro_sock);
+
        init_pipe(reopen_log_pipe);
 
        /* Setup the database */
@@ -1936,6 +2031,13 @@ int main(int argc, char *argv[])
        /* Tell the kernel we're up and running. */
        xenbus_notify_running();
 
+#if defined(XEN_SYSTEMD_ENABLED)
+       if (sd_booted()) {
+               sd_notify(1, "READY=1");
+               fprintf(stderr, SD_NOTICE "xenstored is ready\n");
+       }
+#endif
+
        /* Main loop. */
        for (;;) {
                struct connection *conn, *next;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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