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



commit c9c1373347d67e8c68725aa7d6d298ca53bea98a
Author:     Luis R. Rodriguez <mcgrof@xxxxxxxx>
AuthorDate: Thu Jul 17 16:28:14 2014 -0700
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Thu Jul 24 16:23:20 2014 +0100

    oxenstored: add support for systemd active sockets
    
    This adds systemd socket activation support for the Ocaml xenstored.
    Ocaml lacks systemd library support so we provide our own C helpers
    as is done with other functionality lacking on Ocaml.
    
    Active sockets enables oxenstored 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].
    
    An important difference with socket activation is that systemd will set
    FD_CLOEXEC for us on the socket before giving it to us, we'll sprinkly
    the Unix.set_close_on_exec for LSB init next as a separate commit.
    
    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
    
    Cc: David Scott <dave.scott@xxxxxxxxxxxxx>
    Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
    Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Cc: Vincent Hanquez <Vincent.Hanquez@xxxxxxxxxxxxx>
    Acked-by: Dave Scott <Dave.Scott@xxxxxxxxxx>
    Acked-by: Anil Madhavapeddy <anil@xxxxxxxxxx>
    Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
---
 tools/ocaml/xenstored/Makefile        |    8 ++-
 tools/ocaml/xenstored/systemd.ml      |   17 ++++
 tools/ocaml/xenstored/systemd.mli     |   24 +++++
 tools/ocaml/xenstored/systemd_stubs.c |  152 +++++++++++++++++++++++++++++++++
 tools/ocaml/xenstored/utils.ml        |   20 +++--
 tools/ocaml/xenstored/xenstored.ml    |    2 +
 6 files changed, 215 insertions(+), 8 deletions(-)

diff --git a/tools/ocaml/xenstored/Makefile b/tools/ocaml/xenstored/Makefile
index 7fa8f53..382a813 100644
--- a/tools/ocaml/xenstored/Makefile
+++ b/tools/ocaml/xenstored/Makefile
@@ -15,6 +15,11 @@ syslog_OBJS = syslog
 syslog_C_OBJS = syslog_stubs
 OCAML_LIBRARY = syslog
 
+LIBS += systemd.cma systemd.cmxa
+systemd_OBJS = systemd
+systemd_C_OBJS = systemd_stubs
+OCAML_LIBRARY += systemd
+
 OBJS = define \
        stdext \
        trie \
@@ -36,11 +41,12 @@ OBJS = define \
        process \
        xenstored
 
-INTF = symbol.cmi trie.cmi syslog.cmi
+INTF = symbol.cmi trie.cmi syslog.cmi systemd.cmi
 
 XENSTOREDLIBS = \
        unix.cmxa \
        -ccopt -L -ccopt . syslog.cmxa \
+       -ccopt -L -ccopt . systemd.cmxa \
        -ccopt -L -ccopt $(OCAML_TOPLEVEL)/libs/mmap 
$(OCAML_TOPLEVEL)/libs/mmap/xenmmap.cmxa \
        -ccopt -L -ccopt $(OCAML_TOPLEVEL)/libs/eventchn 
$(OCAML_TOPLEVEL)/libs/eventchn/xeneventchn.cmxa \
        -ccopt -L -ccopt $(OCAML_TOPLEVEL)/libs/xc 
$(OCAML_TOPLEVEL)/libs/xc/xenctrl.cmxa \
diff --git a/tools/ocaml/xenstored/systemd.ml b/tools/ocaml/xenstored/systemd.ml
new file mode 100644
index 0000000..2aa39ea
--- /dev/null
+++ b/tools/ocaml/xenstored/systemd.ml
@@ -0,0 +1,17 @@
+(*
+ * Copyright (C) 2014 Luis R. Rodriguez <mcgrof@xxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *)
+
+external sd_listen_fds: string -> Unix.file_descr = "ocaml_sd_listen_fds"
+external sd_booted: unit -> bool = "ocaml_sd_booted"
+external sd_notify_ready: unit -> unit = "ocaml_sd_notify_ready"
diff --git a/tools/ocaml/xenstored/systemd.mli 
b/tools/ocaml/xenstored/systemd.mli
new file mode 100644
index 0000000..85c9f2e
--- /dev/null
+++ b/tools/ocaml/xenstored/systemd.mli
@@ -0,0 +1,24 @@
+(*
+ * Copyright (C) 2014 Luis R. Rodriguez <mcgrof@xxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *)
+
+(** Calls the C library sd_listen_fds() function for us. Although
+ *  the library doesn't accept argument we send one over to help
+ *  us do sanity checks on the expected sockets *)
+val sd_listen_fds: string -> Unix.file_descr
+
+(** Tells us whether or not systemd support was compiled in *)
+val sd_booted: unit -> bool
+
+(** Tells systemd we're ready *)
+external sd_notify_ready: unit -> unit = "ocaml_sd_notify_ready"
diff --git a/tools/ocaml/xenstored/systemd_stubs.c 
b/tools/ocaml/xenstored/systemd_stubs.c
new file mode 100644
index 0000000..a368ac1
--- /dev/null
+++ b/tools/ocaml/xenstored/systemd_stubs.c
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2014 Luis R. Rodriguez <mcgrof@xxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <caml/mlvalues.h>
+#include <caml/memory.h>
+#include <caml/alloc.h>
+#include <caml/custom.h>
+#include <caml/signals.h>
+#include <caml/fail.h>
+#include <config.h>
+
+#if defined(HAVE_SYSTEMD)
+
+#include <sys/socket.h>
+#include <systemd/sd-daemon.h>
+
+/* Will work regardless of the order systemd gives them to us */
+static int oxen_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 oxen_verify_socket_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 oxen_get_sd_fd(connect_to);
+}
+
+CAMLprim value ocaml_sd_listen_fds(value connect_to)
+{
+       CAMLparam1(connect_to);
+       CAMLlocal1(sock_ret);
+       int sock = -EBADR, 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);
+               caml_failwith("ocaml_sd_listen_fds() failed to get any 
sockets");
+       } 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);
+               caml_failwith("ocaml_sd_listen_fds() mismatch");
+       }
+
+       sock = oxen_verify_socket_socket(String_val(connect_to));
+       if (sock <= 0) {
+               fprintf(stderr, "failed to verify sock %s\n",
+                       String_val(connect_to));
+               caml_failwith("ocaml_sd_listen_fds_init() invalid socket");
+       }
+
+       sock_ret = Val_int(sock);
+
+       CAMLreturn(sock_ret);
+}
+
+CAMLprim value ocaml_sd_booted(value ignore)
+{
+       CAMLparam1(ignore);
+       CAMLlocal1(ret);
+
+       ret = Val_false;
+
+       if (sd_booted())
+               ret = Val_true;
+
+       CAMLreturn(ret);
+}
+
+CAMLprim value ocaml_sd_notify_ready(value ignore)
+{
+       CAMLparam1(ignore);
+       CAMLlocal1(ret);
+
+       ret = Val_int(0);
+
+       sd_notify(1, "READY=1");
+
+       CAMLreturn(ret);
+}
+
+#else
+
+CAMLprim value ocaml_sd_listen_fds(value connect_to)
+{
+       CAMLparam1(connect_to);
+       CAMLlocal1(sock_ret);
+
+       sock_ret = Val_int(-1);
+
+       CAMLreturn(sock_ret);
+}
+
+CAMLprim value ocaml_sd_booted(value ignore)
+{
+       CAMLparam1(ignore);
+       CAMLlocal1(ret);
+
+       ret = Val_false;
+
+       CAMLreturn(ret);
+}
+
+CAMLprim value ocaml_sd_notify_ready(value ignore)
+{
+       CAMLparam1(ignore);
+       CAMLlocal1(ret);
+
+       ret = Val_int(-1);
+
+       CAMLreturn(ret);
+}
+#endif
diff --git a/tools/ocaml/xenstored/utils.ml b/tools/ocaml/xenstored/utils.ml
index 68b70c5..0cfeded 100644
--- a/tools/ocaml/xenstored/utils.ml
+++ b/tools/ocaml/xenstored/utils.ml
@@ -73,14 +73,20 @@ let trim_path path =
 let join_by_null ls = String.concat "\000" ls
 
 (* unix utils *)
+let create_regular_unix_socket name =
+        Unixext.unlink_safe name;
+        Unixext.mkdir_rec (Filename.dirname name) 0o700;
+        let sockaddr = Unix.ADDR_UNIX(name) in
+        let sock = Unix.socket Unix.PF_UNIX Unix.SOCK_STREAM 0 in
+        Unix.bind sock sockaddr;
+        Unix.listen sock 1;
+        sock
+
 let create_unix_socket name =
-       Unixext.unlink_safe name;
-       Unixext.mkdir_rec (Filename.dirname name) 0o700;
-       let sockaddr = Unix.ADDR_UNIX(name) in
-       let sock = Unix.socket Unix.PF_UNIX Unix.SOCK_STREAM 0 in
-       Unix.bind sock sockaddr;
-       Unix.listen sock 1;
-       sock
+        if Systemd.sd_booted() then
+                Systemd.sd_listen_fds name
+        else
+                create_regular_unix_socket name
 
 let read_file_single_integer filename =
        let fd = Unix.openfile filename [ Unix.O_RDONLY ] 0o640 in
diff --git a/tools/ocaml/xenstored/xenstored.ml 
b/tools/ocaml/xenstored/xenstored.ml
index 438ecb9..1c02f2f 100644
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -383,6 +383,8 @@ let _ =
        while not !quit
        do
                try
+                        if Systemd.sd_booted() then
+                                Systemd.sd_notify_ready ();
                        main_loop ()
                with exc ->
                        error "caught exception %s" (Printexc.to_string exc);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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