lib: Use sd_journal directly (optionally)

This was the last caller of libgsystem that isn't
`gs_file_get_path_cached()`.  I think the use case ostree has where
the same code can be called via command line and via a shared library
*and* via a daemon is rather unusual, so let's just copy the code for
logging from libgsystem into here.

For example rpm-ostree hard depends on a daemon mode, so it'll just
use `sd_journal` directly.

Closes: #341
Approved by: jlebon

8 files changed, 216 insertions, 10 deletions

diff --git a/Makefile-libostree.am b/Makefile-libostree.am
index d6b83528..8c2fd297 100644
--- a/Makefile-libostree.am
+++ b/Makefile-libostree.am
@@ -156,6 +156,11 @@ libostree_1_la_CFLAGS += $(OT_DEP_LIBARCHIVE_CFLAGS)
 libostree_1_la_LIBADD += $(OT_DEP_LIBARCHIVE_LIBS)
 endif
 
+if BUILDOPT_LIBSYSTEMD
+libostree_1_la_CFLAGS += $(LIBSYSTEMD_CFLAGS)
+libostree_1_la_LIBADD += $(LIBSYSTEMD_LIBS)
+endif
+
 if USE_LIBSOUP
 libostree_1_la_SOURCES += \
 	src/libostree/ostree-fetcher.h \
diff --git a/Makefile-ostree.am b/Makefile-ostree.am
index 0ef5c4ee..33875dc4 100644
--- a/Makefile-ostree.am
+++ b/Makefile-ostree.am
@@ -99,7 +99,7 @@ ostree_bin_shared_cflags = $(AM_CFLAGS) -I$(srcdir)/src/libotutil -I$(srcdir)/sr
 ostree_bin_shared_ldadd = libglnx.la libbsdiff.la libotutil.la libostree-kernel-args.la libostree-1.la
 
 ostree_CFLAGS = $(ostree_bin_shared_cflags) $(OT_INTERNAL_GIO_UNIX_CFLAGS) -I$(srcdir)/libglnx
-ostree_LDADD = $(ostree_bin_shared_ldadd) $(OT_INTERNAL_GIO_UNIX_LIBS)
+ostree_LDADD = $(ostree_bin_shared_ldadd) $(OT_INTERNAL_GIO_UNIX_LIBS) $(LIBSYSTEMD_LIBS)
 
 if USE_LIBSOUP
 ostree_SOURCES += \
diff --git a/Makefile-otutil.am b/Makefile-otutil.am
index efcb04b7..ee892a70 100644
--- a/Makefile-otutil.am
+++ b/Makefile-otutil.am
@@ -36,6 +36,8 @@ libotutil_la_SOURCES = \
 	src/libotutil/ot-variant-utils.h \
 	src/libotutil/ot-gio-utils.c \
 	src/libotutil/ot-gio-utils.h \
+	src/libotutil/ot-log-utils.c \
+	src/libotutil/ot-log-utils.h \
 	src/libotutil/ot-gpg-utils.c \
 	src/libotutil/ot-gpg-utils.h \
 	src/libotutil/otutil.c \
@@ -43,5 +45,5 @@ libotutil_la_SOURCES = \
 	src/libotutil/ot-tool-util.c \
 	src/libotutil/ot-tool-util.h \
 	$(NULL)
-libotutil_la_CFLAGS = $(AM_CFLAGS) -I$(srcdir)/libglnx -I$(srcdir)/src/libotutil -DLOCALEDIR=\"$(datadir)/locale\" $(OT_INTERNAL_GIO_UNIX_CFLAGS) $(OT_INTERNAL_GPGME_CFLAGS)
-libotutil_la_LIBADD = $(OT_INTERNAL_GIO_UNIX_LIBS) $(OT_INTERNAL_GPGME_LIBS)
+libotutil_la_CFLAGS = $(AM_CFLAGS) -I$(srcdir)/libglnx -I$(srcdir)/src/libotutil -DLOCALEDIR=\"$(datadir)/locale\" $(OT_INTERNAL_GIO_UNIX_CFLAGS) $(OT_INTERNAL_GPGME_CFLAGS) $(LIBSYSTEMD_CFLAGS)
+libotutil_la_LIBADD = $(OT_INTERNAL_GIO_UNIX_LIBS) $(OT_INTERNAL_GPGME_LIBS) $(LIBSYSTEMD_LIBS)
diff --git a/configure.ac b/configure.ac
index 18f9f277..d28c410a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -251,7 +251,13 @@ AC_ARG_WITH(mkinitcpio,
               [with_mkinitcpio=no])
 AM_CONDITIONAL(BUILDOPT_MKINITCPIO, test x$with_mkinitcpio = xyes)
 
-AS_IF([test "x$with_dracut" = "xyes" || test "x$with_dracut" = "xyesbutnoconf" || test "x$with_mkinitcpio" = "xyes"], [
+dnl We have separate checks for libsystemd and the unit dir for historical reasons
+PKG_CHECK_MODULES([LIBSYSTEMD], [libsystemd], [have_libsystemd=yes], [have_libsystemd=no])
+AM_CONDITIONAL(BUILDOPT_LIBSYSTEMD, test x$have_libsystemd = xyes)
+AM_COND_IF(BUILDOPT_LIBSYSTEMD,
+           AC_DEFINE([HAVE_LIBSYSTEMD], 1, [Define if we have libsystemd]))
+
+AS_IF([test "x$have_libsystemd" = "xyes"], [
   with_systemd=yes
   AC_ARG_WITH([systemdsystemunitdir],
               AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files]),
@@ -309,6 +315,7 @@ echo "
     libsoup (retrieve remote HTTP repositories):  $with_soup
     libsoup TLS client certs:                     $have_libsoup_client_certs
     SELinux:                                      $with_selinux
+    systemd:                                      $have_libsystemd
     libmount:                                     $with_libmount
     libarchive (parse tar files directly):        $with_libarchive
     static deltas:                                yes (always enabled now)
@@ -322,7 +329,4 @@ AS_IF([test x$with_builtin_grub2_mkconfig = xyes], [
 ], [
     echo "    grub2-mkconfig path:                          $GRUB2_MKCONFIG"
 ])
-AS_IF([test "x$with_systemd" = "xyes"], [
-    echo "    systemd unit dir:                             $with_systemdsystemunitdir"
-])
 echo ""
diff --git a/src/libostree/ostree-sysroot-deploy.c b/src/libostree/ostree-sysroot-deploy.c
index 4616bab1..cc1a1faa 100644
--- a/src/libostree/ostree-sysroot-deploy.c
+++ b/src/libostree/ostree-sysroot-deploy.c
@@ -473,7 +473,7 @@ merge_etc_changes (GFile          *orig_etc,
       goto out;
     }
 
-  gs_log_structured_print_id_v (OSTREE_CONFIGMERGE_ID,
+  ot_log_structured_print_id_v (OSTREE_CONFIGMERGE_ID,
                                 "Copying /etc changes: %u modified, %u removed, %u added", 
                                 modified->len,
                                 removed->len,
@@ -773,7 +773,7 @@ selinux_relabel_var_if_needed (OstreeSysroot                 *sysroot,
       
   if (!g_file_query_exists (deployment_var_labeled, NULL))
     {
-      gs_log_structured_print_id_v (OSTREE_VARRELABEL_ID,
+      ot_log_structured_print_id_v (OSTREE_VARRELABEL_ID,
                                     "Relabeling /var (no stamp file '%s' found)",
                                     gs_file_get_path_cached (deployment_var_labeled));
 
@@ -1927,7 +1927,7 @@ ostree_sysroot_write_deployments (OstreeSysroot     *self,
         }
     }
 
-  gs_log_structured_print_id_v (OSTREE_DEPLOYMENT_COMPLETE_ID,
+  ot_log_structured_print_id_v (OSTREE_DEPLOYMENT_COMPLETE_ID,
                                 "%s; bootconfig swap: %s deployment count change: %i",
                                 (bootloader_is_atomic ? "Transaction complete" : "Bootloader updated"),
                                 requires_new_bootversion ? "yes" : "no",
diff --git a/src/libotutil/ot-log-utils.c b/src/libotutil/ot-log-utils.c
new file mode 100644
index 00000000..e1ce1690
--- /dev/null
+++ b/src/libotutil/ot-log-utils.c
@@ -0,0 +1,163 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2016 Colin Walters <walters@verbum.org>
+ *
+ * This library 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; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Colin Walters <walters@verbum.org>
+ */
+
+#include "config.h"
+
+#include <gio/gio.h>
+
+#include <string.h>
+
+#include "otutil.h"
+#include "libglnx.h"
+
+#ifdef HAVE_LIBSYSTEMD
+#define SD_JOURNAL_SUPPRESS_LOCATION
+#include <systemd/sd-journal.h>
+#endif
+#include <glib-unix.h>
+
+/**
+ * ot_log_structured:
+ * @message: Text message to send 
+ * @keys: (allow-none) (array zero-terminated=1) (element-type utf8): Optional structured data
+ * 
+ * Log structured data in an operating-system specific fashion.  The
+ * parameter @opts should be an array of UTF-8 KEY=VALUE strings.
+ * This function does not support binary data.  See
+ * http://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html
+ * for more information about fields that can be used on a systemd
+ * system.
+ */
+static void
+ot_log_structured (const char *message,
+                   const char *const *keys)
+{
+#ifdef HAVE_LIBSYSTEMD
+    const char *const*iter;
+    g_autofree char *msgkey = NULL;
+    guint i, n_opts;
+    struct iovec *iovs;
+
+    for (n_opts = 0, iter = keys; *iter; iter++, n_opts++)
+        ;
+
+    n_opts++; /* Add one for MESSAGE= */
+    iovs = g_alloca (sizeof (struct iovec) * n_opts);
+    
+    for (i = 0, iter = keys; *iter; iter++, i++) {
+        iovs[i].iov_base = (char*)keys[i];
+        iovs[i].iov_len = strlen (keys[i]);
+    }
+    g_assert(i == n_opts-1);
+    msgkey = g_strconcat ("MESSAGE=", message, NULL);
+    iovs[i].iov_base = msgkey;
+    iovs[i].iov_len = strlen (msgkey);
+    
+    // The code location isn't useful since we're wrapping
+    sd_journal_sendv (iovs, n_opts);
+#else
+    g_print ("%s\n", message);
+#endif
+}
+
+/**
+ * ot_stdout_is_journal:
+ *
+ * Use this function when you want your code to behave differently
+ * depeneding on whether your program was started as a systemd unit,
+ * or e.g. interactively at a terminal.
+ *
+ * Returns: %TRUE if stdout is (probably) connnected to the systemd journal
+ */
+static gboolean
+ot_stdout_is_journal (void)
+{
+  static gsize initialized;
+  static gboolean stdout_is_socket;
+
+  if (g_once_init_enter (&initialized))
+    {
+      guint64 pid = (guint64) getpid ();
+      g_autofree char *fdpath = g_strdup_printf ("/proc/%" G_GUINT64_FORMAT "/fd/1", pid);
+      char buf[1024];
+      ssize_t bytes_read;
+
+      if ((bytes_read = readlink (fdpath, buf, sizeof(buf) - 1)) != -1)
+        {
+          buf[bytes_read] = '\0';
+          stdout_is_socket = g_str_has_prefix (buf, "socket:");
+        }
+      else
+        stdout_is_socket = FALSE;
+
+      g_once_init_leave (&initialized, TRUE);
+    }
+
+  return stdout_is_socket;
+}
+
+/**
+ * gs_log_structured_print:
+ * @message: A message to log
+ * @keys: (allow-none) (array zero-terminated=1) (element-type utf8): Optional structured data
+ *
+ * Like gs_log_structured(), but also print to standard output (if it
+ * is not already connected to the system log).
+ */
+static void
+ot_log_structured_print (const char *message,
+                         const char *const *keys)
+{
+  ot_log_structured (message, keys);
+
+#ifdef HAVE_LIBSYSTEMD
+  if (!ot_stdout_is_journal ())
+    g_print ("%s\n", message);
+#endif
+}
+
+/**
+ * ot_log_structured_print_id_v:
+ * @message_id: A unique MESSAGE_ID
+ * @format: A format string
+ *
+ * The provided @message_id is a unique MESSAGE_ID (see <ulink url="http://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html"> for more information).
+ *
+ * This function otherwise acts as ot_log_structured_print(), taking
+ * @format as a format string.
+ */
+void
+ot_log_structured_print_id_v (const char *message_id,
+                              const char *format,
+                              ...)
+{
+  const char *key0 = glnx_strjoina ("MESSAGE_ID=", message_id);
+  const char *keys[] = { key0, NULL };
+  g_autofree char *msg = NULL;
+  va_list args;
+
+  va_start (args, format);
+  msg = g_strdup_vprintf (format, args);
+  va_end (args);
+
+  ot_log_structured_print (msg, (const char *const *)keys);
+}
diff --git a/src/libotutil/ot-log-utils.h b/src/libotutil/ot-log-utils.h
new file mode 100644
index 00000000..5e0502ab
--- /dev/null
+++ b/src/libotutil/ot-log-utils.h
@@ -0,0 +1,31 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ *
+ * Copyright (C) 2016 Colin Walters <walters@verbum.org>.
+ *
+ * This library 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; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#pragma once
+
+#include "ot-unix-utils.h"
+
+G_BEGIN_DECLS
+
+void ot_log_structured_print_id_v (const char *message_id,
+                                   const char *format,
+                                   ...);
+
+G_END_DECLS
diff --git a/src/libotutil/otutil.h b/src/libotutil/otutil.h
index 754f9253..6790d8ff 100644
--- a/src/libotutil/otutil.h
+++ b/src/libotutil/otutil.h
@@ -47,5 +47,6 @@
 #include <ot-spawn-utils.h>
 #include <ot-checksum-utils.h>
 #include <ot-gpg-utils.h>
+#include <ot-log-utils.h>
 
 void ot_ptrarray_add_many (GPtrArray  *a, ...) G_GNUC_NULL_TERMINATED;