lib/sysroot: Add journal-msg signal

This will allow us to drop the awful hack in rpm-ostree where we watch our own
stdout. In general, libraries shouldn't write to stdout.

Also we can kill the systemd journal wrapper code. There's some duplication at
each call site now...but it's easier than trying to write a `sd_journal_send()`
wrapper.

I was originally going to have this emit all of the structured data too as a
`GVariant` but decided it wasn't worth it right now.

Closes: #1052
Approved by: jlebon

8 files changed, 75 insertions, 211 deletions

diff --git a/Makefile-otutil.am b/Makefile-otutil.am
index db632705..ff7533e9 100644
--- a/Makefile-otutil.am
+++ b/Makefile-otutil.am
@@ -36,8 +36,6 @@ 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 \
diff --git a/src/libostree/ostree-sysroot-deploy.c b/src/libostree/ostree-sysroot-deploy.c
index 7e72a3ef..622f9975 100644
--- a/src/libostree/ostree-sysroot-deploy.c
+++ b/src/libostree/ostree-sysroot-deploy.c
@@ -47,9 +47,9 @@
 #include "ostree-linuxfsutil.h"
 #include "libglnx.h"
 
-#define OSTREE_VARRELABEL_ID          "da679b08acd34504b789d96f818ea781"
-#define OSTREE_CONFIGMERGE_ID         "d3863baec13e4449ab0384684a8af3a7"
 #ifdef HAVE_LIBSYSTEMD
+#define OSTREE_VARRELABEL_ID          SD_ID128_MAKE(da,67,9b,08,ac,d3,45,04,b7,89,d9,6f,81,8e,a7,81)
+#define OSTREE_CONFIGMERGE_ID         SD_ID128_MAKE(d3,86,3b,ae,c1,3e,44,49,ab,03,84,68,4a,8a,f3,a7)
 #define OSTREE_DEPLOYMENT_COMPLETE_ID SD_ID128_MAKE(dd,44,0e,3e,54,90,83,b6,3d,0e,fc,7d,c1,52,55,f1)
 #endif
 
@@ -429,11 +429,19 @@ merge_configuration_from (OstreeSysroot    *sysroot,
                          cancellable, error))
     return glnx_prefix_error (error, "While computing configuration diff");
 
-  ot_log_structured_print_id_v (OSTREE_CONFIGMERGE_ID,
-                                "Copying /etc changes: %u modified, %u removed, %u added",
-                                modified->len,
-                                removed->len,
-                                added->len);
+  { g_autofree char *msg =
+      g_strdup_printf ("Copying /etc changes: %u modified, %u removed, %u added",
+                       modified->len, removed->len, added->len);
+#ifdef HAVE_LIBSYSTEMD
+    sd_journal_send ("MESSAGE_ID=" SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(OSTREE_CONFIGMERGE_ID),
+                     "MESSAGE=%s", msg,
+                     "ETC_N_MODIFIED=%u", modified->len,
+                     "ETC_N_REMOVED=%u", removed->len,
+                     "ETC_N_ADDED=%u", added->len,
+                     NULL);
+#endif
+    _ostree_sysroot_emit_journal_msg (sysroot, msg);
+  }
 
   glnx_fd_close int orig_etc_fd = -1;
   if (!glnx_opendirat (merge_deployment_dfd, "usr/etc", TRUE, &orig_etc_fd, error))
@@ -688,9 +696,15 @@ selinux_relabel_var_if_needed (OstreeSysroot                 *sysroot,
 
   if (!deployment_var_labeled)
     {
-      ot_log_structured_print_id_v (OSTREE_VARRELABEL_ID,
-                                    "Relabeling /var (no stamp file '%s' found)",
-                                    selabeled);
+      { g_autofree char *msg =
+          g_strdup_printf ("Relabeling /var (no stamp file '%s' found)", selabeled);
+#ifdef HAVE_LIBSYSTEMD
+        sd_journal_send ("MESSAGE_ID=" SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(OSTREE_VARRELABEL_ID),
+                         "MESSAGE=%s", msg,
+                         NULL);
+#endif
+        _ostree_sysroot_emit_journal_msg (sysroot, msg);
+      }
 
       g_autoptr(GFile) deployment_var_path = ot_fdrel_to_gfile (os_deploy_dfd, "var");
       if (!selinux_relabel_dir (sysroot, sepolicy,
@@ -1917,8 +1931,7 @@ ostree_sysroot_write_deployments_with_options (OstreeSysroot     *self,
                      "OSTREE_SYNCFS_EXTRA_MSEC=%" G_GUINT64_FORMAT, syncstats.extra_syncfs_msec,
                      NULL);
 #endif
-    if (!ot_stdout_is_journal ())
-      g_print ("%s\n", msg);
+    _ostree_sysroot_emit_journal_msg (self, msg);
   }
 
   if (!_ostree_sysroot_bump_mtime (self, error))
diff --git a/src/libostree/ostree-sysroot-private.h b/src/libostree/ostree-sysroot-private.h
index 07c4bf6e..4c6cb328 100644
--- a/src/libostree/ostree-sysroot-private.h
+++ b/src/libostree/ostree-sysroot-private.h
@@ -69,6 +69,10 @@ struct OstreeSysroot {
 #define _OSTREE_SYSROOT_DEPLOYMENT_RUNSTATE_DIR "/run/ostree/deployment-state/"
 #define _OSTREE_SYSROOT_DEPLOYMENT_RUNSTATE_FLAG_DEVELOPMENT "unlocked-development"
 
+void
+_ostree_sysroot_emit_journal_msg (OstreeSysroot  *self,
+                                  const char     *msg);
+
 gboolean
 _ostree_sysroot_read_boot_loader_configs (OstreeSysroot *self,
                                           int            bootversion,
diff --git a/src/libostree/ostree-sysroot.c b/src/libostree/ostree-sysroot.c
index 20539e4d..5bdfe116 100644
--- a/src/libostree/ostree-sysroot.c
+++ b/src/libostree/ostree-sysroot.c
@@ -58,9 +58,19 @@ find_booted_deployment (OstreeSysroot       *self,
  */
 typedef struct {
   GObjectClass parent_class;
+
+  /* Signals */
+  void (*journal_msg) (OstreeSysroot *sysroot,
+                       const char    *msg);
 } OstreeSysrootClass;
 
 enum {
+  JOURNAL_MSG_SIGNAL,
+  LAST_SIGNAL,
+};
+static guint signals[LAST_SIGNAL] = { 0 };
+
+enum {
   PROP_0,
 
   PROP_PATH
@@ -159,6 +169,27 @@ ostree_sysroot_class_init (OstreeSysrootClass *klass)
                                                         "",
                                                         G_TYPE_FILE,
                                                         G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
+
+  /**
+   * OstreeSysroot::journal-msg:
+   * @self: Self
+   * @msg: Human-readable string (should not contain newlines)
+   *
+   * libostree will log to the journal various events, such as the /etc merge
+   * status, and transaction completion. Connect to this signal to also
+   * synchronously receive the text for those messages. This is intended to be
+   * used by command line tools which link to libostree as a library.
+   *
+   * Currently, the structured data is only available via the systemd journal.
+   *
+   * Since: 2017.10
+   */
+  signals[JOURNAL_MSG_SIGNAL] =
+    g_signal_new ("journal-msg",
+                  G_OBJECT_CLASS_TYPE (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (OstreeSysrootClass, journal_msg),
+                  NULL, NULL, NULL, G_TYPE_NONE, 1, G_TYPE_STRING);
 }
 
 static void
@@ -319,6 +350,13 @@ ostree_sysroot_ensure_initialized (OstreeSysroot  *self,
   return TRUE;
 }
 
+void
+_ostree_sysroot_emit_journal_msg (OstreeSysroot  *self,
+                                  const char     *msg)
+{
+  g_signal_emit (self, signals[JOURNAL_MSG_SIGNAL], 0, msg);
+}
+
 gboolean
 _ostree_sysroot_parse_deploy_path_name (const char *name,
                                         char      **out_csum,
diff --git a/src/libotutil/ot-log-utils.c b/src/libotutil/ot-log-utils.c
deleted file mode 100644
index c8a3bda7..00000000
--- a/src/libotutil/ot-log-utils.c
+++ /dev/null
@@ -1,163 +0,0 @@
-/* -*- 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
- */
-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
deleted file mode 100644
index 4433ee16..00000000
--- a/src/libotutil/ot-log-utils.h
+++ /dev/null
@@ -1,33 +0,0 @@
-/* -*- 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
-
-gboolean ot_stdout_is_journal (void);
-
-void ot_log_structured_print_id_v (const char *message_id,
-                                   const char *format,
-                                   ...) G_GNUC_PRINTF(2, 3);
-
-G_END_DECLS
diff --git a/src/libotutil/otutil.h b/src/libotutil/otutil.h
index dfe951d0..0647515c 100644
--- a/src/libotutil/otutil.h
+++ b/src/libotutil/otutil.h
@@ -51,7 +51,6 @@
 #include <ot-variant-utils.h>
 #include <ot-checksum-utils.h>
 #include <ot-gpg-utils.h>
-#include <ot-log-utils.h>
 #include <ot-checksum-instream.h>
 
 void ot_ptrarray_add_many (GPtrArray  *a, ...) G_GNUC_NULL_TERMINATED; 
diff --git a/src/ostree/ot-main.c b/src/ostree/ot-main.c
index 5b6e301d..81d10b98 100644
--- a/src/ostree/ot-main.c
+++ b/src/ostree/ot-main.c
@@ -358,6 +358,13 @@ ostree_option_context_parse (GOptionContext *context,
   return TRUE;
 }
 
+static void
+on_sysroot_journal_msg (OstreeSysroot *sysroot,
+                        const char    *msg)
+{
+  g_print ("%s\n", msg);
+}
+
 gboolean
 ostree_admin_option_context_parse (GOptionContext *context,
                                    const GOptionEntry *main_entries,
@@ -381,6 +388,7 @@ ostree_admin_option_context_parse (GOptionContext *context,
     sysroot_path = g_file_new_for_path (opt_sysroot);
 
   g_autoptr(OstreeSysroot) sysroot = ostree_sysroot_new (sysroot_path);
+  g_signal_connect (sysroot, "journal-msg", G_CALLBACK (on_sysroot_journal_msg), NULL);
 
   if (flags & OSTREE_ADMIN_BUILTIN_FLAG_SUPERUSER)
     {