environment-generator: new generator to peruse environment.d

Why the strange name: the prefix is necessary to follow our own advice that
environment generators should have numerical prefixes. I also put -d- in the
name because otherwise the name was very easy to mistake with
systemd.environment-generator. This additional letter clarifies that this
on special generator that supports environment.d files.

src/environment-d-generator/Makefile

@@ -0,0 +1 @@
+../Makefile

src/environment-d-generator/environment-d-generator.c

@@ -0,0 +1,107 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2017 Zbigniew Jędrzejewski-Szmek
+
+  systemd 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 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "sd-path.h"
+
+#include "conf-files.h"
+#include "def.h"
+#include "escape.h"
+#include "fileio.h"
+#include "log.h"
+#include "path-lookup.h"
+
+static int environment_dirs(char ***ret) {
+        _cleanup_strv_free_ char **dirs = NULL;
+        _cleanup_free_ char *c = NULL;
+        int r;
+
+        dirs = strv_split_nulstr(CONF_PATHS_NULSTR("environment.d"));
+        if (!dirs)
+                return -ENOMEM;
+
+        /* ~/.config/systemd/environment.d */
+        r = sd_path_home(SD_PATH_USER_CONFIGURATION, "environment.d", &c);
+        if (r < 0)
+                return r;
+
+        r = strv_extend_front(&dirs, c);
+        if (r < 0)
+                return r;
+
+        *ret = dirs;
+        dirs = NULL;
+        return 0;
+}
+
+static int load_and_print(void) {
+        _cleanup_strv_free_ char **dirs = NULL, **files = NULL, **env = NULL;
+        char **i;
+        int r;
+
+        r = environment_dirs(&dirs);
+        if (r < 0)
+                return r;
+
+        r = conf_files_list_strv(&files, ".conf", NULL, (const char **) dirs);
+        if (r < 0)
+                return r;
+
+        /* This will mutate the existing environment, based on the presumption
+         * that in case of failure, a partial update is better than none. */
+
+        STRV_FOREACH(i, files) {
+                r = merge_env_file(&env, NULL, *i);
+                if (r == -ENOMEM)
+                        return r;
+        }
+
+        STRV_FOREACH(i, env) {
+                char *t;
+                _cleanup_free_ char *q = NULL;
+
+                t = strchr(*i, '=');
+                assert(t);
+
+                q = shell_maybe_quote(t + 1);
+                if (!q)
+                        return log_oom();
+
+                printf("%.*s=%s\n", (int) (t - *i), *i, q);
+        }
+
+        return 0;
+}
+
+int main(int argc, char *argv[]) {
+        int r;
+
+        log_parse_environment();
+        log_open();
+
+        if (argc > 1) {
+                log_error("This program takes no arguments.");
+                return EXIT_FAILURE;
+        }
+
+        r = load_and_print();
+        if (r < 0)
+                log_error_errno(r, "Failed to load environment.d: %m");
+
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}

src/shared/path-lookup.c

@@ -503,8 +503,7 @@ int lookup_paths_init(
                         append = true;
                 }
 
-                /* FIXME: empty components in other places should be
-                 * rejected. */
+                /* FIXME: empty components in other places should be rejected. */
 
                 r = path_split_and_make_absolute(e, &paths);
                 if (r < 0)