sd-path: add new type SD_PATH_SEARCH_SYSCTL (#38680)

Aim of this patches set, is to add a new type SD_PATH_SEARCH_SYSCTL for
sd_path_lookup() and sd_path_lookup_strv(). This new type is used to get the
directories list used by systemd-sysctl:

-  /etc/sysctl.d/
-  /run/sysctl.d/
-  /usr/local/lib/sysctl.d/
-  /usr/lib/sysctl.d/

This implements the change in libsystemd, systemd-path, and systemd-sysctl.

man/sd_path_lookup.xml

@@ -76,6 +76,7 @@
         <constant>SD_PATH_SEARCH_CONFIGURATION_FACTORY</constant>,
         <constant>SD_PATH_SEARCH_STATE_FACTORY</constant>,
         <constant>SD_PATH_SEARCH_CONFIGURATION</constant>,
+        <constant>SD_PATH_SEARCH_SYSCTL</constant>,
 
         <constant>SD_PATH_SYSTEMD_UTIL</constant>,
         <constant>SD_PATH_SYSTEMD_SYSTEM_UNIT</constant>,

src/libsystemd/sd-path/sd-path.c

@@ -683,7 +683,11 @@ static int get_search(uint64_t type, char ***ret) {
 
                 *ret = TAKE_PTR(l);
                 return 0;
-        }}
+        }
+
+        case SD_PATH_SEARCH_SYSCTL:
+                return strv_from_nulstr(ret, CONF_PATHS_NULSTR("sysctl.d"));
+        }
 
         return -EOPNOTSUPP;
 }

src/path/path-tool.c

@@ -66,6 +66,7 @@ static const char* const path_table[_SD_PATH_MAX] = {
         [SD_PATH_SEARCH_CONFIGURATION_FACTORY]                = "search-configuration-factory",
         [SD_PATH_SEARCH_STATE_FACTORY]                        = "search-state-factory",
         [SD_PATH_SEARCH_CONFIGURATION]                        = "search-configuration",
+        [SD_PATH_SEARCH_SYSCTL]                               = "search-sysctl",
 
         [SD_PATH_SYSTEMD_UTIL]                                = "systemd-util",
 

src/sysctl/sysctl.c

@@ -4,6 +4,8 @@
 #include <stdio.h>
 #include <sys/stat.h>
 
+#include "sd-path.h"
+
 #include "alloc-util.h"
 #include "build.h"
 #include "conf-files.h"
@@ -279,10 +281,10 @@ static int parse_line(const char *fname, unsigned line, const char *buffer, bool
         return 0;
 }
 
-static int parse_file(OrderedHashmap **sysctl_options, const char *path, bool ignore_enoent) {
+static int parse_file(OrderedHashmap **sysctl_options, const char *path, bool ignore_enoent, const char **search_paths) {
         return conf_file_read(
                         /* root = */ NULL,
-                        (const char**) CONF_PATHS_STRV("sysctl.d"),
+                        search_paths,
                         path,
                         parse_line,
                         sysctl_options,
@@ -305,7 +307,7 @@ static int read_credential_lines(OrderedHashmap **sysctl_options) {
         if (!j)
                 return log_oom();
 
-        return parse_file(sysctl_options, j, /* ignore_enoent= */ true);
+        return parse_file(sysctl_options, j, /* ignore_enoent= */ true, /* search_paths= */ NULL);
 }
 
 static int cat_config(char **files) {
@@ -440,8 +442,13 @@ static int parse_argv(int argc, char *argv[]) {
 
 static int run(int argc, char *argv[]) {
         _cleanup_ordered_hashmap_free_ OrderedHashmap *sysctl_options = NULL;
+        _cleanup_strv_free_ char **search_paths = NULL;
         int r;
 
+        r = sd_path_lookup_strv(SD_PATH_SEARCH_SYSCTL, /* suffix= */ NULL, &search_paths);
+        if (r < 0)
+               return log_error_errno(r, "Failed to get sysctl.d/ search paths: %m");
+
         r = parse_argv(argc, argv);
         if (r <= 0)
                 return r;
@@ -458,12 +465,12 @@ static int run(int argc, char *argv[]) {
                                 /* Use (argument):n, where n==1 for the first positional arg */
                                 RET_GATHER(r, parse_line("(argument)", ++pos, *arg, /* invalid_config = */ NULL, &sysctl_options));
                         else
-                                RET_GATHER(r, parse_file(&sysctl_options, *arg, false));
+                                RET_GATHER(r, parse_file(&sysctl_options, *arg, /* ignore_enoent= */ false, (const char**) search_paths));
                 }
         } else {
                 _cleanup_strv_free_ char **files = NULL;
 
-                r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("sysctl.d"));
+                r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) search_paths);
                 if (r < 0)
                         return log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 
@@ -471,7 +478,7 @@ static int run(int argc, char *argv[]) {
                         return cat_config(files);
 
                 STRV_FOREACH(f, files)
-                        RET_GATHER(r, parse_file(&sysctl_options, *f, true));
+                        RET_GATHER(r, parse_file(&sysctl_options, *f, /* ignore_enoent= */ true, /* search_paths= */ NULL));
 
                 RET_GATHER(r, read_credential_lines(&sysctl_options));
         }

src/systemd/sd-path.h

@@ -129,6 +129,8 @@ __extension__ enum {
         SD_PATH_USER_CREDENTIAL_STORE_ENCRYPTED,
         SD_PATH_USER_SEARCH_CREDENTIAL_STORE_ENCRYPTED,
 
+        SD_PATH_SEARCH_SYSCTL,
+
         _SD_PATH_MAX,
         _SD_PATH_INVALID = UINT64_MAX
 };