Add SPDX license identifiers to source files under the LGPL

[thirdparty/systemd.git] / src / system-update-generator / system-update-generator.c

diff --git a/src/system-update-generator/system-update-generator.c b/src/system-update-generator/system-update-generator.c
index 6660192f5e06beb650792f6ceefa5c4a3beea60a..1796bae340bfe4552bc103b49a82d4ebea5f6b95 100644 (file)
--- a/src/system-update-generator/system-update-generator.c
+++ b/src/system-update-generator/system-update-generator.c
@@ -1,5 +1,4 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
+/* SPDX-License-Identifier: LGPL-2.1+ */
 /***
   This file is part of systemd.
 
@@ -22,47 +21,55 @@
 #include <errno.h>
 #include <unistd.h>
 
+#include "fs-util.h"
 #include "log.h"
+#include "proc-cmdline.h"
+#include "special.h"
+#include "string-util.h"
 #include "util.h"
-#include "unit-name.h"
-#include "path-util.h"
 
 /*
- * Implements the logic described in
- * http://freedesktop.org/wiki/Software/systemd/SystemUpdates
+ * Implements the logic described in systemd.offline-updates(7).
  */
 
 static const char *arg_dest = "/tmp";
 
 static int generate_symlink(void) {
-        struct stat st;
-        char *p;
+        const char *p = NULL;
 
-        if (lstat("/system-update", &st) < 0) {
+        if (laccess("/system-update", F_OK) < 0) {
                 if (errno == ENOENT)
                         return 0;
 
-                log_error("Failed to check for system update: %m");
+                log_error_errno(errno, "Failed to check for system update: %m");
                 return -EINVAL;
         }
 
-        p = strappend(arg_dest, "/default.target");
-        if (!p)
-                return log_oom();
+        p = strjoina(arg_dest, "/" SPECIAL_DEFAULT_TARGET);
+        if (symlink(SYSTEM_DATA_UNIT_PATH "/system-update.target", p) < 0)
+                return log_error_errno(errno, "Failed to create symlink %s: %m", p);
 
-        if (symlink(SYSTEM_DATA_UNIT_PATH "/system-update.target", p) < 0) {
-                free(p);
-                log_error("Failed to create symlink: %m");
-                return -errno;
-        }
+        return 1;
+}
+
+static int parse_proc_cmdline_item(const char *key, const char *value, void *data) {
+        assert(key);
 
-        free(p);
+        /* Check if a run level is specified on the kernel command line. The
+         * command line has higher priority than any on-disk configuration, so
+         * it'll make any symlink we create moot.
+         */
+
+        if (streq(key, "systemd.unit") && !proc_cmdline_value_missing(key, value))
+                log_warning("Offline system update overriden by kernel command line systemd.unit= setting");
+        else if (!value && runlevel_to_target(key))
+                log_warning("Offline system update overriden by runlevel \"%s\" on the kernel command line", key);
 
         return 0;
 }
 
 int main(int argc, char *argv[]) {
-        int r;
+        int r, k;
 
         if (argc > 1 && argc != 4) {
                 log_error("This program takes three or no arguments.");
@@ -80,5 +87,11 @@ int main(int argc, char *argv[]) {
 
         r = generate_symlink();
 
+        if (r > 0) {
+                k = proc_cmdline_parse(parse_proc_cmdline_item, NULL, 0);
+                if (k < 0)
+                        log_warning_errno(k, "Failed to parse kernel command line, ignoring: %m");
+        }
+
         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }