hibernate-resume: add a tool to write a device node's major:minor to /sys/power/resume.

This can be used to initiate a resume from hibernation by path to a swap
device containing the hibernation image.

The respective templated unit is also added. It is instantiated using
path to the desired resume device.

2 files changed, 82 insertions, 0 deletions

diff --git a/src/hibernate-resume/Makefile b/src/hibernate-resume/Makefile
new file mode 120000
index 0000000000..d0b0e8e008
--- /dev/null
+++ b/src/hibernate-resume/Makefile
@@ -0,0 +1 @@
+../Makefile
\ No newline at end of file
diff --git a/src/hibernate-resume/hibernate-resume.c b/src/hibernate-resume/hibernate-resume.c
new file mode 100644
index 0000000000..8f68f81f9e
--- /dev/null
+++ b/src/hibernate-resume/hibernate-resume.c
@@ -0,0 +1,81 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Ivan Shapovalov
+
+  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 <stdio.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "util.h"
+#include "fileio.h"
+
+int main(int argc, char *argv[]) {
+        struct stat st;
+        const char *device;
+        _cleanup_free_ char *major_minor = NULL;
+        int r;
+
+        if (argc != 2) {
+                log_error("This program expects one argument.");
+                return EXIT_FAILURE;
+        }
+
+        log_set_target(LOG_TARGET_AUTO);
+        log_parse_environment();
+        log_open();
+
+        umask(0022);
+
+        device = argv[1];
+
+        if (stat(device, &st) < 0) {
+                log_error("Failed to stat '%s': %m", device);
+                return EXIT_FAILURE;
+        }
+
+        if (!S_ISBLK(st.st_mode)) {
+                log_error("Resume device '%s' is not a block device.", device);
+                return EXIT_FAILURE;
+        }
+
+        if (asprintf(&major_minor, "%d:%d", major(st.st_rdev), minor(st.st_rdev)) < 0) {
+                log_oom();
+                return EXIT_FAILURE;
+        }
+
+        r = write_string_file("/sys/power/resume", major_minor);
+        if (r < 0) {
+                log_error("Failed to write '%s' to /sys/power/resume: %s", major_minor, strerror(-r));
+                return EXIT_FAILURE;
+        }
+
+        /*
+         * The write above shall not return.
+         *
+         * However, failed resume is a normal condition (may mean that there is
+         * no hibernation image).
+         */
+
+        log_info("Could not resume from '%s' (%s).", device, major_minor);
+        return EXIT_SUCCESS;
+}