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authorLennart Poettering <lennart@poettering.net>2014-06-13 12:43:49 +0200
committerLennart Poettering <lennart@poettering.net>2014-06-13 13:26:32 +0200
commit8ea48dfcd33e8db0c01bf8c57c3bbcfdc3c86d4b (patch)
tree474a196fe6cea93499ede05e35af8ba6ae526a65 /src/update-done/update-done.c
parentdc92e62c6c34f242aa54aa187e50a94ed7695c51 (diff)
update-done: add minimal tool to manage system updates for /etc and /var, if /usr has changed
In order to support offline updates to /usr, we need to be able to run certain tasks on next boot-up to bring /etc and /var in line with the updated /usr. Hence, let's devise a mechanism how we can detect whether /etc or /var are not up-to-date with /usr anymore: we keep "touch files" in /etc/.updated and /var/.updated that are mtime-compared with /usr. This means: Whenever the vendor OS tree in /usr is updated, and any services that shall be executed at next boot shall be triggered, it is sufficient to update the mtime of /usr itself. At next boot, if /etc/.updated and/or /var/.updated is older than than /usr (or missing), we know we have to run the update tools once. After that is completed we need to update the mtime of these files to the one of /usr, to keep track that we made the necessary updates, and won't repeat them on next reboot. A subsequent commit adds a new ConditionNeedsUpdate= condition that allows checking on boot whether /etc or /var are outdated and need updating. This is an early step to allow booting up with an empty /etc, with automatic rebuilding of the necessary cache files or user databases therein, as well as supporting later updates of /usr that then propagate to /etc and /var again.
Diffstat (limited to 'src/update-done/update-done.c')
-rw-r--r--src/update-done/update-done.c104
1 files changed, 104 insertions, 0 deletions
diff --git a/src/update-done/update-done.c b/src/update-done/update-done.c
new file mode 100644
index 0000000000..10ba85ca92
--- /dev/null
+++ b/src/update-done/update-done.c
@@ -0,0 +1,104 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2014 Lennart Poettering
+
+ 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 "util.h"
+
+static int apply_timestamp(const char *path, struct timespec *ts) {
+ struct timespec twice[2];
+ struct stat st;
+
+ assert(path);
+ assert(ts);
+
+ if (stat(path, &st) >= 0) {
+ /* Is the timestamp file already newer than the OS? If so, there's nothing to do. */
+ if (st.st_mtim.tv_sec > ts->tv_sec ||
+ (st.st_mtim.tv_sec == ts->tv_sec && st.st_mtim.tv_nsec >= ts->tv_nsec))
+ return 0;
+
+ /* It is older? Then let's update it */
+ twice[0] = *ts;
+ twice[1] = *ts;
+
+ if (utimensat(AT_FDCWD, path, twice, AT_SYMLINK_NOFOLLOW) < 0) {
+
+ if (errno == EROFS) {
+ log_debug("Can't update timestamp file %s, file system is read-only.", path);
+ return 0;
+ }
+
+ log_error("Failed to update timestamp on %s: %m", path);
+ return -errno;
+ }
+
+ } else if (errno == ENOENT) {
+ _cleanup_close_ int fd = -1;
+
+ /* The timestamp file doesn't exist yet? Then let's create it. */
+
+ fd = open(path, O_CREAT|O_EXCL|O_WRONLY|O_TRUNC|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0644);
+ if (fd < 0) {
+
+ if (errno == EROFS) {
+ log_debug("Can't create timestamp file %s, file system is read-only.", path);
+ return 0;
+ }
+
+ log_error("Failed to create timestamp file %s: %m", path);
+ return -errno;
+ }
+
+ twice[0] = *ts;
+ twice[1] = *ts;
+
+ if (futimens(fd, twice) < 0) {
+ log_error("Failed to update timestamp on %s: %m", path);
+ return -errno;
+ }
+ } else {
+ log_error("Failed to stat() timestamp file %s: %m", path);
+ return -errno;
+ }
+
+ return 0;
+}
+
+int main(int argc, char *argv[]) {
+ struct stat st;
+ int r, q;
+
+ log_set_target(LOG_TARGET_AUTO);
+ log_parse_environment();
+ log_open();
+
+ if (stat("/usr", &st) < 0) {
+ log_error("Failed to stat /usr: %m");
+ return EXIT_FAILURE;
+ }
+
+ r = apply_timestamp("/etc/.updated", &st.st_mtim);
+
+ q = apply_timestamp("/var/.updated", &st.st_mtim);
+ if (q < 0 && r == 0)
+ r = q;
+
+ return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}