From 8ea48dfcd33e8db0c01bf8c57c3bbcfdc3c86d4b Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Fri, 13 Jun 2014 12:43:49 +0200 Subject: 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 A subsequent commit adds a new ConditionNeedsUpdate= condition that allows checking on boot whether /etc or /var are outdated and need updating.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. --- src/update-done/Makefile | 1 + src/update-done/update-done.c | 104 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 105 insertions(+) create mode 120000 src/update-done/Makefile create mode 100644 src/update-done/update-done.c (limited to 'src') diff --git a/src/update-done/Makefile b/src/update-done/Makefile new file mode 120000 index 0000000000..d0b0e8e008 --- /dev/null +++ b/src/update-done/Makefile @@ -0,0 +1 @@ +../Makefile \ No newline at end of file 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 . +***/ + +#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; +} -- cgit v1.2.3-54-g00ecf