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authorIvan Shapovalov <intelfx@intelfx.name>2016-09-13 03:04:35 +0300
committerIvan Shapovalov <intelfx@intelfx.name>2016-09-15 06:36:42 +0300
commitfb8b0869a7bc30e23be175cf978df23192d59118 (patch)
tree9524b559719dd9a03e100739f68123a4f4dcea8b /src/shared/condition.c
parent3a730176b36bc1191c54b149a8147bbf6ec8e482 (diff)
update-done, condition: write the timestamp to the file as well and use it to prevent false-positives
This fixes https://bugs.freedesktop.org/show_bug.cgi?id=90192 and #4130 for real. Also, remove timestamp check in update-done.c altogether since the whole operation is idempotent.
Diffstat (limited to 'src/shared/condition.c')
-rw-r--r--src/shared/condition.c42
1 files changed, 40 insertions, 2 deletions
diff --git a/src/shared/condition.c b/src/shared/condition.c
index 6bb42c0692..f13fa6a9fd 100644
--- a/src/shared/condition.c
+++ b/src/shared/condition.c
@@ -37,6 +37,7 @@
#include "condition.h"
#include "extract-word.h"
#include "fd-util.h"
+#include "fileio.h"
#include "glob-util.h"
#include "hostname-util.h"
#include "ima-util.h"
@@ -309,8 +310,45 @@ static int condition_test_needs_update(Condition *c) {
if (lstat("/usr/", &usr) < 0)
return true;
- return usr.st_mtim.tv_sec > other.st_mtim.tv_sec ||
- (usr.st_mtim.tv_sec == other.st_mtim.tv_sec && usr.st_mtim.tv_nsec > other.st_mtim.tv_nsec);
+ /*
+ * First, compare seconds as they are always accurate...
+ */
+ if (usr.st_mtim.tv_sec != other.st_mtim.tv_sec)
+ return usr.st_mtim.tv_sec > other.st_mtim.tv_sec;
+
+ /*
+ * ...then compare nanoseconds.
+ *
+ * A false positive is only possible when /usr's nanoseconds > 0
+ * (otherwise /usr cannot be strictly newer than the target file)
+ * AND the target file's nanoseconds == 0
+ * (otherwise the filesystem supports nsec timestamps, see stat(2)).
+ */
+ if (usr.st_mtim.tv_nsec > 0 && other.st_mtim.tv_nsec == 0) {
+ _cleanup_free_ char *timestamp_str = NULL;
+ uint64_t timestamp;
+ int r;
+
+ r = parse_env_file(p, NULL, "TimestampNSec", &timestamp_str, NULL);
+ if (r < 0) {
+ log_error_errno(-r, "Failed to parse timestamp file '%s', using mtime: %m", p);
+ return true;
+ } else if (r == 0) {
+ log_debug("No data in timestamp file '%s', using mtime", p);
+ return true;
+ }
+
+ r = safe_atou64(timestamp_str, &timestamp);
+ if (r < 0) {
+ log_error_errno(-r, "Failed to parse timestamp value '%s' in file '%s', using mtime: %m",
+ timestamp_str, p);
+ return true;
+ }
+
+ other.st_mtim.tv_nsec = timestamp % NSEC_PER_SEC;
+ }
+
+ return usr.st_mtim.tv_nsec > other.st_mtim.tv_nsec;
}
static int condition_test_first_boot(Condition *c) {