In commit
c4fb8c6a - fsck: do not use statics
not only statics were changed but also a couple of
statics-unrelated changes were made.
This included the handling of the child termination status
as follows:
- if (WIFEXITED(status))
- status = WEXITSTATUS(status);
- else if (WIFSIGNALED(status)) {
+ status = WEXITSTATUS(status);
+ if (WIFSIGNALED(status)) {
Change to unconditionally call WEXITSTATUS() was not semantics-preserving,
since you can only reasonably call WEXITSTATUS() on status if
you checked WIFEXITED() before; see `man 2 waitpid`:
WEXITSTATUS(status)
[...]
This macro should be employed only if WIFEXITED
returned true.
`status = WEXITSTATUS(status)` unconditionally masks away the
parts of status that indicate whether a signal was raised,
so that afterwards WIFSIGNALED() is true even if no signal
was raised.
As a result, busybox's `fsck` wrapper set `status = EXIT_ERROR = 8`,
thus not forwarding the exit code of the filesystem-specific
fsck utility (such as fsck.ext4) to the caller and returning
exit code 8 instead.
The exit codes of fsck have well-specified meanings (see `man fsck`)
that operating systems use in order to decide whether they should
prompt the user due to unrecoverable errors, or continue booting
after errors were successfully fixed automatically.
Consequently, this regression in busybox's fsck stopped my server
from booting though, and manual intervention via a keyboard was
needed.
Remark: Tracking down this issue would have been significantly
less effort if unrelated code changes were not snuck into a
commit labelled "fsck: do not use statics".
This issue was found as part of the NixOS project
(https://github.com/NixOS/nixpkgs/issues/40174#issuecomment-387405554)
and this fix has been tested on it.
Signed-off-by: Niklas Hambüchen <[email protected]>
---
e2fsprogs/fsck.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/e2fsprogs/fsck.c b/e2fsprogs/fsck.c
index 1c285bb..1a6f7d0 100644
--- a/e2fsprogs/fsck.c
+++ b/e2fsprogs/fsck.c
@@ -448,8 +448,9 @@ static int wait_one(int flags)
}
child_died:
- status = WEXITSTATUS(status);
- if (WIFSIGNALED(status)) {
+ if (WIFEXITED(status))
+ status = WEXITSTATUS(status);
+ else if (WIFSIGNALED(status)) {
sig = WTERMSIG(status);
status = EXIT_UNCORRECTED;
if (sig != SIGINT) {
--
2.7.4
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