systemd/SOURCES/0778-journalctl-in-follow-mode-watch-stdout-for-POLLHUP-P.patch

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2022-11-08 08:08:02 +00:00
From 67d3aade15bede6b162e8bfe88db60311efb0d1f Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 24 Oct 2018 21:49:52 +0200
Subject: [PATCH] journalctl: in --follow mode watch stdout for POLLHUP/POLLERR
and exit
Fixes: #9374
(cherry picked from commit 2a1e0f2228bbdfbc18635e959f47df7da50b62fe)
Resolves: #2003236
---
src/journal/journalctl.c | 65 +++++++++++++++++++++++++++++-----------
1 file changed, 48 insertions(+), 17 deletions(-)
diff --git a/src/journal/journalctl.c b/src/journal/journalctl.c
index 56b1be530d..fa83dce562 100644
--- a/src/journal/journalctl.c
+++ b/src/journal/journalctl.c
@@ -2064,14 +2064,46 @@ static int sync_journal(void) {
return send_signal_and_wait(SIGRTMIN+1, "/run/systemd/journal/synced");
}
-int main(int argc, char *argv[]) {
+static int wait_for_change(sd_journal *j, int poll_fd) {
+ struct pollfd pollfds[] = {
+ { .fd = poll_fd, .events = POLLIN },
+ { .fd = STDOUT_FILENO },
+ };
+
+ struct timespec ts;
+ usec_t timeout;
int r;
+
+ assert(j);
+ assert(poll_fd >= 0);
+
+ /* Much like sd_journal_wait() but also keeps an eye on STDOUT, and exits as soon as we see a POLLHUP on that,
+ * i.e. when it is closed. */
+
+ r = sd_journal_get_timeout(j, &timeout);
+ if (r < 0)
+ return log_error_errno(r, "Failed to determine journal waiting time: %m");
+
+ if (ppoll(pollfds, ELEMENTSOF(pollfds), timeout == USEC_INFINITY ? NULL : timespec_store(&ts, timeout), NULL) < 0)
+ return log_error_errno(errno, "Couldn't wait for journal event: %m");
+
+ if (pollfds[1].revents & (POLLHUP|POLLERR)) { /* STDOUT has been closed? */
+ log_debug("Standard output has been closed.");
+ return -ECANCELED;
+ }
+
+ r = sd_journal_process(j);
+ if (r < 0)
+ return log_error_errno(r, "Failed to process journal events: %m");
+
+ return 0;
+}
+
+int main(int argc, char *argv[]) {
+ bool previous_boot_id_valid = false, first_line = true, ellipsized = false, need_seek = false;
_cleanup_(sd_journal_closep) sd_journal *j = NULL;
- bool need_seek = false;
sd_id128_t previous_boot_id;
- bool previous_boot_id_valid = false, first_line = true;
- int n_shown = 0;
- bool ellipsized = false;
+ int n_shown = 0, r, poll_fd = -1;
setlocale(LC_ALL, "");
log_parse_environment();
@@ -2391,15 +2423,15 @@ int main(int argc, char *argv[]) {
/* Opening the fd now means the first sd_journal_wait() will actually wait */
if (arg_follow) {
- r = sd_journal_get_fd(j);
- if (r == -EMFILE) {
- log_warning("Insufficent watch descriptors available. Reverting to -n.");
+ poll_fd = sd_journal_get_fd(j);
+ if (poll_fd == -EMFILE) {
+ log_warning_errno(poll_fd, "Insufficent watch descriptors available. Reverting to -n.");
arg_follow = false;
- } else if (r == -EMEDIUMTYPE) {
- log_error_errno(r, "The --follow switch is not supported in conjunction with reading from STDIN.");
+ } else if (poll_fd == -EMEDIUMTYPE) {
+ log_error_errno(poll_fd, "The --follow switch is not supported in conjunction with reading from STDIN.");
goto finish;
- } else if (r < 0) {
- log_error_errno(r, "Failed to get journal fd: %m");
+ } else if (poll_fd < 0) {
+ log_error_errno(poll_fd, "Failed to get journal fd: %m");
goto finish;
}
}
@@ -2621,7 +2653,7 @@ int main(int argc, char *argv[]) {
need_seek = true;
if (r == -EADDRNOTAVAIL)
break;
- else if (r < 0 || ferror(stdout))
+ else if (r < 0)
goto finish;
n_shown++;
@@ -2659,11 +2691,10 @@ int main(int argc, char *argv[]) {
}
fflush(stdout);
- r = sd_journal_wait(j, (uint64_t) -1);
- if (r < 0) {
- log_error_errno(r, "Couldn't wait for journal event: %m");
+
+ r = wait_for_change(j, poll_fd);
+ if (r < 0)
goto finish;
- }
first_line = false;
}