On Wed, 15 Feb 2023 03:24:29 -0500 Laine Stump <laine(a)redhat.com> wrote:Once a log file (specified on the commandline) is opened, the logging functions will stop sending error logs to stderr, which is annoying if passt has been started by another process that wants to collect error messages from stderr so it can report why passt failed to start. It would be much nicer if passt continued sending all log messages to stderr until it daemonizes itself (at which point the process that started passt can assume that it was started successfully). The system log mask is set to LOG_EMERG when the process starts, and we're already using that to do "special" logging during the period from process start until the log level requested on the commandline is processed (setting the log mask to something else). This period *almost* matches with "the time before the process is daemonized"; if we just delay setting the log mask a tiny bit, then it will match exactly, and we can use it to determine if we need to send log messages to stderr even when a log file has been specified and opened. This patch delays the setting of the log mask until immediately before the call to __daemon(). It also modifies logfn() slightly, so that it will log to stderr any time log mask is LOG_EMERG, even if a log file has been opened. Signed-off-by: Laine Stump <laine(a)redhat.com> --- log.c | 4 ++-- passt.c | 17 ++++++++++------- 2 files changed, 12 insertions(+), 9 deletions(-) diff --git a/log.c b/log.c index 468c730..6dc6673 100644 --- a/log.c +++ b/log.c @@ -66,8 +66,8 @@ void name(const char *format, ...) { \ va_end(args); \ } \ \ - if ((setlogmask(0) & LOG_MASK(LOG_DEBUG) || \ - setlogmask(0) == LOG_MASK(LOG_EMERG)) && log_file == -1) { \ + if ((setlogmask(0) & LOG_MASK(LOG_DEBUG) && log_file == -1) || \ + setlogmask(0) == LOG_MASK(LOG_EMERG)) { \ va_start(args, format); \ (void)vfprintf(stderr, format, args); \ va_end(args); \Strictly speaking, I think this is correct, but it causes duplicate messages to be printed on interactive terminals, or with -e/--stderr, because in that case we already set LOG_PERROR in our __openlog() wrapper. I had a quick attempt at reworking this whole mess, with a table clearly gathering conditions and logging outcomes, but it's actually not that straightforward. So I'd rather just post a follow-up patch for this, at least for the moment. -- Stefano