Denys Vlasenko wrote:
This isn't just an academic question.  uClibc 0.9.30 doesn't set FD_CLOEXEC
on the logging descriptor.

It does. uClibc-0.9.30/libc/misc/syslog/syslog.c

void
openlog(const char *ident, int logstat, int logfac)
{
        int logType = SOCK_DGRAM;

        __UCLIBC_MUTEX_LOCK(mylock);

        if (ident != NULL)
                LogTag = ident;
        LogStat = logstat;
        if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
                LogFacility = logfac;
        if (LogFile == -1) {
retry:
                if (LogStat & LOG_NDELAY) {
                        if ((LogFile = socket(AF_UNIX, logType, 0)) == -1) {
                                goto DONE;
                        }
 HERE ====>             fcntl(LogFile, F_SETFD, 1); /* 1 == FD_CLOEXEC */
                        /* We don't want to block if e.g. syslogd is SIGSTOPed 
*/
                        fcntl(LogFile, F_SETFL, O_NONBLOCK | fcntl(LogFile, 
F_GETFL));
                }
        }

Oops, I missed the tricky (and strange) hardcoding of the constant, because id-utils doesn't index comments. I did also use strace to verify on an actual running system that uClibc wasn't setting FD_CLOEXEC, but that system is using uClibc-0.9.29. So it looks like this was fixed in 0.9.30. I'd bet that there are still lots of systems using older versions of uClibc though.

--Doug.

...
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