From 4139fe5aec935ba3f462dcaf6aafb6e5eadf1ab9 Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Tue, 3 Jun 2008 14:26:12 +0000 Subject: Fix bug 575 and other small problems noticed along the way. The bug: this blocks in syslogd is stopped: #include int main() { int i; for (i = 0; i < 10000; i++) syslog(LOG_INFO, "Testing, disregard...................."); return 0; } Fix: set O_NONBLOCK on fd to "/dev/log". Other fixes: do not try to write to fd -1, do not spin forever or EAGAIN, use constant sockaddr instead of recreating identical one each time, eliminate one intermediate function (SUGPIPE sig handler), use smallints where appropriate, add a few comments. Size: text data bss dec hex filename - 1140 16 21 1177 499 libc/misc/syslog/syslog.o + 1123 13 2 1138 472 libc/misc/syslog/syslog.o --- libc/misc/syslog/syslog.c | 88 +++++++++++++++++++++++++---------------------- 1 file changed, 46 insertions(+), 42 deletions(-) (limited to 'libc/misc/syslog') diff --git a/libc/misc/syslog/syslog.c b/libc/misc/syslog/syslog.c index d8648b879..5bb81c282 100644 --- a/libc/misc/syslog/syslog.c +++ b/libc/misc/syslog/syslog.c @@ -108,25 +108,34 @@ libc_hidden_proto(vsnprintf) __UCLIBC_MUTEX_STATIC(mylock, PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP); -static int LogFile = -1; /* fd for log */ -static smalluint connected; /* have done connect */ -static int LogStat = 0; /* status bits, set by openlog() */ -static const char *LogTag = "syslog"; /* string to tag the entry with */ -static int LogFacility = LOG_USER; /* default facility code */ -static int LogMask = 0xff; /* mask of priorities to be logged */ -static struct sockaddr SyslogAddr; /* AF_UNIX address of local logger */ +static int LogFile = -1; /* fd for log */ +static smalluint connected; /* have done connect */ +/* all bits in option argument for openlog() fit in 8 bits */ +static smalluint LogStat = 0; /* status bits, set by openlog() */ +static const char *LogTag = "syslog"; /* string to tag the entry with */ +/* this fits in 8 bits too (LOG_LOCAL7 = 23<<3 = 184), + * but NB: LOG_FACMASK is bigger (= 0x03f8 = 127<<3) for some strange reason. + * Oh well. */ +static int LogFacility = LOG_USER;/* default facility code */ +/* bits mask of priorities (eight prios - 8 bits is enough) */ +static smalluint LogMask = 0xff; /* mask of priorities to be logged */ +/* AF_UNIX address of local logger (we use struct sockaddr + * instead of struct sockaddr_un since "/dev/log" is small enough) */ +static const struct sockaddr SyslogAddr = { + .sa_family = AF_UNIX, /* sa_family_t (usually a short) */ + .sa_data = _PATH_LOG /* char [14] */ +}; static void -closelog_intern(const smalluint to_default) +closelog_intern(int sig) { __UCLIBC_MUTEX_LOCK(mylock); if (LogFile != -1) { - (void) close(LogFile); + (void) close(LogFile); } LogFile = -1; connected = 0; - if (to_default) - { + if (sig != 0) { LogStat = 0; LogTag = "syslog"; LogFacility = LOG_USER; @@ -135,12 +144,6 @@ closelog_intern(const smalluint to_default) __UCLIBC_MUTEX_UNLOCK(mylock); } -static void -sigpipe_handler (attribute_unused int sig) -{ - closelog_intern (0); -} - /* * OPENLOG -- open system log */ @@ -157,22 +160,19 @@ openlog( const char *ident, int logstat, int logfac ) if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0) LogFacility = logfac; if (LogFile == -1) { - SyslogAddr.sa_family = AF_UNIX; - (void)strncpy(SyslogAddr.sa_data, _PATH_LOG, - sizeof(SyslogAddr.sa_data)); retry: if (LogStat & LOG_NDELAY) { if ((LogFile = socket(AF_UNIX, logType, 0)) == -1) { goto DONE; } - fcntl(LogFile, F_SETFD, 1); + 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)); } } if (LogFile != -1 && !connected) { - if (connect(LogFile, &SyslogAddr, sizeof(SyslogAddr) - - sizeof(SyslogAddr.sa_data) + strlen(SyslogAddr.sa_data)) != -1) - { + if (connect(LogFile, &SyslogAddr, sizeof(SyslogAddr)) != -1) { connected = 1; } else { if (LogFile != -1) { @@ -208,7 +208,7 @@ vsyslog( int pri, const char *fmt, va_list ap ) int sigpipe; memset (&action, 0, sizeof (action)); - action.sa_handler = sigpipe_handler; + action.sa_handler = closelog_intern; sigemptyset (&action.sa_mask); sigpipe = sigaction (SIGPIPE, &action, &oldaction); @@ -255,7 +255,7 @@ vsyslog( int pri, const char *fmt, va_list ap ) __set_errno(saved_errno); p += vsnprintf(p, end - p, fmt, ap); if (p >= end || p < head_end) { /* Returned -1 in case of error... */ - static const char truncate_msg[12] = "[truncated] "; + static const char truncate_msg[12] = "[truncated] "; /* no NUL! */ memmove(head_end + sizeof(truncate_msg), head_end, end - head_end - sizeof(truncate_msg)); memcpy(head_end, truncate_msg, sizeof(truncate_msg)); @@ -280,29 +280,33 @@ vsyslog( int pri, const char *fmt, va_list ap ) /* Output the message to the local logger using NUL as a message delimiter. */ p = tbuf; *last_chr = 0; - do { - rc = write(LogFile, p, last_chr + 1 - p); - if (rc < 0) { - if ((errno==EAGAIN) || (errno==EINTR)) - rc=0; - else { - closelog_intern(0); - break; + if (LogFile >= 0) { + do { + rc = write(LogFile, p, last_chr + 1 - p); + if (rc < 0) { + /* I don't think looping forever on EAGAIN is a good idea. + * Imagine that syslogd is SIGSTOPed... */ + if (/* (errno != EAGAIN) && */ (errno != EINTR)) { + closelog_intern(1); /* 1: reset LogXXX globals to default */ + goto write_err; + } + rc = 0; } - } - p+=rc; - } while (p <= last_chr); - if (rc >= 0) + p += rc; + } while (p <= last_chr); goto getout; + } + write_err: /* * Output the message to the console; don't worry about blocking, * if console blocks everything will. Make sure the error reported * is the one from the syslogd failure. */ - /* should mode be `O_WRONLY | O_NOCTTY' ? -- Uli */ - if (LogStat & LOG_CONS && - (fd = open(_PATH_CONSOLE, O_WRONLY, 0)) >= 0) { + /* should mode be O_WRONLY | O_NOCTTY? -- Uli */ + /* yes, but in Linux "/dev/console" never becomes ctty anyway -- vda */ + if ((LogStat & LOG_CONS) && + (fd = open(_PATH_CONSOLE, O_WRONLY)) >= 0) { p = strchr(tbuf, '>') + 1; last_chr[0] = '\r'; last_chr[1] = '\n'; @@ -334,7 +338,7 @@ libc_hidden_def(syslog) void closelog( void ) { - closelog_intern(1); + closelog_intern(0); /* 0: do not reset LogXXX globals to default */ } libc_hidden_def(closelog) -- cgit v1.2.3