[ulogd2 PATCH 3/4] ulogd: Use (FILE *)(-1) as dummy logfile when logging to syslog

[ulogd2 PATCH 3/4] ulogd: Use (FILE *)(-1) as dummy logfile when logging to syslog

[Felix Janda]

Fixes compilation error with musl libc:

ulogd.c:86:13: error: storage size of 'syslog_dummy' isn't known
 static FILE syslog_dummy;

Signed-off-by: Felix Janda <felix.janda@posteo.de>
---
 src/ulogd.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/ulogd.c b/src/ulogd.c
index e7cde39..093f7ec 100644
--- a/src/ulogd.c
+++ b/src/ulogd.c
@@ -83,7 +83,7 @@ static char *ulogd_logfile = NULL;
 static const char *ulogd_configfile = ULOGD_CONFIGFILE;
 static const char *ulogd_pidfile = NULL;
 static int ulogd_pidfile_fd = -1;
-static FILE syslog_dummy;
+#define SYSLOG_DUMMY ((FILE *)(-1))
 
 static int info_mode = 0;
 
@@ -427,7 +427,7 @@ void __ulogd_log(int level, char *file, int line, const char *format, ...)
 	if (level < loglevel_ce.u.value)
 		return;
 
-	if (logfile == &syslog_dummy) {
+	if (logfile == SYSLOG_DUMMY) {
 		/* FIXME: this omits the 'file' string */
 		va_start(ap, format);
 		vsyslog(ulogd2syslog_level(level), format, ap);
@@ -950,7 +950,7 @@ static int logfile_open(const char *name)
 		logfile = stdout;
 	} else if (!strcmp(name, "syslog")) {
 		openlog("ulogd", LOG_PID, LOG_DAEMON);
-		logfile = &syslog_dummy;
+		logfile = SYSLOG_DUMMY;
 	} else {
 		logfile = fopen(ulogd_logfile, "a");
 		if (!logfile) {
@@ -1240,7 +1240,7 @@ static void sigterm_handler(int signal)
 	unload_plugins();
 #endif
 
-	if (logfile != NULL  && logfile != stdout && logfile != &syslog_dummy) {
+	if (logfile != NULL  && logfile != stdout && logfile != SYSLOG_DUMMY) {
 		fclose(logfile);
 		logfile = NULL;
 	}
@@ -1262,7 +1262,7 @@ static void signal_handler(int signal)
 	switch (signal) {
 	case SIGHUP:
 		/* reopen logfile */
-		if (logfile != stdout && logfile != &syslog_dummy) {
+		if (logfile != stdout && logfile != SYSLOG_DUMMY) {
 			fclose(logfile);
 			logfile = fopen(ulogd_logfile, "a");
  			if (!logfile) {
-- 
2.3.6

Re: [ulogd2 PATCH 3/4] ulogd: Use (FILE *)(-1) as dummy logfile when logging to syslog

[Jan Engelhardt]

On Saturday 2015-05-16 15:37, Felix Janda wrote:

>-static FILE syslog_dummy;
>+#define SYSLOG_DUMMY ((FILE *)(-1))

^This will likely introduce a "cast to pointer from integer of different 
size" warning on LP64 targets.

syslog_dummy = fopen("/dev/null", "w");

would be, at the cost of one more open fd, a "nice" solution,
since syslog_dummy is guaranteed to be unique, without making
any assumptions about any magic value(s) being unused.

That, or turn the assumptive macro into
	#define SYSLOG_DUMMY ((FILE *)(intptr_t)-1)

Re: [ulogd2 PATCH 3/4] ulogd: Use (FILE *)(-1) as dummy logfile when logging to syslog

[Felix Janda]

Jan Engelhardt wrote:
> On Saturday 2015-05-16 15:37, Felix Janda wrote:
> 
> >-static FILE syslog_dummy;
> >+#define SYSLOG_DUMMY ((FILE *)(-1))
> 
> ^This will likely introduce a "cast to pointer from integer of different 
> size" warning on LP64 targets.
> 
> syslog_dummy = fopen("/dev/null", "w");
> 
> would be, at the cost of one more open fd, a "nice" solution,
> since syslog_dummy is guaranteed to be unique, without making
> any assumptions about any magic value(s) being unused.

This seems seems like a cleaner approach.
Preparing a new patch...

> That, or turn the assumptive macro into
> 	#define SYSLOG_DUMMY ((FILE *)(intptr_t)-1)

Thanks,
Felix