BUILD: introduce "--with-syslog=stderr" option

to be used in containers-like environments where
no system wide logger is available.

Makefile.am

@@ -8,6 +8,10 @@ if WITH_JOURNALD
     extra_distcheck_flags += --with-syslog=journald
 endif
 
+if WITH_STDERR_SYSLOG
+    extra_distcheck_flags += --with-syslog=stderr
+endif
+
 DISTCHECK_CONFIGURE_FLAGS = --with-ldb-lib-dir="$$dc_install_base"/lib/ldb \
                             $(extra_distcheck_flags) \
                             $(AUX_DISTCHECK_CONFIGURE_FLAGS)

src/conf_macros.m4

@@ -144,21 +144,26 @@ AC_DEFUN([WITH_INITSCRIPT],
 AC_DEFUN([WITH_SYSLOG],
   [ AC_ARG_WITH([syslog],
                 [AC_HELP_STRING([--with-syslog=SYSLOG_TYPE],
-                                [Type of your system logger (syslog|journald). [syslog]]
+                                [Type of your system logger (syslog|journald|stderr). [syslog]]
                                )
                 ],
                 [],
                 [with_syslog="syslog"]
                )
 
   if test x"$with_syslog" = xsyslog || \
-     test x"$with_syslog" = xjournald; then
+     test x"$with_syslog" = xjournald || \
+     test x"$with_syslog" = xstderr; then
         syslog=$with_syslog
   else
-      AC_MSG_ERROR([Unknown syslog type, supported types are syslog and journald])
+      AC_MSG_ERROR([Unknown syslog type, supported types are syslog, journald and stderr])
   fi
 
   AM_CONDITIONAL([WITH_JOURNALD], [test x"$syslog" = xjournald])
+  AM_CONDITIONAL([WITH_STDERR_SYSLOG], [test x"$syslog" = xstderr])
+  if test x"$with_syslog" = xstderr; then
+      AC_DEFINE_UNQUOTED([WITH_STDERR_SYSLOG], 1, [Send syslog to stderr])
+  fi
   ])
 
 AC_DEFUN([WITH_ENVIRONMENT_FILE],

src/util/sss_log.c

@@ -26,10 +26,15 @@
 
 #ifdef WITH_JOURNALD
 #include <systemd/sd-journal.h>
-#else  /* WITH_JOURNALD */
+#else
+#ifdef WITH_STDERR_SYSLOG
+#include <stdio.h>
+#else
 #include <syslog.h>
-#endif /* WITH_JOURNALD */
+#endif
+#endif
 
+#if !defined(WITH_STDERR_SYSLOG)
 static int sss_to_syslog(int priority)
 {
     switch(priority) {
@@ -59,13 +64,19 @@ static int sss_to_syslog(int priority)
 
 static void sss_log_internal(int priority, int facility, const char *format,
                              va_list ap);
+#endif
+
 
 void sss_log(int priority, const char *format, ...)
 {
     va_list ap;
 
     va_start(ap, format);
+#if !defined(WITH_STDERR_SYSLOG)
     sss_log_internal(priority, LOG_DAEMON, format, ap);
+#else
+    vfprintf(stderr, format, ap);
+#endif
     va_end(ap);
 }
 
@@ -74,7 +85,11 @@ void sss_log_ext(int priority, int facility, const char *format, ...)
     va_list ap;
 
     va_start(ap, format);
+#if !defined(WITH_STDERR_SYSLOG)
     sss_log_internal(priority, facility, format, ap);
+#else
+    vfprintf(stderr, format, ap);
+#endif
     va_end(ap);
 }
 
@@ -114,6 +129,7 @@ static void sss_log_internal(int priority, int facility, const char *format,
 }
 
 #else /* WITH_JOURNALD */
+#if !defined(WITH_STDERR_SYSLOG)
 
 static void sss_log_internal(int priority, int facility, const char *format,
                             va_list ap)
@@ -123,4 +139,5 @@ static void sss_log_internal(int priority, int facility, const char *format,
     vsyslog(facility|syslog_priority, format, ap);
 }
 
+#endif /* !WITH_STDERR_SYSLOG */
 #endif /* WITH_JOURNALD */