Workaround for _PATH_UTMP and _PATH_WTMP defines on musl libc

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/initctl.c

@@ -31,7 +31,6 @@
 #include <signal.h>
 #include <stdio.h>
 #include <time.h>
-#include <utmp.h>
 #include <arpa/inet.h>
 #include <lite/lite.h>
 
@@ -40,6 +39,7 @@
 #include "serv.h"
 #include "service.h"
 #include "util.h"
+#include "utmp-api.h"
 
 #define _PATH_COND _PATH_VARRUN "finit/cond/"
 

src/utmp-api.c

@@ -25,16 +25,12 @@
 
 #include <paths.h>
 #include <time.h>
-#include <utmp.h>
 #include <arpa/inet.h>
 #include <sys/utsname.h>
 #include <lite/lite.h>
 
 #include "helpers.h"
-
-#ifndef _PATH_BTMP
-#define _PATH_BTMP "/var/log/btmp"
-#endif
+#include "utmp-api.h"
 
 #define MAX_NO 5
 #define MAX_SZ 100 * 1024

src/utmp-api.h

@@ -24,6 +24,24 @@
 #ifndef FINIT_UTMP_API_H_
 #define FINIT_UTMP_API_H_
 
+#include <utmp.h>
+
+/*
+ * musl libc default to /dev/null/utmp and /dev/null/wtmp, respectively.
+ * See https://www.openwall.com/lists/musl/2012/03/04/4 for reasoning.
+ *
+ * Also, there's no __MUSL__, so we cannot make a libc-specific check
+ * here to work around this, that's why everyone pays.
+ */
+#undef _PATH_UTMP
+#undef _PATH_WTMP
+#undef _PATH_BTMP
+
+#define _PATH_UTMP "/var/run/wtmp"
+#define _PATH_WTMP "/var/log/wtmp"
+#define _PATH_BTMP "/var/log/btmp"
+
+
 int utmp_set         (int type, int pid, char *line, char *id, char *user);
 int utmp_set_boot    (void);
 int utmp_set_halt    (void);