commit c9f7b4d356a453a01aa77a6bb74ca7ef49732c08
Author: Mike Gilbert <floppymaster@gmail.com>
Date:   Tue Jan 10 02:39:05 2017 -0500

    build-sys: add check for gperf lookup function signature (#5055)
    
    gperf-3.1 generates lookup functions that take a size_t length
    parameter instead of unsigned int. Test for this at configure time.
    
    Fixes: https://github.com/systemd/systemd/issues/5039

diff --git a/configure.ac b/configure.ac
index 11bd46c..d58fff5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -255,6 +255,28 @@ AC_CHECK_SIZEOF(rlim_t,,[
        #include <sys/resource.h>
 ])
 
+GPERF_TEST="$(echo foo,bar | ${GPERF} -L ANSI-C)"
+
+AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM([
+                #include <string.h>
+                const char * in_word_set(const char *, size_t);
+                $GPERF_TEST]
+        )],
+        [GPERF_LEN_TYPE=size_t],
+        [AC_COMPILE_IFELSE(
+                [AC_LANG_PROGRAM([
+                        #include <string.h>
+                        const char * in_word_set(const char *, unsigned);
+                        $GPERF_TEST]
+                )],
+                [GPERF_LEN_TYPE=unsigned],
+                [AC_MSG_ERROR([** unable to determine gperf len type])]
+        )]
+)
+
+AC_DEFINE_UNQUOTED([GPERF_LEN_TYPE], [$GPERF_LEN_TYPE], [gperf len type])
+
 # ------------------------------------------------------------------------------
 # we use python to build the man page index
 have_python=no
diff --git a/src/shared/af-list.c b/src/shared/af-list.c
index 3fac9c5..4b291d1 100644
--- a/src/shared/af-list.c
+++ b/src/shared/af-list.c
@@ -23,7 +23,7 @@
 #include "af-list.h"
 #include "macro.h"
 
-static const struct af_name* lookup_af(register const char *str, register unsigned int len);
+static const struct af_name* lookup_af(register const char *str, register GPERF_LEN_TYPE len);
 
 #include "af-from-name.h"
 #include "af-to-name.h"
diff --git a/src/shared/arphrd-list.c b/src/shared/arphrd-list.c
index 6792d1e..2d598dc 100644
--- a/src/shared/arphrd-list.c
+++ b/src/shared/arphrd-list.c
@@ -23,7 +23,7 @@
 #include "arphrd-list.h"
 #include "macro.h"
 
-static const struct arphrd_name* lookup_arphrd(register const char *str, register unsigned int len);
+static const struct arphrd_name* lookup_arphrd(register const char *str, register GPERF_LEN_TYPE len);
 
 #include "arphrd-from-name.h"
 #include "arphrd-to-name.h"
diff --git a/src/shared/cap-list.c b/src/shared/cap-list.c
index 3e773a0..d68cc78 100644
--- a/src/shared/cap-list.c
+++ b/src/shared/cap-list.c
@@ -26,7 +26,7 @@
 #include "parse-util.h"
 #include "util.h"
 
-static const struct capability_name* lookup_capability(register const char *str, register unsigned int len);
+static const struct capability_name* lookup_capability(register const char *str, register GPERF_LEN_TYPE len);
 
 #include "cap-from-name.h"
 #include "cap-to-name.h"
diff --git a/src/shared/errno-list.c b/src/shared/errno-list.c
index 31b66ba..c6a01ee 100644
--- a/src/shared/errno-list.c
+++ b/src/shared/errno-list.c
@@ -23,7 +23,7 @@
 #include "errno-list.h"
 
 static const struct errno_name* lookup_errno(register const char *str,
-                                                 register unsigned int len);
+                                             register GPERF_LEN_TYPE len);
 
 #include "errno-to-name.h"
 #include "errno-from-name.h"
diff --git a/src/login/logind.h b/src/login/logind.h
index 086fa1e..7556ee2 100644
--- a/src/login/logind.h
+++ b/src/login/logind.h
@@ -182,7 +182,7 @@ int manager_unit_is_active(Manager *manager, const char *unit);
 int manager_job_is_active(Manager *manager, const char *path);
 
 /* gperf lookup function */
-const struct ConfigPerfItem* logind_gperf_lookup(const char *key, unsigned length);
+const struct ConfigPerfItem* logind_gperf_lookup(const char *key, GPERF_LEN_TYPE length);
 
 int manager_set_lid_switch_ignore(Manager *m, usec_t until);