sysif: work around glibc warnings about makedev macros.

The GNU C library is deprecating the practice of <sys/types.h>
defining the makedev, major and minor macros. A loud,
multi-line warning is issued for programs which include this
header and then use the macros. The new way is to rely on
the <sys/sysmacros.h> header instead. Of course, that might
not exist.

* configure (have_makedev): New variable. Upgrade the makedev
test to try it with <sys/sysmacros.h> first, then fall back
on <sys/types.h>. A new config macro HAVE_SYS_SYSMACROS_H
is created in config.h if sysmacros exists.

* sysif.c: If config.h defines HAVE_SYS_SYSMACROS_H to a
nonzero value, then include <sys/sysmacros.h>.

2 files changed, 24 insertions, 7 deletions

diff --git a/configure b/configure
index 1076887c..bf17637d 100755
--- a/configure
+++ b/configure
@@ -128,6 +128,7 @@ have_dbl_decimal_dig=
 have_unistd=
 have_sys_types=
 have_sys_time=
+have_makedev=
 have_syslog=
 have_glob=
 have_ftw=
@@ -2006,8 +2007,9 @@ fi
 
 printf "Checking for makedev ... "
 
-cat > conftest.c <<!
-#include <sys/types.h>
+for try_header in sysmacros types ; do
+  cat > conftest.c <<!
+#include <sys/${try_header}.h>
 
 int main(void)
 {
@@ -2017,11 +2019,23 @@ int main(void)
   return 0;
 }
 !
-if conftest ; then
-  printf "yes\n"
-  printf "#define HAVE_MAKEDEV 1\n" >> config.h
-  have_sys_types=y
-else
+  if conftest ; then
+    printf "yes\n"
+    printf "#define HAVE_MAKEDEV 1\n" >> config.h
+    case $try_header in
+    sysmacros )
+      printf "#define HAVE_SYS_SYSMACROS_H 1\n" >> config.h
+      ;;
+    types )
+      have_sys_types=y
+      ;;
+    esac
+    have_makedev=y
+    break
+  fi
+done
+
+if [ -z "$have_makedev" ] ; then
   printf "no\n"
 fi
 
diff --git a/sysif.c b/sysif.c
index 8111d4f5..1020f075 100644
--- a/sysif.c
+++ b/sysif.c
@@ -53,6 +53,9 @@
 #if HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
+#if HAVE_SYS_SYSMACROS_H
+#include <sys/sysmacros.h>
+#endif
 #if HAVE_POLL
 #include <poll.h>
 #endif