ioctl: The POSIX signature differs from BSD and glibc

BSD and glibc have the signature for request as unsigned long.
musl and Solaris have a signed int.

As such, we need to detect this at compile time and adjust the
signature of our internal ioctl functions to match.
To keep the onwire format the same, memcpy the request to the
unsigned long request and back again, thus preserving the signedness.

1 files changed, 22 insertions, 1 deletions

diff --git a/configure b/configure
index 0cb27ce1..263afbf7 100755
--- a/configure
+++ b/configure
@@ -549,7 +549,7 @@ if [ "$PRIVSEP" = yes ]; then
 			fi
 		done
 	fi
-	: ${PRIVSEP_USER:= _dhcpcd}
+	: ${PRIVSEP_USER:=_dhcpcd}
 
 	echo "CPPFLAGS+=	-DPRIVSEP" >>$CONFIG_MK
 	echo "#ifndef PRIVSEP_USER" >>$CONFIG_H
@@ -737,6 +737,27 @@ fi
 rm -f _clock_gettime.c _clock_gettime
 $abort && exit 1
 
+printf "Testing ioctl request type ... "
+cat <<EOF >_ioctl.c
+#include <sys/ioctl.h>
+int main(void) {
+	unsigned long req = 0;
+	return ioctl(3, req, &req);
+}
+EOF
+if $XCC _ioctl.c -o _ioctl 2>&3; then
+	IOCTL_REQ="unsigned long"
+else
+	IOCTL_REQ="int"
+fi
+echo "$IOCTL_REQ"
+# Our default is unsigned long
+# We can still define it, but it makes the code path slightly bigger
+if [ "$IOCTL_REQ" != "unsigned long" ]; then
+	echo "#define	IOCTL_REQUEST_TYPE	$IOCTL_REQ" >>$CONFIG_H
+fi
+rm -f _ioctl.c _ioctl
+
 printf "Testing for inet_ntoa ... "
 cat <<EOF >_inet_ntoa.c
 #include <netinet/in.h>