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, 11 insertions, 1 deletions

diff --git a/src/if.h b/src/if.h
index 8165a498..e371e970 100644
--- a/src/if.h
+++ b/src/if.h
@@ -62,6 +62,16 @@
 #endif
 
 #include "config.h"
+
+/* POSIX defines ioctl request as an int, which Solaris and musl use.
+ * Everyone else use an unsigned long, which happens to be the bigger one
+ * so we use that in our on wire API. */
+#ifdef IOCTL_REQUEST_TYPE
+typedef IOCTL_REQUEST_TYPE	ioctl_request_t;
+#else
+typedef unsigned long		ioctl_request_t;
+#endif
+
 #include "dhcpcd.h"
 #include "ipv4.h"
 #include "ipv6.h"
@@ -110,7 +120,7 @@ int if_getifaddrs(struct ifaddrs **);
 int if_getsubnet(struct dhcpcd_ctx *, const char *, int, void *, size_t);
 #endif
 
-int if_ioctl(struct dhcpcd_ctx *, unsigned long, void *, size_t);
+int if_ioctl(struct dhcpcd_ctx *, ioctl_request_t, void *, size_t);
 int if_getflags(struct interface *ifp);
 int if_setflag(struct interface *ifp, short flag);
 #define if_up(ifp) if_setflag((ifp), (IFF_UP | IFF_RUNNING))