v4l2: v4l2_compat: Fix ioctl() prototype with musl C library

The musl C library, as well as the POSIX standard, define the ioctl()
function's request argument as an int. glibc and uclibc, on the other
hand, define it as an unsigned long.

This difference between the function prototype and the implementation in
the V4L2 adaptation layer causes a compilation error with musl. Fix it
by detecting the function prototype and declaring the libcamera ioctl()
handler accordingly.

Signed-off-by: Laurent Pinchart <[email protected]>
Reviewed-by: Kieran Bingham <[email protected]>
Reviewed-by: Paul Elder <[email protected]>
Signed-off-by: Kieran Bingham <[email protected]>

meson.build

@@ -90,6 +90,15 @@ if cc.has_header_symbol('sys/mman.h', 'memfd_create', prefix : '#define _GNU_SOU
     config_h.set('HAVE_MEMFD_CREATE', 1)
 endif
 
+ioctl_posix_test = '''
+#include <sys/ioctl.h>
+int ioctl (int, int, ...);
+'''
+
+if cc.compiles(ioctl_posix_test)
+    config_h.set('HAVE_POSIX_IOCTL', 1)
+endif
+
 if cc.has_header_symbol('stdlib.h', 'secure_getenv', prefix : '#define _GNU_SOURCE')
     config_h.set('HAVE_SECURE_GETENV', 1)
 endif

src/v4l2/v4l2_compat.cpp

@@ -154,7 +154,11 @@ LIBCAMERA_PUBLIC int munmap(void *addr, size_t length)
 	return V4L2CompatManager::instance()->munmap(addr, length);
 }
 
+#if HAVE_POSIX_IOCTL
+LIBCAMERA_PUBLIC int ioctl(int fd, int request, ...)
+#else
 LIBCAMERA_PUBLIC int ioctl(int fd, unsigned long request, ...)
+#endif
 {
 	void *arg;
 	extract_va_arg(void *, arg, request);