veb: support sendfile() syscall on FreeBSD (#21541)

vlib/veb/sendfile_freebsd.c.v

@@ -0,0 +1,12 @@
+module veb
+
+fn C.sendfile(in_fd int, out_fd int, offset int, count int, voidptr offsetp, voidptr hdr, flags int) int
+
+fn sendfile(out_fd int, in_fd int, nr_bytes int) int {
+	// out_fd must be a stream socket descriptor.
+	r := C.sendfile(in_fd, out_fd, 0, nr_bytes, unsafe { nil }, unsafe { nil }, 0)
+	if r == 0 {
+		return nr_bytes
+	}
+	return r
+}

vlib/veb/veb.v

@@ -391,7 +391,7 @@ fn handle_timeout(mut pv picoev.Picoev, mut params RequestParams, fd int) {
 fn handle_write_file(mut pv picoev.Picoev, mut params RequestParams, fd int) {
 	mut bytes_to_write := int(params.file_responses[fd].total - params.file_responses[fd].pos)
 
-	$if linux {
+	$if linux || freebsd {
 		bytes_written := sendfile(fd, params.file_responses[fd].file.fd, bytes_to_write)
 		params.file_responses[fd].pos += bytes_written
 	} $else {

vlib/x/vweb/sendfile_freebsd.c.v

@@ -0,0 +1,12 @@
+module vweb
+
+fn C.sendfile(in_fd int, out_fd int, offset int, count int, voidptr offsetp, voidptr hdr, flags int) int
+
+fn sendfile(out_fd int, in_fd int, nr_bytes int) int {
+	// out_fd must be a stream socket descriptor.
+	r := C.sendfile(in_fd, out_fd, 0, nr_bytes, unsafe { nil }, unsafe { nil }, 0)
+	if r == 0 {
+		return nr_bytes
+	}
+	return r
+}

vlib/x/vweb/vweb.v

@@ -391,7 +391,7 @@ fn handle_timeout(mut pv picoev.Picoev, mut params RequestParams, fd int) {
 fn handle_write_file(mut pv picoev.Picoev, mut params RequestParams, fd int) {
 	mut bytes_to_write := int(params.file_responses[fd].total - params.file_responses[fd].pos)
 
-	$if linux {
+	$if linux || freebsd {
 		bytes_written := sendfile(fd, params.file_responses[fd].file.fd, bytes_to_write)
 		params.file_responses[fd].pos += bytes_written
 	} $else {