kernel: pseudodevices (null, full and zero)

kernel-src/io/pseudodevices.c

@@ -0,0 +1,45 @@
+#include <kernel/devfs.h>
+#include <errno.h>
+#include <string.h>
+#include <logging.h>
+
+static int null_write(int minor, void *buffer, size_t count, uintmax_t offset, int flags, size_t *wcount) {
+	*wcount = count;
+	return 0;
+}
+
+static int full_write(int minor, void *buffer, size_t count, uintmax_t offset, int flags, size_t *wcount) {
+	return ENOSPC;
+}
+
+static int zero_read(int minor, void *buffer, size_t count, uintmax_t offset, int flags, size_t *rcount) {
+	*rcount = count;
+	memset(buffer, 0, count);
+	return 0;
+}
+
+static int null_read(int minor, void *buffer, size_t count, uintmax_t offset, int flags, size_t *rcount) {
+	*rcount = 0;
+	return 0;
+}
+
+static devops_t nullops = {
+	.read = null_read,
+	.write = null_write
+};
+
+static devops_t fullops = {
+	.read = zero_read,
+	.write = full_write
+};
+
+static devops_t zeroops = {
+	.read = zero_read,
+	.write = null_write
+};
+
+void pseudodevices_init() {
+	__assert(devfs_register(&nullops, "null", V_TYPE_CHDEV, DEV_MAJOR_NULL, 0, 0644) == 0);
+	__assert(devfs_register(&fullops, "full", V_TYPE_CHDEV, DEV_MAJOR_FULL, 0, 0644) == 0);
+	__assert(devfs_register(&zeroops, "zero", V_TYPE_CHDEV, DEV_MAJOR_ZERO, 0, 0644) == 0);
+}