null: merge /dev/zero and add a /dev/full

present on both FreeBSD and Linux.
useful to test a "disk full" condition.

Change-Id: Ibac6b50e8063c90e3e324ec04ac136c34298cc7f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/9617
Reviewed-by: waddlesplash <[email protected]>
Tested-by: Commit checker robot <[email protected]>

build/jam/packages/Haiku

@@ -161,7 +161,6 @@ AddDriversToPackage :
 	null
 	<driver>tty
 	usb_modeswitch
-	zero
 	;
 AddDriversToPackage audio hmulti :
 	$(SYSTEM_ADD_ONS_DRIVERS_AUDIO) ;

build/jam/packages/HaikuBootstrap

@@ -106,7 +106,6 @@ AddDriversToPackage :
 	null
 	random
 	<driver>tty
-	zero
 	;
 AddDriversToPackage audio hmulti
 	: $(SYSTEM_ADD_ONS_DRIVERS_AUDIO) ;

src/add-ons/kernel/drivers/common/Jamfile

@@ -7,11 +7,7 @@ KernelAddon dprintf :
 	;
 
 KernelAddon null :
-	null.c
-	;
-
-KernelAddon zero :
-	zero.c
+	null.cpp
 	;
 
 KernelAddon console :

src/add-ons/kernel/drivers/common/null.cpp

@@ -8,10 +8,13 @@
 
 
 #include <Drivers.h>
+#include <KernelExport.h>
 #include <string.h>
 
 
-#define DEVICE_NAME "null"
+#define DEVICE_NAME_FULL "full"
+#define DEVICE_NAME_NULL "null"
+#define DEVICE_NAME_ZERO "zero"
 
 int32 api_version = B_CUR_DRIVER_API_VERSION;
 
@@ -53,6 +56,16 @@ null_read(void *cookie, off_t pos, void *buffer, size_t *_length)
 }
 
 
+static status_t
+zero_read(void *cookie, off_t pos, void *buffer, size_t *_length)
+{
+	if (user_memset(buffer, 0, *_length) < B_OK)
+		return B_BAD_ADDRESS;
+
+	return B_OK;
+}
+
+
 static status_t
 null_write(void *cookie, off_t pos, const void *buffer, size_t *_length)
 {
@@ -60,6 +73,13 @@ null_write(void *cookie, off_t pos, const void *buffer, size_t *_length)
 }
 
 
+static status_t
+full_write(void *cookie, off_t pos, const void *buffer, size_t *_length)
+{
+	return B_DEVICE_FULL;
+}
+
+
 //	#pragma mark -
 
 
@@ -74,7 +94,9 @@ const char **
 publish_devices(void)
 {
 	static const char *devices[] = {
-		DEVICE_NAME, 
+		DEVICE_NAME_FULL,
+		DEVICE_NAME_NULL,
+		DEVICE_NAME_ZERO,
 		NULL
 	};
 
@@ -85,24 +107,40 @@ publish_devices(void)
 device_hooks *
 find_device(const char *name)
 {
-	static device_hooks hooks = {
+	static device_hooks fullHooks = {
+		&null_open,
+		&null_close,
+		&null_freecookie,
+		&null_ioctl,
+		&null_read,
+		&full_write,
+	};
+
+	static device_hooks nullHooks = {
 		&null_open,
 		&null_close,
 		&null_freecookie,
 		&null_ioctl,
 		&null_read,
 		&null_write,
-		/* Leave select/deselect/readv/writev undefined. The kernel will
-		 * use its own default implementation. The basic hooks above this
-		 * line MUST be defined, however. */
-		NULL,
-		NULL,
-		NULL,
-		NULL
 	};
 
-	if (!strcmp(name, DEVICE_NAME))
-		return &hooks;
+	static device_hooks zeroHooks = {
+		&null_open,
+		&null_close,
+		&null_freecookie,
+		&null_ioctl,
+		&zero_read,
+		&null_write,
+	};
+
+
+	if (strcmp(name, DEVICE_NAME_FULL) == 0)
+		return &fullHooks;
+	if (strcmp(name, DEVICE_NAME_NULL) == 0)
+		return &nullHooks;
+	if (strcmp(name, DEVICE_NAME_ZERO) == 0)
+		return &zeroHooks;
 
 	return NULL;
 }

src/add-ons/kernel/drivers/common/zero.c

@@ -1,123 +0,0 @@
-/*
-** Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
-** Distributed under the terms of the NewOS License.
-*/
-
-
-#include <Drivers.h>
-#include <KernelExport.h>
-
-#include <string.h>
-
-
-#define DEVICE_NAME "zero"
-
-int32 api_version = B_CUR_DRIVER_API_VERSION;
-
-
-static status_t
-zero_open(const char *name, uint32 flags, void **cookie)
-{
-	*cookie = NULL;
-	return B_OK;
-}
-
-
-static status_t
-zero_close(void *cookie)
-{
-	return B_OK;
-}
-
-
-static status_t
-zero_freecookie(void *cookie)
-{
-	return B_OK;
-}
-
-
-static status_t
-zero_ioctl(void *cookie, uint32 op, void *buffer, size_t length)
-{
-	return EPERM;
-}
-
-
-static status_t
-zero_read(void *cookie, off_t pos, void *buffer, size_t *_length)
-{
-	if (user_memset(buffer, 0, *_length) < B_OK)
-		return B_BAD_ADDRESS;
-
-	return B_OK;
-}
-
-
-static status_t
-zero_write(void *cookie, off_t pos, const void *buffer, size_t *_length)
-{
-	return B_OK;
-}
-
-
-//	#pragma mark -
-
-
-status_t
-init_hardware(void)
-{
-	return B_OK;
-}
-
-
-const char **
-publish_devices(void)
-{
-	static const char *devices[] = {
-		DEVICE_NAME, 
-		NULL
-	};
-
-	return devices;
-}
-
-
-device_hooks *
-find_device(const char *name)
-{
-	static device_hooks hooks = {
-		&zero_open,
-		&zero_close,
-		&zero_freecookie,
-		&zero_ioctl,
-		&zero_read,
-		&zero_write,
-		/* Leave select/deselect/readv/writev undefined. The kernel will
-		 * use its own default implementation. The basic hooks above this
-		 * line MUST be defined, however. */
-		NULL,
-		NULL,
-		NULL,
-		NULL
-	};
-
-	if (!strcmp(name, DEVICE_NAME))
-		return &hooks;
-
-	return NULL;
-}
-
-
-status_t
-init_driver(void)
-{
-	return B_OK;
-}
-
-
-void
-uninit_driver(void)
-{
-}
-