[PATCH 2/2] console: Add ioctl for flushing the scrollback buffer
From: Manuel SchÃlling
Date: Mon Apr 18 2016 - 15:58:11 EST
Tools like clear_console rely on the fact that scrollback history is
flushed when switching back and forth between consoles.
Persistent scrollback buffers for each console breaks this, so this
patch adds a ioctl() callf for flushing the scrollback history.
Signed-off-by: Manuel SchÃlling <manuel.schoelling@xxxxxx>
---
drivers/tty/vt/vt_ioctl.c | 20 ++++++++++++++++++++
drivers/usb/misc/sisusbvga/sisusb_con.c | 1 +
drivers/video/console/dummycon.c | 1 +
drivers/video/console/mdacon.c | 6 ++++++
drivers/video/console/newport_con.c | 1 +
drivers/video/console/sticon.c | 7 +++++++
drivers/video/console/vgacon.c | 23 +++++++++++++++++++++++
include/linux/console.h | 1 +
include/uapi/linux/vt.h | 1 +
9 files changed, 61 insertions(+)
diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index 97d5a74..18adc23 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -903,6 +903,26 @@ int vt_ioctl(struct tty_struct *tty,
break;
}
+ /*
+ * flush the specified VT's scollback buffer
+ */
+ case VT_FLUSH_SCROLLBACK: {
+ if (!perm)
+ return -EPERM;
+ if (arg == 0 || arg > MAX_NR_CONSOLES)
+ ret = -ENXIO;
+ else {
+ struct vc_data *data = vc_cons[arg-1].d;
+
+ if (!data)
+ ret = -ENXIO;
+ else
+ ret = data->vc_sw->con_flush_scrollback(data);
+ }
+
+ break;
+ }
+
case PIO_FONT: {
if (!perm)
return -EPERM;
diff --git a/drivers/usb/misc/sisusbvga/sisusb_con.c b/drivers/usb/misc/sisusbvga/sisusb_con.c
index ace3430..cc5fc10 100644
--- a/drivers/usb/misc/sisusbvga/sisusb_con.c
+++ b/drivers/usb/misc/sisusbvga/sisusb_con.c
@@ -1442,6 +1442,7 @@ static const struct consw sisusb_dummy_con = {
.con_font_copy = SISUSBCONDUMMY,
.con_set_palette = SISUSBCONDUMMY,
.con_scrolldelta = SISUSBCONDUMMY,
+ .con_flush_scrollback = SISUSBCONDUMMY,
};
int
diff --git a/drivers/video/console/dummycon.c b/drivers/video/console/dummycon.c
index 0efc52f..d2888e5 100644
--- a/drivers/video/console/dummycon.c
+++ b/drivers/video/console/dummycon.c
@@ -73,5 +73,6 @@ const struct consw dummy_con = {
.con_font_copy = DUMMY,
.con_set_palette = DUMMY,
.con_scrolldelta = DUMMY,
+ .con_flush_scrollback = DUMMY,
};
EXPORT_SYMBOL_GPL(dummy_con);
diff --git a/drivers/video/console/mdacon.c b/drivers/video/console/mdacon.c
index 296e945..10ebcbe 100644
--- a/drivers/video/console/mdacon.c
+++ b/drivers/video/console/mdacon.c
@@ -510,6 +510,11 @@ static int mdacon_scrolldelta(struct vc_data *c, int lines)
return 0;
}
+static int mdacon_flush_scrollback(struct vc_data *c)
+{
+ return 0;
+}
+
static void mdacon_cursor(struct vc_data *c, int mode)
{
if (mode == CM_ERASE) {
@@ -579,6 +584,7 @@ static const struct consw mda_con = {
.con_blank = mdacon_blank,
.con_set_palette = mdacon_set_palette,
.con_scrolldelta = mdacon_scrolldelta,
+ .con_flush_scrollback = mdacon_flush_scrollback,
.con_build_attr = mdacon_build_attr,
.con_invert_region = mdacon_invert_region,
};
diff --git a/drivers/video/console/newport_con.c b/drivers/video/console/newport_con.c
index bb4e962..d04183c 100644
--- a/drivers/video/console/newport_con.c
+++ b/drivers/video/console/newport_con.c
@@ -738,6 +738,7 @@ const struct consw newport_con = {
.con_scrolldelta = newport_scrolldelta,
.con_set_origin = DUMMY,
.con_save_screen = DUMMY
+ .con_flush_scrollback = DUMMY,
};
static int newport_probe(struct gio_device *dev,
diff --git a/drivers/video/console/sticon.c b/drivers/video/console/sticon.c
index 026fd12..46046d6 100644
--- a/drivers/video/console/sticon.c
+++ b/drivers/video/console/sticon.c
@@ -345,6 +345,12 @@ static void sticon_save_screen(struct vc_data *conp)
{
}
+static int sticon_flush_scrollback(struct vc_data *c)
+{
+ return 0;
+}
+
+
static const struct consw sti_con = {
.owner = THIS_MODULE,
.con_startup = sticon_startup,
@@ -360,6 +366,7 @@ static const struct consw sti_con = {
.con_blank = sticon_blank,
.con_set_palette = sticon_set_palette,
.con_scrolldelta = sticon_scrolldelta,
+ .con_flush_scrollback = sticon_flush_scrollback,
.con_set_origin = sticon_set_origin,
.con_save_screen = sticon_save_screen,
.con_build_attr = sticon_build_attr,
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 6c0b9ba..b5ea94f 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -379,12 +379,34 @@ static int vgacon_scrolldelta(struct vc_data *c, int lines)
return 1;
}
+
+/* flush the scrollback buffer of a console */
+static int vgacon_flush_scrollback(struct vc_data *c)
+{
+ size_t size = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
+ struct vgacon_scrollback_info *vgacon_scrollback_prev;
+
+ vgacon_scrollback_prev = vgacon_scrollback_cur;
+ vgacon_scrollback_cur = &vgacon_scrollbacks[c->vc_num];
+
+ if (vgacon_scrollback_cur != NULL)
+ vgacon_scrollback_reset(size);
+
+ vgacon_scrollback_cur = vgacon_scrollback_prev;
+
+ return 0;
+}
#else
#define vgacon_scrollback_startup(...) do { } while (0)
#define vgacon_scrollback_init(...) do { } while (0)
#define vgacon_scrollback_update(...) do { } while (0)
#define vgacon_switch_scrollback(...) do { } while (0)
+static int vgacon_flush_scrollback(struct vc_data *c)
+{
+ return 0;
+}
+
static void vgacon_restore_screen(struct vc_data *c)
{
if (c->vc_origin != c->vc_visible_origin)
@@ -1492,6 +1514,7 @@ const struct consw vga_con = {
.con_resize = vgacon_resize,
.con_set_palette = vgacon_set_palette,
.con_scrolldelta = vgacon_scrolldelta,
+ .con_flush_scrollback = vgacon_flush_scrollback,
.con_set_origin = vgacon_set_origin,
.con_save_screen = vgacon_save_screen,
.con_build_attr = vgacon_build_attr,
diff --git a/include/linux/console.h b/include/linux/console.h
index e49cc1e..946ff20 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -49,6 +49,7 @@ struct consw {
unsigned int);
int (*con_set_palette)(struct vc_data *, unsigned char *);
int (*con_scrolldelta)(struct vc_data *, int);
+ int (*con_flush_scrollback)(struct vc_data *);
int (*con_set_origin)(struct vc_data *);
void (*con_save_screen)(struct vc_data *);
u8 (*con_build_attr)(struct vc_data *, u8, u8, u8, u8, u8, u8);
diff --git a/include/uapi/linux/vt.h b/include/uapi/linux/vt.h
index 978578b..b799541 100644
--- a/include/uapi/linux/vt.h
+++ b/include/uapi/linux/vt.h
@@ -83,5 +83,6 @@ struct vt_setactivate {
};
#define VT_SETACTIVATE 0x560F /* Activate and set the mode of a console */
+#define VT_FLUSH_SCROLLBACK 0x5610 /* Flush the scrollback buffer */
#endif /* _UAPI_LINUX_VT_H */
--
2.1.4