[PATCH 2/3] vt: selection: handle storing of characters above U+FFFF

[Adam Borowski]

Those above U+10FFFF get replaced with U+FFFD.

Signed-off-by: Adam Borowski <kilob...@angband.pl>
---
 drivers/tty/vt/selection.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index 34e7110f310d..69ca337d3220 100644
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -116,8 +116,8 @@ static inline int atedge(const int p, int size_row)
        return (!(p % size_row) || !((p + 2) % size_row));
 }
 
-/* stores the char in UTF8 and returns the number of bytes used (1-3) */
-static int store_utf8(u16 c, char *p)
+/* stores the char in UTF8 and returns the number of bytes used (1-4) */
+static int store_utf8(u32 c, char *p)
 {
        if (c < 0x80) {
                /*  0******* */
@@ -128,13 +128,26 @@ static int store_utf8(u16 c, char *p)
                p[0] = 0xc0 | (c >> 6);
                p[1] = 0x80 | (c & 0x3f);
                return 2;
-       } else {
+       } else if (c < 0x10000) {
                /* 1110**** 10****** 10****** */
                p[0] = 0xe0 | (c >> 12);
                p[1] = 0x80 | ((c >> 6) & 0x3f);
                p[2] = 0x80 | (c & 0x3f);
                return 3;
-       }
+       } else if (c < 0x110000) {
+               /* 11110*** 10****** 10****** 10****** */
+               p[0] = 0xf0 | (c >> 18);
+               p[1] = 0x80 | ((c >> 12) & 0x3f);
+               p[2] = 0x80 | ((c >> 6) & 0x3f);
+               p[3] = 0x80 | (c & 0x3f);
+               return 4;
+       } else {
+               /* outside Unicode, replace with U+FFFD */
+               p[0] = 0xef;
+               p[1] = 0xbf;
+               p[2] = 0xbd;
+               return 3;
+       }
 }
 
 /**
@@ -273,7 +286,7 @@ int set_selection(const struct tiocl_selection __user *sel, 
struct tty_struct *t
        sel_end = new_sel_end;
 
        /* Allocate a new buffer before freeing the old one ... */
-       multiplier = use_unicode ? 3 : 1;  /* chars can take up to 3 bytes */
+       multiplier = use_unicode ? 4 : 1;  /* chars can take up to 4 bytes */
        bp = kmalloc_array((sel_end - sel_start) / 2 + 1, multiplier,
                           GFP_KERNEL);
        if (!bp) {
-- 
2.18.0