fix(input): never escape CSI bytes

3 files changed, 28 insertions, 14 deletions

diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index 5565e17597..bddf2e21d2 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -1010,12 +1010,11 @@ void ins_char_typebuf(int c)
     buf[utf_char2bytes(c, buf)] = NUL;
     char_u *p = buf;
     while (*p) {
-      if ((uint8_t)(*p) == CSI || (uint8_t)(*p) == K_SPECIAL) {
-        bool is_csi = (uint8_t)(*p) == CSI;
+      if ((uint8_t)(*p) == K_SPECIAL) {
         memmove(p + 3, p + 1, STRLEN(p + 1) + 1);
         *p++ = K_SPECIAL;
-        *p++ = is_csi ? KS_EXTRA : KS_SPECIAL;
-        *p++ = is_csi ? KE_CSI : KE_FILLER;
+        *p++ = KS_SPECIAL;
+        *p++ = KE_FILLER;
       } else {
         p++;
       }
diff --git a/src/nvim/os/input.c b/src/nvim/os/input.c
index 3790eba212..54cfaee80a 100644
--- a/src/nvim/os/input.c
+++ b/src/nvim/os/input.c
@@ -234,9 +234,9 @@ size_t input_enqueue(String keys)
   while (rbuffer_space(input_buffer) >= 19 && ptr < end) {
     // A "<x>" form occupies at least 1 characters, and produces up
     // to 19 characters (1 + 5 * 3 for the char and 3 for a modifier).
-    // In the case of K_SPECIAL(0x80) or CSI(0x9B), 3 bytes are escaped and
-    // needed, but since the keys are UTF-8, so the first byte cannot be
-    // K_SPECIAL(0x80) or CSI(0x9B).
+    // In the case of K_SPECIAL(0x80), 3 bytes are escaped and needed,
+    // but since the keys are UTF-8, so the first byte cannot be
+    // K_SPECIAL(0x80).
     uint8_t buf[19] = { 0 };
     unsigned int new_size
       = trans_special((const uint8_t **)&ptr, (size_t)(end - ptr), buf, true,
@@ -263,12 +263,8 @@ size_t input_enqueue(String keys)
       continue;
     }
 
-    // copy the character, escaping CSI and K_SPECIAL
-    if ((uint8_t)*ptr == CSI) {
-      rbuffer_write(input_buffer, (char *)&(uint8_t){ K_SPECIAL }, 1);
-      rbuffer_write(input_buffer, (char *)&(uint8_t){ KS_EXTRA }, 1);
-      rbuffer_write(input_buffer, (char *)&(uint8_t){ KE_CSI }, 1);
-    } else if ((uint8_t)*ptr == K_SPECIAL) {
+    // copy the character, escaping K_SPECIAL
+    if ((uint8_t)(*ptr) == K_SPECIAL) {
       rbuffer_write(input_buffer, (char *)&(uint8_t){ K_SPECIAL }, 1);
       rbuffer_write(input_buffer, (char *)&(uint8_t){ KS_SPECIAL }, 1);
       rbuffer_write(input_buffer, (char *)&(uint8_t){ KE_FILLER }, 1);
diff --git a/test/functional/ui/input_spec.lua b/test/functional/ui/input_spec.lua
index ea8968a653..11718a6e18 100644
--- a/test/functional/ui/input_spec.lua
+++ b/test/functional/ui/input_spec.lua
@@ -114,11 +114,30 @@ describe('mappings', function()
   end)
 end)
 
-describe('input utf sequences that contain CSI/K_SPECIAL', function()
+describe('input utf sequences that contain K_SPECIAL (0x80)', function()
   it('ok', function()
     feed('i…<esc>')
     expect('…')
   end)
+
+  it('can be mapped', function()
+    command('inoremap … E280A6')
+    feed('i…<esc>')
+    expect('E280A6')
+  end)
+end)
+
+describe('input utf sequences that contain CSI (0x9B)', function()
+  it('ok', function()
+    feed('iě<esc>')
+    expect('ě')
+  end)
+
+  it('can be mapped', function()
+    command('inoremap ě C49B')
+    feed('iě<esc>')
+    expect('C49B')
+  end)
 end)
 
 describe('input non-printable chars', function()