Merge #6707 from ZyX-I/fix-strchr-invalid

3 files changed, 83 insertions, 5 deletions

diff --git a/src/nvim/strings.c b/src/nvim/strings.c
index f19cf7a261..c5fd8741b8 100644
--- a/src/nvim/strings.c
+++ b/src/nvim/strings.c
@@ -428,16 +428,15 @@ int vim_strnicmp(const char *s1, const char *s2, size_t len)
 /// strchr() version which handles multibyte strings
 ///
 /// @param[in]  string  String to search in.
-/// @param[in]  c  Character to search for. Must be a valid character.
+/// @param[in]  c  Character to search for.
 ///
 /// @return Pointer to the first byte of the found character in string or NULL
-///         if it was not found. NUL character is never found, use `strlen()`
-///         instead.
+///         if it was not found or character is invalid. NUL character is never
+///         found, use `strlen()` instead.
 char_u *vim_strchr(const char_u *const string, const int c)
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
 {
-  assert(c >= 0);
-  if (c == 0) {
+  if (c <= 0) {
     return NULL;
   } else if (c < 0x80) {
     return (char_u *)strchr((const char *)string, c);
diff --git a/test/functional/ui/screen_basic_spec.lua b/test/functional/ui/screen_basic_spec.lua
index 5d89416e4a..bfcdc7f652 100644
--- a/test/functional/ui/screen_basic_spec.lua
+++ b/test/functional/ui/screen_basic_spec.lua
@@ -565,6 +565,46 @@ describe('Screen', function()
       ]])
     end)
   end)
+
+  describe('press enter', function()
+    it('does not crash on <F1> at “Press ENTER”', function()
+      command('nnoremap <F1> :echo "TEST"<CR>')
+      feed(':ls<CR>')
+      screen:expect([[
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        :ls                                                  |
+          1 %a   "[No Name]"                    line 1       |
+        {7:Press ENTER or type command to continue}^              |
+      ]])
+      feed('<F1>')
+      screen:expect([[
+        ^                                                     |
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        TEST                                                 |
+      ]])
+    end)
+  end)
 end)
 
 describe('nvim_ui_attach()', function()
diff --git a/test/unit/strings_spec.lua b/test/unit/strings_spec.lua
index 3bc3dc7130..e54c82b26a 100644
--- a/test/unit/strings_spec.lua
+++ b/test/unit/strings_spec.lua
@@ -99,3 +99,42 @@ describe('vim_strnsave_unquoted()', function()
     eq('/Program\\nFiles/sh', vim_strnsave_unquoted('/Program"\\n"Files/sh'))
   end)
 end)
+
+describe('vim_strchr()', function()
+  local vim_strchr = function(s, c)
+    local str = to_cstr(s)
+    local res = strings.vim_strchr(str, c)
+    if res == nil then
+      return nil
+    else
+      return res - str
+    end
+  end
+  itp('handles NUL and <0 correctly', function()
+    eq(nil, vim_strchr('abc', 0))
+    eq(nil, vim_strchr('abc', -1))
+  end)
+  itp('works', function()
+    eq(0, vim_strchr('abc', ('a'):byte()))
+    eq(1, vim_strchr('abc', ('b'):byte()))
+    eq(2, vim_strchr('abc', ('c'):byte()))
+    eq(0, vim_strchr('a«b»c', ('a'):byte()))
+    eq(3, vim_strchr('a«b»c', ('b'):byte()))
+    eq(6, vim_strchr('a«b»c', ('c'):byte()))
+
+    eq(nil, vim_strchr('«»', ('«'):byte()))
+    -- 0xAB == 171 == '«'
+    eq(nil, vim_strchr('\171', 0xAB))
+    eq(0, vim_strchr('«»', 0xAB))
+    eq(3, vim_strchr('„«»“', 0xAB))
+
+    eq(7, vim_strchr('„«»“', 0x201C))
+    eq(nil, vim_strchr('„«»“', 0x201D))
+    eq(0, vim_strchr('„«»“', 0x201E))
+
+    eq(0, vim_strchr('\244\143\188\128', 0x10FF00))
+    eq(2, vim_strchr('«\244\143\188\128»', 0x10FF00))
+    --                   |0xDBFF     |0xDF00  - surrogate pair for 0x10FF00
+    eq(nil, vim_strchr('«\237\175\191\237\188\128»', 0x10FF00))
+  end)
+end)