win: defaults: 'shellcmdflag', 'shellxquote' #7343

closes #7698

Wrapping a command in double-quotes allows cmd.exe to safely dequote the
entire command as if the user entered the entire command in an
interactive prompt. This reduces the need to escape nested and uneven
double quotes.

The `/s` flag of cmd.exe makes the behaviour more reliable:

    :set shellcmdflag=/s\ /c

Before this patch, cmd.exe cannot use cygwin echo.exe (as opposed to
cmd.exe `echo` builtin) even if it is wrapped in double quotes.

Example:
:: internal echo
> cmd /s /c " echo foo\:bar" "
foo\:bar"

:: cygwin echo.exe
> cmd /s /c " "echo" foo\:bar" "
foo:bar

1 files changed, 30 insertions, 10 deletions

diff --git a/test/functional/eval/system_spec.lua b/test/functional/eval/system_spec.lua
index 446afefb59..201426c40b 100644
--- a/test/functional/eval/system_spec.lua
+++ b/test/functional/eval/system_spec.lua
@@ -120,33 +120,47 @@ describe('system()', function()
     end
   end)
 
-  describe('executes shell function if passed a string', function()
+  describe('executes shell function', function()
     local screen
 
     before_each(function()
-        clear()
-        screen = Screen.new()
-        screen:attach()
+      clear()
+      screen = Screen.new()
+      screen:attach()
     end)
 
     after_each(function()
-        screen:detach()
+      screen:detach()
     end)
 
     if iswin() then
+      local function test_more()
+        eq('root = true', eval([[get(split(system('"more" ".editorconfig"'), "\n"), 0, '')]]))
+      end
+      local function test_shell_unquoting()
+        eval([[system('"ping" "-n" "1" "127.0.0.1"')]])
+        eq(0, eval('v:shell_error'))
+        eq('"a b"\n', eval([[system('cmd /s/c "cmd /s/c "cmd /s/c "echo "a b""""')]]))
+        eq('"a b"\n', eval([[system('powershell -NoProfile -NoLogo -ExecutionPolicy RemoteSigned -Command echo ''\^"a b\^"''')]]))
+      end
+
       it('with shell=cmd.exe', function()
         command('set shell=cmd.exe')
         eq('""\n', eval([[system('echo ""')]]))
         eq('"a b"\n', eval([[system('echo "a b"')]]))
         eq('a \nb\n', eval([[system('echo a & echo b')]]))
         eq('a \n', eval([[system('echo a 2>&1')]]))
+        test_more()
         eval([[system('cd "C:\Program Files"')]])
         eq(0, eval('v:shell_error'))
+        test_shell_unquoting()
       end)
 
       it('with shell=cmd', function()
         command('set shell=cmd')
         eq('"a b"\n', eval([[system('echo "a b"')]]))
+        test_more()
+        test_shell_unquoting()
       end)
 
       it('with shell=$COMSPEC', function()
@@ -154,6 +168,8 @@ describe('system()', function()
         if comspecshell == 'cmd.exe' then
           command('set shell=$COMSPEC')
           eq('"a b"\n', eval([[system('echo "a b"')]]))
+          test_more()
+          test_shell_unquoting()
         else
           pending('$COMSPEC is not cmd.exe: ' .. comspecshell)
         end
@@ -187,7 +203,7 @@ describe('system()', function()
       ]])
     end)
 
-    it('`yes` and is interrupted with CTRL-C', function()
+    it('`yes` interrupted with CTRL-C', function()
       feed(':call system("' .. (iswin()
         and 'for /L %I in (1,0,2) do @echo y'
         or  'yes') .. '")<cr>')
@@ -239,6 +255,8 @@ describe('system()', function()
       end
     end)
     it('to backgrounded command does not crash', function()
+      -- cmd.exe doesn't background a command with &
+      if iswin() then return end
       -- This is indeterminate, just exercise the codepath. May get E5677.
       feed_command('call system("echo -n echoed &")')
       local v_errnum = string.match(eval("v:errmsg"), "^E%d*:")
@@ -254,6 +272,8 @@ describe('system()', function()
       eq("input", eval('system("cat -", "input")'))
     end)
     it('to backgrounded command does not crash', function()
+      -- cmd.exe doesn't background a command with &
+      if iswin() then return end
       -- This is indeterminate, just exercise the codepath. May get E5677.
       feed_command('call system("cat - &", "input")')
       local v_errnum = string.match(eval("v:errmsg"), "^E%d*:")
@@ -299,7 +319,7 @@ describe('system()', function()
     after_each(delete_file(fname))
 
     it('replaces NULs by SOH characters', function()
-      eq('part1\001part2\001part3\n', eval('system("cat '..fname..'")'))
+      eq('part1\001part2\001part3\n', eval([[system('"cat" "]]..fname..[["')]]))
     end)
   end)
 
@@ -366,7 +386,7 @@ describe('systemlist()', function()
     end
   end)
 
-  describe('exectues shell function', function()
+  describe('executes shell function', function()
     local screen
 
     before_each(function()
@@ -399,7 +419,7 @@ describe('systemlist()', function()
       ]])
     end)
 
-    it('`yes` and is interrupted with CTRL-C', function()
+    it('`yes` interrupted with CTRL-C', function()
       feed(':call systemlist("yes | xargs")<cr>')
       screen:expect([[
                                                              |
@@ -464,7 +484,7 @@ describe('systemlist()', function()
     after_each(delete_file(fname))
 
     it('replaces NULs by newline characters', function()
-      eq({'part1\npart2\npart3'}, eval('systemlist("cat '..fname..'")'))
+      eq({'part1\npart2\npart3'}, eval([[systemlist('"cat" "]]..fname..[["')]]))
     end)
   end)