test/env: multibyte env var to child process

Note: the test fails on non-Windows CI (Travis linux, Quickbuild bsd):
even on master before the env.c changes in this patch-series.
Maybe the unix part of printenv-test.c needs to be revisited.

Signed-off-by: Justin M. Keyes <justinkz@gmail.com>

test/functional/eval/let_spec.lua

@@ -7,6 +7,7 @@ local eval = helpers.eval
 local meths = helpers.meths
 local redir_exec = helpers.redir_exec
 local source = helpers.source
+local nvim_dir = helpers.nvim_dir
 
 before_each(clear)
 
@@ -45,7 +46,7 @@ describe(':let', function()
     ]=])
   end)
 
-  it("multibyte environment variables", function()
+  it("multibyte env var #8398 #9267", function()
     command("let $NVIM_TEST = 'AìaB'")
     eq('AìaB', eval('$NVIM_TEST'))
     command("let $NVIM_TEST = 'AaあB'")
@@ -56,4 +57,26 @@ describe(':let', function()
     command("let $NVIM_TEST = '"..mbyte.."'")
     eq(mbyte, eval('$NVIM_TEST'))
   end)
+
+  it("multibyte env var to child process #8398 #9267",  function()
+    if (not helpers.iswin()) and require('test.helpers').isCI() then
+      -- Fails on non-Windows CI. Buffering/timing issue?
+      pending('fails on unix CI', function() end)
+    end
+    local cmd_get_child_env = "let g:env_from_child = system(['"..nvim_dir.."/printenv-test', 'NVIM_TEST'])"
+    command("let $NVIM_TEST = 'AìaB'")
+    command(cmd_get_child_env)
+    eq(eval('$NVIM_TEST'), eval('g:env_from_child'))
+
+    command("let $NVIM_TEST = 'AaあB'")
+    command(cmd_get_child_env)
+    eq(eval('$NVIM_TEST'), eval('g:env_from_child'))
+
+    local mbyte = [[\p* .ม .ม .ม .ม่ .ม่ .ม่ ֹ ֹ ֹ .ֹ .ֹ .ֹ ֹֻ ֹֻ ֹֻ
+                    .ֹֻ .ֹֻ .ֹֻ ֹֻ ֹֻ ֹֻ .ֹֻ .ֹֻ .ֹֻ ֹ ֹ ֹ .ֹ .ֹ .ֹ ֹ ֹ ֹ .ֹ .ֹ .ֹ ֹֻ ֹֻ
+                    .ֹֻ .ֹֻ .ֹֻ a a a ca ca ca à à à]]
+    command("let $NVIM_TEST = '"..mbyte.."'")
+    command(cmd_get_child_env)
+    eq(eval('$NVIM_TEST'), eval('g:env_from_child'))
+  end)
 end)

test/functional/fixtures/CMakeLists.txt

@@ -3,3 +3,7 @@ target_link_libraries(tty-test ${LIBUV_LIBRARIES})
 
 add_executable(shell-test shell-test.c)
 add_executable(printargs-test printargs-test.c)
+add_executable(printenv-test printenv-test.c)
+if(WIN32)
+  set_target_properties(printenv-test PROPERTIES LINK_FLAGS -municode)
+endif()

test/functional/fixtures/printenv-test.c

@@ -0,0 +1,59 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+
+#include <stdio.h>
+
+#ifdef WIN32
+# include <windows.h>
+#else
+# include <stdlib.h>
+#endif
+
+#ifdef WIN32
+int wmain(int argc, wchar_t **argv)
+#else
+int main(int argc, char **argv)
+#endif
+{
+  if (argc != 2) {
+    return 1;
+  }
+
+#ifdef WIN32
+  wchar_t *value = _wgetenv(argv[1]);
+  if (value == NULL) {
+    return 1;
+  }
+  int utf8_len = WideCharToMultiByte(CP_UTF8,
+                                     0,
+                                     value,
+                                     -1,
+                                     NULL,
+                                     0,
+                                     NULL,
+                                     NULL);
+  if (utf8_len == 0) {
+    return (int)GetLastError();
+  }
+  char *utf8_value = (char *)calloc((size_t)utf8_len, sizeof(char));
+  utf8_len = WideCharToMultiByte(CP_UTF8,
+                                 0,
+                                 value,
+                                 -1,
+                                 utf8_value,
+                                 utf8_len,
+                                 NULL,
+                                 NULL);
+  fprintf(stderr, "%s", utf8_value);
+  free(utf8_value);
+#else
+  char *value = getenv(argv[1]);
+  if (value == NULL) {
+    fprintf(stderr, "env var not found: %s", argv[1]);
+    return 1;
+  }
+  // Print to stderr to avoid buffering.
+  fprintf(stderr, "%s", value);
+#endif
+  return 0;
+}

test/helpers.lua

@@ -751,6 +751,7 @@ local module = {
   hasenv = hasenv,
   hexdump = hexdump,
   intchar2lua = intchar2lua,
+  isCI = isCI,
   map = map,
   matches = matches,
   mergedicts_copy = mergedicts_copy,