3 files changed, 143 insertions, 4 deletions

diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index 0df857352b..6997156d4c 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -196,16 +196,19 @@ void init_homedir(void)
     const char *homedrive = os_getenv("HOMEDRIVE");
     const char *homepath = os_getenv("HOMEPATH");
     if (homepath == NULL) {
-        homepath = "\\";
+      homepath = "\\";
     }
-    if (homedrive != NULL && strlen(homedrive) + strlen(homepath) < MAXPATHL) {
+    if (homedrive != NULL
+        && strlen(homedrive) + strlen(homepath) < MAXPATHL) {
       snprintf(os_buf, MAXPATHL, "%s%s", homedrive, homepath);
       if (os_buf[0] != NUL) {
         var = os_buf;
-        vim_setenv("HOME", os_buf);
       }
     }
   }
+  if (var == NULL) {
+    var = os_getenv("USERPROFILE");
+  }
 #endif
 
   if (var != NULL) {
@@ -608,6 +611,12 @@ char *vim_getenv(const char *name)
     return xstrdup(kos_env_path);
   }
 
+#ifdef WIN32
+  if (strcmp(name, "HOME") == 0) {
+    return xstrdup(homedir);
+  }
+#endif
+
   bool vimruntime = (strcmp(name, "VIMRUNTIME") == 0);
   if (!vimruntime && strcmp(name, "VIM") != 0) {
     return NULL;
@@ -758,7 +767,12 @@ size_t home_replace(const buf_T *const buf, const char_u *src,
     dirlen = strlen(homedir);
   }
 
-  const char *const homedir_env = os_getenv("HOME");
+  const char *homedir_env = os_getenv("HOME");
+#ifdef WIN32
+  if (homedir_env == NULL) {
+    homedir_env = os_getenv("USERPROFILE");
+  }
+#endif
   char *homedir_env_mod = (char *)homedir_env;
   bool must_free = false;
 
diff --git a/src/nvim/testdir/Makefile b/src/nvim/testdir/Makefile
index 87d7ff5bad..0379235ec0 100644
--- a/src/nvim/testdir/Makefile
+++ b/src/nvim/testdir/Makefile
@@ -116,6 +116,7 @@ NEW_TESTS ?= \
 	    test_visual.res \
 	    test_winbuf_close.res \
 	    test_window_id.res \
+	    test_windows_home.res \
 	    test_wordcount.res \
 	    test_writefile.res \
 	    test_alot_latin.res \
diff --git a/src/nvim/testdir/test_windows_home.vim b/src/nvim/testdir/test_windows_home.vim
new file mode 100644
index 0000000000..082f217e11
--- /dev/null
+++ b/src/nvim/testdir/test_windows_home.vim
@@ -0,0 +1,124 @@
+" Test for $HOME on Windows.
+
+if !has('win32')
+  finish
+endif
+
+let s:env = {}
+
+func s:restore_env()
+  for i in keys(s:env)
+    exe 'let ' . i . '=s:env["' . i . '"]'
+  endfor
+endfunc
+
+func s:save_env(...)
+  for i in a:000
+    exe 'let s:env["' . i . '"]=' . i
+  endfor
+endfunc
+
+func s:unlet_env(...)
+  for i in a:000
+    exe 'let ' . i . '=""'
+  endfor
+endfunc
+
+func CheckHomeIsMissingFromSubprocessEnvironment()
+  silent! let out = system('set')
+  let env = filter(split(out, "\n"), 'v:val=~"^HOME="')
+  call assert_equal(0, len(env))
+endfunc
+
+func CheckHomeIsInSubprocessEnvironment(exp)
+  silent! let out = system('set')
+  let env = filter(split(out, "\n"), 'v:val=~"^HOME="')
+  let home = len(env) == 0 ? "" : substitute(env[0], '[^=]\+=', '', '')
+  call assert_equal(a:exp, home)
+endfunc
+
+func CheckHome(exp, ...)
+  "call assert_equal(a:exp, $HOME)
+  "call assert_equal(a:exp, expand('~', ':p'))
+  if !a:0
+    call CheckHomeIsMissingFromSubprocessEnvironment()
+  else
+    call CheckHomeIsInSubprocessEnvironment(a:exp)
+  endif
+endfunc
+
+func TestWindowsHome()
+  command! -nargs=* SaveEnv call <SID>save_env(<f-args>)
+  command! -nargs=* RestoreEnv call <SID>restore_env()
+  command! -nargs=* UnletEnv call <SID>unlet_env(<f-args>)
+
+  SaveEnv $HOME $USERPROFILE $HOMEDRIVE $HOMEPATH
+  try
+    RestoreEnv
+    UnletEnv $HOME $USERPROFILE $HOMEPATH
+    let $HOMEDRIVE = 'C:'
+    call CheckHome('C:\')
+
+    RestoreEnv
+    UnletEnv $HOME $USERPROFILE
+    let $HOMEDRIVE = 'C:'
+    let $HOMEPATH = '\foobar'
+    call CheckHome('C:\foobar')
+
+    RestoreEnv
+    UnletEnv $HOME $HOMEDRIVE $HOMEPATH
+    let $USERPROFILE = 'C:\foo'
+    call CheckHome('C:\foo')
+
+    RestoreEnv
+    UnletEnv $HOME
+    let $USERPROFILE = 'C:\foo'
+    let $HOMEDRIVE = 'C:'
+    let $HOMEPATH = '\baz'
+    call CheckHome('C:\foo')
+
+    RestoreEnv
+    let $HOME = 'C:\bar'
+    let $USERPROFILE = 'C:\foo'
+    let $HOMEDRIVE = 'C:'
+    let $HOMEPATH = '\baz'
+    call CheckHome('C:\bar', 1)
+
+    RestoreEnv
+    let $HOME = '%USERPROFILE%\bar'
+    let $USERPROFILE = 'C:\foo'
+    let $HOMEDRIVE = 'C:'
+    let $HOMEPATH = '\baz'
+    call CheckHome('%USERPROFILE%\bar', 1)
+
+    RestoreEnv
+    let $HOME = '%USERPROFILE'
+    let $USERPROFILE = 'C:\foo'
+    let $HOMEDRIVE = 'C:'
+    let $HOMEPATH = '\baz'
+    call CheckHome('%USERPROFILE', 1)
+
+    RestoreEnv
+    let $HOME = 'C:\%USERPROFILE%'
+    let $USERPROFILE = 'C:\foo'
+    let $HOMEDRIVE = 'C:'
+    let $HOMEPATH = '\baz'
+    call CheckHome('C:\%USERPROFILE%', 1)
+
+    if has('channel')
+      RestoreEnv
+      UnletEnv $HOME
+      let env = ''
+      let job = job_start('cmd /c set', {'out_cb': {ch,x->[env,execute('let env=x')]}})
+      sleep 1
+      let env = filter(split(env, "\n"), 'v:val=="HOME"')
+      let home = len(env) == 0 ? "" : env[0]
+      call assert_equal('', home)
+    endif
+  finally
+    RestoreEnv
+    delcommand SaveEnv
+    delcommand RestoreEnv
+    delcommand UnletEnv
+  endtry
+endfunc