feat: NVIM_APPNAME supports relative paths #25233

Problem:
NVIM_APPNAME does not allow path separators in the name, so relative
paths can't be used:

    NVIM_APPNAME="neovim-configs/first-config" nvim
    NVIM_APPNAME="neovim-configs/second-config" nvim

Solution:
Let NVIM_APPNAME be a relative path. Absolute paths are not supported.

fix #23056
fix #24966

2 files changed, 29 insertions, 6 deletions

diff --git a/test/functional/core/fileio_spec.lua b/test/functional/core/fileio_spec.lua
index 8de78234ce..f2b360f0d8 100644
--- a/test/functional/core/fileio_spec.lua
+++ b/test/functional/core/fileio_spec.lua
@@ -377,4 +377,14 @@ describe('tmpdir', function()
     rm_tmpdir()
     eq('E5431: tempdir disappeared (3 times)', meths.get_vvar('errmsg'))
   end)
+
+  it('$NVIM_APPNAME relative path', function()
+    clear({ env={
+      NVIM_APPNAME='a/b',
+      NVIM_LOG_FILE=testlog,
+      TMPDIR=os_tmpdir,
+    } })
+    matches([=[.*[/\\]a%%b%.[^/\\]+]=], funcs.tempname())
+  end)
+
 end)
diff --git a/test/functional/options/defaults_spec.lua b/test/functional/options/defaults_spec.lua
index 9b531bcafc..7858b626de 100644
--- a/test/functional/options/defaults_spec.lua
+++ b/test/functional/options/defaults_spec.lua
@@ -598,8 +598,7 @@ describe('stdpath()', function()
   end)
 
   it('reacts to $NVIM_APPNAME', function()
-    local appname = "NVIM_APPNAME_TEST____________________________________" ..
-      "______________________________________________________________________"
+    local appname = 'NVIM_APPNAME_TEST' .. ('_'):rep(106)
     clear({env={ NVIM_APPNAME=appname }})
     eq(appname, funcs.fnamemodify(funcs.stdpath('config'), ':t'))
     eq(appname, funcs.fnamemodify(funcs.stdpath('cache'), ':t'))
@@ -616,10 +615,24 @@ describe('stdpath()', function()
 
     -- Check that Nvim rejects invalid APPNAMEs
     -- Call jobstart() and jobwait() in the same RPC request to reduce flakiness.
-    eq(1, exec_lua([[
-      local child = vim.fn.jobstart({ vim.v.progpath }, { env = { NVIM_APPNAME = 'a/b\\c' } })
-      return vim.fn.jobwait({ child }, 3000)[1]
-    ]]))
+    local function test_appname(testAppname, expected_exitcode)
+      local lua_code = string.format([[
+        local child = vim.fn.jobstart({ vim.v.progpath, '--clean', '--headless', '+qall!' }, { env = { NVIM_APPNAME = %q } })
+        return vim.fn.jobwait({ child }, %d)[1]
+      ]], alter_slashes(testAppname), 3000)
+      eq(expected_exitcode, exec_lua(lua_code))
+    end
+    -- Invalid appnames:
+    test_appname('a/../b', 1)
+    test_appname('../a', 1)
+    test_appname('a/..', 1)
+    test_appname('..', 1)
+    test_appname('.', 1)
+    test_appname('/', 1)
+    test_appname(is_os('win') and 'C:/a/b' or '/a/b', 1)
+    -- Valid appnames:
+    test_appname('a/b', 0)
+    test_appname('a/b\\c', 0)
   end)
 
   describe('returns a String', function()