add os.joinenvs

1 files changed, 18 insertions, 1 deletions

diff --git a/xmake/core/base/os.lua b/xmake/core/base/os.lua
index 071db0dfa..10b6d0bcc 100644
--- a/xmake/core/base/os.lua
+++ b/xmake/core/base/os.lua
@@ -696,7 +696,6 @@ function os.execv(program, argv, opt)
     if opt.envs then
         local envars = os.getenvs()
         for k, v in pairs(opt.envs) do
-            -- TODO
             if type(v) == "table" then
                 v = path.joinenv(v)
             end
@@ -1066,6 +1065,24 @@ function os.addenvs(envs)
     return oldenvs
 end
 
+-- join environment variables
+function os.joinenvs(envs, oldenvs)
+    oldenvs = oldenvs or os.getenvs()
+    local newenvs = oldenvs
+    if envs then
+        newenvs = table.copy(oldenvs)
+        for name, values in pairs(envs) do
+            local oldenv = oldenvs[name]
+            if oldenv == "" or oldenv == nil then
+                newenvs[name] = values
+            elseif not oldenv:startswith(values) then
+                newenvs[name] = values .. path.envsep() .. oldenv
+            end
+        end
+    end
+    return newenvs
+end
+
 -- set values to environment variable
 function os.setenv(name, ...)
     local ok