replacing yield_all with yield_past to control stack yielding

This change should allow popen, pipes, and threads to specify with exactness how many coroutines back they want to yield. This makes popen and threads immune to internal coroutine scenarios

Also using a code cleanup provided by @SDPhantom

src/main/resources/assets/opencomputers/loot/openos/boot/01_process.lua

@@ -6,7 +6,11 @@ local _coroutine = coroutine -- real coroutine backend
 _G.coroutine = setmetatable(
   {
     resume = function(co, ...)
-      return assert(process.info(co), "thread has no proc").data.coroutine_handler.resume(co, ...)
+      local proc = process.info(co)
+      -- proc is nil if the process closed, natural resume will likely complain the coroutine is dead
+      -- but if proc is dead and an aborted coroutine is alive, it doesn't have any proc data like stack info
+      -- if the user really wants to resume it, let them
+      return (proc and proc.data.coroutine_handler.resume or _coroutine.resume)(co, ...)
     end
   },
   {
@@ -51,10 +55,7 @@ end
 _coroutine.wrap = function(f)
   local thread = coroutine.create(f)
   return function(...)
-    local result_pack = table.pack(coroutine.resume(thread, ...))
+    return select(2, coroutine.resume(thread, ...))
-    local result, reason = result_pack[1], result_pack[2]
-    assert(result, reason)
-    return select(2, table.unpack(result_pack))
   end
 end
 

src/main/resources/assets/opencomputers/loot/openos/lib/pipe.lua

@@ -22,17 +22,18 @@ function pipe.createCoroutineStack(root, env, name)
   function pco.yield(...)
     return _root_co.yield(nil, ...)
   end
-  function pco.yield_all(...)
+  function pco.yield_past(co, ...)
-    return _root_co.yield(true, ...)
+    return _root_co.yield(co, ...)
   end
   function pco.resume(co, ...)
     checkArg(1, co, "thread")
     local args = table.pack(...)
     while true do -- for consecutive sysyields
       local result = table.pack(_root_co.resume(co, table.unpack(args, 1, args.n)))
+      local target = result[2] == true and pco.root or result[2]
       if not result[1] or _root_co.status(co) == "dead" then
         return table.unpack(result, 1, result.n)
-      elseif result[2] and pco.root ~= co then
+      elseif target and target ~= co then
         args = table.pack(_root_co.yield(table.unpack(result, 2, result.n)))
       else
         return true, table.unpack(result, 3, result.n)
@@ -70,7 +71,8 @@ local pipe_stream =
         return self
       end
       -- not reading, it is requesting a yield
-      result = table.pack(coroutine.yield_all(table.unpack(result, 2, result.n)))
+      -- yield_past(true) will exit this coroutine stack
+      result = table.pack(coroutine.yield_past(true, table.unpack(result, 2, result.n)))
       result = table.pack(coroutine.resume(self.next, table.unpack(result, 1, result.n))) -- the request was for an event
     end
   end,
@@ -113,7 +115,7 @@ local pipe_stream =
       -- natural yield (i.e. for events). To differentiate this yield from natural
       -- yields we set read_mode here, which the pipe_stream write detects
       self.read_mode = true
-      coroutine.yield_all()
+      coroutine.yield_past(self.next) -- next is the first croutine in this stack
       self.read_mode = false
     end
     local result = string.sub(self.buffer, 1, n)
@@ -158,16 +160,24 @@ end
 
 local chain_stream =
 {
-  read = function(self, value)
+  read = function(self, value, ...)
     if self.io_stream.closed then return nil end
-    -- handler is currently on yield all [else we wouldn't have control here]
+    -- wake up prog
-    local read_ok, ret = self.pco.resume(self.pco.root, value)
+    self.ready = false -- the pipe proc sets this true when ios completes
-    -- ret can be non string when a process ends
+    local ret = table.pack(coroutine.resume(self.pco.root, value, ...))
-    ret = type(ret) == "string" and ret or nil
+    if coroutine.status(self.pco.root) == "dead" then
-    return select(read_ok and 2 or 1, nil, ret)
+      return nil
+    elseif not ret[1] then
+      return table.unpack(ret, 1, ret.n)
+    end
+    if not self.ready then
+      -- prog yielded back without writing/reading
+      return self:read(coroutine.yield())
+    end
+    return ret[2]
   end,
   write = function(self, ...)
-    return self:read(table.concat({...}))
+    return self:read(...)
   end,
   close = function(self)
     self.io_stream:close()
@@ -181,8 +191,8 @@ function pipe.popen(prog, mode, env)
   end
 
   local r = mode == "r"
-  local key = r and "read" or "write"
 
+  local chain = {}
   -- to simplify the code - shell.execute is run within a function to pass (prog, env)
   -- if cmd_proc where to come second (mode=="w") then the pipe_proc would have to pass
   -- the starting args. which is possible, just more complicated
@@ -194,22 +204,27 @@ function pipe.popen(prog, mode, env)
   -- the stream needs its own process for io
   local pipe_proc = process.load(function()
     local n = r and 0 or ""
+    local key = r and "read" or "write"
     local ios = stream.io_stream
     while not ios.closed do
-      n = coroutine.yield_all(ios[key](ios, n))
+      -- read from pipe
+      local ret = table.pack(ios[key](ios, n))
+      stream.ready = true
+      -- yield outside the chain now
+      n = coroutine.yield_past(chain[1], table.unpack(ret, 1, ret.n))
     end
   end, nil, nil, "pipe_handler")
 
-  local pipe_index = r and 2 or 1
+  chain[r and 1 or 2] = cmd_proc
-  local cmd_index = r and 1 or 2
+  chain[r and 2 or 1] = pipe_proc
-  local chain = {[cmd_index]=cmd_proc, [pipe_index]=pipe_proc}
 
   -- link the cmd and pipe proc io
   pipe.buildPipeChain(chain)
-  local cmd_stack = process.info(chain[1]).data.coroutine_handler
+  local cmd_data = process.info(chain[1]).data
+  local cmd_stack = cmd_data.coroutine_handler
 
   -- store handle to io_stream from easy access later
-  stream.io_stream = process.info(chain[1]).data.io[1].stream
+  stream.io_stream = cmd_data.io[1].stream
   stream.pco = cmd_stack
 
   -- popen commands start out running, like threads

src/main/resources/assets/opencomputers/loot/openos/lib/thread.lua

@@ -213,11 +213,11 @@ function thread.create(fp, ...)
 
   function mt.process.data.pull(_, timeout)
     mt.register(timeout)
-    -- yield_all will yield this pco stack
+    -- yield_past(root) will yield until out of this thread
     -- the callback will resume this stack
     local event_data
     repeat
-      event_data = table.pack(t.pco.yield_all(timeout))
+      event_data = table.pack(t.pco.yield_past(t.pco.root, timeout))
       -- during sleep, we may have been suspended
     until t:status() ~= "suspended"
     return table.unpack(event_data, 1, event_data.n)