Added -u flag to cp.lua, added -u flag to install.lua. Closes #1092.

Run `/mnt/???/bin/install.lua -u` to update OpenOS more comfortably now, asks for each changed file, to avoid blindly overwriting user-changed files.
Made install.lua a bit more clever, looking for an actual mount point for an address, not blindly hoping that `/mnt/(first three chars of address)` exists. Also made it use the cp.lua on its own file system (since that's needed for updating the first time, e.g.).

src/main/resources/assets/opencomputers/loot/OpenOS/bin/cp.lua

@@ -7,6 +7,8 @@ if #args < 2 then
   io.write(" -i: prompt before overwrite (overrides -n option).\n")
   io.write(" -n: do not overwrite an existing file.\n")
   io.write(" -r: copy directories recursively.\n")
+  io.write(" -u: copy only when the SOURCE file differs from the destination\n")
+  io.write("     file or when the destination file is missing.\n")
   io.write(" -v: verbose output.")
   return
 end
@@ -19,7 +21,7 @@ local to = shell.resolve(args[#args])
 
 local function status(from, to)
   if options.v then
-    print(from .. " -> " .. to)
+    io.write(from .. " -> " .. to .. "\n")
   end
   os.sleep(0) -- allow interrupting
 end
@@ -27,9 +29,33 @@ end
 local result, reason
 
 local function prompt(message)
-  io.write(message .. " ")
+  io.write(message .. " [Y/n]\n")
   local result = io.read()
-  return result and result:sub(1, 1):lower() == "y"
+  return result and (result == "" or result:sub(1, 1):lower() == "y")
+end
+
+local function areEqual(path1, path2)
+  local f1 = io.open(path1, "rb")
+  if not f1 then
+    return nil, "could not open `" .. path1 .. "' for update test"
+  end
+  local f2 = io.open(path2, "rb")
+  if not f2 then
+    f1:close()
+    return nil, "could not open `" .. path2 .. "' for update test"
+  end
+  local result = true
+  local chunkSize = 4 * 1024
+  repeat
+    local s1, s2 = f1:read(chunkSize), f2:read(chunkSize)
+    if s1 ~= s2 then
+      result = false
+      break
+    end
+  until not s1 or not s2
+  f1:close()
+  f2:close()
+  return result
 end
 
 local function recurse(fromPath, toPath)
@@ -70,6 +96,11 @@ local function recurse(fromPath, toPath)
           return nil, "cannot overwrite directory `" .. toPath .. "' with non-directory"
         end
       else
+        if options.u then
+          if areEqual(fromPath, toPath) then
+            return true
+          end
+        end
         if options.i then
           if not prompt("overwrite `" .. toPath .. "'?") then
             return true

src/main/resources/assets/opencomputers/loot/OpenOS/bin/install.lua

@@ -1,22 +1,24 @@
 local component = require("component")
 local computer = require("computer")
 local event = require("event")
+local filesystem = require("filesystem")
 local unicode = require("unicode")
 local shell = require("shell")
 
 local args, options = shell.parse(...)
 
+local fromAddress = options.from and component.get(options.from) or filesystem.get(os.getenv("_")).address
 local candidates = {}
 for address in component.list("filesystem") do
   local dev = component.proxy(address)
-  if not dev.isReadOnly() and dev.address ~= computer.tmpAddress() then
+  if not dev.isReadOnly() and dev.address ~= computer.tmpAddress() and dev.address ~= fromAddress then
     table.insert(candidates, dev)
   end
 end
 
 if #candidates == 0 then
-  print("No writable disks found, aborting.")
-  return
+  io.write("No writable disks found, aborting.\n")
+  os.exit()
 end
 
 for i = 1, #candidates do
@@ -26,45 +28,53 @@ for i = 1, #candidates do
   else
     label = candidates[i].address
   end
-  print(i .. ") " .. label)
+  io.write(i .. ") " .. label .. "\n")
 end
 
-print("To select the device to install to, please enter a number between 1 and " .. #candidates .. ".")
-print("Press 'q' to cancel the installation.")
+io.write("To select the device to install to, please enter a number between 1 and " .. #candidates .. ".\n")
+io.write("Press 'q' to cancel the installation.\n")
 local choice
 while not choice do
   result = io.read()
   if result:sub(1, 1):lower() == "q" then
-    return
+    os.exit()
   end
   local number = tonumber(result)
   if number and number > 0 and number <= #candidates then
     choice = candidates[number]
   else
-    print("Invalid input, please try again.")
+    io.write("Invalid input, please try again.\n")
+  end
+end
+
+local function findMount(address)
+  for fs, path in filesystem.mounts() do
+    if fs.address == component.get(address) then
+      return path
+    end
   end
 end
-candidates = nil
 
 local name = options.name or "OpenOS"
-print("Installing " .. name .." to device " .. (choice.getLabel() or choice.address))
+io.write("Installing " .. name .." to device " .. (choice.getLabel() or choice.address) .. "\n")
 os.sleep(0.25)
-local origin = options.from and options.from:sub(1,3) or computer.getBootAddress():sub(1, 3)
-local fromDir = options.fromDir or "/"
-local mnt = choice.address:sub(1, 3)
-local result, reason = os.execute("/bin/cp -vr /mnt/" .. origin .. fromDir .. "* /mnt/" .. mnt .. "/")
+local cpPath = filesystem.concat(findMount(filesystem.get(os.getenv("_")).address), "bin/cp")
+local cpOptions = "-vr" .. (options.u and "ui " or "")
+local cpSource = filesystem.concat(findMount(fromAddress), options.fromDir or "/", "*")
+local cpDest = findMount(choice.address) .. "/"
+local result, reason = os.execute(cpPath .. " " .. cpOptions .. " " .. cpSource .. " " .. cpDest)
 if not result then
   error(reason, 0)
 end
 if not options.nolabelset then pcall(choice.setLabel, name) end
 
 if not options.noreboot then
-  print("All done! " .. ((not options.noboot) and "Set as boot device and r" or "R") .. "eboot now? [Y/n]")
+  io.write("All done! " .. ((not options.noboot) and "Set as boot device and r" or "R") .. "eboot now? [Y/n]\n")
   local result = io.read()
   if not result or result == "" or result:sub(1, 1):lower() == "y" then
     if not options.noboot then computer.setBootAddress(choice.address)end
-    print("\nRebooting now!")
+    io.write("\nRebooting now!\n")
     computer.shutdown(true)
   end
 end
-print("Returning to shell.")
+io.write("Returning to shell.\n")

src/main/resources/assets/opencomputers/loot/OpenOS/bin/sh.lua

@@ -17,6 +17,9 @@ function memoryStream:close()
 end
 
 function memoryStream:seek()
+  if self.closed then
+    error("attempt to use a closed stream")
+  end
   return nil, "bad file descriptor"
 end
 
@@ -24,8 +27,9 @@ function memoryStream:read(n)
   if self.closed then
     if self.buffer == "" and self.redirect.read then
       return self.redirect.read:read(n)
+    else
+      error("attempt to use a closed stream")
     end
-    return nil -- eof
   end
   if self.buffer == "" then
     self.args = table.pack(coroutine.yield(table.unpack(self.result)))
@@ -36,19 +40,24 @@ function memoryStream:read(n)
 end
 
 function memoryStream:write(value)
-  local ok
+  if not self.redirect.write and self.closed then
+    error("attempt to use a closed stream")
+  end
   if self.redirect.write then
-    ok = self.redirect.write:write(value)
+    self.redirect.write:write(value)
   end
   if not self.closed then
     self.buffer = self.buffer .. value
     self.result = table.pack(coroutine.resume(self.next, table.unpack(self.args)))
-    ok = true
+    if coroutine.status(self.next) == "dead" then
+      self:close()
+    end
+    if not self.result[1] then
+      error(self.result[2], 0)
+    end
+    table.remove(self.result, 1)
   end
-  if ok then
-    return true
-  end
-  return nil, "stream is closed"
+  return true
 end
 
 function memoryStream.new()
@@ -328,16 +337,15 @@ local function execute(env, command, ...)
       result = table.pack(coroutine.resume(threads[i], table.unpack(args, 2, args.n)))
       if coroutine.status(threads[i]) ~= "dead" then
         args = table.pack(pcall(event.pull, table.unpack(result, 2, result.n)))
-      elseif not args[1] then
-        args[2] = debug.traceback(threads[i], args[2])
       end
     end
     if pipes[i] then
-      pipes[i]:close()
+      pcall(pipes[i].close, pipes[i])
     end
     if not result[1] then
       if type(result[2]) == "table" and result[2].reason == "terminated" then
         if result[2].code then
+          result[1] = true
           result.n = 1
         else
           result[2] = "terminated"
@@ -473,7 +481,7 @@ if #args == 0 and (io.input() == io.stdin or options.i) and not options.c then
           term.write("\n")
         end
         if not result then
-          io.stderr:write((tostring(reason) or "unknown error").. "\n")
+          io.stderr:write((reason and tostring(reason) or "unknown error") .. "\n")
         end
       end
     end
@@ -491,7 +499,7 @@ elseif #args == 0 and (io.input() ~= io.stdin) then
     elseif command ~= "" then
       local result, reason = os.execute(command)
       if not result then
-        io.stderr:write((tostring(reason) or "unknown error").. "\n")
+        io.stderr:write((reason and tostring(reason) or "unknown error") .. "\n")
       end
     end
   end