feat(term): getting/setting terminal config flags

1 files changed, 210 insertions, 2 deletions

diff --git a/system/init.lua b/system/init.lua
index 77e0c3b..c3ea94d 100644
--- a/system/init.lua
+++ b/system/init.lua
@@ -1,2 +1,210 @@
-local system = require 'system.core'
-return system
+--- Lua System Library.
+-- @module init
+
+local sys = require 'system.core'
+local global_backup -- global backup for terminal settings
+
+
+
+local add_gc_method do
+  -- feature detection; __GC meta-method, not available in all Lua versions
+  local has_gc = false
+  local tt = setmetatable({}, {  -- luacheck: ignore
+    __gc = function() has_gc = true end
+  })
+
+  -- clear table and run GC to trigger
+  tt = nil
+  collectgarbage()
+  collectgarbage()
+
+
+  if has_gc then
+    -- use default GC mechanism since it is available
+    function add_gc_method(t, f)
+      setmetatable(t, { __gc = f })
+    end
+  else
+    -- create workaround using a proxy userdata, typical for Lua 5.1
+    function add_gc_method(t, f)
+      local proxy = newproxy(true)
+      getmetatable(proxy).__gc = function()
+        t["__gc_proxy"] = nil
+        f(t)
+      end
+      t["__gc_proxy"] = proxy
+    end
+  end
+end
+
+
+
+--- Returns a backup of terminal setting for stdin/out/err.
+-- Handles terminal/console flags and non-block flags on the streams.
+-- Backs up terminal/console flags only if a stream is a tty.
+-- @return table with backup of terminal settings
+function sys.termbackup()
+  local backup = {}
+
+  if sys.isatty(io.stdin) then
+    backup.console_in = sys.getconsoleflags(io.stdin)
+    backup.term_in = sys.tcgetattr(io.stdin)
+  end
+  if sys.isatty(io.stdout) then
+    backup.console_out = sys.getconsoleflags(io.stdout)
+    backup.term_out = sys.tcgetattr(io.stdout)
+  end
+  if sys.isatty(io.stderr) then
+    backup.console_err = sys.getconsoleflags(io.stderr)
+    backup.term_err = sys.tcgetattr(io.stderr)
+  end
+
+  backup.block_in = sys.getnonblock(io.stdin)
+  backup.block_out = sys.getnonblock(io.stdout)
+  backup.block_err = sys.getnonblock(io.stderr)
+
+  return backup
+end
+
+
+
+--- Restores terminal settings from a backup
+-- @tparam table backup the backup of terminal settings, see `termbackup`.
+-- @treturn boolean true
+function sys.termrestore(backup)
+  if backup.console_in  then sys.setconsoleflags(io.stdin, backup.console_in) end
+  if backup.term_in     then sys.tcsetattr(io.stdin, sys.TCSANOW, backup.term_in) end
+  if backup.console_out then sys.setconsoleflags(io.stdout, backup.console_out) end
+  if backup.term_out    then sys.tcsetattr(io.stdout, sys.TCSANOW, backup.term_out) end
+  if backup.console_err then sys.setconsoleflags(io.stderr, backup.console_err) end
+  if backup.term_err    then sys.tcsetattr(io.stderr, sys.TCSANOW, backup.term_err) end
+
+  if backup.block_in  ~= nil then sys.setnonblock(io.stdin,  backup.block_in) end
+  if backup.block_out ~= nil then sys.setnonblock(io.stdout, backup.block_out) end
+  if backup.block_err ~= nil then sys.setnonblock(io.stderr, backup.block_err) end
+  return true
+end
+
+
+
+--- Backs up terminal settings and restores them on application exit.
+-- Calls `termbackup` to back up terminal settings and sets up a GC method to
+-- automatically restore them on application exit (also works on Lua 5.1).
+-- @treturn[1] boolean true
+-- @treturn[2] nil if the backup was already created
+-- @treturn[2] string error message
+function sys.autotermrestore()
+  if global_backup then
+    return nil, "global terminal backup was already set up"
+  end
+  global_backup = sys.termbackup()
+  add_gc_method(global_backup, function(self)
+    sys.termrestore(self) end)
+  return true
+end
+
+
+
+do
+  local oldunpack = unpack or table.unpack
+  local pack = function(...) return { n = select("#", ...), ... } end
+  local unpack = function(t) return oldunpack(t, 1, t.n) end
+
+  --- Wraps a function to automatically restore terminal settings upon returning.
+  -- Calls `termbackup` before calling the function and `termrestore` after.
+  -- @tparam function f function to wrap
+  -- @treturn function wrapped function
+  function sys.termwrap(f)
+    if type(f) ~= "function" then
+      error("arg #1 to wrap, expected function, got " .. type(f), 2)
+    end
+
+    return function(...)
+      local bu = sys.termbackup()
+      local results = pack(f(...))
+      sys.termrestore(bu)
+      return unpack(results)
+    end
+  end
+end
+
+
+
+--- Debug function for console flags (Windows).
+-- Pretty prints the current flags set for the handle.
+-- @param fh file handle (`io.stdin`, `io.stdout`, `io.stderr`)
+-- @usage -- Print the flags for stdin/out/err
+-- system.listconsoleflags(io.stdin)
+-- system.listconsoleflags(io.stdout)
+-- system.listconsoleflags(io.stderr)
+function sys.listconsoleflags(fh)
+  local flagtype
+  if fh == io.stdin then
+    print "------ STDIN FLAGS WINDOWS ------"
+    flagtype = "CIF_"
+  elseif fh == io.stdout then
+    print "------ STDOUT FLAGS WINDOWS ------"
+    flagtype = "COF_"
+  elseif fh == io.stderr then
+    print "------ STDERR FLAGS WINDOWS ------"
+    flagtype = "COF_"
+  end
+
+  local flags = assert(sys.getconsoleflags(fh))
+  local out = {}
+  for k,v in pairs(sys) do
+    if type(k) == "string" and k:sub(1,4) == flagtype then
+      if flags:has(v) then
+        out[#out+1] = string.format("%10d [x] %s",v:value(),k)
+      else
+        out[#out+1] = string.format("%10d [ ] %s",v:value(),k)
+      end
+    end
+  end
+  table.sort(out)
+  for k,v in pairs(out) do
+    print(v)
+  end
+end
+
+
+
+--- Debug function for terminal flags (Posix).
+-- Pretty prints the current flags set for the handle.
+-- @param fh file handle (`io.stdin`, `io.stdout`, `io.stderr`)
+-- @usage -- Print the flags for stdin/out/err
+-- system.listconsoleflags(io.stdin)
+-- system.listconsoleflags(io.stdout)
+-- system.listconsoleflags(io.stderr)
+function sys.listtermflags(fh)
+  if fh == io.stdin then
+    print "------ STDIN FLAGS POSIX ------"
+  elseif fh == io.stdout then
+    print "------ STDOUT FLAGS POSIX ------"
+  elseif fh == io.stderr then
+    print "------ STDERR FLAGS POSIX ------"
+  end
+
+  local flags = assert(sys.tcgetattr(fh))
+  for _, flagtype in ipairs { "iflag", "oflag", "lflag" } do
+    local prefix = flagtype:sub(1,1):upper() .. "_"  -- I_, O_, or L_, the constant prefixes
+    local out = {}
+    for k,v in pairs(sys) do
+      if type(k) == "string" and k:sub(1,2) == prefix then
+        if flags[flagtype]:has(v) then
+          out[#out+1] = string.format("%10d [x] %s",v:value(),k)
+        else
+          out[#out+1] = string.format("%10d [ ] %s",v:value(),k)
+        end
+      end
+    end
+    table.sort(out)
+    for k,v in pairs(out) do
+      print(v)
+    end
+  end
+end
+
+
+
+return sys