From 2ad49dfd0c1cca74bab0321680701169726dd255 Mon Sep 17 00:00:00 2001
From: Uli Schlachter <psychon@znc.in>
Date: Sun, 28 Feb 2016 12:05:55 +0100
Subject: [PATCH 1/4] Fix some broken documentation in gears.debug

Signed-off-by: Uli Schlachter <psychon@znc.in>
---
 lib/gears/debug.lua | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/gears/debug.lua b/lib/gears/debug.lua
index ec27ed5d..8bf5f5c1 100644
--- a/lib/gears/debug.lua
+++ b/lib/gears/debug.lua
@@ -62,13 +62,13 @@ function debug.dump(data, tag, depth)
     print(debug.dump_return(data, tag, depth))
 end
 
--- Print an warning message
+--- Print an warning message
 -- @tparam string message The warning message to print
 function debug.print_warning(message)
     io.stderr:write(os.date("%Y-%m-%d %T W: ") .. tostring(message) .. "\n")
 end
 
--- Print an error message
+--- Print an error message
 -- @tparam string message The error message to print
 function debug.print_error(message)
     io.stderr:write(os.date("%Y-%m-%d %T E: ") .. tostring(message) .. "\n")

From 01f11003d6207dc153daf7dc7203a8c9090e3cf1 Mon Sep 17 00:00:00 2001
From: Uli Schlachter <psychon@znc.in>
Date: Sun, 28 Feb 2016 12:07:02 +0100
Subject: [PATCH 2/4] Add gears.protected_call

This library is a wrapper around pcall() / xpcall() that prints an error message
via gears.debug.print_error() in case of errors.

Signed-off-by: Uli Schlachter <psychon@znc.in>
---
 lib/gears/init.lua                 |  1 +
 lib/gears/protected_call.lua       | 58 ++++++++++++++++++++++++++++++
 spec/gears/protected_call_spec.lua | 43 ++++++++++++++++++++++
 3 files changed, 102 insertions(+)
 create mode 100644 lib/gears/protected_call.lua
 create mode 100644 spec/gears/protected_call_spec.lua

diff --git a/lib/gears/init.lua b/lib/gears/init.lua
index 6f5198d4..4f5e83f6 100644
--- a/lib/gears/init.lua
+++ b/lib/gears/init.lua
@@ -17,6 +17,7 @@ return
     cache = require("gears.cache");
     matrix = require("gears.matrix");
     shape = require("gears.shape");
+    protected_call = require("gears.protected_call");
 }
 
 -- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80
diff --git a/lib/gears/protected_call.lua b/lib/gears/protected_call.lua
new file mode 100644
index 00000000..41f9dfa7
--- /dev/null
+++ b/lib/gears/protected_call.lua
@@ -0,0 +1,58 @@
+---------------------------------------------------------------------------
+-- @author Uli Schlachter
+-- @copyright 2016 Uli Schlachter
+-- @release @AWESOME_VERSION@
+-- @module gears.protected_call
+---------------------------------------------------------------------------
+
+local gdebug = require("gears.debug")
+local tostring = tostring
+local traceback = debug.traceback
+local unpack = unpack or table.unpack -- luacheck: globals unpack (compatibility with Lua 5.1)
+local xpcall = xpcall
+
+local protected_call = {}
+
+local function error_handler(err)
+    gdebug.print_error(traceback("Error during a protected call: " .. tostring(err)))
+end
+
+local function handle_result(success, ...)
+    if success then
+        return ...
+    end
+end
+
+local do_pcall
+if _VERSION <= "Lua 5.1" then
+    -- Lua 5.1 doesn't support arguments in xpcall :-(
+    do_pcall = function(func, ...)
+        local args = { ... }
+        return handle_result(xpcall(function()
+            return func(unpack(args))
+        end, error_handler))
+    end
+else
+    do_pcall = function(func, ...)
+        return handle_result(xpcall(func, error_handler, ...))
+    end
+end
+
+--- Call a function in protected mode and handle error-reporting.
+-- If the function call succeeds, all results of the function are returned.
+-- Otherwise, an error message is printed and nothing is returned.
+-- @tparam function func The function to call
+-- @param ... Arguments to the function
+-- @return The result of the given function, or nothing if an error occurred.
+function protected_call.call(func, ...)
+    return do_pcall(func, ...)
+end
+
+local pcall_mt = {}
+function pcall_mt:__call(...)
+    return do_pcall(...)
+end
+
+return setmetatable(protected_call, pcall_mt)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80
diff --git a/spec/gears/protected_call_spec.lua b/spec/gears/protected_call_spec.lua
new file mode 100644
index 00000000..602f9bd9
--- /dev/null
+++ b/spec/gears/protected_call_spec.lua
@@ -0,0 +1,43 @@
+---------------------------------------------------------------------------
+-- @author Uli Schlachter
+-- @copyright 2016 Uli Schlachter
+---------------------------------------------------------------------------
+
+local gdebug = require("gears.debug")
+local protected_call = require("gears.protected_call")
+
+describe("gears.protected_call", function()
+    -- Stop the error reporting during tests
+    local orig_print_error = gdebug.print_error
+    local errors
+    before_each(function()
+        errors = {}
+        gdebug.print_error = function(err)
+            table.insert(errors, err)
+        end
+    end)
+    after_each(function()
+        gdebug.print_error = orig_print_error
+    end)
+
+    it("Call with arguments and result", function()
+        local called = false
+        local function f(...)
+            called = true
+            assert.is_same({ ... }, { 1, "second" })
+            return "first", 2
+        end
+        local results = { protected_call(f, 1, "second") }
+        assert.is_true(called)
+        assert.is_same({ "first", 2 }, results)
+        assert.is_same(errors, {})
+    end)
+
+    it("Call with error", function()
+        assert.is_same({}, { protected_call(error, "I was called") })
+        assert.is_same(#errors, 1)
+        assert.is_truthy(string.find(errors[1], "I was called"))
+    end)
+end)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

From 7bf2f17a8a6781159e189e64934a11031ba8797d Mon Sep 17 00:00:00 2001
From: Uli Schlachter <psychon@znc.in>
Date: Sun, 28 Feb 2016 12:11:36 +0100
Subject: [PATCH 3/4] Make gears.widget.{fit,layout}_widget more robust

This commit makes these methods invoke the method on a widget in a protected
context. Thanks to this, e.g. the wibox and other widgets are protected from
errors in a child widget.

Additionally, fit_widget() now assumes 0 if a widget's :fit() method didn't
provide a number.

Signed-off-by: Uli Schlachter <psychon@znc.in>
---
 lib/wibox/widget/base.lua | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/wibox/widget/base.lua b/lib/wibox/widget/base.lua
index c528ad1d..d347a43c 100644
--- a/lib/wibox/widget/base.lua
+++ b/lib/wibox/widget/base.lua
@@ -8,6 +8,7 @@
 local object = require("gears.object")
 local cache = require("gears.cache")
 local matrix = require("gears.matrix")
+local protected_call = require("gears.protected_call")
 local util = require("awful.util")
 local setmetatable = setmetatable
 local pairs = pairs
@@ -144,7 +145,7 @@ local widget_dependencies = setmetatable({}, { __mode = "kv" })
 local function get_cache(widget, kind)
     if not widget._widget_caches[kind] then
         widget._widget_caches[kind] = cache.new(function(...)
-            return widget[kind](widget, ...)
+            return protected_call(widget[kind], widget, ...)
         end)
     end
     return widget._widget_caches[kind]
@@ -222,9 +223,9 @@ function base.fit_widget(parent, context, widget, width, height)
         end
     end
 
-    -- Apply forced size
-    w = widget._forced_width or w
-    h = widget._forced_height or h
+    -- Apply forced size and handle nil's
+    w = widget._forced_width or w or 0
+    h = widget._forced_height or h or 0
 
     -- Also sanitize the output.
     w = math.max(0, math.min(w, width))

From 8560c6d2af9c6d8747b0f0df587ad6bb97633921 Mon Sep 17 00:00:00 2001
From: Uli Schlachter <psychon@znc.in>
Date: Sun, 28 Feb 2016 12:28:55 +0100
Subject: [PATCH 4/4] Use gears.protected_call where applicable

Signed-off-by: Uli Schlachter <psychon@znc.in>
---
 lib/awful/menu.lua      | 10 +++-------
 lib/awful/spawn.lua     | 17 +++++------------
 lib/beautiful/init.lua  | 10 +++-------
 lib/gears/timer.lua     | 19 +++++--------------
 lib/wibox/hierarchy.lua | 12 +++---------
 5 files changed, 19 insertions(+), 49 deletions(-)

diff --git a/lib/awful/menu.lua b/lib/awful/menu.lua
index 2e29179d..8fdd51cb 100644
--- a/lib/awful/menu.lua
+++ b/lib/awful/menu.lua
@@ -20,13 +20,13 @@ local beautiful = require("beautiful")
 local dpi = require("beautiful").xresources.apply_dpi
 local object = require("gears.object")
 local surface = require("gears.surface")
+local protected_call = require("gears.protected_call")
 local cairo = require("lgi").cairo
 local setmetatable = setmetatable
 local tonumber = tonumber
 local string = string
 local ipairs = ipairs
 local pairs = pairs
-local pcall = pcall
 local print = print
 local table = table
 local type = type
@@ -374,12 +374,8 @@ function menu:add(args, index)
     local theme = load_theme(args.theme or {}, self.theme)
     args.theme = theme
     args.new = args.new or menu.entry
-    local success, item = pcall(args.new, self, args)
-    if not success then
-        print("Error while creating menu entry: " .. item)
-        return
-    end
-    if not item.widget then
+    local item = protected_call(args.new, self, args)
+    if (not item) or (not item.widget) then
         print("Error while checking menu entry: no property widget found.")
         return
     end
diff --git a/lib/awful/spawn.lua b/lib/awful/spawn.lua
index 395f666a..b25ca803 100644
--- a/lib/awful/spawn.lua
+++ b/lib/awful/spawn.lua
@@ -24,6 +24,7 @@ local lgi = require("lgi")
 local Gio = lgi.Gio
 local GLib = lgi.GLib
 local util   = require("awful.util")
+local protected_call = require("gears.protected_call")
 
 local spawn = {}
 
@@ -205,10 +206,7 @@ function spawn.read_lines(input_stream, line_callback, done_callback, close)
             stream:close()
         end
         if done_callback then
-            xpcall(done_callback, function(err)
-                print(debug.traceback("Error while calling done_callback:"
-                    ..  tostring(err), 2))
-            end)
+            protected_call(done_callback)
         end
     end
     local start_read, finish_read
@@ -226,14 +224,9 @@ function spawn.read_lines(input_stream, line_callback, done_callback, close)
             done()
         else
             -- Read a line
-            xpcall(function()
-                -- This needs tostring() for older lgi versions which returned
-                -- "GLib.Bytes" instead of Lua strings (I guess)
-                line_callback(tostring(line))
-            end, function(err)
-                print(debug.traceback("Error while calling line_callback: "
-                    .. tostring(err), 2))
-            end)
+            -- This needs tostring() for older lgi versions which returned
+            -- "GLib.Bytes" instead of Lua strings (I guess)
+            protected_call(line_callback, tostring(line))
 
             -- Read the next line
             start_read()
diff --git a/lib/beautiful/init.lua b/lib/beautiful/init.lua
index 7725f310..d7f95f2f 100644
--- a/lib/beautiful/init.lua
+++ b/lib/beautiful/init.lua
@@ -18,6 +18,7 @@ local lgi = require("lgi")
 local Pango = lgi.Pango
 local PangoCairo = lgi.PangoCairo
 local gears_debug = require("gears.debug")
+local protected_call = require("gears.protected_call")
 
 local xresources = require("beautiful.xresources")
 
@@ -109,7 +110,6 @@ end
 --   containing all the theme values.
 function beautiful.init(config)
     if config then
-        local success
         local homedir = os.getenv("HOME")
 
         -- If config is the path to the theme file,
@@ -118,16 +118,12 @@ function beautiful.init(config)
         if type(config) == 'string' then
             -- Expand the '~' $HOME shortcut
             config = config:gsub("^~/", homedir .. "/")
-            success, theme = xpcall(function() return dofile(config) end,
-                                    debug.traceback)
+            theme = protected_call(dofile, config)
         elseif type(config) == 'table' then
-            success = true
             theme = config
         end
 
-        if not success then
-            return gears_debug.print_error("beautiful: error loading theme file " .. theme)
-        elseif theme then
+        if theme then
             -- expand '~'
             if homedir then
                 for k, v in pairs(theme) do
diff --git a/lib/gears/timer.lua b/lib/gears/timer.lua
index 1c50cefe..7c320ef2 100644
--- a/lib/gears/timer.lua
+++ b/lib/gears/timer.lua
@@ -17,6 +17,7 @@ local traceback = debug.traceback
 local unpack = unpack or table.unpack -- luacheck: globals unpack (compatibility with Lua 5.1)
 local glib = require("lgi").GLib
 local object = require("gears.object")
+local protected_call = require("gears.protected_call")
 
 --- Timer objects. This type of object is useful when triggering events repeatedly.
 -- The timer will emit the "timeout" signal every N seconds, N being the timeout
@@ -43,11 +44,7 @@ function timer:start()
         return
     end
     self.data.source_id = glib.timeout_add(glib.PRIORITY_DEFAULT, self.data.timeout * 1000, function()
-        xpcall(function()
-                self:emit_signal("timeout")
-            end, function(err)
-                print(debug.traceback("Error during executing timeout handler: "..tostring(err)))
-            end)
+        protected_call(self.emit_signal, self, "timeout")
         return true
     end)
     self:emit_signal("start")
@@ -126,10 +123,8 @@ end
 function timer.start_new(timeout, callback)
     local t = timer.new({ timeout = timeout })
     t:connect_signal("timeout", function()
-        local success, cont = xpcall(callback, function(err)
-            print(debug.traceback("Error during executing timeout handler: "..tostring(err), 2))
-        end)
-        if not success or not cont then
+        local cont = protected_call(callback)
+        if not cont then
             t:stop()
         end
     end)
@@ -160,11 +155,7 @@ end
 local delayed_calls = {}
 capi.awesome.connect_signal("refresh", function()
     for _, callback in ipairs(delayed_calls) do
-        xpcall(function()
-                callback[1](unpack(callback, 2))
-            end, function(err)
-                print(debug.traceback("Error during delayed call: "..tostring(err), 2))
-            end)
+        protected_call(unpack(callback))
     end
     delayed_calls = {}
 end)
diff --git a/lib/wibox/hierarchy.lua b/lib/wibox/hierarchy.lua
index 502d912f..5e6abc47 100644
--- a/lib/wibox/hierarchy.lua
+++ b/lib/wibox/hierarchy.lua
@@ -10,6 +10,7 @@
 ---------------------------------------------------------------------------
 
 local matrix = require("gears.matrix")
+local protected_call = require("gears.protected_call")
 local cairo = require("lgi").cairo
 local base = require("wibox.widget.base")
 local no_parent = base.no_parent_I_know_what_I_am_doing
@@ -274,17 +275,10 @@ function hierarchy:draw(context, cr)
         local opacity = widget.opacity
         local function call(func, extra_arg1, extra_arg2)
             if not func then return end
-            local function error_function(err)
-                print(debug.traceback("Error while drawing widget: " .. tostring(err), 2))
-            end
             if not extra_arg2 then
-                xpcall(function()
-                    func(widget, context, cr, self:get_size())
-                end, error_function)
+                protected_call(func, widget, context, cr, self:get_size())
             else
-                xpcall(function()
-                    func(widget, context, extra_arg1, extra_arg2, cr, self:get_size())
-                end, error_function)
+                protected_call(func, widget, context, extra_arg1, extra_arg2, cr, self:get_size())
             end
         end