From 78bde1b41e5cb692ea9ffbfff4d35edf3162dcdf Mon Sep 17 00:00:00 2001
From: Philipp Gesang <phg@phi-gamma.net>
Date: Fri, 6 Jul 2018 10:10:05 +0200
Subject: rem, common: handle string sanitization

---
 common.lua | 39 ++++++++++++++++++++++++++++++++++-----
 rem.lua    | 49 +++++++++++++++++++++++++++++--------------------
 2 files changed, 63 insertions(+), 25 deletions(-)

diff --git a/common.lua b/common.lua
index c009207..6afde62 100644
--- a/common.lua
+++ b/common.lua
@@ -1,3 +1,5 @@
+local lpeg = require "lpeg"
+
 local string        = require "string"
 local stringformat  = string.format
 
@@ -20,11 +22,38 @@ end
 
 local set_verbosity = function (n) verboselvl = n end
 
+local trim_whitespace
+local unescape_string
+do
+  local P                 = lpeg.P
+  local S                 = lpeg.S
+  local Cs                = lpeg.Cs
+  local p_ws_char         = S" \n\r\t\v"
+  local p_ws              = p_ws_char^1
+  local p_ws_trailing     = p_ws * P (-1)
+  local p_ws_drop         = Cs (  (p_ws^-1 / "")
+                                * (1 - p_ws_trailing)^0
+                                * (p_ws^-1 * P (-1) / ""))
+
+  local p_escape_char     = (P"\\n" / "\n")
+                          + (P"\\r" / "\r")
+                          + (P"\\t" / "\t")
+                          + (P"\\v" / "\v")
+  local p_unescape        = Cs ((p_escape_char + 1)^0)
+
+  local lpegmatch         = lpeg.match
+
+  trim_whitespace = function (s) return lpegmatch (p_ws_drop , s) end
+  unescape_string = function (s) return lpegmatch (p_unescape, s) end
+end
+
 return
-  { println       = mk_out ("stdout", 0, true)
-  , errorln       = mk_out ("stderr", 0, true)
-  , noiseln       = mk_out ("stderr", 1, true)
-  , debugln       = mk_out ("stderr", 2, true)
-  , set_verbosity = set_verbosity
+  { println               = mk_out ("stdout", 0, true)
+  , errorln               = mk_out ("stderr", 0, true)
+  , noiseln               = mk_out ("stderr", 1, true)
+  , debugln               = mk_out ("stderr", 2, true)
+  , set_verbosity         = set_verbosity
+  , trim_whitespace       = trim_whitespace
+  , unescape_string       = unescape_string
   }
 
diff --git a/rem.lua b/rem.lua
index e1fdc1f..ed3a355 100644
--- a/rem.lua
+++ b/rem.lua
@@ -6,30 +6,33 @@
 
 local inspect = require "ext.inspect"
 
-local pcall         = pcall
+local pcall               = pcall
 
-local io            = require "io"
-local iostdout      = io.stdout
+local io                  = require "io"
+local iostdout            = io.stdout
 
-local math          = require "math"
-local mathfloor     = math.floor
+local math                = require "math"
+local mathfloor           = math.floor
 
-local os            = os
-local osdate        = os.date
-local ostime        = os.time
+local os                  = os
+local osdate              = os.date
+local ostime              = os.time
 
-local string        = require "string"
-local stringformat  = string.format
-local stringsub     = string.sub
+local string              = require "string"
+local stringformat        = string.format
+local stringsub           = string.sub
+local stringgsub          = string.gsub
 
-local table         = require "table"
-local tableconcat   = table.concat
+local table               = require "table"
+local tableconcat         = table.concat
 
-local common        = require "common"
-local println       = common.println
-local errorln       = common.errorln
-local noiseln       = common.noiseln
-local debugln       = common.debugln
+local common              = require "common"
+local println             = common.println
+local errorln             = common.errorln
+local noiseln             = common.noiseln
+local debugln             = common.debugln
+local trim_whitespace     = common.trim_whitespace
+local unescape_string     = common.unescape_string
 
 local seconds_of_time = function (t)
   return t % 60
@@ -245,7 +248,13 @@ local rem_of_vcalendars do
   end
 
   local msg_of_description = function (val)
-    return val.value
+    local sane = unescape_string (val.value)
+
+    return trim_whitespace (sane)
+  end
+
+  local msg_of_string = function (s)
+    return stringgsub (s, "\n", "^M")
   end
 
   local rem_of_vevent = function (ev)
@@ -280,7 +289,7 @@ local rem_of_vcalendars do
       error ("could not derive message text from event values")
     end
 
-    return stringformat ("REM %s MSG %s", date, msg)
+    return stringformat ("REM %s MSG %s", date, msg_of_string (msg))
   end
 
   local rem_of_vcalendar = function (vcal)
-- 
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