From 4ab4495fbd7df630ad313b9a93a2950c644fbd64 Mon Sep 17 00:00:00 2001
From: Philipp Gesang <phg@phi-gamma.net>
Date: Mon, 2 May 2016 20:59:14 +0200
Subject: [letterspace] fix crash with fonts with missing glyphs

Fix issue #351

The letterspace node handler dereferences kern values of non-existant
character information under some circumstances, causing Luatex to crash.
To avoid this crash, check more thoroughly for the presence of the
fields accessed.

Discovered by @schlcht
---
 src/luaotfload-letterspace.lua | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

(limited to 'src/luaotfload-letterspace.lua')

diff --git a/src/luaotfload-letterspace.lua b/src/luaotfload-letterspace.lua
index 007fa51..bda56b2 100644
--- a/src/luaotfload-letterspace.lua
+++ b/src/luaotfload-letterspace.lua
@@ -411,11 +411,20 @@ kerncharacters = function (head)
             if keeptogether and keeptogether(prev, start) then
               -- keep 'm
             elseif identifiers[lastfont] then
-              local kerns = chardata[lastfont] and chardata[lastfont][prevchar].kerns
-              local kern = kerns and kerns[lastchar] or 0
-              krn = kern + quaddata[lastfont]*krn -- here
-              insert_node_before(head,start,kern_injector(fillup,krn))
-              done = true
+              local lastfontchars = chardata[lastfont]
+              if lastfontchars then
+                local prevchardata  = lastfontchars[prevchar]
+                if not prevchardata then
+                  --- font doesn’t contain the glyph
+                else
+                  local kern = 0
+                  local kerns = prevchardata.kerns
+                  if kerns then kern = kerns[lastchar] end
+                  krn = kern + quaddata[lastfont]*krn -- here
+                  insert_node_before(head,start,kern_injector(fillup,krn))
+                  done = true
+                end
+              end
             end
           else
             krn = quaddata[lastfont]*krn -- here
@@ -477,10 +486,19 @@ kerncharacters = function (head)
               and getid(prv)   == glyph_code
               and getfont(prv) == lastfont
             then
+              local kern     = 0
               local prevchar = getchar(prv)
               local lastchar = getchar(start)
-              local kerns = chardata[lastfont] and chardata[lastfont][prevchar].kerns
-              local kern = kerns and kerns[lastchar] or 0
+              local lastfontchars = chardata[lastfont]
+              if lastfontchars then
+                local prevchardata = lastfontchars[prevchar]
+                if not prevchardata then
+                  --- font doesn’t contain the glyph
+                else
+                  local kerns = prevchardata.kerns
+                  if kerns then kern = kerns[lastchar] end
+                end
+              end
               krn = kern + quaddata[lastfont]*krn -- here
             else
               krn = quaddata[lastfont]*krn -- here
-- 
cgit v1.2.3


From 687430a81dcd658d664e6a8c7dca6f53bc093a8c Mon Sep 17 00:00:00 2001
From: Philipp Gesang <phg@phi-gamma.net>
Date: Mon, 2 May 2016 21:07:14 +0200
Subject: [letterspace] remove useless state variable

---
 src/luaotfload-letterspace.lua | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

(limited to 'src/luaotfload-letterspace.lua')

diff --git a/src/luaotfload-letterspace.lua b/src/luaotfload-letterspace.lua
index bda56b2..40b3015 100644
--- a/src/luaotfload-letterspace.lua
+++ b/src/luaotfload-letterspace.lua
@@ -277,7 +277,7 @@ local kernfactors = { } --- fontid -> factor
 
 local kerncharacters
 kerncharacters = function (head)
-  local start, done   = head, false
+  local start         = head
   local lastfont      = nil
   local keepligature  = letterspace.keepligature --- function
   local keeptogether  = letterspace.keeptogether --- function
@@ -352,7 +352,6 @@ kerncharacters = function (head)
             start = c
             setfield(s, "components", nil)
             free_node(s)
-            done = true
             c = getfield (start, "components")
           end
         end
@@ -378,7 +377,6 @@ kerncharacters = function (head)
             local shrunk    = (getfield(spec,"shrink")  * newwd) / wd
             setfield(prev, "spec",
                      spec_injector(fillup, newwd, stretched, shrunk))
-            done = true
           end
 
         elseif pid == kern_code then
@@ -400,7 +398,6 @@ kerncharacters = function (head)
               local prev_kern = getfield(prev, "kern")
               prev_kern = prev_kern + quaddata[lastfont] * krn
               setfield (prev, "kern", prev_kern)
-              done = true
             end
           end
 
@@ -422,14 +419,12 @@ kerncharacters = function (head)
                   if kerns then kern = kerns[lastchar] end
                   krn = kern + quaddata[lastfont]*krn -- here
                   insert_node_before(head,start,kern_injector(fillup,krn))
-                  done = true
                 end
               end
             end
           else
             krn = quaddata[lastfont]*krn -- here
             insert_node_before(head,start,kern_injector(fillup,krn))
-            done = true
           end
 
         elseif pid == disc_code then
@@ -514,7 +509,7 @@ kerncharacters = function (head)
       start = getnext(start)
     end
   end
-  return head, done
+  return head
 end
 
 ---=================================================================---
@@ -566,7 +561,7 @@ local enablefontkerning = function ( )
     logreport ("term", 5, "letterspace",
                "kerncharacters() invoked with node.direct interface \z
                (``%s`` -> ``%s``)", tostring (hd), tostring (direct_hd))
-    local direct_hd, _done = kerncharacters (direct_hd)
+    local direct_hd = kerncharacters (direct_hd)
     if not direct_hd then --- bad
       logreport ("both", 0, "letterspace",
                  "kerncharacters() failed to return a valid new head")
-- 
cgit v1.2.3