* xdisp.c (handle_fontified_prop): Be careful with font-lock changing

the buffer's point-max.

Fixes: debbugs:7876

2 files changed, 14 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 297ea12aee7..0539b849efc 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2011-01-24  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * xdisp.c (handle_fontified_prop): Be careful with font-lock changing
+        the buffer's point-max (bug#7876).
+
 2011-01-23  Chong Yidong  <cyd@stupidchicken.com>
 
         * lisp.h (XPNTR): Obey DATA_SEG_BITS in all non-USE_LSB_TAG cases.
diff --git a/src/xdisp.c b/src/xdisp.c
index 219150b9f97..d625b05075d 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -3337,6 +3337,8 @@ handle_fontified_prop (it)
       val = Vfontification_functions;
       specbind (Qfontification_functions, Qnil);
 
+      xassert (it->end_charpos == ZV);
+      
       if (!CONSP (val) || EQ (XCAR (val), Qlambda))
         safe_call1 (val, pos);
       else
@@ -3376,6 +3378,13 @@ handle_fontified_prop (it)
 
       unbind_to (count, Qnil);
 
+      /* The fontification code may have added/removed text.
+         It could do even a lot worse, but let's at least protect against
+         the most obvious case where only the text past `pos' gets changed',
+         as is/was done in grep.el where some escapes sequences are turned
+         into face properties (bug#7876).  */
+      it->end_charpos = ZV;
+      
       /* Return HANDLED_RECOMPUTE_PROPS only if function fontified
          something.  This avoids an endless loop if they failed to
          fontify the text for which reason ever.  */