Avoid buffer text relocations in calls to STRING_CHAR_* macros.

 src/charset.c (maybe_unify_char): Inhibit relocation of buffer text
 for the duration of call to load_charset, to avoid problems with
 callers of maybe_unify_char that access buffer text through C
 pointers.
 src/ralloc.c (r_alloc_inhibit_buffer_relocation): Increment and
 decrement the inhibition flag, instead of just setting or
 resetting it.

Fixes: debbugs:11519

1 files changed, 9 insertions, 0 deletions

diff --git a/src/charset.c b/src/charset.c
index 57e1603fc19..d287fc0bece 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1641,6 +1641,12 @@ maybe_unify_char (int c, Lisp_Object val)
     return c;
 
   CHECK_CHARSET_GET_CHARSET (val, charset);
+#ifdef REL_ALLOC
+  /* The call to load_charset below can allocate memory, whcih screws
+     callers of this function through STRING_CHAR_* macros that hold C
+     pointers to buffer text, if REL_ALLOC is used.  */
+  r_alloc_inhibit_buffer_relocation (1);
+#endif
   load_charset (charset, 1);
   if (! inhibit_load_charset_map)
     {
@@ -1656,6 +1662,9 @@ maybe_unify_char (int c, Lisp_Object val)
       if (unified > 0)
 	c = unified;
     }
+#ifdef REL_ALLOC
+  r_alloc_inhibit_buffer_relocation (0);
+#endif
   return c;
 }