1 files changed, 19 insertions, 1 deletions

diff --git a/src/coding.c b/src/coding.c
index 2144fe5fcd4..27931c123d2 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -1005,6 +1005,10 @@ record_conversion_result (struct coding_system *coding,
     }
 }
 
+/* This wrapper macro is used to preserve validity of pointers into
+   buffer text across calls to decode_char, which could cause
+   relocation of buffers if it loads a charset map, because loading a
+   charset map allocates large structures.  */
 #define CODING_DECODE_CHAR(coding, src, src_base, src_end, charset, code, c) \
   do {                                                                       \
     charset_map_loaded = 0;                                                  \
@@ -2178,7 +2182,7 @@ emacs_mule_char (coding, src, nbytes, nchars, id, cmp_status)
         default:
           abort ();
         }
-      c = DECODE_CHAR (charset, code);
+      CODING_DECODE_CHAR (coding, src, src_base, src_end, charset, code, c);
       if (c < 0)
         goto invalid_code;
     }
@@ -2525,9 +2529,23 @@ decode_coding_emacs_mule (coding)
       else
         {
           int nchars, nbytes;
+          /* emacs_mule_char can load a charset map from a file, which
+             allocates a large structure and might cause buffer text
+             to be relocated as result.  Thus, we need to remember the
+             original pointer to buffer text, and fixup all related
+             pointers after the call.  */
+          const unsigned char *orig = coding->source;
+          EMACS_INT offset;
 
           c = emacs_mule_char (coding, src_base, &nbytes, &nchars, &id,
                                cmp_status);
+          offset = coding->source - orig;
+          if (offset)
+            {
+              src += offset;
+              src_base += offset;
+              src_end += offset;
+            }
           if (c < 0)
             {
               if (c == -1)