1 files changed, 15 insertions, 17 deletions

diff --git a/src/fileio.c b/src/fileio.c
index b8d7de46f67..119c6d1b200 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -3179,11 +3179,7 @@ This does code conversion according to the value of\n\
      But if we discover the need for conversion, we give up on this method
      and let the following if-statement handle the replace job.  */
   if (!NILP (replace)
-      && (! CODING_REQUIRE_CONVERSION (&coding)
-          || (coding.type == coding_type_undecided
-              && ! CODING_REQUIRE_EOL_CONVERSION (&coding))
-          || (coding.eol_type == CODING_EOL_UNDECIDED
-              && ! CODING_REQUIRE_TEXT_CONVERSION (&coding))))
+      && CODING_MAY_REQUIRE_NO_CONVERSION (&coding))
     {
       int same_at_start = BEGV;
       int same_at_end = ZV;
@@ -3218,7 +3214,8 @@ This does code conversion according to the value of\n\
           if (coding.type == coding_type_undecided)
             detect_coding (&coding, buffer, nread);
           if (coding.type != coding_type_undecided
-              && CODING_REQUIRE_TEXT_CONVERSION (&coding))
+              && coding.type != coding_type_no_conversion
+              && coding.type != coding_type_emacs_mule)
             /* We found that the file should be decoded somehow.
                Let's give up here.  */
             {
@@ -3229,7 +3226,7 @@ This does code conversion according to the value of\n\
           if (coding.eol_type == CODING_EOL_UNDECIDED)
             detect_eol (&coding, buffer, nread);
           if (coding.eol_type != CODING_EOL_UNDECIDED
-              && CODING_REQUIRE_EOL_CONVERSION (&coding))
+              && coding.eol_type != CODING_EOL_LF)
             /* We found that the format of eol should be decoded.
                Let's give up here.  */
             {
@@ -3304,7 +3301,7 @@ This does code conversion according to the value of\n\
               if (same_at_end > same_at_start
                   && FETCH_BYTE (same_at_end - 1) >= 0200
                   && ! NILP (current_buffer->enable_multibyte_characters)
-                  && CODING_REQUIRE_CONVERSION (&coding))
+                  && ! CODING_REQUIRE_NO_CONVERSION (&coding))
                 giveup_match_end = 1;
               break;
             }
@@ -3398,7 +3395,7 @@ This does code conversion according to the value of\n\
 
           how_much += this;
 
-          if (CODING_REQUIRE_CONVERSION (&coding))
+          if (! CODING_REQUIRE_NO_CONVERSION (&coding))
             {
               int require, produced, consumed;
 
@@ -3543,9 +3540,9 @@ This does code conversion according to the value of\n\
     {
         /* try is reserved in some compilers (Microsoft C) */
       int trytry = min (total - how_much, READ_BUF_SIZE - unprocessed);
-      char *destination = (CODING_REQUIRE_CONVERSION (&coding)
-                           ? read_buf + unprocessed
-                           : (char *) (POS_ADDR (PT + inserted - 1) + 1));
+      char *destination = (CODING_REQUIRE_NO_CONVERSION (&coding)
+                           ? (char *) (POS_ADDR (PT + inserted - 1) + 1)
+                           : read_buf + unprocessed);
       int this;
 
       /* Allow quitting out of the actual I/O.  */
@@ -3568,7 +3565,7 @@ This does code conversion according to the value of\n\
       if (! not_regular)
         how_much += this;
 
-      if (CODING_REQUIRE_CONVERSION (&coding))
+      if (! CODING_REQUIRE_NO_CONVERSION (&coding))
         {
           int require, produced, consumed;
 
@@ -3831,9 +3828,10 @@ to the file, instead of any buffer contents, and END is ignored.")
       val = Qnil;
     else if (!NILP (Vcoding_system_for_write))
       val = Vcoding_system_for_write;
-    else if (NILP (current_buffer->enable_multibyte_characters) ||
-             ! NILP (Fsymbol_value (Qbuffer_file_coding_system)))
-      val = Fsymbol_value (Qbuffer_file_coding_system);
+    else if (NILP (current_buffer->enable_multibyte_characters))
+      val = (NILP (Flocal_variable_p (Qbuffer_file_coding_system))
+             ? Qnil
+             : Fsymbol_value (Qbuffer_file_coding_system));
     else
       {
         Lisp_Object args[7], coding_systems;
@@ -3842,7 +3840,7 @@ to the file, instead of any buffer contents, and END is ignored.")
           args[3] = filename, args[4] = append, args[5] = visit,
           args[6] = lockname;
         coding_systems = Ffind_operation_coding_system (7, args);
-        val = (CONSP (coding_systems)
+        val = (CONSP (coding_systems) && !NILP (XCONS (coding_systems)->cdr)
                ? XCONS (coding_systems)->cdr
                : current_buffer->buffer_file_coding_system);
       }