gas line buffer handling

[Alan Modra <amodra at gmail dot com>]

This fixes a segfault when macro definitions end on the last line of a
file, and that line isn't properly terminated with a newline.  gas
used to throw away the last line in cases like this, whereas in other
cases gas added the missing newline.  So I've also made gas
consistently provide a missing newline.

	PR gas/18687
	* input-scrub.c (input_scrub_next_buffer): Rearrange and simplify
	loop.  Don't drop lines at end of file lacking a newline, add a
	newline instead.  Ensure partial_size is zero whenever
	partial_where is NULL.  Adjust buffer size for extra char.
	(input_scrub_push, input_scrub_begin): Adjust buffer size here too.

diff --git a/gas/input-scrub.c b/gas/input-scrub.c
index b94f4e4..c8e1e29 100644
--- a/gas/input-scrub.c
+++ b/gas/input-scrub.c
@@ -164,7 +164,7 @@ input_scrub_push (char *saved_position)
   sb_index = -1;
 
   buffer_start = (char *) xmalloc ((BEFORE_SIZE + buffer_length
-                                    + buffer_length + AFTER_SIZE));
+                                    + buffer_length + AFTER_SIZE + 1));
   memcpy (buffer_start, BEFORE_STRING, (int) BEFORE_SIZE);
 
   return saved;
@@ -209,7 +209,7 @@ input_scrub_begin (void)
   buffer_length = input_file_buffer_size ();
 
   buffer_start = (char *) xmalloc ((BEFORE_SIZE + buffer_length
-                                    + buffer_length + AFTER_SIZE));
+                                    + buffer_length + AFTER_SIZE + 1));
   memcpy (buffer_start, BEFORE_STRING, (int) BEFORE_SIZE);
 
   /* Line number things.  */
@@ -329,6 +329,7 @@ input_scrub_next_buffer (char **bufp)
 	    }
 	  --macro_nest;
 	  partial_where = NULL;
+	  partial_size = 0;
 	  if (next_saved_file != NULL)
 	    *bufp = input_scrub_pop (next_saved_file);
 	  return partial_where;
@@ -341,79 +342,68 @@ input_scrub_next_buffer (char **bufp)
       return partial_where;
     }
 
-  *bufp = buffer_start + BEFORE_SIZE;
-
   if (partial_size)
     {
       memmove (buffer_start + BEFORE_SIZE, partial_where,
 	       (unsigned int) partial_size);
       memcpy (buffer_start + BEFORE_SIZE, save_source, AFTER_SIZE);
     }
-  limit = input_file_give_next_buffer (buffer_start
-				       + BEFORE_SIZE
-				       + partial_size);
-  if (limit)
+
+  while (1)
     {
-      char *p;		/* Find last newline.  */
-      /* Terminate the buffer to avoid confusing TC_EOL_IN_INSN.  */
-      *limit = '\0';
-      for (p = limit - 1; *p != '\n' || TC_EOL_IN_INSN (p); --p)
-	;
-      ++p;
-
-      while (p <= buffer_start + BEFORE_SIZE)
+      char *p;
+
+      *bufp = buffer_start + BEFORE_SIZE;
+      limit = input_file_give_next_buffer (buffer_start
+					   + BEFORE_SIZE
+					   + partial_size);
+      if (!limit)
 	{
-	  int limoff;
-
-	  limoff = limit - buffer_start;
-	  buffer_length += input_file_buffer_size ();
-	  buffer_start = (char *) xrealloc (buffer_start,
-                                            (BEFORE_SIZE
-                                             + 2 * buffer_length
-                                             + AFTER_SIZE));
-	  *bufp = buffer_start + BEFORE_SIZE;
-	  limit = input_file_give_next_buffer (buffer_start + limoff);
-
-	  if (limit == NULL)
-	    {
-	      as_warn (_("partial line at end of file ignored"));
-	      partial_where = NULL;
-	      if (next_saved_file)
-		*bufp = input_scrub_pop (next_saved_file);
-	      return NULL;
-	    }
+	  if (partial_size == 0)
+	    break;
 
+	  as_warn (_("end of file not at end of a line; newline inserted"));
+	  p = buffer_start + BEFORE_SIZE + partial_size;
+	  *p++ = '\n';
+	  limit = p;
+	}
+      else
+	{
 	  /* Terminate the buffer to avoid confusing TC_EOL_IN_INSN.  */
 	  *limit = '\0';
+
+	  /* Find last newline.  */
 	  for (p = limit - 1; *p != '\n' || TC_EOL_IN_INSN (p); --p)
 	    ;
 	  ++p;
 	}
 
-      partial_where = p;
-      partial_size = limit - p;
-      memcpy (save_source, partial_where, (int) AFTER_SIZE);
-      memcpy (partial_where, AFTER_STRING, (int) AFTER_SIZE);
-    }
-  else
-    {
-      partial_where = 0;
-      if (partial_size > 0)
+      if (p != buffer_start + BEFORE_SIZE)
 	{
-	  as_warn (_("partial line at end of file ignored"));
+	  partial_where = p;
+	  partial_size = limit - p;
+	  memcpy (save_source, partial_where, (int) AFTER_SIZE);
+	  memcpy (partial_where, AFTER_STRING, (int) AFTER_SIZE);
+	  return partial_where;
 	}
 
-      /* Tell the listing we've finished the file.  */
-      LISTING_EOF ();
-
-      /* If we should pop to another file at EOF, do it.  */
-      if (next_saved_file)
-	{
-	  *bufp = input_scrub_pop (next_saved_file);	/* Pop state */
-	  /* partial_where is now correct to return, since we popped it.  */
-	}
+      partial_size = limit - (buffer_start + BEFORE_SIZE);
+      buffer_length += input_file_buffer_size ();
+      buffer_start = (char *) xrealloc (buffer_start,
+					(BEFORE_SIZE
+					 + 2 * buffer_length
+					 + AFTER_SIZE + 1));
     }
-  return (partial_where);
+
+  /* Tell the listing we've finished the file.  */
+  LISTING_EOF ();
+
+  /* If we should pop to another file at EOF, do it.  */
+  partial_where = NULL;
+  if (next_saved_file)
+    *bufp = input_scrub_pop (next_saved_file);
+
+  return partial_where;
 }
 
 /* The remaining part of this file deals with line numbers, error

-- 
Alan Modra
Australia Development Lab, IBM