1 files changed, 52 insertions, 27 deletions

diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 65a42f063a..190c281c76 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -268,6 +268,9 @@ open_buffer (
 bool buf_valid(buf_T *buf)
   FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
 {
+  if (buf == NULL) {
+    return false;
+  }
   FOR_ALL_BUFFERS(bp) {
     if (bp == buf) {
       return true;
@@ -479,6 +482,18 @@ void buf_clear_file(buf_T *buf)
   buf->b_ml.ml_flags = ML_EMPTY;                /* empty buffer */
 }
 
+/// Clears the current buffer contents.
+void buf_clear(void)
+{
+  linenr_T line_count = curbuf->b_ml.ml_line_count;
+  while (!(curbuf->b_ml.ml_flags & ML_EMPTY)) {
+    ml_delete((linenr_T)1, false);
+  }
+  deleted_lines_mark(1, line_count);  // prepare for display
+  ml_close(curbuf, true);             // free memline_T
+  buf_clear_file(curbuf);
+}
+
 /// buf_freeall() - free all things allocated for a buffer that are related to
 /// the file.  Careful: get here with "curwin" NULL when exiting.
 ///
@@ -678,7 +693,7 @@ void handle_swap_exists(buf_T *old_curbuf)
     swap_exists_did_quit = true;
     close_buffer(curwin, curbuf, DOBUF_UNLOAD, false);
     if (!buf_valid(old_curbuf) || old_curbuf == curbuf) {
-      old_curbuf = buflist_new(NULL, NULL, 1L, BLN_CURBUF | BLN_LISTED, 0);
+      old_curbuf = buflist_new(NULL, NULL, 1L, BLN_CURBUF | BLN_LISTED);
     }
     if (old_curbuf != NULL) {
       enter_buffer(old_curbuf);
@@ -1320,29 +1335,29 @@ void do_autochdir(void)
   }
 }
 
-/*
- * functions for dealing with the buffer list
- */
+//
+// functions for dealing with the buffer list
+//
 
-/*
- * Add a file name to the buffer list.  Return a pointer to the buffer.
- * If the same file name already exists return a pointer to that buffer.
- * If it does not exist, or if fname == NULL, a new entry is created.
- * If (flags & BLN_CURBUF) is TRUE, may use current buffer.
- * If (flags & BLN_LISTED) is TRUE, add new buffer to buffer list.
- * If (flags & BLN_DUMMY) is TRUE, don't count it as a real buffer.
- * This is the ONLY way to create a new buffer.
- */
 static int top_file_num = 1;            /* highest file number */
 
-buf_T *
-buflist_new(
-    char_u *ffname,            // full path of fname or relative
-    char_u *sfname,            // short fname or NULL
-    linenr_T lnum,             // preferred cursor line
-    int flags,                 // BLN_ defines
-    handle_T bufnr
-)
+/// Add a file name to the buffer list.
+/// If the same file name already exists return a pointer to that buffer.
+/// If it does not exist, or if fname == NULL, a new entry is created.
+/// If (flags & BLN_CURBUF) is TRUE, may use current buffer.
+/// If (flags & BLN_LISTED) is TRUE, add new buffer to buffer list.
+/// If (flags & BLN_DUMMY) is TRUE, don't count it as a real buffer.
+/// If (flags & BLN_NEW) is TRUE, don't use an existing buffer.
+/// This is the ONLY way to create a new buffer.
+///
+/// @param ffname full path of fname or relative
+/// @param sfname short fname or NULL
+/// @param lnum   preferred cursor line
+/// @param flags  BLN_ defines
+/// @param bufnr
+///
+/// @return pointer to the buffer
+buf_T * buflist_new(char_u *ffname, char_u *sfname, linenr_T lnum, int flags)
 {
   buf_T       *buf;
 
@@ -1460,9 +1475,7 @@ buflist_new(
     }
     lastbuf = buf;
 
-    // If bufnr is nonzero it is assumed to be a previously
-    // reserved buffer number (handle)
-    buf->handle = bufnr != 0 ? bufnr : top_file_num++;
+    buf->b_fnum = top_file_num++;
     handle_register_buffer(buf);
     if (top_file_num < 0) {  // wrap around (may cause duplicates)
       EMSG(_("W14: Warning: List of file names overflow"));
@@ -2379,7 +2392,7 @@ buf_T *setaltfname(char_u *ffname, char_u *sfname, linenr_T lnum)
   buf_T       *buf;
 
   // Create a buffer.  'buflisted' is not set if it's a new buffer
-  buf = buflist_new(ffname, sfname, lnum, 0, 0);
+  buf = buflist_new(ffname, sfname, lnum, 0);
   if (buf != NULL && !cmdmod.keepalt) {
     curwin->w_alt_fnum = buf->b_fnum;
   }
@@ -2416,7 +2429,7 @@ int buflist_add(char_u *fname, int flags)
 {
   buf_T       *buf;
 
-  buf = buflist_new(fname, NULL, (linenr_T)0, flags, 0);
+  buf = buflist_new(fname, NULL, (linenr_T)0, flags);
   if (buf != NULL) {
     return buf->b_fnum;
   }
@@ -5199,7 +5212,7 @@ bool buf_contents_changed(buf_T *buf)
   bool differ = true;
 
   // Allocate a buffer without putting it in the buffer list.
-  buf_T *newbuf = buflist_new(NULL, NULL, (linenr_T)1, BLN_DUMMY, 0);
+  buf_T *newbuf = buflist_new(NULL, NULL, (linenr_T)1, BLN_DUMMY);
   if (newbuf == NULL) {
     return true;
   }
@@ -5259,3 +5272,15 @@ wipe_buffer (
     unblock_autocmds();
   }
 }
+
+/// Creates or switches to a special-purpose buffer.
+///
+/// @param bufnr     Buffer to switch to, or 0 to create a new buffer.
+void buf_open_special(handle_T bufnr, char *bufname, char *buftype)
+{
+  (void)do_ecmd((int)bufnr, NULL, NULL, NULL, ECMD_ONE, ECMD_HIDE, NULL);
+  (void)setfname(curbuf, (char_u *)bufname, NULL, true);
+  set_option_value((char_u *)"bt", 0L, (char_u *)buftype, OPT_LOCAL);
+  set_option_value((char_u *)"swf", 0L, NULL, OPT_LOCAL);
+  RESET_BINDING(curwin);
+}