Introduce nvim namespace: Move files.

Move files from src/ to src/nvim/.
- src/nvim/ becomes the new root dir for nvim executable sources.
- src/libnvim/ is planned to become root dir of the neovim library.

1 files changed, 0 insertions, 2880 deletions

diff --git a/src/undo.c b/src/undo.c
deleted file mode 100644
index 47ce8ee8da..0000000000
--- a/src/undo.c
+++ /dev/null
@@ -1,2880 +0,0 @@
-/*
- * VIM - Vi IMproved	by Bram Moolenaar
- *
- * Do ":help uganda"  in Vim to read copying and usage conditions.
- * Do ":help credits" in Vim to see a list of people who contributed.
- * See README.txt for an overview of the Vim source code.
- */
-
-/*
- * undo.c: multi level undo facility
- *
- * The saved lines are stored in a list of lists (one for each buffer):
- *
- * b_u_oldhead------------------------------------------------+
- *							      |
- *							      V
- *		  +--------------+    +--------------+	  +--------------+
- * b_u_newhead--->| u_header	 |    | u_header     |	  | u_header	 |
- *		  |	uh_next------>|     uh_next------>|	uh_next---->NULL
- *	   NULL<--------uh_prev  |<---------uh_prev  |<---------uh_prev  |
- *		  |	uh_entry |    |     uh_entry |	  |	uh_entry |
- *		  +--------|-----+    +--------|-----+	  +--------|-----+
- *			   |		       |		   |
- *			   V		       V		   V
- *		  +--------------+    +--------------+	  +--------------+
- *		  | u_entry	 |    | u_entry      |	  | u_entry	 |
- *		  |	ue_next  |    |     ue_next  |	  |	ue_next  |
- *		  +--------|-----+    +--------|-----+	  +--------|-----+
- *			   |		       |		   |
- *			   V		       V		   V
- *		  +--------------+	      NULL		  NULL
- *		  | u_entry	 |
- *		  |	ue_next  |
- *		  +--------|-----+
- *			   |
- *			   V
- *			  etc.
- *
- * Each u_entry list contains the information for one undo or redo.
- * curbuf->b_u_curhead points to the header of the last undo (the next redo),
- * or is NULL if nothing has been undone (end of the branch).
- *
- * For keeping alternate undo/redo branches the uh_alt field is used.  Thus at
- * each point in the list a branch may appear for an alternate to redo.  The
- * uh_seq field is numbered sequentially to be able to find a newer or older
- * branch.
- *
- *		   +---------------+	+---------------+
- * b_u_oldhead --->| u_header	   |	| u_header	|
- *		   |   uh_alt_next ---->|   uh_alt_next ----> NULL
- *	   NULL <----- uh_alt_prev |<------ uh_alt_prev |
- *		   |   uh_prev	   |	|   uh_prev	|
- *		   +-----|---------+	+-----|---------+
- *			 |		      |
- *			 V		      V
- *		   +---------------+	+---------------+
- *		   | u_header	   |	| u_header	|
- *		   |   uh_alt_next |	|   uh_alt_next |
- * b_u_newhead --->|   uh_alt_prev |	|   uh_alt_prev |
- *		   |   uh_prev	   |	|   uh_prev	|
- *		   +-----|---------+	+-----|---------+
- *			 |		      |
- *			 V		      V
- *		       NULL		+---------------+    +---------------+
- *					| u_header	|    | u_header      |
- *					|   uh_alt_next ---->|	 uh_alt_next |
- *					|   uh_alt_prev |<------ uh_alt_prev |
- *					|   uh_prev	|    |	 uh_prev     |
- *					+-----|---------+    +-----|---------+
- *					      |			   |
- *					     etc.		  etc.
- *
- *
- * All data is allocated and will all be freed when the buffer is unloaded.
- */
-
-/* Uncomment the next line for including the u_check() function.  This warns
- * for errors in the debug information. */
-/* #define U_DEBUG 1 */
-#define UH_MAGIC 0x18dade       /* value for uh_magic when in use */
-#define UE_MAGIC 0xabc123       /* value for ue_magic when in use */
-
-#include <string.h>
-
-#include "vim.h"
-#include "undo.h"
-#include "edit.h"
-#include "eval.h"
-#include "fileio.h"
-#include "fold.h"
-#include "mark.h"
-#include "memline.h"
-#include "message.h"
-#include "misc1.h"
-#include "misc2.h"
-#include "memory.h"
-#include "crypt.h"
-#include "garray.h"
-#include "option.h"
-#include "os_unix.h"
-#include "path.h"
-#include "quickfix.h"
-#include "screen.h"
-#include "sha256.h"
-#include "os/os.h"
-#include "os/time.h"
-
-static long get_undolevel(void);
-static void u_unch_branch(u_header_T *uhp);
-static u_entry_T *u_get_headentry(void);
-static void u_getbot(void);
-static void u_doit(int count);
-static void u_undoredo(int undo);
-static void u_undo_end(int did_undo, int absolute);
-static void u_add_time(char_u *buf, size_t buflen, time_t tt);
-static void u_freeheader(buf_T *buf, u_header_T *uhp, u_header_T **uhpp);
-static void u_freebranch(buf_T *buf, u_header_T *uhp, u_header_T **uhpp);
-static void u_freeentries(buf_T *buf, u_header_T *uhp,
-                          u_header_T **uhpp);
-static void u_freeentry(u_entry_T *, long);
-static void corruption_error(char *mesg, char_u *file_name);
-static void u_free_uhp(u_header_T *uhp);
-static size_t fwrite_crypt(buf_T *buf, char_u *ptr, size_t len,
-                           FILE *fp);
-static char_u *read_string_decrypt(buf_T *buf, FILE *fd, int len);
-static int serialize_header(FILE *fp, buf_T *buf, char_u *hash);
-static int serialize_uhp(FILE *fp, buf_T *buf, u_header_T *uhp);
-static u_header_T *unserialize_uhp(FILE *fp, char_u *file_name);
-static int serialize_uep(FILE *fp, buf_T *buf, u_entry_T *uep);
-static u_entry_T *unserialize_uep(FILE *fp, int *error,
-                                  char_u *file_name);
-static void serialize_pos(pos_T pos, FILE *fp);
-static void unserialize_pos(pos_T *pos, FILE *fp);
-static void serialize_visualinfo(visualinfo_T *info, FILE *fp);
-static void unserialize_visualinfo(visualinfo_T *info, FILE *fp);
-static void put_header_ptr(FILE *fp, u_header_T *uhp);
-
-static char_u *u_save_line(linenr_T);
-
-/* used in undo_end() to report number of added and deleted lines */
-static long u_newcount, u_oldcount;
-
-/*
- * When 'u' flag included in 'cpoptions', we behave like vi.  Need to remember
- * the action that "u" should do.
- */
-static int undo_undoes = FALSE;
-
-static int lastmark = 0;
-
-#if defined(U_DEBUG) || defined(PROTO)
-/*
- * Check the undo structures for being valid.  Print a warning when something
- * looks wrong.
- */
-static int seen_b_u_curhead;
-static int seen_b_u_newhead;
-static int header_count;
-
-static void u_check_tree(u_header_T *uhp,
-    u_header_T *exp_uh_next,
-    u_header_T *exp_uh_alt_prev) {
-  u_entry_T *uep;
-
-  if (uhp == NULL)
-    return;
-  ++header_count;
-  if (uhp == curbuf->b_u_curhead && ++seen_b_u_curhead > 1) {
-    EMSG("b_u_curhead found twice (looping?)");
-    return;
-  }
-  if (uhp == curbuf->b_u_newhead && ++seen_b_u_newhead > 1) {
-    EMSG("b_u_newhead found twice (looping?)");
-    return;
-  }
-
-  if (uhp->uh_magic != UH_MAGIC)
-    EMSG("uh_magic wrong (may be using freed memory)");
-  else {
-    /* Check pointers back are correct. */
-    if (uhp->uh_next.ptr != exp_uh_next) {
-      EMSG("uh_next wrong");
-      smsg((char_u *)"expected: 0x%x, actual: 0x%x",
-          exp_uh_next, uhp->uh_next.ptr);
-    }
-    if (uhp->uh_alt_prev.ptr != exp_uh_alt_prev) {
-      EMSG("uh_alt_prev wrong");
-      smsg((char_u *)"expected: 0x%x, actual: 0x%x",
-          exp_uh_alt_prev, uhp->uh_alt_prev.ptr);
-    }
-
-    /* Check the undo tree at this header. */
-    for (uep = uhp->uh_entry; uep != NULL; uep = uep->ue_next) {
-      if (uep->ue_magic != UE_MAGIC) {
-        EMSG("ue_magic wrong (may be using freed memory)");
-        break;
-      }
-    }
-
-    /* Check the next alt tree. */
-    u_check_tree(uhp->uh_alt_next.ptr, uhp->uh_next.ptr, uhp);
-
-    /* Check the next header in this branch. */
-    u_check_tree(uhp->uh_prev.ptr, uhp, NULL);
-  }
-}
-
-static void u_check(int newhead_may_be_NULL)                 {
-  seen_b_u_newhead = 0;
-  seen_b_u_curhead = 0;
-  header_count = 0;
-
-  u_check_tree(curbuf->b_u_oldhead, NULL, NULL);
-
-  if (seen_b_u_newhead == 0 && curbuf->b_u_oldhead != NULL
-      && !(newhead_may_be_NULL && curbuf->b_u_newhead == NULL))
-    EMSGN("b_u_newhead invalid: 0x%x", curbuf->b_u_newhead);
-  if (curbuf->b_u_curhead != NULL && seen_b_u_curhead == 0)
-    EMSGN("b_u_curhead invalid: 0x%x", curbuf->b_u_curhead);
-  if (header_count != curbuf->b_u_numhead) {
-    EMSG("b_u_numhead invalid");
-    smsg((char_u *)"expected: %" PRId64 ", actual: %" PRId64,
-        (int64_t)header_count, (int64_t)curbuf->b_u_numhead);
-  }
-}
-
-#endif
-
-/*
- * Save the current line for both the "u" and "U" command.
- * Careful: may trigger autocommands that reload the buffer.
- * Returns OK or FAIL.
- */
-int u_save_cursor(void)
-{
-  return u_save((linenr_T)(curwin->w_cursor.lnum - 1),
-      (linenr_T)(curwin->w_cursor.lnum + 1));
-}
-
-/*
- * Save the lines between "top" and "bot" for both the "u" and "U" command.
- * "top" may be 0 and bot may be curbuf->b_ml.ml_line_count + 1.
- * Careful: may trigger autocommands that reload the buffer.
- * Returns FAIL when lines could not be saved, OK otherwise.
- */
-int u_save(linenr_T top, linenr_T bot)
-{
-  if (undo_off)
-    return OK;
-
-  if (top > curbuf->b_ml.ml_line_count
-      || top >= bot
-      || bot > curbuf->b_ml.ml_line_count + 1)
-    return FALSE;       /* rely on caller to do error messages */
-
-  if (top + 2 == bot)
-    u_saveline((linenr_T)(top + 1));
-
-  return u_savecommon(top, bot, (linenr_T)0, FALSE);
-}
-
-/*
- * Save the line "lnum" (used by ":s" and "~" command).
- * The line is replaced, so the new bottom line is lnum + 1.
- * Careful: may trigger autocommands that reload the buffer.
- * Returns FAIL when lines could not be saved, OK otherwise.
- */
-int u_savesub(linenr_T lnum)
-{
-  if (undo_off)
-    return OK;
-
-  return u_savecommon(lnum - 1, lnum + 1, lnum + 1, FALSE);
-}
-
-/*
- * A new line is inserted before line "lnum" (used by :s command).
- * The line is inserted, so the new bottom line is lnum + 1.
- * Careful: may trigger autocommands that reload the buffer.
- * Returns FAIL when lines could not be saved, OK otherwise.
- */
-int u_inssub(linenr_T lnum)
-{
-  if (undo_off)
-    return OK;
-
-  return u_savecommon(lnum - 1, lnum, lnum + 1, FALSE);
-}
-
-/*
- * Save the lines "lnum" - "lnum" + nlines (used by delete command).
- * The lines are deleted, so the new bottom line is lnum, unless the buffer
- * becomes empty.
- * Careful: may trigger autocommands that reload the buffer.
- * Returns FAIL when lines could not be saved, OK otherwise.
- */
-int u_savedel(linenr_T lnum, long nlines)
-{
-  if (undo_off)
-    return OK;
-
-  return u_savecommon(lnum - 1, lnum + nlines,
-      nlines == curbuf->b_ml.ml_line_count ? 2 : lnum, FALSE);
-}
-
-/*
- * Return TRUE when undo is allowed.  Otherwise give an error message and
- * return FALSE.
- */
-int undo_allowed(void)
-{
-  /* Don't allow changes when 'modifiable' is off.  */
-  if (!curbuf->b_p_ma) {
-    EMSG(_(e_modifiable));
-    return FALSE;
-  }
-
-#ifdef HAVE_SANDBOX
-  /* In the sandbox it's not allowed to change the text. */
-  if (sandbox != 0) {
-    EMSG(_(e_sandbox));
-    return FALSE;
-  }
-#endif
-
-  /* Don't allow changes in the buffer while editing the cmdline.  The
-   * caller of getcmdline() may get confused. */
-  if (textlock != 0) {
-    EMSG(_(e_secure));
-    return FALSE;
-  }
-
-  return TRUE;
-}
-
-/*
- * Get the undolevle value for the current buffer.
- */
-static long get_undolevel(void)
-{
-  if (curbuf->b_p_ul == NO_LOCAL_UNDOLEVEL)
-    return p_ul;
-  return curbuf->b_p_ul;
-}
-
-/*
- * Common code for various ways to save text before a change.
- * "top" is the line above the first changed line.
- * "bot" is the line below the last changed line.
- * "newbot" is the new bottom line.  Use zero when not known.
- * "reload" is TRUE when saving for a buffer reload.
- * Careful: may trigger autocommands that reload the buffer.
- * Returns FAIL when lines could not be saved, OK otherwise.
- */
-int u_savecommon(linenr_T top, linenr_T bot, linenr_T newbot, int reload)
-{
-  linenr_T lnum;
-  long i;
-  u_header_T  *uhp;
-  u_header_T  *old_curhead;
-  u_entry_T   *uep;
-  u_entry_T   *prev_uep;
-  long size;
-
-  if (!reload) {
-    /* When making changes is not allowed return FAIL.  It's a crude way
-     * to make all change commands fail. */
-    if (!undo_allowed())
-      return FAIL;
-
-
-    /*
-     * Saving text for undo means we are going to make a change.  Give a
-     * warning for a read-only file before making the change, so that the
-     * FileChangedRO event can replace the buffer with a read-write version
-     * (e.g., obtained from a source control system).
-     */
-    change_warning(0);
-    if (bot > curbuf->b_ml.ml_line_count + 1) {
-      /* This happens when the FileChangedRO autocommand changes the
-       * file in a way it becomes shorter. */
-      EMSG(_("E881: Line count changed unexpectedly"));
-      return FAIL;
-    }
-  }
-
-#ifdef U_DEBUG
-  u_check(FALSE);
-#endif
-
-  size = bot - top - 1;
-
-  /*
-   * If curbuf->b_u_synced == TRUE make a new header.
-   */
-  if (curbuf->b_u_synced) {
-    /* Need to create new entry in b_changelist. */
-    curbuf->b_new_change = TRUE;
-
-    if (get_undolevel() >= 0) {
-      /*
-       * Make a new header entry.  Do this first so that we don't mess
-       * up the undo info when out of memory.
-       */
-      uhp = xmalloc(sizeof(u_header_T));
-#ifdef U_DEBUG
-      uhp->uh_magic = UH_MAGIC;
-#endif
-    } else
-      uhp = NULL;
-
-    /*
-     * If we undid more than we redid, move the entry lists before and
-     * including curbuf->b_u_curhead to an alternate branch.
-     */
-    old_curhead = curbuf->b_u_curhead;
-    if (old_curhead != NULL) {
-      curbuf->b_u_newhead = old_curhead->uh_next.ptr;
-      curbuf->b_u_curhead = NULL;
-    }
-
-    /*
-     * free headers to keep the size right
-     */
-    while (curbuf->b_u_numhead > get_undolevel()
-           && curbuf->b_u_oldhead != NULL) {
-      u_header_T      *uhfree = curbuf->b_u_oldhead;
-
-      if (uhfree == old_curhead)
-        /* Can't reconnect the branch, delete all of it. */
-        u_freebranch(curbuf, uhfree, &old_curhead);
-      else if (uhfree->uh_alt_next.ptr == NULL)
-        /* There is no branch, only free one header. */
-        u_freeheader(curbuf, uhfree, &old_curhead);
-      else {
-        /* Free the oldest alternate branch as a whole. */
-        while (uhfree->uh_alt_next.ptr != NULL)
-          uhfree = uhfree->uh_alt_next.ptr;
-        u_freebranch(curbuf, uhfree, &old_curhead);
-      }
-#ifdef U_DEBUG
-      u_check(TRUE);
-#endif
-    }
-
-    if (uhp == NULL) {                  /* no undo at all */
-      if (old_curhead != NULL)
-        u_freebranch(curbuf, old_curhead, NULL);
-      curbuf->b_u_synced = FALSE;
-      return OK;
-    }
-
-    uhp->uh_prev.ptr = NULL;
-    uhp->uh_next.ptr = curbuf->b_u_newhead;
-    uhp->uh_alt_next.ptr = old_curhead;
-    if (old_curhead != NULL) {
-      uhp->uh_alt_prev.ptr = old_curhead->uh_alt_prev.ptr;
-      if (uhp->uh_alt_prev.ptr != NULL)
-        uhp->uh_alt_prev.ptr->uh_alt_next.ptr = uhp;
-      old_curhead->uh_alt_prev.ptr = uhp;
-      if (curbuf->b_u_oldhead == old_curhead)
-        curbuf->b_u_oldhead = uhp;
-    } else
-      uhp->uh_alt_prev.ptr = NULL;
-    if (curbuf->b_u_newhead != NULL)
-      curbuf->b_u_newhead->uh_prev.ptr = uhp;
-
-    uhp->uh_seq = ++curbuf->b_u_seq_last;
-    curbuf->b_u_seq_cur = uhp->uh_seq;
-    uhp->uh_time = time(NULL);
-    uhp->uh_save_nr = 0;
-    curbuf->b_u_time_cur = uhp->uh_time + 1;
-
-    uhp->uh_walk = 0;
-    uhp->uh_entry = NULL;
-    uhp->uh_getbot_entry = NULL;
-    uhp->uh_cursor = curwin->w_cursor;          /* save cursor pos. for undo */
-    if (virtual_active() && curwin->w_cursor.coladd > 0)
-      uhp->uh_cursor_vcol = getviscol();
-    else
-      uhp->uh_cursor_vcol = -1;
-
-    /* save changed and buffer empty flag for undo */
-    uhp->uh_flags = (curbuf->b_changed ? UH_CHANGED : 0) +
-                    ((curbuf->b_ml.ml_flags & ML_EMPTY) ? UH_EMPTYBUF : 0);
-
-    /* save named marks and Visual marks for undo */
-    memmove(uhp->uh_namedm, curbuf->b_namedm, sizeof(pos_T) * NMARKS);
-    uhp->uh_visual = curbuf->b_visual;
-
-    curbuf->b_u_newhead = uhp;
-    if (curbuf->b_u_oldhead == NULL)
-      curbuf->b_u_oldhead = uhp;
-    ++curbuf->b_u_numhead;
-  } else {
-    if (get_undolevel() < 0)            /* no undo at all */
-      return OK;
-
-    /*
-     * When saving a single line, and it has been saved just before, it
-     * doesn't make sense saving it again.  Saves a lot of memory when
-     * making lots of changes inside the same line.
-     * This is only possible if the previous change didn't increase or
-     * decrease the number of lines.
-     * Check the ten last changes.  More doesn't make sense and takes too
-     * long.
-     */
-    if (size == 1) {
-      uep = u_get_headentry();
-      prev_uep = NULL;
-      for (i = 0; i < 10; ++i) {
-        if (uep == NULL)
-          break;
-
-        /* If lines have been inserted/deleted we give up.
-         * Also when the line was included in a multi-line save. */
-        if ((curbuf->b_u_newhead->uh_getbot_entry != uep
-             ? (uep->ue_top + uep->ue_size + 1
-                != (uep->ue_bot == 0
-                    ? curbuf->b_ml.ml_line_count + 1
-                    : uep->ue_bot))
-             : uep->ue_lcount != curbuf->b_ml.ml_line_count)
-            || (uep->ue_size > 1
-                && top >= uep->ue_top
-                && top + 2 <= uep->ue_top + uep->ue_size + 1))
-          break;
-
-        /* If it's the same line we can skip saving it again. */
-        if (uep->ue_size == 1 && uep->ue_top == top) {
-          if (i > 0) {
-            /* It's not the last entry: get ue_bot for the last
-             * entry now.  Following deleted/inserted lines go to
-             * the re-used entry. */
-            u_getbot();
-            curbuf->b_u_synced = FALSE;
-
-            /* Move the found entry to become the last entry.  The
-             * order of undo/redo doesn't matter for the entries
-             * we move it over, since they don't change the line
-             * count and don't include this line.  It does matter
-             * for the found entry if the line count is changed by
-             * the executed command. */
-            prev_uep->ue_next = uep->ue_next;
-            uep->ue_next = curbuf->b_u_newhead->uh_entry;
-            curbuf->b_u_newhead->uh_entry = uep;
-          }
-
-          /* The executed command may change the line count. */
-          if (newbot != 0)
-            uep->ue_bot = newbot;
-          else if (bot > curbuf->b_ml.ml_line_count)
-            uep->ue_bot = 0;
-          else {
-            uep->ue_lcount = curbuf->b_ml.ml_line_count;
-            curbuf->b_u_newhead->uh_getbot_entry = uep;
-          }
-          return OK;
-        }
-        prev_uep = uep;
-        uep = uep->ue_next;
-      }
-    }
-
-    /* find line number for ue_bot for previous u_save() */
-    u_getbot();
-  }
-
-  /*
-   * add lines in front of entry list
-   */
-  uep = xmalloc(sizeof(u_entry_T));
-  memset(uep, 0, sizeof(u_entry_T));
-#ifdef U_DEBUG
-  uep->ue_magic = UE_MAGIC;
-#endif
-
-  uep->ue_size = size;
-  uep->ue_top = top;
-  if (newbot != 0)
-    uep->ue_bot = newbot;
-  /*
-   * Use 0 for ue_bot if bot is below last line.
-   * Otherwise we have to compute ue_bot later.
-   */
-  else if (bot > curbuf->b_ml.ml_line_count)
-    uep->ue_bot = 0;
-  else {
-    uep->ue_lcount = curbuf->b_ml.ml_line_count;
-    curbuf->b_u_newhead->uh_getbot_entry = uep;
-  }
-
-  if (size > 0) {
-    uep->ue_array = xmalloc(sizeof(char_u *) * size);
-    for (i = 0, lnum = top + 1; i < size; ++i) {
-      fast_breakcheck();
-      if (got_int) {
-        u_freeentry(uep, i);
-        return FAIL;
-      }
-      if ((uep->ue_array[i] = u_save_line(lnum++)) == NULL) {
-        u_freeentry(uep, i);
-        goto nomem;
-      }
-    }
-  } else
-    uep->ue_array = NULL;
-  uep->ue_next = curbuf->b_u_newhead->uh_entry;
-  curbuf->b_u_newhead->uh_entry = uep;
-  curbuf->b_u_synced = FALSE;
-  undo_undoes = FALSE;
-
-#ifdef U_DEBUG
-  u_check(FALSE);
-#endif
-  return OK;
-
-nomem:
-  msg_silent = 0;       /* must display the prompt */
-  if (ask_yesno((char_u *)_("No undo possible; continue anyway"), TRUE)
-      == 'y') {
-    undo_off = TRUE;                /* will be reset when character typed */
-    return OK;
-  }
-  do_outofmem_msg((long_u)0);
-  return FAIL;
-}
-
-
-# define UF_START_MAGIC     "Vim\237UnDo\345"  /* magic at start of undofile */
-# define UF_START_MAGIC_LEN     9
-# define UF_HEADER_MAGIC        0x5fd0  /* magic at start of header */
-# define UF_HEADER_END_MAGIC    0xe7aa  /* magic after last header */
-# define UF_ENTRY_MAGIC         0xf518  /* magic at start of entry */
-# define UF_ENTRY_END_MAGIC     0x3581  /* magic after last entry */
-# define UF_VERSION             2       /* 2-byte undofile version number */
-# define UF_VERSION_CRYPT       0x8002  /* idem, encrypted */
-
-/* extra fields for header */
-# define UF_LAST_SAVE_NR        1
-
-/* extra fields for uhp */
-# define UHP_SAVE_NR            1
-
-static char_u e_not_open[] = N_("E828: Cannot open undo file for writing: %s");
-
-/*
- * Compute the hash for the current buffer text into hash[UNDO_HASH_SIZE].
- */
-void u_compute_hash(char_u *hash)
-{
-  context_sha256_T ctx;
-  linenr_T lnum;
-  char_u              *p;
-
-  sha256_start(&ctx);
-  for (lnum = 1; lnum <= curbuf->b_ml.ml_line_count; ++lnum) {
-    p = ml_get(lnum);
-    sha256_update(&ctx, p, (uint32_t)(STRLEN(p) + 1));
-  }
-  sha256_finish(&ctx, hash);
-}
-
-/*
- * Return an allocated string of the full path of the target undofile.
- * When "reading" is TRUE find the file to read, go over all directories in
- * 'undodir'.
- * When "reading" is FALSE use the first name where the directory exists.
- * Returns NULL when there is no place to write or no file to read.
- */
-char_u *u_get_undo_file_name(char_u *buf_ffname, int reading)
-{
-  char_u      *dirp;
-  char_u dir_name[IOSIZE + 1];
-  char_u      *munged_name = NULL;
-  char_u      *undo_file_name = NULL;
-  int dir_len;
-  char_u      *p;
-  char_u      *ffname = buf_ffname;
-#ifdef HAVE_READLINK
-  char_u fname_buf[MAXPATHL];
-#endif
-
-  if (ffname == NULL)
-    return NULL;
-
-#ifdef HAVE_READLINK
-  /* Expand symlink in the file name, so that we put the undo file with the
-   * actual file instead of with the symlink. */
-  if (resolve_symlink(ffname, fname_buf) == OK)
-    ffname = fname_buf;
-#endif
-
-  /* Loop over 'undodir'.  When reading find the first file that exists.
-   * When not reading use the first directory that exists or ".". */
-  dirp = p_udir;
-  while (*dirp != NUL) {
-    dir_len = copy_option_part(&dirp, dir_name, IOSIZE, ",");
-    if (dir_len == 1 && dir_name[0] == '.') {
-      /* Use same directory as the ffname,
-       * "dir/name" -> "dir/.name.un~" */
-      undo_file_name = vim_strnsave(ffname, (int)(STRLEN(ffname) + 5));
-      if (undo_file_name == NULL)
-        break;
-      p = path_tail(undo_file_name);
-      memmove(p + 1, p, STRLEN(p) + 1);
-      *p = '.';
-      STRCAT(p, ".un~");
-    } else {
-      dir_name[dir_len] = NUL;
-      if (os_isdir(dir_name)) {
-        if (munged_name == NULL) {
-          munged_name = vim_strsave(ffname);
-          if (munged_name == NULL)
-            return NULL;
-          for (p = munged_name; *p != NUL; mb_ptr_adv(p))
-            if (vim_ispathsep(*p))
-              *p = '%';
-        }
-        undo_file_name = concat_fnames(dir_name, munged_name, TRUE);
-      }
-    }
-
-    // When reading check if the file exists.
-    if (undo_file_name != NULL &&
-        (!reading || os_file_exists(undo_file_name))) {
-      break;
-    }
-    free(undo_file_name);
-    undo_file_name = NULL;
-  }
-
-  free(munged_name);
-  return undo_file_name;
-}
-
-static void corruption_error(char *mesg, char_u *file_name)
-{
-  EMSG3(_("E825: Corrupted undo file (%s): %s"), mesg, file_name);
-}
-
-static void u_free_uhp(u_header_T *uhp)
-{
-  u_entry_T   *nuep;
-  u_entry_T   *uep;
-
-  uep = uhp->uh_entry;
-  while (uep != NULL) {
-    nuep = uep->ue_next;
-    u_freeentry(uep, uep->ue_size);
-    uep = nuep;
-  }
-  free(uhp);
-}
-
-/*
- * Like fwrite() but crypt the bytes when 'key' is set.
- * Returns 1 if successful.
- */
-static size_t fwrite_crypt(buf_T *buf, char_u *ptr, size_t len, FILE *fp)
-{
-  char_u  *copy;
-  char_u small_buf[100];
-  size_t i;
-
-  if (*buf->b_p_key == NUL)
-    return fwrite(ptr, len, (size_t)1, fp);
-  if (len < 100)
-    copy = small_buf;      /* no malloc()/free() for short strings */
-  else {
-    copy = xmalloc(len);
-  }
-  crypt_encode(ptr, len, copy);
-  i = fwrite(copy, len, (size_t)1, fp);
-  if (copy != small_buf)
-    free(copy);
-  return i;
-}
-
-/*
- * Read a string of length "len" from "fd".
- * When 'key' is set decrypt the bytes.
- */
-static char_u *read_string_decrypt(buf_T *buf, FILE *fd, int len)
-{
-  char_u  *ptr;
-
-  ptr = read_string(fd, len);
-  if (ptr != NULL && *buf->b_p_key != NUL)
-    crypt_decode(ptr, len);
-  return ptr;
-}
-
-static int serialize_header(FILE *fp, buf_T *buf, char_u *hash)
-{
-  int len;
-
-  /* Start writing, first the magic marker and undo info version. */
-  if (fwrite(UF_START_MAGIC, (size_t)UF_START_MAGIC_LEN, (size_t)1, fp) != 1)
-    return FAIL;
-
-  /* If the buffer is encrypted then all text bytes following will be
-   * encrypted.  Numbers and other info is not crypted. */
-  if (*buf->b_p_key != NUL) {
-    char_u *header;
-    int header_len;
-
-    put_bytes(fp, (long_u)UF_VERSION_CRYPT, 2);
-    header = prepare_crypt_write(buf, &header_len);
-    if (header == NULL)
-      return FAIL;
-    len = (int)fwrite(header, (size_t)header_len, (size_t)1, fp);
-    free(header);
-    if (len != 1) {
-      crypt_pop_state();
-      return FAIL;
-    }
-  } else
-    put_bytes(fp, (long_u)UF_VERSION, 2);
-
-
-  /* Write a hash of the buffer text, so that we can verify it is still the
-   * same when reading the buffer text. */
-  if (fwrite(hash, (size_t)UNDO_HASH_SIZE, (size_t)1, fp) != 1)
-    return FAIL;
-
-  /* buffer-specific data */
-  put_bytes(fp, (long_u)buf->b_ml.ml_line_count, 4);
-  len = buf->b_u_line_ptr != NULL ? (int)STRLEN(buf->b_u_line_ptr) : 0;
-  put_bytes(fp, (long_u)len, 4);
-  if (len > 0 && fwrite_crypt(buf, buf->b_u_line_ptr, (size_t)len, fp) != 1)
-    return FAIL;
-  put_bytes(fp, (long_u)buf->b_u_line_lnum, 4);
-  put_bytes(fp, (long_u)buf->b_u_line_colnr, 4);
-
-  /* Undo structures header data */
-  put_header_ptr(fp, buf->b_u_oldhead);
-  put_header_ptr(fp, buf->b_u_newhead);
-  put_header_ptr(fp, buf->b_u_curhead);
-
-  put_bytes(fp, (long_u)buf->b_u_numhead, 4);
-  put_bytes(fp, (long_u)buf->b_u_seq_last, 4);
-  put_bytes(fp, (long_u)buf->b_u_seq_cur, 4);
-  put_time(fp, buf->b_u_time_cur);
-
-  /* Optional fields. */
-  putc(4, fp);
-  putc(UF_LAST_SAVE_NR, fp);
-  put_bytes(fp, (long_u)buf->b_u_save_nr_last, 4);
-
-  putc(0, fp);    /* end marker */
-
-  return OK;
-}
-
-static int serialize_uhp(FILE *fp, buf_T *buf, u_header_T *uhp)
-{
-  int i;
-  u_entry_T   *uep;
-
-  if (put_bytes(fp, (long_u)UF_HEADER_MAGIC, 2) == FAIL)
-    return FAIL;
-
-  put_header_ptr(fp, uhp->uh_next.ptr);
-  put_header_ptr(fp, uhp->uh_prev.ptr);
-  put_header_ptr(fp, uhp->uh_alt_next.ptr);
-  put_header_ptr(fp, uhp->uh_alt_prev.ptr);
-  put_bytes(fp, uhp->uh_seq, 4);
-  serialize_pos(uhp->uh_cursor, fp);
-  put_bytes(fp, (long_u)uhp->uh_cursor_vcol, 4);
-  put_bytes(fp, (long_u)uhp->uh_flags, 2);
-  /* Assume NMARKS will stay the same. */
-  for (i = 0; i < NMARKS; ++i)
-    serialize_pos(uhp->uh_namedm[i], fp);
-  serialize_visualinfo(&uhp->uh_visual, fp);
-  put_time(fp, uhp->uh_time);
-
-  /* Optional fields. */
-  putc(4, fp);
-  putc(UHP_SAVE_NR, fp);
-  put_bytes(fp, (long_u)uhp->uh_save_nr, 4);
-
-  putc(0, fp);    /* end marker */
-
-  /* Write all the entries. */
-  for (uep = uhp->uh_entry; uep != NULL; uep = uep->ue_next) {
-    put_bytes(fp, (long_u)UF_ENTRY_MAGIC, 2);
-    if (serialize_uep(fp, buf, uep) == FAIL)
-      return FAIL;
-  }
-  put_bytes(fp, (long_u)UF_ENTRY_END_MAGIC, 2);
-  return OK;
-}
-
-static u_header_T *unserialize_uhp(FILE *fp, char_u *file_name)
-{
-  u_header_T  *uhp;
-  int i;
-  u_entry_T   *uep, *last_uep;
-  int c;
-  int error;
-
-  uhp = xmalloc(sizeof(u_header_T));
-  memset(uhp, 0, sizeof(u_header_T));
-#ifdef U_DEBUG
-  uhp->uh_magic = UH_MAGIC;
-#endif
-  uhp->uh_next.seq = get4c(fp);
-  uhp->uh_prev.seq = get4c(fp);
-  uhp->uh_alt_next.seq = get4c(fp);
-  uhp->uh_alt_prev.seq = get4c(fp);
-  uhp->uh_seq = get4c(fp);
-  if (uhp->uh_seq <= 0) {
-    corruption_error("uh_seq", file_name);
-    free(uhp);
-    return NULL;
-  }
-  unserialize_pos(&uhp->uh_cursor, fp);
-  uhp->uh_cursor_vcol = get4c(fp);
-  uhp->uh_flags = get2c(fp);
-  for (i = 0; i < NMARKS; ++i)
-    unserialize_pos(&uhp->uh_namedm[i], fp);
-  unserialize_visualinfo(&uhp->uh_visual, fp);
-  uhp->uh_time = get8ctime(fp);
-
-  /* Optional fields. */
-  for (;; ) {
-    int len = getc(fp);
-    int what;
-
-    if (len == 0)
-      break;
-    what = getc(fp);
-    switch (what) {
-    case UHP_SAVE_NR:
-      uhp->uh_save_nr = get4c(fp);
-      break;
-    default:
-      /* field not supported, skip */
-      while (--len >= 0)
-        (void)getc(fp);
-    }
-  }
-
-  /* Unserialize the uep list. */
-  last_uep = NULL;
-  while ((c = get2c(fp)) == UF_ENTRY_MAGIC) {
-    error = FALSE;
-    uep = unserialize_uep(fp, &error, file_name);
-    if (last_uep == NULL)
-      uhp->uh_entry = uep;
-    else
-      last_uep->ue_next = uep;
-    last_uep = uep;
-    if (uep == NULL || error) {
-      u_free_uhp(uhp);
-      return NULL;
-    }
-  }
-  if (c != UF_ENTRY_END_MAGIC) {
-    corruption_error("entry end", file_name);
-    u_free_uhp(uhp);
-    return NULL;
-  }
-
-  return uhp;
-}
-
-/*
- * Serialize "uep" to "fp".
- */
-static int serialize_uep(FILE *fp, buf_T *buf, u_entry_T *uep)
-{
-  int i;
-  size_t len;
-
-  put_bytes(fp, (long_u)uep->ue_top, 4);
-  put_bytes(fp, (long_u)uep->ue_bot, 4);
-  put_bytes(fp, (long_u)uep->ue_lcount, 4);
-  put_bytes(fp, (long_u)uep->ue_size, 4);
-  for (i = 0; i < uep->ue_size; ++i) {
-    len = STRLEN(uep->ue_array[i]);
-    if (put_bytes(fp, (long_u)len, 4) == FAIL)
-      return FAIL;
-    if (len > 0 && fwrite_crypt(buf, uep->ue_array[i], len, fp) != 1)
-      return FAIL;
-  }
-  return OK;
-}
-
-static u_entry_T *unserialize_uep(FILE *fp, int *error, char_u *file_name)
-{
-  int i;
-  u_entry_T   *uep;
-  char_u      **array;
-  char_u      *line;
-  int line_len;
-
-  uep = xmalloc(sizeof(u_entry_T));
-  memset(uep, 0, sizeof(u_entry_T));
-#ifdef U_DEBUG
-  uep->ue_magic = UE_MAGIC;
-#endif
-  uep->ue_top = get4c(fp);
-  uep->ue_bot = get4c(fp);
-  uep->ue_lcount = get4c(fp);
-  uep->ue_size = get4c(fp);
-  if (uep->ue_size > 0) {
-    array = xmalloc(sizeof(char_u *) * uep->ue_size);
-    memset(array, 0, sizeof(char_u *) * uep->ue_size);
-  } else
-    array = NULL;
-  uep->ue_array = array;
-
-  for (i = 0; i < uep->ue_size; ++i) {
-    line_len = get4c(fp);
-    if (line_len >= 0)
-      line = read_string_decrypt(curbuf, fp, line_len);
-    else {
-      line = NULL;
-      corruption_error("line length", file_name);
-    }
-    if (line == NULL) {
-      *error = TRUE;
-      return uep;
-    }
-    array[i] = line;
-  }
-  return uep;
-}
-
-/*
- * Serialize "pos" to "fp".
- */
-static void serialize_pos(pos_T pos, FILE *fp)
-{
-  put_bytes(fp, (long_u)pos.lnum, 4);
-  put_bytes(fp, (long_u)pos.col, 4);
-  put_bytes(fp, (long_u)pos.coladd, 4);
-}
-
-/*
- * Unserialize the pos_T at the current position in fp.
- */
-static void unserialize_pos(pos_T *pos, FILE *fp)
-{
-  pos->lnum = get4c(fp);
-  if (pos->lnum < 0)
-    pos->lnum = 0;
-  pos->col = get4c(fp);
-  if (pos->col < 0)
-    pos->col = 0;
-  pos->coladd = get4c(fp);
-  if (pos->coladd < 0)
-    pos->coladd = 0;
-}
-
-/*
- * Serialize "info" to "fp".
- */
-static void serialize_visualinfo(visualinfo_T *info, FILE *fp)
-{
-  serialize_pos(info->vi_start, fp);
-  serialize_pos(info->vi_end, fp);
-  put_bytes(fp, (long_u)info->vi_mode, 4);
-  put_bytes(fp, (long_u)info->vi_curswant, 4);
-}
-
-/*
- * Unserialize the visualinfo_T at the current position in fp.
- */
-static void unserialize_visualinfo(visualinfo_T *info, FILE *fp)
-{
-  unserialize_pos(&info->vi_start, fp);
-  unserialize_pos(&info->vi_end, fp);
-  info->vi_mode = get4c(fp);
-  info->vi_curswant = get4c(fp);
-}
-
-/*
- * Write the pointer to an undo header.  Instead of writing the pointer itself
- * we use the sequence number of the header.  This is converted back to
- * pointers when reading. */
-static void put_header_ptr(FILE *fp, u_header_T *uhp)
-{
-  put_bytes(fp, (long_u)(uhp != NULL ? uhp->uh_seq : 0), 4);
-}
-
-/*
- * Write the undo tree in an undo file.
- * When "name" is not NULL, use it as the name of the undo file.
- * Otherwise use buf->b_ffname to generate the undo file name.
- * "buf" must never be null, buf->b_ffname is used to obtain the original file
- * permissions.
- * "forceit" is TRUE for ":wundo!", FALSE otherwise.
- * "hash[UNDO_HASH_SIZE]" must be the hash value of the buffer text.
- */
-void u_write_undo(char_u *name, int forceit, buf_T *buf, char_u *hash)
-{
-  u_header_T  *uhp;
-  char_u      *file_name;
-  int mark;
-#ifdef U_DEBUG
-  int headers_written = 0;
-#endif
-  int fd;
-  FILE        *fp = NULL;
-  int perm;
-  int write_ok = FALSE;
-  int do_crypt = FALSE;
-
-  if (name == NULL) {
-    file_name = u_get_undo_file_name(buf->b_ffname, FALSE);
-    if (file_name == NULL) {
-      if (p_verbose > 0) {
-        verbose_enter();
-        smsg((char_u *)
-            _("Cannot write undo file in any directory in 'undodir'"));
-        verbose_leave();
-      }
-      return;
-    }
-  } else
-    file_name = name;
-
-  /*
-   * Decide about the permission to use for the undo file.  If the buffer
-   * has a name use the permission of the original file.  Otherwise only
-   * allow the user to access the undo file.
-   */
-  perm = 0600;
-  if (buf->b_ffname != NULL) {
-    perm = os_getperm(buf->b_ffname);
-    if (perm < 0) {
-      perm = 0600;
-    }
-  }
-
-  /* strip any s-bit */
-  perm = perm & 0777;
-
-  /* If the undo file already exists, verify that it actually is an undo
-   * file, and delete it. */
-  if (os_file_exists(file_name)) {
-    if (name == NULL || !forceit) {
-      /* Check we can read it and it's an undo file. */
-      fd = mch_open((char *)file_name, O_RDONLY, 0);
-      if (fd < 0) {
-        if (name != NULL || p_verbose > 0) {
-          if (name == NULL)
-            verbose_enter();
-          smsg((char_u *)
-              _("Will not overwrite with undo file, cannot read: %s"),
-              file_name);
-          if (name == NULL)
-            verbose_leave();
-        }
-        goto theend;
-      } else {
-        char_u mbuf[UF_START_MAGIC_LEN];
-        int len;
-
-        len = read_eintr(fd, mbuf, UF_START_MAGIC_LEN);
-        close(fd);
-        if (len < UF_START_MAGIC_LEN
-            || memcmp(mbuf, UF_START_MAGIC, UF_START_MAGIC_LEN) != 0) {
-          if (name != NULL || p_verbose > 0) {
-            if (name == NULL)
-              verbose_enter();
-            smsg((char_u *)
-                _("Will not overwrite, this is not an undo file: %s"),
-                file_name);
-            if (name == NULL)
-              verbose_leave();
-          }
-          goto theend;
-        }
-      }
-    }
-    os_remove((char *)file_name);
-  }
-
-  /* If there is no undo information at all, quit here after deleting any
-   * existing undo file. */
-  if (buf->b_u_numhead == 0 && buf->b_u_line_ptr == NULL) {
-    if (p_verbose > 0)
-      verb_msg((char_u *)_("Skipping undo file write, nothing to undo"));
-    goto theend;
-  }
-
-  fd = mch_open((char *)file_name,
-      O_CREAT|O_WRONLY|O_EXCL|O_NOFOLLOW, perm);
-  if (fd < 0) {
-    EMSG2(_(e_not_open), file_name);
-    goto theend;
-  }
-  (void)os_setperm(file_name, perm);
-  if (p_verbose > 0) {
-    verbose_enter();
-    smsg((char_u *)_("Writing undo file: %s"), file_name);
-    verbose_leave();
-  }
-
-#ifdef U_DEBUG
-  /* Check there is no problem in undo info before writing. */
-  u_check(FALSE);
-#endif
-
-#ifdef UNIX
-  /*
-   * Try to set the group of the undo file same as the original file. If
-   * this fails, set the protection bits for the group same as the
-   * protection bits for others.
-   */
-  FileInfo file_info_old;
-  FileInfo file_info_new;
-  if (os_get_file_info((char *)buf->b_ffname, &file_info_old)
-      && os_get_file_info((char *)file_name, &file_info_new)
-      && file_info_old.stat.st_gid != file_info_new.stat.st_gid
-# ifdef HAVE_FCHOWN  /* sequent-ptx lacks fchown() */
-      && fchown(fd, (uid_t)-1, file_info_old.stat.st_gid) != 0
-# endif
-      ) {
-    os_setperm(file_name, (perm & 0707) | ((perm & 07) << 3));
-  }
-# ifdef HAVE_SELINUX
-  if (buf->b_ffname != NULL)
-    mch_copy_sec(buf->b_ffname, file_name);
-# endif
-#endif
-
-  fp = fdopen(fd, "w");
-  if (fp == NULL) {
-    EMSG2(_(e_not_open), file_name);
-    close(fd);
-    os_remove((char *)file_name);
-    goto theend;
-  }
-
-  /* Undo must be synced. */
-  u_sync(TRUE);
-
-  /*
-   * Write the header.
-   */
-  if (serialize_header(fp, buf, hash) == FAIL)
-    goto write_error;
-  if (*buf->b_p_key != NUL)
-    do_crypt = TRUE;
-
-  /*
-   * Iteratively serialize UHPs and their UEPs from the top down.
-   */
-  mark = ++lastmark;
-  uhp = buf->b_u_oldhead;
-  while (uhp != NULL) {
-    /* Serialize current UHP if we haven't seen it */
-    if (uhp->uh_walk != mark) {
-      uhp->uh_walk = mark;
-#ifdef U_DEBUG
-      ++headers_written;
-#endif
-      if (serialize_uhp(fp, buf, uhp) == FAIL)
-        goto write_error;
-    }
-
-    /* Now walk through the tree - algorithm from undo_time(). */
-    if (uhp->uh_prev.ptr != NULL && uhp->uh_prev.ptr->uh_walk != mark)
-      uhp = uhp->uh_prev.ptr;
-    else if (uhp->uh_alt_next.ptr != NULL
-             && uhp->uh_alt_next.ptr->uh_walk != mark)
-      uhp = uhp->uh_alt_next.ptr;
-    else if (uhp->uh_next.ptr != NULL && uhp->uh_alt_prev.ptr == NULL
-             && uhp->uh_next.ptr->uh_walk != mark)
-      uhp = uhp->uh_next.ptr;
-    else if (uhp->uh_alt_prev.ptr != NULL)
-      uhp = uhp->uh_alt_prev.ptr;
-    else
-      uhp = uhp->uh_next.ptr;
-  }
-
-  if (put_bytes(fp, (long_u)UF_HEADER_END_MAGIC, 2) == OK)
-    write_ok = TRUE;
-#ifdef U_DEBUG
-  if (headers_written != buf->b_u_numhead) {
-    EMSGN("Written %" PRId64 " headers, ...", headers_written);
-    EMSGN("... but numhead is %" PRId64, buf->b_u_numhead);
-  }
-#endif
-
-write_error:
-  fclose(fp);
-  if (!write_ok)
-    EMSG2(_("E829: write error in undo file: %s"), file_name);
-
-#ifdef HAVE_ACL
-  if (buf->b_ffname != NULL) {
-    vim_acl_T acl;
-
-    /* For systems that support ACL: get the ACL from the original file. */
-    acl = mch_get_acl(buf->b_ffname);
-    mch_set_acl(file_name, acl);
-    mch_free_acl(acl);
-  }
-#endif
-
-theend:
-  if (do_crypt)
-    crypt_pop_state();
-  if (file_name != name)
-    free(file_name);
-}
-
-/*
- * Load the undo tree from an undo file.
- * If "name" is not NULL use it as the undo file name.  This also means being
- * a bit more verbose.
- * Otherwise use curbuf->b_ffname to generate the undo file name.
- * "hash[UNDO_HASH_SIZE]" must be the hash value of the buffer text.
- */
-void u_read_undo(char_u *name, char_u *hash, char_u *orig_name)
-{
-  char_u      *file_name;
-  FILE        *fp;
-  long version, str_len;
-  char_u      *line_ptr = NULL;
-  linenr_T line_lnum;
-  colnr_T line_colnr;
-  linenr_T line_count;
-  int num_head = 0;
-  long old_header_seq, new_header_seq, cur_header_seq;
-  long seq_last, seq_cur;
-  long last_save_nr = 0;
-  short old_idx = -1, new_idx = -1, cur_idx = -1;
-  long num_read_uhps = 0;
-  time_t seq_time;
-  int i, j;
-  int c;
-  u_header_T  *uhp;
-  u_header_T  **uhp_table = NULL;
-  char_u read_hash[UNDO_HASH_SIZE];
-  char_u magic_buf[UF_START_MAGIC_LEN];
-#ifdef U_DEBUG
-  int         *uhp_table_used;
-#endif
-  int do_decrypt = FALSE;
-
-  if (name == NULL) {
-    file_name = u_get_undo_file_name(curbuf->b_ffname, TRUE);
-    if (file_name == NULL)
-      return;
-
-#ifdef UNIX
-    /* For safety we only read an undo file if the owner is equal to the
-     * owner of the text file or equal to the current user. */
-    FileInfo file_info_orig;
-    FileInfo file_info_undo;
-    if (os_get_file_info((char *)orig_name, &file_info_orig)
-        && os_get_file_info((char *)file_name, &file_info_undo)
-        && file_info_orig.stat.st_uid != file_info_undo.stat.st_uid
-        && file_info_undo.stat.st_uid != getuid()) {
-      if (p_verbose > 0) {
-        verbose_enter();
-        smsg((char_u *)_("Not reading undo file, owner differs: %s"),
-            file_name);
-        verbose_leave();
-      }
-      return;
-    }
-#endif
-  } else
-    file_name = name;
-
-  if (p_verbose > 0) {
-    verbose_enter();
-    smsg((char_u *)_("Reading undo file: %s"), file_name);
-    verbose_leave();
-  }
-
-  fp = mch_fopen((char *)file_name, "r");
-  if (fp == NULL) {
-    if (name != NULL || p_verbose > 0)
-      EMSG2(_("E822: Cannot open undo file for reading: %s"), file_name);
-    goto error;
-  }
-
-  /*
-   * Read the undo file header.
-   */
-  if (fread(magic_buf, UF_START_MAGIC_LEN, 1, fp) != 1
-      || memcmp(magic_buf, UF_START_MAGIC, UF_START_MAGIC_LEN) != 0) {
-    EMSG2(_("E823: Not an undo file: %s"), file_name);
-    goto error;
-  }
-  version = get2c(fp);
-  if (version == UF_VERSION_CRYPT) {
-    if (*curbuf->b_p_key == NUL) {
-      EMSG2(_("E832: Non-encrypted file has encrypted undo file: %s"),
-          file_name);
-      goto error;
-    }
-    if (prepare_crypt_read(fp) == FAIL) {
-      EMSG2(_("E826: Undo file decryption failed: %s"), file_name);
-      goto error;
-    }
-    do_decrypt = TRUE;
-  } else if (version != UF_VERSION)   {
-    EMSG2(_("E824: Incompatible undo file: %s"), file_name);
-    goto error;
-  }
-
-  if (fread(read_hash, UNDO_HASH_SIZE, 1, fp) != 1) {
-    corruption_error("hash", file_name);
-    goto error;
-  }
-  line_count = (linenr_T)get4c(fp);
-  if (memcmp(hash, read_hash, UNDO_HASH_SIZE) != 0
-      || line_count != curbuf->b_ml.ml_line_count) {
-    if (p_verbose > 0 || name != NULL) {
-      if (name == NULL)
-        verbose_enter();
-      give_warning((char_u *)
-          _("File contents changed, cannot use undo info"), TRUE);
-      if (name == NULL)
-        verbose_leave();
-    }
-    goto error;
-  }
-
-  /* Read undo data for "U" command. */
-  str_len = get4c(fp);
-  if (str_len < 0)
-    goto error;
-  if (str_len > 0)
-    line_ptr = read_string_decrypt(curbuf, fp, str_len);
-  line_lnum = (linenr_T)get4c(fp);
-  line_colnr = (colnr_T)get4c(fp);
-  if (line_lnum < 0 || line_colnr < 0) {
-    corruption_error("line lnum/col", file_name);
-    goto error;
-  }
-
-  /* Begin general undo data */
-  old_header_seq = get4c(fp);
-  new_header_seq = get4c(fp);
-  cur_header_seq = get4c(fp);
-  num_head = get4c(fp);
-  seq_last = get4c(fp);
-  seq_cur = get4c(fp);
-  seq_time = get8ctime(fp);
-
-  /* Optional header fields. */
-  for (;; ) {
-    int len = getc(fp);
-    int what;
-
-    if (len == 0 || len == EOF)
-      break;
-    what = getc(fp);
-    switch (what) {
-    case UF_LAST_SAVE_NR:
-      last_save_nr = get4c(fp);
-      break;
-    default:
-      /* field not supported, skip */
-      while (--len >= 0)
-        (void)getc(fp);
-    }
-  }
-
-  /* uhp_table will store the freshly created undo headers we allocate
-   * until we insert them into curbuf. The table remains sorted by the
-   * sequence numbers of the headers.
-   * When there are no headers uhp_table is NULL. */
-  if (num_head > 0) {
-    uhp_table = xmalloc(num_head * sizeof(u_header_T *));
-  }
-
-  while ((c = get2c(fp)) == UF_HEADER_MAGIC) {
-    if (num_read_uhps >= num_head) {
-      corruption_error("num_head too small", file_name);
-      goto error;
-    }
-
-    uhp = unserialize_uhp(fp, file_name);
-    if (uhp == NULL)
-      goto error;
-    uhp_table[num_read_uhps++] = uhp;
-  }
-
-  if (num_read_uhps != num_head) {
-    corruption_error("num_head", file_name);
-    goto error;
-  }
-  if (c != UF_HEADER_END_MAGIC) {
-    corruption_error("end marker", file_name);
-    goto error;
-  }
-
-#ifdef U_DEBUG
-  size_t amount = num_head * sizeof(int) + 1;
-  uhp_table_used = xmalloc(amount);
-  memset(uhp_table_used, 0, amount);
-# define SET_FLAG(j) ++ uhp_table_used[j]
-#else
-# define SET_FLAG(j)
-#endif
-
-  /* We have put all of the headers into a table. Now we iterate through the
-   * table and swizzle each sequence number we have stored in uh_*_seq into
-   * a pointer corresponding to the header with that sequence number. */
-  for (i = 0; i < num_head; i++) {
-    uhp = uhp_table[i];
-    if (uhp == NULL)
-      continue;
-    for (j = 0; j < num_head; j++)
-      if (uhp_table[j] != NULL && i != j
-          && uhp_table[i]->uh_seq == uhp_table[j]->uh_seq) {
-        corruption_error("duplicate uh_seq", file_name);
-        goto error;
-      }
-    for (j = 0; j < num_head; j++)
-      if (uhp_table[j] != NULL
-          && uhp_table[j]->uh_seq == uhp->uh_next.seq) {
-        uhp->uh_next.ptr = uhp_table[j];
-        SET_FLAG(j);
-        break;
-      }
-    for (j = 0; j < num_head; j++)
-      if (uhp_table[j] != NULL
-          && uhp_table[j]->uh_seq == uhp->uh_prev.seq) {
-        uhp->uh_prev.ptr = uhp_table[j];
-        SET_FLAG(j);
-        break;
-      }
-    for (j = 0; j < num_head; j++)
-      if (uhp_table[j] != NULL
-          && uhp_table[j]->uh_seq == uhp->uh_alt_next.seq) {
-        uhp->uh_alt_next.ptr = uhp_table[j];
-        SET_FLAG(j);
-        break;
-      }
-    for (j = 0; j < num_head; j++)
-      if (uhp_table[j] != NULL
-          && uhp_table[j]->uh_seq == uhp->uh_alt_prev.seq) {
-        uhp->uh_alt_prev.ptr = uhp_table[j];
-        SET_FLAG(j);
-        break;
-      }
-    if (old_header_seq > 0 && old_idx < 0 && uhp->uh_seq == old_header_seq) {
-      old_idx = i;
-      SET_FLAG(i);
-    }
-    if (new_header_seq > 0 && new_idx < 0 && uhp->uh_seq == new_header_seq) {
-      new_idx = i;
-      SET_FLAG(i);
-    }
-    if (cur_header_seq > 0 && cur_idx < 0 && uhp->uh_seq == cur_header_seq) {
-      cur_idx = i;
-      SET_FLAG(i);
-    }
-  }
-
-  /* Now that we have read the undo info successfully, free the current undo
-   * info and use the info from the file. */
-  u_blockfree(curbuf);
-  curbuf->b_u_oldhead = old_idx < 0 ? NULL : uhp_table[old_idx];
-  curbuf->b_u_newhead = new_idx < 0 ? NULL : uhp_table[new_idx];
-  curbuf->b_u_curhead = cur_idx < 0 ? NULL : uhp_table[cur_idx];
-  curbuf->b_u_line_ptr = line_ptr;
-  curbuf->b_u_line_lnum = line_lnum;
-  curbuf->b_u_line_colnr = line_colnr;
-  curbuf->b_u_numhead = num_head;
-  curbuf->b_u_seq_last = seq_last;
-  curbuf->b_u_seq_cur = seq_cur;
-  curbuf->b_u_time_cur = seq_time;
-  curbuf->b_u_save_nr_last = last_save_nr;
-  curbuf->b_u_save_nr_cur = last_save_nr;
-
-  curbuf->b_u_synced = TRUE;
-  free(uhp_table);
-
-#ifdef U_DEBUG
-  for (i = 0; i < num_head; ++i)
-    if (uhp_table_used[i] == 0)
-      EMSGN("uhp_table entry %" PRId64 " not used, leaking memory", i);
-  free(uhp_table_used);
-  u_check(TRUE);
-#endif
-
-  if (name != NULL)
-    smsg((char_u *)_("Finished reading undo file %s"), file_name);
-  goto theend;
-
-error:
-  free(line_ptr);
-  if (uhp_table != NULL) {
-    for (i = 0; i < num_read_uhps; i++)
-      if (uhp_table[i] != NULL)
-        u_free_uhp(uhp_table[i]);
-    free(uhp_table);
-  }
-
-theend:
-  if (do_decrypt)
-    crypt_pop_state();
-  if (fp != NULL)
-    fclose(fp);
-  if (file_name != name)
-    free(file_name);
-  return;
-}
-
-
-
-/*
- * If 'cpoptions' contains 'u': Undo the previous undo or redo (vi compatible).
- * If 'cpoptions' does not contain 'u': Always undo.
- */
-void u_undo(int count)
-{
-  /*
-   * If we get an undo command while executing a macro, we behave like the
-   * original vi. If this happens twice in one macro the result will not
-   * be compatible.
-   */
-  if (curbuf->b_u_synced == FALSE) {
-    u_sync(TRUE);
-    count = 1;
-  }
-
-  if (vim_strchr(p_cpo, CPO_UNDO) == NULL)
-    undo_undoes = TRUE;
-  else
-    undo_undoes = !undo_undoes;
-  u_doit(count);
-}
-
-/*
- * If 'cpoptions' contains 'u': Repeat the previous undo or redo.
- * If 'cpoptions' does not contain 'u': Always redo.
- */
-void u_redo(int count)
-{
-  if (vim_strchr(p_cpo, CPO_UNDO) == NULL)
-    undo_undoes = FALSE;
-  u_doit(count);
-}
-
-/*
- * Undo or redo, depending on 'undo_undoes', 'count' times.
- */
-static void u_doit(int startcount)
-{
-  int count = startcount;
-
-  if (!undo_allowed())
-    return;
-
-  u_newcount = 0;
-  u_oldcount = 0;
-  if (curbuf->b_ml.ml_flags & ML_EMPTY)
-    u_oldcount = -1;
-  while (count--) {
-    /* Do the change warning now, so that it triggers FileChangedRO when
-     * needed.  This may cause the file to be reloaded, that must happen
-     * before we do anything, because it may change curbuf->b_u_curhead
-     * and more. */
-    change_warning(0);
-
-    if (undo_undoes) {
-      if (curbuf->b_u_curhead == NULL)                  /* first undo */
-        curbuf->b_u_curhead = curbuf->b_u_newhead;
-      else if (get_undolevel() > 0)                     /* multi level undo */
-        /* get next undo */
-        curbuf->b_u_curhead = curbuf->b_u_curhead->uh_next.ptr;
-      /* nothing to undo */
-      if (curbuf->b_u_numhead == 0 || curbuf->b_u_curhead == NULL) {
-        /* stick curbuf->b_u_curhead at end */
-        curbuf->b_u_curhead = curbuf->b_u_oldhead;
-        beep_flush();
-        if (count == startcount - 1) {
-          MSG(_("Already at oldest change"));
-          return;
-        }
-        break;
-      }
-
-      u_undoredo(TRUE);
-    } else {
-      if (curbuf->b_u_curhead == NULL || get_undolevel() <= 0) {
-        beep_flush();           /* nothing to redo */
-        if (count == startcount - 1) {
-          MSG(_("Already at newest change"));
-          return;
-        }
-        break;
-      }
-
-      u_undoredo(FALSE);
-
-      /* Advance for next redo.  Set "newhead" when at the end of the
-       * redoable changes. */
-      if (curbuf->b_u_curhead->uh_prev.ptr == NULL)
-        curbuf->b_u_newhead = curbuf->b_u_curhead;
-      curbuf->b_u_curhead = curbuf->b_u_curhead->uh_prev.ptr;
-    }
-  }
-  u_undo_end(undo_undoes, FALSE);
-}
-
-/*
- * Undo or redo over the timeline.
- * When "step" is negative go back in time, otherwise goes forward in time.
- * When "sec" is FALSE make "step" steps, when "sec" is TRUE use "step" as
- * seconds.
- * When "file" is TRUE use "step" as a number of file writes.
- * When "absolute" is TRUE use "step" as the sequence number to jump to.
- * "sec" must be FALSE then.
- */
-void undo_time(long step, int sec, int file, int absolute)
-{
-  long target;
-  long closest;
-  long closest_start;
-  long closest_seq = 0;
-  long val;
-  u_header_T      *uhp;
-  u_header_T      *last;
-  int mark;
-  int nomark;
-  int round;
-  int dosec = sec;
-  int dofile = file;
-  int above = FALSE;
-  int did_undo = TRUE;
-
-  /* First make sure the current undoable change is synced. */
-  if (curbuf->b_u_synced == FALSE)
-    u_sync(TRUE);
-
-  u_newcount = 0;
-  u_oldcount = 0;
-  if (curbuf->b_ml.ml_flags & ML_EMPTY)
-    u_oldcount = -1;
-
-  /* "target" is the node below which we want to be.
-   * Init "closest" to a value we can't reach. */
-  if (absolute) {
-    target = step;
-    closest = -1;
-  } else {
-    /* When doing computations with time_t subtract starttime, because
-     * time_t converted to a long may result in a wrong number. */
-    if (dosec)
-      target = (long)(curbuf->b_u_time_cur - starttime) + step;
-    else if (dofile) {
-      if (step < 0) {
-        /* Going back to a previous write. If there were changes after
-         * the last write, count that as moving one file-write, so
-         * that ":earlier 1f" undoes all changes since the last save. */
-        uhp = curbuf->b_u_curhead;
-        if (uhp != NULL)
-          uhp = uhp->uh_next.ptr;
-        else
-          uhp = curbuf->b_u_newhead;
-        if (uhp != NULL && uhp->uh_save_nr != 0)
-          /* "uh_save_nr" was set in the last block, that means
-           * there were no changes since the last write */
-          target = curbuf->b_u_save_nr_cur + step;
-        else
-          /* count the changes since the last write as one step */
-          target = curbuf->b_u_save_nr_cur + step + 1;
-        if (target <= 0)
-          /* Go to before first write: before the oldest change. Use
-           * the sequence number for that. */
-          dofile = FALSE;
-      } else {
-        /* Moving forward to a newer write. */
-        target = curbuf->b_u_save_nr_cur + step;
-        if (target > curbuf->b_u_save_nr_last) {
-          /* Go to after last write: after the latest change. Use
-           * the sequence number for that. */
-          target = curbuf->b_u_seq_last + 1;
-          dofile = FALSE;
-        }
-      }
-    } else
-      target = curbuf->b_u_seq_cur + step;
-    if (step < 0) {
-      if (target < 0)
-        target = 0;
-      closest = -1;
-    } else {
-      if (dosec)
-        closest = (long)(time(NULL) - starttime + 1);
-      else if (dofile)
-        closest = curbuf->b_u_save_nr_last + 2;
-      else
-        closest = curbuf->b_u_seq_last + 2;
-      if (target >= closest)
-        target = closest - 1;
-    }
-  }
-  closest_start = closest;
-  closest_seq = curbuf->b_u_seq_cur;
-
-  /*
-   * May do this twice:
-   * 1. Search for "target", update "closest" to the best match found.
-   * 2. If "target" not found search for "closest".
-   *
-   * When using the closest time we use the sequence number in the second
-   * round, because there may be several entries with the same time.
-   */
-  for (round = 1; round <= 2; ++round) {
-    /* Find the path from the current state to where we want to go.  The
-     * desired state can be anywhere in the undo tree, need to go all over
-     * it.  We put "nomark" in uh_walk where we have been without success,
-     * "mark" where it could possibly be. */
-    mark = ++lastmark;
-    nomark = ++lastmark;
-
-    if (curbuf->b_u_curhead == NULL)            /* at leaf of the tree */
-      uhp = curbuf->b_u_newhead;
-    else
-      uhp = curbuf->b_u_curhead;
-
-    while (uhp != NULL) {
-      uhp->uh_walk = mark;
-      if (dosec)
-        val = (long)(uhp->uh_time - starttime);
-      else if (dofile)
-        val = uhp->uh_save_nr;
-      else
-        val = uhp->uh_seq;
-
-      if (round == 1 && !(dofile && val == 0)) {
-        /* Remember the header that is closest to the target.
-         * It must be at least in the right direction (checked with
-         * "b_u_seq_cur").  When the timestamp is equal find the
-         * highest/lowest sequence number. */
-        if ((step < 0 ? uhp->uh_seq <= curbuf->b_u_seq_cur
-             : uhp->uh_seq > curbuf->b_u_seq_cur)
-            && ((dosec && val == closest)
-                ? (step < 0
-                   ? uhp->uh_seq < closest_seq
-                                   : uhp->uh_seq > closest_seq)
-                : closest == closest_start
-                || (val > target
-                    ? (closest > target
-                       ? val - target <= closest - target
-                       : val - target <= target - closest)
-                    : (closest > target
-                       ? target - val <= closest - target
-                       : target - val <= target - closest)))) {
-          closest = val;
-          closest_seq = uhp->uh_seq;
-        }
-      }
-
-      /* Quit searching when we found a match.  But when searching for a
-       * time we need to continue looking for the best uh_seq. */
-      if (target == val && !dosec) {
-        target = uhp->uh_seq;
-        break;
-      }
-
-      /* go down in the tree if we haven't been there */
-      if (uhp->uh_prev.ptr != NULL && uhp->uh_prev.ptr->uh_walk != nomark
-          && uhp->uh_prev.ptr->uh_walk != mark)
-        uhp = uhp->uh_prev.ptr;
-
-      /* go to alternate branch if we haven't been there */
-      else if (uhp->uh_alt_next.ptr != NULL
-               && uhp->uh_alt_next.ptr->uh_walk != nomark
-               && uhp->uh_alt_next.ptr->uh_walk != mark)
-        uhp = uhp->uh_alt_next.ptr;
-
-      /* go up in the tree if we haven't been there and we are at the
-       * start of alternate branches */
-      else if (uhp->uh_next.ptr != NULL && uhp->uh_alt_prev.ptr == NULL
-               && uhp->uh_next.ptr->uh_walk != nomark
-               && uhp->uh_next.ptr->uh_walk != mark) {
-        /* If still at the start we don't go through this change. */
-        if (uhp == curbuf->b_u_curhead)
-          uhp->uh_walk = nomark;
-        uhp = uhp->uh_next.ptr;
-      } else {
-        /* need to backtrack; mark this node as useless */
-        uhp->uh_walk = nomark;
-        if (uhp->uh_alt_prev.ptr != NULL)
-          uhp = uhp->uh_alt_prev.ptr;
-        else
-          uhp = uhp->uh_next.ptr;
-      }
-    }
-
-    if (uhp != NULL)        /* found it */
-      break;
-
-    if (absolute) {
-      EMSGN(_("E830: Undo number %" PRId64 " not found"), step);
-      return;
-    }
-
-    if (closest == closest_start) {
-      if (step < 0)
-        MSG(_("Already at oldest change"));
-      else
-        MSG(_("Already at newest change"));
-      return;
-    }
-
-    target = closest_seq;
-    dosec = FALSE;
-    dofile = FALSE;
-    if (step < 0)
-      above = TRUE;             /* stop above the header */
-  }
-
-  /* If we found it: Follow the path to go to where we want to be. */
-  if (uhp != NULL) {
-    /*
-     * First go up the tree as much as needed.
-     */
-    while (!got_int) {
-      /* Do the change warning now, for the same reason as above. */
-      change_warning(0);
-
-      uhp = curbuf->b_u_curhead;
-      if (uhp == NULL)
-        uhp = curbuf->b_u_newhead;
-      else
-        uhp = uhp->uh_next.ptr;
-      if (uhp == NULL || uhp->uh_walk != mark
-          || (uhp->uh_seq == target && !above))
-        break;
-      curbuf->b_u_curhead = uhp;
-      u_undoredo(TRUE);
-      uhp->uh_walk = nomark;            /* don't go back down here */
-    }
-
-    /*
-     * And now go down the tree (redo), branching off where needed.
-     */
-    while (!got_int) {
-      /* Do the change warning now, for the same reason as above. */
-      change_warning(0);
-
-      uhp = curbuf->b_u_curhead;
-      if (uhp == NULL)
-        break;
-
-      /* Go back to the first branch with a mark. */
-      while (uhp->uh_alt_prev.ptr != NULL
-             && uhp->uh_alt_prev.ptr->uh_walk == mark)
-        uhp = uhp->uh_alt_prev.ptr;
-
-      /* Find the last branch with a mark, that's the one. */
-      last = uhp;
-      while (last->uh_alt_next.ptr != NULL
-             && last->uh_alt_next.ptr->uh_walk == mark)
-        last = last->uh_alt_next.ptr;
-      if (last != uhp) {
-        /* Make the used branch the first entry in the list of
-         * alternatives to make "u" and CTRL-R take this branch. */
-        while (uhp->uh_alt_prev.ptr != NULL)
-          uhp = uhp->uh_alt_prev.ptr;
-        if (last->uh_alt_next.ptr != NULL)
-          last->uh_alt_next.ptr->uh_alt_prev.ptr =
-            last->uh_alt_prev.ptr;
-        last->uh_alt_prev.ptr->uh_alt_next.ptr = last->uh_alt_next.ptr;
-        last->uh_alt_prev.ptr = NULL;
-        last->uh_alt_next.ptr = uhp;
-        uhp->uh_alt_prev.ptr = last;
-
-        if (curbuf->b_u_oldhead == uhp)
-          curbuf->b_u_oldhead = last;
-        uhp = last;
-        if (uhp->uh_next.ptr != NULL)
-          uhp->uh_next.ptr->uh_prev.ptr = uhp;
-      }
-      curbuf->b_u_curhead = uhp;
-
-      if (uhp->uh_walk != mark)
-        break;              /* must have reached the target */
-
-      /* Stop when going backwards in time and didn't find the exact
-       * header we were looking for. */
-      if (uhp->uh_seq == target && above) {
-        curbuf->b_u_seq_cur = target - 1;
-        break;
-      }
-
-      u_undoredo(FALSE);
-
-      /* Advance "curhead" to below the header we last used.  If it
-      * becomes NULL then we need to set "newhead" to this leaf. */
-      if (uhp->uh_prev.ptr == NULL)
-        curbuf->b_u_newhead = uhp;
-      curbuf->b_u_curhead = uhp->uh_prev.ptr;
-      did_undo = FALSE;
-
-      if (uhp->uh_seq == target)        /* found it! */
-        break;
-
-      uhp = uhp->uh_prev.ptr;
-      if (uhp == NULL || uhp->uh_walk != mark) {
-        /* Need to redo more but can't find it... */
-        EMSG2(_(e_intern2), "undo_time()");
-        break;
-      }
-    }
-  }
-  u_undo_end(did_undo, absolute);
-}
-
-/*
- * u_undoredo: common code for undo and redo
- *
- * The lines in the file are replaced by the lines in the entry list at
- * curbuf->b_u_curhead. The replaced lines in the file are saved in the entry
- * list for the next undo/redo.
- *
- * When "undo" is TRUE we go up in the tree, when FALSE we go down.
- */
-static void u_undoredo(int undo)
-{
-  char_u      **newarray = NULL;
-  linenr_T oldsize;
-  linenr_T newsize;
-  linenr_T top, bot;
-  linenr_T lnum;
-  linenr_T newlnum = MAXLNUM;
-  long i;
-  u_entry_T   *uep, *nuep;
-  u_entry_T   *newlist = NULL;
-  int old_flags;
-  int new_flags;
-  pos_T namedm[NMARKS];
-  visualinfo_T visualinfo;
-  int empty_buffer;                         /* buffer became empty */
-  u_header_T  *curhead = curbuf->b_u_curhead;
-
-  /* Don't want autocommands using the undo structures here, they are
-   * invalid till the end. */
-  block_autocmds();
-
-#ifdef U_DEBUG
-  u_check(FALSE);
-#endif
-  old_flags = curhead->uh_flags;
-  new_flags = (curbuf->b_changed ? UH_CHANGED : 0) +
-              ((curbuf->b_ml.ml_flags & ML_EMPTY) ? UH_EMPTYBUF : 0);
-  setpcmark();
-
-  /*
-   * save marks before undo/redo
-   */
-  memmove(namedm, curbuf->b_namedm, sizeof(pos_T) * NMARKS);
-  visualinfo = curbuf->b_visual;
-  curbuf->b_op_start.lnum = curbuf->b_ml.ml_line_count;
-  curbuf->b_op_start.col = 0;
-  curbuf->b_op_end.lnum = 0;
-  curbuf->b_op_end.col = 0;
-
-  for (uep = curhead->uh_entry; uep != NULL; uep = nuep) {
-    top = uep->ue_top;
-    bot = uep->ue_bot;
-    if (bot == 0)
-      bot = curbuf->b_ml.ml_line_count + 1;
-    if (top > curbuf->b_ml.ml_line_count || top >= bot
-        || bot > curbuf->b_ml.ml_line_count + 1) {
-      unblock_autocmds();
-      EMSG(_("E438: u_undo: line numbers wrong"));
-      changed();                /* don't want UNCHANGED now */
-      return;
-    }
-
-    oldsize = bot - top - 1;        /* number of lines before undo */
-    newsize = uep->ue_size;         /* number of lines after undo */
-
-    if (top < newlnum) {
-      /* If the saved cursor is somewhere in this undo block, move it to
-       * the remembered position.  Makes "gwap" put the cursor back
-       * where it was. */
-      lnum = curhead->uh_cursor.lnum;
-      if (lnum >= top && lnum <= top + newsize + 1) {
-        curwin->w_cursor = curhead->uh_cursor;
-        newlnum = curwin->w_cursor.lnum - 1;
-      } else {
-        /* Use the first line that actually changed.  Avoids that
-         * undoing auto-formatting puts the cursor in the previous
-         * line. */
-        for (i = 0; i < newsize && i < oldsize; ++i)
-          if (STRCMP(uep->ue_array[i], ml_get(top + 1 + i)) != 0)
-            break;
-        if (i == newsize && newlnum == MAXLNUM && uep->ue_next == NULL) {
-          newlnum = top;
-          curwin->w_cursor.lnum = newlnum + 1;
-        } else if (i < newsize)   {
-          newlnum = top + i;
-          curwin->w_cursor.lnum = newlnum + 1;
-        }
-      }
-    }
-
-    empty_buffer = FALSE;
-
-    /* delete the lines between top and bot and save them in newarray */
-    if (oldsize > 0) {
-      newarray = xmalloc(sizeof(char_u *) * oldsize);
-      /* delete backwards, it goes faster in most cases */
-      for (lnum = bot - 1, i = oldsize; --i >= 0; --lnum) {
-        /* what can we do when we run out of memory? */
-        if ((newarray[i] = u_save_line(lnum)) == NULL)
-          do_outofmem_msg((long_u)0);
-        /* remember we deleted the last line in the buffer, and a
-         * dummy empty line will be inserted */
-        if (curbuf->b_ml.ml_line_count == 1)
-          empty_buffer = TRUE;
-        ml_delete(lnum, FALSE);
-      }
-    } else
-      newarray = NULL;
-
-    /* insert the lines in u_array between top and bot */
-    if (newsize) {
-      for (lnum = top, i = 0; i < newsize; ++i, ++lnum) {
-        /*
-         * If the file is empty, there is an empty line 1 that we
-         * should get rid of, by replacing it with the new line
-         */
-        if (empty_buffer && lnum == 0)
-          ml_replace((linenr_T)1, uep->ue_array[i], TRUE);
-        else
-          ml_append(lnum, uep->ue_array[i], (colnr_T)0, FALSE);
-        free(uep->ue_array[i]);
-      }
-      free((char_u *)uep->ue_array);
-    }
-
-    /* adjust marks */
-    if (oldsize != newsize) {
-      mark_adjust(top + 1, top + oldsize, (long)MAXLNUM,
-          (long)newsize - (long)oldsize);
-      if (curbuf->b_op_start.lnum > top + oldsize)
-        curbuf->b_op_start.lnum += newsize - oldsize;
-      if (curbuf->b_op_end.lnum > top + oldsize)
-        curbuf->b_op_end.lnum += newsize - oldsize;
-    }
-
-    changed_lines(top + 1, 0, bot, newsize - oldsize);
-
-    /* set '[ and '] mark */
-    if (top + 1 < curbuf->b_op_start.lnum)
-      curbuf->b_op_start.lnum = top + 1;
-    if (newsize == 0 && top + 1 > curbuf->b_op_end.lnum)
-      curbuf->b_op_end.lnum = top + 1;
-    else if (top + newsize > curbuf->b_op_end.lnum)
-      curbuf->b_op_end.lnum = top + newsize;
-
-    u_newcount += newsize;
-    u_oldcount += oldsize;
-    uep->ue_size = oldsize;
-    uep->ue_array = newarray;
-    uep->ue_bot = top + newsize + 1;
-
-    /*
-     * insert this entry in front of the new entry list
-     */
-    nuep = uep->ue_next;
-    uep->ue_next = newlist;
-    newlist = uep;
-  }
-
-  curhead->uh_entry = newlist;
-  curhead->uh_flags = new_flags;
-  if ((old_flags & UH_EMPTYBUF) && bufempty())
-    curbuf->b_ml.ml_flags |= ML_EMPTY;
-  if (old_flags & UH_CHANGED)
-    changed();
-  else
-    unchanged(curbuf, FALSE);
-
-  /*
-   * restore marks from before undo/redo
-   */
-  for (i = 0; i < NMARKS; ++i)
-    if (curhead->uh_namedm[i].lnum != 0) {
-      curbuf->b_namedm[i] = curhead->uh_namedm[i];
-      curhead->uh_namedm[i] = namedm[i];
-    }
-  if (curhead->uh_visual.vi_start.lnum != 0) {
-    curbuf->b_visual = curhead->uh_visual;
-    curhead->uh_visual = visualinfo;
-  }
-
-  /*
-   * If the cursor is only off by one line, put it at the same position as
-   * before starting the change (for the "o" command).
-   * Otherwise the cursor should go to the first undone line.
-   */
-  if (curhead->uh_cursor.lnum + 1 == curwin->w_cursor.lnum
-      && curwin->w_cursor.lnum > 1)
-    --curwin->w_cursor.lnum;
-  if (curwin->w_cursor.lnum <= curbuf->b_ml.ml_line_count) {
-    if (curhead->uh_cursor.lnum == curwin->w_cursor.lnum) {
-      curwin->w_cursor.col = curhead->uh_cursor.col;
-      if (virtual_active() && curhead->uh_cursor_vcol >= 0)
-        coladvance((colnr_T)curhead->uh_cursor_vcol);
-      else
-        curwin->w_cursor.coladd = 0;
-    } else
-      beginline(BL_SOL | BL_FIX);
-  } else {
-    /* We get here with the current cursor line being past the end (eg
-     * after adding lines at the end of the file, and then undoing it).
-     * check_cursor() will move the cursor to the last line.  Move it to
-     * the first column here. */
-    curwin->w_cursor.col = 0;
-    curwin->w_cursor.coladd = 0;
-  }
-
-  /* Make sure the cursor is on an existing line and column. */
-  check_cursor();
-
-  /* Remember where we are for "g-" and ":earlier 10s". */
-  curbuf->b_u_seq_cur = curhead->uh_seq;
-  if (undo)
-    /* We are below the previous undo.  However, to make ":earlier 1s"
-     * work we compute this as being just above the just undone change. */
-    --curbuf->b_u_seq_cur;
-
-  /* Remember where we are for ":earlier 1f" and ":later 1f". */
-  if (curhead->uh_save_nr != 0) {
-    if (undo)
-      curbuf->b_u_save_nr_cur = curhead->uh_save_nr - 1;
-    else
-      curbuf->b_u_save_nr_cur = curhead->uh_save_nr;
-  }
-
-  /* The timestamp can be the same for multiple changes, just use the one of
-   * the undone/redone change. */
-  curbuf->b_u_time_cur = curhead->uh_time;
-
-  unblock_autocmds();
-#ifdef U_DEBUG
-  u_check(FALSE);
-#endif
-}
-
-/*
- * If we deleted or added lines, report the number of less/more lines.
- * Otherwise, report the number of changes (this may be incorrect
- * in some cases, but it's better than nothing).
- */
-static void 
-u_undo_end (
-    int did_undo,                   /* just did an undo */
-    int absolute                   /* used ":undo N" */
-)
-{
-  char        *msgstr;
-  u_header_T  *uhp;
-  char_u msgbuf[80];
-
-  if ((fdo_flags & FDO_UNDO) && KeyTyped)
-    foldOpenCursor();
-
-  if (global_busy           /* no messages now, wait until global is finished */
-      || !messaging())        /* 'lazyredraw' set, don't do messages now */
-    return;
-
-  if (curbuf->b_ml.ml_flags & ML_EMPTY)
-    --u_newcount;
-
-  u_oldcount -= u_newcount;
-  if (u_oldcount == -1)
-    msgstr = N_("more line");
-  else if (u_oldcount < 0)
-    msgstr = N_("more lines");
-  else if (u_oldcount == 1)
-    msgstr = N_("line less");
-  else if (u_oldcount > 1)
-    msgstr = N_("fewer lines");
-  else {
-    u_oldcount = u_newcount;
-    if (u_newcount == 1)
-      msgstr = N_("change");
-    else
-      msgstr = N_("changes");
-  }
-
-  if (curbuf->b_u_curhead != NULL) {
-    /* For ":undo N" we prefer a "after #N" message. */
-    if (absolute && curbuf->b_u_curhead->uh_next.ptr != NULL) {
-      uhp = curbuf->b_u_curhead->uh_next.ptr;
-      did_undo = FALSE;
-    } else if (did_undo)
-      uhp = curbuf->b_u_curhead;
-    else
-      uhp = curbuf->b_u_curhead->uh_next.ptr;
-  } else
-    uhp = curbuf->b_u_newhead;
-
-  if (uhp == NULL)
-    *msgbuf = NUL;
-  else
-    u_add_time(msgbuf, sizeof(msgbuf), uhp->uh_time);
-
-  {
-    win_T   *wp;
-
-    FOR_ALL_WINDOWS(wp)
-    {
-      if (wp->w_buffer == curbuf && wp->w_p_cole > 0)
-        redraw_win_later(wp, NOT_VALID);
-    }
-  }
-
-  smsg((char_u *)_("%" PRId64 " %s; %s #%" PRId64 "  %s"),
-      u_oldcount < 0 ? (int64_t)-u_oldcount : (int64_t)u_oldcount,
-      _(msgstr),
-      did_undo ? _("before") : _("after"),
-      uhp == NULL ? (int64_t)0L : (int64_t)uhp->uh_seq,
-      msgbuf);
-}
-
-/*
- * u_sync: stop adding to the current entry list
- */
-void 
-u_sync (
-    int force              /* Also sync when no_u_sync is set. */
-)
-{
-  /* Skip it when already synced or syncing is disabled. */
-  if (curbuf->b_u_synced || (!force && no_u_sync > 0))
-    return;
-  if (get_undolevel() < 0)
-    curbuf->b_u_synced = TRUE;      /* no entries, nothing to do */
-  else {
-    u_getbot();                     /* compute ue_bot of previous u_save */
-    curbuf->b_u_curhead = NULL;
-  }
-}
-
-/*
- * ":undolist": List the leafs of the undo tree
- */
-void ex_undolist(exarg_T *eap)
-{
-  garray_T ga;
-  u_header_T  *uhp;
-  int mark;
-  int nomark;
-  int changes = 1;
-  int i;
-
-  /*
-   * 1: walk the tree to find all leafs, put the info in "ga".
-   * 2: sort the lines
-   * 3: display the list
-   */
-  mark = ++lastmark;
-  nomark = ++lastmark;
-  ga_init(&ga, (int)sizeof(char *), 20);
-
-  uhp = curbuf->b_u_oldhead;
-  while (uhp != NULL) {
-    if (uhp->uh_prev.ptr == NULL && uhp->uh_walk != nomark
-        && uhp->uh_walk != mark) {
-      ga_grow(&ga, 1);
-      vim_snprintf((char *)IObuff, IOSIZE, "%6ld %7ld  ",
-          uhp->uh_seq, changes);
-      u_add_time(IObuff + STRLEN(IObuff), IOSIZE - STRLEN(IObuff),
-          uhp->uh_time);
-      if (uhp->uh_save_nr > 0) {
-        while (STRLEN(IObuff) < 33)
-          STRCAT(IObuff, " ");
-        vim_snprintf_add((char *)IObuff, IOSIZE,
-            "  %3ld", uhp->uh_save_nr);
-      }
-      ((char_u **)(ga.ga_data))[ga.ga_len++] = vim_strsave(IObuff);
-    }
-
-    uhp->uh_walk = mark;
-
-    /* go down in the tree if we haven't been there */
-    if (uhp->uh_prev.ptr != NULL && uhp->uh_prev.ptr->uh_walk != nomark
-        && uhp->uh_prev.ptr->uh_walk != mark) {
-      uhp = uhp->uh_prev.ptr;
-      ++changes;
-    }
-    /* go to alternate branch if we haven't been there */
-    else if (uhp->uh_alt_next.ptr != NULL
-             && uhp->uh_alt_next.ptr->uh_walk != nomark
-             && uhp->uh_alt_next.ptr->uh_walk != mark)
-      uhp = uhp->uh_alt_next.ptr;
-
-    /* go up in the tree if we haven't been there and we are at the
-     * start of alternate branches */
-    else if (uhp->uh_next.ptr != NULL && uhp->uh_alt_prev.ptr == NULL
-             && uhp->uh_next.ptr->uh_walk != nomark
-             && uhp->uh_next.ptr->uh_walk != mark) {
-      uhp = uhp->uh_next.ptr;
-      --changes;
-    } else {
-      /* need to backtrack; mark this node as done */
-      uhp->uh_walk = nomark;
-      if (uhp->uh_alt_prev.ptr != NULL)
-        uhp = uhp->uh_alt_prev.ptr;
-      else {
-        uhp = uhp->uh_next.ptr;
-        --changes;
-      }
-    }
-  }
-
-  if (ga.ga_len == 0)
-    MSG(_("Nothing to undo"));
-  else {
-    sort_strings((char_u **)ga.ga_data, ga.ga_len);
-
-    msg_start();
-    msg_puts_attr((char_u *)_("number changes  when               saved"),
-        hl_attr(HLF_T));
-    for (i = 0; i < ga.ga_len && !got_int; ++i) {
-      msg_putchar('\n');
-      if (got_int)
-        break;
-      msg_puts(((char_u **)ga.ga_data)[i]);
-    }
-    msg_end();
-
-    ga_clear_strings(&ga);
-  }
-}
-
-/*
- * Put the timestamp of an undo header in "buf[buflen]" in a nice format.
- */
-static void u_add_time(char_u *buf, size_t buflen, time_t tt)
-{
-  struct tm curtime;
-
-  if (time(NULL) - tt >= 100) {
-    os_localtime_r(&tt, &curtime);
-    if (time(NULL) - tt < (60L * 60L * 12L))
-      /* within 12 hours */
-      (void)strftime((char *)buf, buflen, "%H:%M:%S", &curtime);
-    else
-      /* longer ago */
-      (void)strftime((char *)buf, buflen, "%Y/%m/%d %H:%M:%S", &curtime);
-  } else
-  vim_snprintf((char *)buf, buflen, _("%" PRId64 " seconds ago"),
-      (int64_t)(time(NULL) - tt));
-}
-
-/*
- * ":undojoin": continue adding to the last entry list
- */
-void ex_undojoin(exarg_T *eap)
-{
-  if (curbuf->b_u_newhead == NULL)
-    return;                 /* nothing changed before */
-  if (curbuf->b_u_curhead != NULL) {
-    EMSG(_("E790: undojoin is not allowed after undo"));
-    return;
-  }
-  if (!curbuf->b_u_synced)
-    return;                 /* already unsynced */
-  if (get_undolevel() < 0)
-    return;                 /* no entries, nothing to do */
-  else {
-    /* Go back to the last entry */
-    curbuf->b_u_curhead = curbuf->b_u_newhead;
-    curbuf->b_u_synced = FALSE;      /* no entries, nothing to do */
-  }
-}
-
-/*
- * Called after writing or reloading the file and setting b_changed to FALSE.
- * Now an undo means that the buffer is modified.
- */
-void u_unchanged(buf_T *buf)
-{
-  u_unch_branch(buf->b_u_oldhead);
-  buf->b_did_warn = FALSE;
-}
-
-/*
- * After reloading a buffer which was saved for 'undoreload': Find the first
- * line that was changed and set the cursor there.
- */
-void u_find_first_changed(void)
-{
-  u_header_T  *uhp = curbuf->b_u_newhead;
-  u_entry_T   *uep;
-  linenr_T lnum;
-
-  if (curbuf->b_u_curhead != NULL || uhp == NULL)
-    return;      /* undid something in an autocmd? */
-
-  /* Check that the last undo block was for the whole file. */
-  uep = uhp->uh_entry;
-  if (uep->ue_top != 0 || uep->ue_bot != 0)
-    return;
-
-  for (lnum = 1; lnum < curbuf->b_ml.ml_line_count
-       && lnum <= uep->ue_size; ++lnum)
-    if (STRCMP(ml_get_buf(curbuf, lnum, FALSE),
-            uep->ue_array[lnum - 1]) != 0) {
-      clearpos(&(uhp->uh_cursor));
-      uhp->uh_cursor.lnum = lnum;
-      return;
-    }
-  if (curbuf->b_ml.ml_line_count != uep->ue_size) {
-    /* lines added or deleted at the end, put the cursor there */
-    clearpos(&(uhp->uh_cursor));
-    uhp->uh_cursor.lnum = lnum;
-  }
-}
-
-/*
- * Increase the write count, store it in the last undo header, what would be
- * used for "u".
- */
-void u_update_save_nr(buf_T *buf)
-{
-  u_header_T  *uhp;
-
-  ++buf->b_u_save_nr_last;
-  buf->b_u_save_nr_cur = buf->b_u_save_nr_last;
-  uhp = buf->b_u_curhead;
-  if (uhp != NULL)
-    uhp = uhp->uh_next.ptr;
-  else
-    uhp = buf->b_u_newhead;
-  if (uhp != NULL)
-    uhp->uh_save_nr = buf->b_u_save_nr_last;
-}
-
-static void u_unch_branch(u_header_T *uhp)
-{
-  u_header_T  *uh;
-
-  for (uh = uhp; uh != NULL; uh = uh->uh_prev.ptr) {
-    uh->uh_flags |= UH_CHANGED;
-    if (uh->uh_alt_next.ptr != NULL)
-      u_unch_branch(uh->uh_alt_next.ptr);           /* recursive */
-  }
-}
-
-/*
- * Get pointer to last added entry.
- * If it's not valid, give an error message and return NULL.
- */
-static u_entry_T *u_get_headentry(void)
-{
-  if (curbuf->b_u_newhead == NULL || curbuf->b_u_newhead->uh_entry == NULL) {
-    EMSG(_("E439: undo list corrupt"));
-    return NULL;
-  }
-  return curbuf->b_u_newhead->uh_entry;
-}
-
-/*
- * u_getbot(): compute the line number of the previous u_save
- *		It is called only when b_u_synced is FALSE.
- */
-static void u_getbot(void)
-{
-  u_entry_T   *uep;
-  linenr_T extra;
-
-  uep = u_get_headentry();      /* check for corrupt undo list */
-  if (uep == NULL)
-    return;
-
-  uep = curbuf->b_u_newhead->uh_getbot_entry;
-  if (uep != NULL) {
-    /*
-     * the new ue_bot is computed from the number of lines that has been
-     * inserted (0 - deleted) since calling u_save. This is equal to the
-     * old line count subtracted from the current line count.
-     */
-    extra = curbuf->b_ml.ml_line_count - uep->ue_lcount;
-    uep->ue_bot = uep->ue_top + uep->ue_size + 1 + extra;
-    if (uep->ue_bot < 1 || uep->ue_bot > curbuf->b_ml.ml_line_count) {
-      EMSG(_("E440: undo line missing"));
-      uep->ue_bot = uep->ue_top + 1;        /* assume all lines deleted, will
-                                             * get all the old lines back
-                                             * without deleting the current
-                                             * ones */
-    }
-
-    curbuf->b_u_newhead->uh_getbot_entry = NULL;
-  }
-
-  curbuf->b_u_synced = TRUE;
-}
-
-/*
- * Free one header "uhp" and its entry list and adjust the pointers.
- */
-static void 
-u_freeheader (
-    buf_T *buf,
-    u_header_T *uhp,
-    u_header_T **uhpp         /* if not NULL reset when freeing this header */
-)
-{
-  u_header_T      *uhap;
-
-  /* When there is an alternate redo list free that branch completely,
-   * because we can never go there. */
-  if (uhp->uh_alt_next.ptr != NULL)
-    u_freebranch(buf, uhp->uh_alt_next.ptr, uhpp);
-
-  if (uhp->uh_alt_prev.ptr != NULL)
-    uhp->uh_alt_prev.ptr->uh_alt_next.ptr = NULL;
-
-  /* Update the links in the list to remove the header. */
-  if (uhp->uh_next.ptr == NULL)
-    buf->b_u_oldhead = uhp->uh_prev.ptr;
-  else
-    uhp->uh_next.ptr->uh_prev.ptr = uhp->uh_prev.ptr;
-
-  if (uhp->uh_prev.ptr == NULL)
-    buf->b_u_newhead = uhp->uh_next.ptr;
-  else
-    for (uhap = uhp->uh_prev.ptr; uhap != NULL;
-         uhap = uhap->uh_alt_next.ptr)
-      uhap->uh_next.ptr = uhp->uh_next.ptr;
-
-  u_freeentries(buf, uhp, uhpp);
-}
-
-/*
- * Free an alternate branch and any following alternate branches.
- */
-static void 
-u_freebranch (
-    buf_T *buf,
-    u_header_T *uhp,
-    u_header_T **uhpp         /* if not NULL reset when freeing this header */
-)
-{
-  u_header_T      *tofree, *next;
-
-  /* If this is the top branch we may need to use u_freeheader() to update
-   * all the pointers. */
-  if (uhp == buf->b_u_oldhead) {
-    while (buf->b_u_oldhead != NULL)
-      u_freeheader(buf, buf->b_u_oldhead, uhpp);
-    return;
-  }
-
-  if (uhp->uh_alt_prev.ptr != NULL)
-    uhp->uh_alt_prev.ptr->uh_alt_next.ptr = NULL;
-
-  next = uhp;
-  while (next != NULL) {
-    tofree = next;
-    if (tofree->uh_alt_next.ptr != NULL)
-      u_freebranch(buf, tofree->uh_alt_next.ptr, uhpp);         /* recursive */
-    next = tofree->uh_prev.ptr;
-    u_freeentries(buf, tofree, uhpp);
-  }
-}
-
-/*
- * Free all the undo entries for one header and the header itself.
- * This means that "uhp" is invalid when returning.
- */
-static void 
-u_freeentries (
-    buf_T *buf,
-    u_header_T *uhp,
-    u_header_T **uhpp         /* if not NULL reset when freeing this header */
-)
-{
-  u_entry_T       *uep, *nuep;
-
-  /* Check for pointers to the header that become invalid now. */
-  if (buf->b_u_curhead == uhp)
-    buf->b_u_curhead = NULL;
-  if (buf->b_u_newhead == uhp)
-    buf->b_u_newhead = NULL;      /* freeing the newest entry */
-  if (uhpp != NULL && uhp == *uhpp)
-    *uhpp = NULL;
-
-  for (uep = uhp->uh_entry; uep != NULL; uep = nuep) {
-    nuep = uep->ue_next;
-    u_freeentry(uep, uep->ue_size);
-  }
-
-#ifdef U_DEBUG
-  uhp->uh_magic = 0;
-#endif
-  free((char_u *)uhp);
-  --buf->b_u_numhead;
-}
-
-/*
- * free entry 'uep' and 'n' lines in uep->ue_array[]
- */
-static void u_freeentry(u_entry_T *uep, long n)
-{
-  while (n > 0)
-    free(uep->ue_array[--n]);
-  free((char_u *)uep->ue_array);
-#ifdef U_DEBUG
-  uep->ue_magic = 0;
-#endif
-  free((char_u *)uep);
-}
-
-/*
- * invalidate the undo buffer; called when storage has already been released
- */
-void u_clearall(buf_T *buf)
-{
-  buf->b_u_newhead = buf->b_u_oldhead = buf->b_u_curhead = NULL;
-  buf->b_u_synced = TRUE;
-  buf->b_u_numhead = 0;
-  buf->b_u_line_ptr = NULL;
-  buf->b_u_line_lnum = 0;
-}
-
-/*
- * save the line "lnum" for the "U" command
- */
-void u_saveline(linenr_T lnum)
-{
-  if (lnum == curbuf->b_u_line_lnum)        /* line is already saved */
-    return;
-  if (lnum < 1 || lnum > curbuf->b_ml.ml_line_count)   /* should never happen */
-    return;
-  u_clearline();
-  curbuf->b_u_line_lnum = lnum;
-  if (curwin->w_cursor.lnum == lnum)
-    curbuf->b_u_line_colnr = curwin->w_cursor.col;
-  else
-    curbuf->b_u_line_colnr = 0;
-  if ((curbuf->b_u_line_ptr = u_save_line(lnum)) == NULL)
-    do_outofmem_msg((long_u)0);
-}
-
-/*
- * clear the line saved for the "U" command
- * (this is used externally for crossing a line while in insert mode)
- */
-void u_clearline(void)
-{
-  if (curbuf->b_u_line_ptr != NULL) {
-    free(curbuf->b_u_line_ptr);
-    curbuf->b_u_line_ptr = NULL;
-    curbuf->b_u_line_lnum = 0;
-  }
-}
-
-/*
- * Implementation of the "U" command.
- * Differentiation from vi: "U" can be undone with the next "U".
- * We also allow the cursor to be in another line.
- * Careful: may trigger autocommands that reload the buffer.
- */
-void u_undoline(void)
-{
-  colnr_T t;
-  char_u  *oldp;
-
-  if (undo_off)
-    return;
-
-  if (curbuf->b_u_line_ptr == NULL
-      || curbuf->b_u_line_lnum > curbuf->b_ml.ml_line_count) {
-    beep_flush();
-    return;
-  }
-
-  /* first save the line for the 'u' command */
-  if (u_savecommon(curbuf->b_u_line_lnum - 1,
-          curbuf->b_u_line_lnum + 1, (linenr_T)0, FALSE) == FAIL)
-    return;
-  oldp = u_save_line(curbuf->b_u_line_lnum);
-  if (oldp == NULL) {
-    do_outofmem_msg((long_u)0);
-    return;
-  }
-  ml_replace(curbuf->b_u_line_lnum, curbuf->b_u_line_ptr, TRUE);
-  changed_bytes(curbuf->b_u_line_lnum, 0);
-  free(curbuf->b_u_line_ptr);
-  curbuf->b_u_line_ptr = oldp;
-
-  t = curbuf->b_u_line_colnr;
-  if (curwin->w_cursor.lnum == curbuf->b_u_line_lnum)
-    curbuf->b_u_line_colnr = curwin->w_cursor.col;
-  curwin->w_cursor.col = t;
-  curwin->w_cursor.lnum = curbuf->b_u_line_lnum;
-  check_cursor_col();
-}
-
-/*
- * Free all allocated memory blocks for the buffer 'buf'.
- */
-void u_blockfree(buf_T *buf)
-{
-  while (buf->b_u_oldhead != NULL)
-    u_freeheader(buf, buf->b_u_oldhead, NULL);
-  free(buf->b_u_line_ptr);
-}
-
-/*
- * u_save_line(): allocate memory and copy line 'lnum' into it.
- * Returns NULL when out of memory.
- */
-static char_u *u_save_line(linenr_T lnum)
-{
-  return vim_strsave(ml_get(lnum));
-}
-
-/*
- * Check if the 'modified' flag is set, or 'ff' has changed (only need to
- * check the first character, because it can only be "dos", "unix" or "mac").
- * "nofile" and "scratch" type buffers are considered to always be unchanged.
- */
-int bufIsChanged(buf_T *buf)
-{
-  return
-    !bt_dontwrite(buf) &&
-    (buf->b_changed || file_ff_differs(buf, TRUE));
-}
-
-int curbufIsChanged(void)
-{
-  return
-    !bt_dontwrite(curbuf) &&
-    (curbuf->b_changed || file_ff_differs(curbuf, TRUE));
-}
-
-/*
- * For undotree(): Append the list of undo blocks at "first_uhp" to "list".
- * Recursive.
- */
-void u_eval_tree(u_header_T *first_uhp, list_T *list)
-{
-  u_header_T  *uhp = first_uhp;
-  dict_T      *dict;
-
-  while (uhp != NULL) {
-    dict = dict_alloc();
-    if (dict == NULL)
-      return;
-    dict_add_nr_str(dict, "seq", uhp->uh_seq, NULL);
-    dict_add_nr_str(dict, "time", (long)uhp->uh_time, NULL);
-    if (uhp == curbuf->b_u_newhead)
-      dict_add_nr_str(dict, "newhead", 1, NULL);
-    if (uhp == curbuf->b_u_curhead)
-      dict_add_nr_str(dict, "curhead", 1, NULL);
-    if (uhp->uh_save_nr > 0)
-      dict_add_nr_str(dict, "save", uhp->uh_save_nr, NULL);
-
-    if (uhp->uh_alt_next.ptr != NULL) {
-      list_T      *alt_list = list_alloc();
-
-      if (alt_list != NULL) {
-        /* Recursive call to add alternate undo tree. */
-        u_eval_tree(uhp->uh_alt_next.ptr, alt_list);
-        dict_add_list(dict, "alt", alt_list);
-      }
-    }
-
-    list_append_dict(list, dict);
-    uhp = uhp->uh_prev.ptr;
-  }
-}