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, 2611 insertions, 0 deletions

diff --git a/src/nvim/diff.c b/src/nvim/diff.c
new file mode 100644
index 0000000000..e360edc665
--- /dev/null
+++ b/src/nvim/diff.c
@@ -0,0 +1,2611 @@
+/// @file diff.c
+///
+/// Code for diff'ing two, three or four buffers.
+
+#include "vim.h"
+#include "diff.h"
+#include "buffer.h"
+#include "charset.h"
+#include "eval.h"
+#include "ex_cmds.h"
+#include "ex_docmd.h"
+#include "fileio.h"
+#include "fold.h"
+#include "mark.h"
+#include "mbyte.h"
+#include "memline.h"
+#include "message.h"
+#include "misc1.h"
+#include "misc2.h"
+#include "memory.h"
+#include "move.h"
+#include "normal.h"
+#include "option.h"
+#include "path.h"
+#include "screen.h"
+#include "undo.h"
+#include "window.h"
+#include "os/os.h"
+#include "os/shell.h"
+
+static int diff_busy = FALSE;    // ex_diffgetput() is busy
+
+// Flags obtained from the 'diffopt' option
+#define DIFF_FILLER     1        // display filler lines
+#define DIFF_ICASE      2        // ignore case
+#define DIFF_IWHITE     4        // ignore change in white space
+#define DIFF_HORIZONTAL 8        // horizontal splits
+#define DIFF_VERTICAL   16       // vertical splits
+static int diff_flags = DIFF_FILLER;
+
+#define LBUFLEN 50               // length of line in diff file
+
+// TRUE when "diff -a" works, FALSE when it doesn't work, MAYBE when not
+// checked yet
+static int diff_a_works = MAYBE;
+
+static int diff_buf_idx(buf_T *buf);
+static int diff_buf_idx_tp(buf_T *buf, tabpage_T *tp);
+static void diff_mark_adjust_tp(tabpage_T *tp, int idx, linenr_T line1,
+                                linenr_T line2, long amount,
+                                long amount_after);
+static void diff_check_unchanged(tabpage_T *tp, diff_T *dp);
+static int diff_check_sanity(tabpage_T *tp, diff_T *dp);
+static void diff_redraw(int dofold);
+static int diff_write(buf_T *buf, char_u *fname);
+static void diff_file(char_u *tmp_orig, char_u *tmp_new, char_u *tmp_diff);
+static int diff_equal_entry(diff_T *dp, int idx1, int idx2);
+static int diff_cmp(char_u *s1, char_u *s2);
+static void diff_fold_update(diff_T *dp, int skip_idx);
+static void diff_read(int idx_orig, int idx_new, char_u *fname);
+static void diff_copy_entry(diff_T *dprev, diff_T *dp, int idx_orig,
+                            int idx_new);
+static diff_T* diff_alloc_new(tabpage_T *tp, diff_T *dprev, diff_T *dp);
+
+#ifndef USE_CR
+# define tag_fgets vim_fgets
+#endif  // ifndef USE_CR
+
+/// Called when deleting or unloading a buffer: No longer make a diff with it.
+///
+/// @param buf
+void diff_buf_delete(buf_T *buf)
+{
+  tabpage_T *tp;
+  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
+    int i = diff_buf_idx_tp(buf, tp);
+
+    if (i != DB_COUNT) {
+      tp->tp_diffbuf[i] = NULL;
+      tp->tp_diff_invalid = TRUE;
+
+      if (tp == curtab) {
+        diff_redraw(TRUE);
+      }
+    }
+  }
+}
+
+/// Check if the current buffer should be added to or removed from the list of
+/// diff buffers.
+///
+/// @param win
+void diff_buf_adjust(win_T *win)
+{
+
+  if (!win->w_p_diff) {
+    // When there is no window showing a diff for this buffer, remove
+    // it from the diffs.
+    win_T *wp;
+    for (wp = firstwin; wp != NULL; wp = wp->w_next) {
+      if ((wp->w_buffer == win->w_buffer) && wp->w_p_diff) {
+        break;
+      }
+    }
+
+    if (wp == NULL) {
+      int i = diff_buf_idx(win->w_buffer);
+      if (i != DB_COUNT) {
+        curtab->tp_diffbuf[i] = NULL;
+        curtab->tp_diff_invalid = TRUE;
+        diff_redraw(TRUE);
+      }
+    }
+  } else {
+    diff_buf_add(win->w_buffer);
+  }
+}
+
+/// Add a buffer to make diffs for.
+///
+/// Call this when a new buffer is being edited in the current window where
+/// 'diff' is set.
+/// Marks the current buffer as being part of the diff and requiring updating.
+/// This must be done before any autocmd, because a command may use info
+/// about the screen contents.
+///
+/// @param buf The buffer to add.
+void diff_buf_add(buf_T *buf)
+{
+  if (diff_buf_idx(buf) != DB_COUNT) {
+    // It's already there.
+    return;
+  }
+
+  int i;
+  for (i = 0; i < DB_COUNT; ++i) {
+    if (curtab->tp_diffbuf[i] == NULL) {
+      curtab->tp_diffbuf[i] = buf;
+      curtab->tp_diff_invalid = TRUE;
+      diff_redraw(TRUE);
+      return;
+    }
+  }
+
+  EMSGN(_("E96: Can not diff more than %" PRId64 " buffers"), DB_COUNT);
+}
+
+/// Find buffer "buf" in the list of diff buffers for the current tab page.
+///
+/// @param buf The buffer to find.
+///
+/// @return Its index or DB_COUNT if not found.
+static int diff_buf_idx(buf_T *buf)
+{
+  int idx;
+  for (idx = 0; idx < DB_COUNT; ++idx) {
+    if (curtab->tp_diffbuf[idx] == buf) {
+      break;
+    }
+  }
+  return idx;
+}
+
+/// Find buffer "buf" in the list of diff buffers for tab page "tp".
+///
+/// @param buf
+/// @param tp
+///
+/// @return its index or DB_COUNT if not found.
+static int diff_buf_idx_tp(buf_T *buf, tabpage_T *tp)
+{
+  int idx;
+  for (idx = 0; idx < DB_COUNT; ++idx) {
+    if (tp->tp_diffbuf[idx] == buf) {
+      break;
+    }
+  }
+  return idx;
+}
+
+/// Mark the diff info involving buffer "buf" as invalid, it will be updated
+/// when info is requested.
+///
+/// @param buf
+void diff_invalidate(buf_T *buf)
+{
+  tabpage_T *tp;
+  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
+    int i = diff_buf_idx_tp(buf, tp);
+    if (i != DB_COUNT) {
+      tp->tp_diff_invalid = TRUE;
+      if (tp == curtab) {
+        diff_redraw(TRUE);
+      }
+    }
+  }
+}
+
+/// Called by mark_adjust(): update line numbers in "curbuf".
+///
+/// @param line1
+/// @param line2
+/// @param amount
+/// @param amount_after
+void diff_mark_adjust(linenr_T line1, linenr_T line2, long amount,
+                      long amount_after)
+{
+  // Handle all tab pages that use the current buffer in a diff.
+  tabpage_T *tp;
+  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
+    int idx = diff_buf_idx_tp(curbuf, tp);
+    if (idx != DB_COUNT) {
+      diff_mark_adjust_tp(tp, idx, line1, line2, amount, amount_after);
+    }
+  }
+}
+
+/// Update line numbers in tab page "tp" for "curbuf" with index "idx".
+///
+/// This attempts to update the changes as much as possible:
+/// When inserting/deleting lines outside of existing change blocks, create a
+/// new change block and update the line numbers in following blocks.
+/// When inserting/deleting lines in existing change blocks, update them.
+///
+/// @param tp
+/// @param idx
+/// @param line1
+/// @param line2
+/// @param amount
+/// @amount_after
+static void diff_mark_adjust_tp(tabpage_T *tp, int idx, linenr_T line1,
+                                linenr_T line2, long amount, long amount_after)
+{
+  int inserted;
+  int deleted;
+  if (line2 == MAXLNUM) {
+    // mark_adjust(99, MAXLNUM, 9, 0): insert lines
+    inserted = amount;
+    deleted = 0;
+  } else if (amount_after > 0) {
+    // mark_adjust(99, 98, MAXLNUM, 9): a change that inserts lines
+    inserted = amount_after;
+    deleted = 0;
+  } else {
+    // mark_adjust(98, 99, MAXLNUM, -2): delete lines
+    inserted = 0;
+    deleted = -amount_after;
+  }
+
+  diff_T *dprev = NULL;
+  diff_T *dp = tp->tp_first_diff;
+
+  linenr_T last;
+  linenr_T lnum_deleted = line1; // lnum of remaining deletion
+  int n;
+  int off;
+  for (;;) {
+    // If the change is after the previous diff block and before the next
+    // diff block, thus not touching an existing change, create a new diff
+    // block.  Don't do this when ex_diffgetput() is busy.
+    if (((dp == NULL)
+         || (dp->df_lnum[idx] - 1 > line2)
+         || ((line2 == MAXLNUM) && (dp->df_lnum[idx] > line1)))
+        && ((dprev == NULL)
+            || (dprev->df_lnum[idx] + dprev->df_count[idx] < line1))
+        && !diff_busy) {
+      diff_T *dnext = diff_alloc_new(tp, dprev, dp);
+
+      dnext->df_lnum[idx] = line1;
+      dnext->df_count[idx] = inserted;
+      int i;
+      for (i = 0; i < DB_COUNT; ++i) {
+        if ((tp->tp_diffbuf[i] != NULL) && (i != idx)) {
+          if (dprev == NULL) {
+            dnext->df_lnum[i] = line1;
+          } else {
+            dnext->df_lnum[i] = line1
+                + (dprev->df_lnum[i] + dprev->df_count[i])
+                - (dprev->df_lnum[idx] + dprev->df_count[idx]);
+          }
+          dnext->df_count[i] = deleted;
+        }
+      }
+    }
+
+    // if at end of the list, quit
+    if (dp == NULL) {
+      break;
+    }
+
+    //
+    // Check for these situations:
+    //	  1  2	3
+    //	  1  2	3
+    // line1     2	3  4  5
+    //	     2	3  4  5
+    //	     2	3  4  5
+    // line2     2	3  4  5
+    //		3     5  6
+    //		3     5  6
+
+    // compute last line of this change
+    last = dp->df_lnum[idx] + dp->df_count[idx] - 1;
+
+    // 1. change completely above line1: nothing to do
+    if (last >= line1 - 1) {
+      // 6. change below line2: only adjust for amount_after; also when
+      // "deleted" became zero when deleted all lines between two diffs.
+      if (dp->df_lnum[idx] - (deleted + inserted != 0) > line2) {
+        if (amount_after == 0) {
+          // nothing left to change
+          break;
+        }
+        dp->df_lnum[idx] += amount_after;
+      } else {
+        int check_unchanged = FALSE;
+
+        // 2. 3. 4. 5.: inserted/deleted lines touching this diff.
+        if (deleted > 0) {
+          if (dp->df_lnum[idx] >= line1) {
+            off = dp->df_lnum[idx] - lnum_deleted;
+
+            if (last <= line2) {
+              // 4. delete all lines of diff
+              if ((dp->df_next != NULL)
+                  && (dp->df_next->df_lnum[idx] - 1 <= line2)) {
+                // delete continues in next diff, only do
+                // lines until that one
+                n = dp->df_next->df_lnum[idx] - lnum_deleted;
+                deleted -= n;
+                n -= dp->df_count[idx];
+                lnum_deleted = dp->df_next->df_lnum[idx];
+              } else {
+                n = deleted - dp->df_count[idx];
+              }
+              dp->df_count[idx] = 0;
+            } else {
+              // 5. delete lines at or just before top of diff
+              n = off;
+              dp->df_count[idx] -= line2 - dp->df_lnum[idx] + 1;
+              check_unchanged = TRUE;
+            }
+            dp->df_lnum[idx] = line1;
+          } else {
+            off = 0;
+
+            if (last < line2) {
+              // 2. delete at end of of diff
+              dp->df_count[idx] -= last - lnum_deleted + 1;
+
+              if ((dp->df_next != NULL)
+                  && (dp->df_next->df_lnum[idx] - 1 <= line2)) {
+                // delete continues in next diff, only do
+                // lines until that one
+                n = dp->df_next->df_lnum[idx] - 1 - last;
+                deleted -= dp->df_next->df_lnum[idx] - lnum_deleted;
+                lnum_deleted = dp->df_next->df_lnum[idx];
+              } else {
+                n = line2 - last;
+              }
+              check_unchanged = TRUE;
+            } else {
+              // 3. delete lines inside the diff
+              n = 0;
+              dp->df_count[idx] -= deleted;
+            }
+          }
+
+          int i;
+          for (i = 0; i < DB_COUNT; ++i) {
+            if ((tp->tp_diffbuf[i] != NULL) && (i != idx)) {
+              dp->df_lnum[i] -= off;
+              dp->df_count[i] += n;
+            }
+          }
+        } else {
+          if (dp->df_lnum[idx] <= line1) {
+            // inserted lines somewhere in this diff
+            dp->df_count[idx] += inserted;
+            check_unchanged = TRUE;
+          } else {
+            // inserted lines somewhere above this diff
+            dp->df_lnum[idx] += inserted;
+          }
+        }
+
+        if (check_unchanged) {
+          // Check if inserted lines are equal, may reduce the size of the
+          // diff.
+          //
+          // TODO: also check for equal lines in the middle and perhaps split
+          // the block.
+          diff_check_unchanged(tp, dp);
+        }
+      }
+    }
+
+    // check if this block touches the previous one, may merge them.
+    if ((dprev != NULL)
+        && (dprev->df_lnum[idx] + dprev->df_count[idx] == dp->df_lnum[idx])) {
+      int i;
+      for (i = 0; i < DB_COUNT; ++i) {
+        if (tp->tp_diffbuf[i] != NULL) {
+          dprev->df_count[i] += dp->df_count[i];
+        }
+      }
+      dprev->df_next = dp->df_next;
+      free(dp);
+      dp = dprev->df_next;
+    } else {
+      // Advance to next entry.
+      dprev = dp;
+      dp = dp->df_next;
+    }
+  }
+
+  dprev = NULL;
+  dp = tp->tp_first_diff;
+
+  while (dp != NULL) {
+    // All counts are zero, remove this entry.
+    int i;
+    for (i = 0; i < DB_COUNT; ++i) {
+      if ((tp->tp_diffbuf[i] != NULL) && (dp->df_count[i] != 0)) {
+        break;
+      }
+    }
+
+    if (i == DB_COUNT) {
+      diff_T *dnext = dp->df_next;
+      free(dp);
+      dp = dnext;
+
+      if (dprev == NULL) {
+        tp->tp_first_diff = dnext;
+      } else {
+        dprev->df_next = dnext;
+      }
+    } else {
+      // Advance to next entry.
+      dprev = dp;
+      dp = dp->df_next;
+    }
+  }
+
+  if (tp == curtab) {
+    diff_redraw(TRUE);
+
+    // Need to recompute the scroll binding, may remove or add filler
+    // lines (e.g., when adding lines above w_topline). But it's slow when
+    // making many changes, postpone until redrawing.
+    diff_need_scrollbind = TRUE;
+  }
+}
+
+/// Allocate a new diff block and link it between "dprev" and "dp".
+///
+/// @param tp
+/// @param dprev
+/// @param dp
+///
+/// @return The new diff block.
+static diff_T* diff_alloc_new(tabpage_T *tp, diff_T *dprev, diff_T *dp)
+{
+  diff_T *dnew = xmalloc(sizeof(*dnew));
+
+  dnew->df_next = dp;
+  if (dprev == NULL) {
+    tp->tp_first_diff = dnew;
+  } else {
+    dprev->df_next = dnew;
+  }
+
+  return dnew;
+}
+
+/// Check if the diff block "dp" can be made smaller for lines at the start and
+/// end that are equal.  Called after inserting lines.
+///
+/// This may result in a change where all buffers have zero lines, the caller
+/// must take care of removing it.
+///
+/// @param tp
+/// @param dp
+static void diff_check_unchanged(tabpage_T *tp, diff_T *dp)
+{
+  // Find the first buffers, use it as the original, compare the other
+  // buffer lines against this one.
+  int i_org;
+  for (i_org = 0; i_org < DB_COUNT; ++i_org) {
+    if (tp->tp_diffbuf[i_org] != NULL) {
+      break;
+    }
+  }
+
+  // safety check
+  if (i_org == DB_COUNT) {
+    return;
+  }
+
+  if (diff_check_sanity(tp, dp) == FAIL) {
+    return;
+  }
+
+  // First check lines at the top, then at the bottom.
+  int off_org = 0;
+  int off_new = 0;
+  int dir = FORWARD;
+  for (;;) {
+    // Repeat until a line is found which is different or the number of
+    // lines has become zero.
+    while (dp->df_count[i_org] > 0) {
+      // Copy the line, the next ml_get() will invalidate it.
+      if (dir == BACKWARD) {
+        off_org = dp->df_count[i_org] - 1;
+      }
+      char_u *line_org = vim_strsave(ml_get_buf(tp->tp_diffbuf[i_org],
+                                                dp->df_lnum[i_org] + off_org,
+                                                FALSE));
+
+      if (line_org == NULL) {
+        return;
+      }
+
+      int i_new;
+      for (i_new = i_org + 1; i_new < DB_COUNT; ++i_new) {
+        if (tp->tp_diffbuf[i_new] == NULL) {
+          continue;
+        }
+
+        if (dir == BACKWARD) {
+          off_new = dp->df_count[i_new] - 1;
+        }
+
+        // if other buffer doesn't have this line, it was inserted
+        if ((off_new < 0) || (off_new >= dp->df_count[i_new])) {
+          break;
+        }
+
+        if (diff_cmp(line_org, ml_get_buf(tp->tp_diffbuf[i_new],
+                                          dp->df_lnum[i_new] + off_new,
+                                          FALSE)) != 0) {
+          break;
+        }
+      }
+      free(line_org);
+
+      // Stop when a line isn't equal in all diff buffers.
+      if (i_new != DB_COUNT) {
+        break;
+      }
+
+      // Line matched in all buffers, remove it from the diff.
+      for (i_new = i_org; i_new < DB_COUNT; ++i_new) {
+        if (tp->tp_diffbuf[i_new] != NULL) {
+          if (dir == FORWARD) {
+            dp->df_lnum[i_new]++;
+          }
+          dp->df_count[i_new]--;
+        }
+      }
+    }
+
+    if (dir == BACKWARD) {
+      break;
+    }
+    dir = BACKWARD;
+  }
+}
+
+/// Check if a diff block doesn't contain invalid line numbers.
+/// This can happen when the diff program returns invalid results.
+///
+/// @param tp
+/// @param dp
+///
+/// @return OK if the diff block doesn't contain invalid line numbers.
+static int diff_check_sanity(tabpage_T *tp, diff_T *dp)
+{
+  int i;
+  for (i = 0; i < DB_COUNT; ++i) {
+    if (tp->tp_diffbuf[i] != NULL) {
+      if (dp->df_lnum[i] + dp->df_count[i] - 1
+          > tp->tp_diffbuf[i]->b_ml.ml_line_count) {
+        return FAIL;
+      }
+    }
+  }
+  return OK;
+}
+
+/// Mark all diff buffers in the current tab page for redraw.
+///
+/// @param dofold Also recompute the folds
+static void diff_redraw(int dofold)
+{
+  win_T *wp;
+  for (wp = firstwin; wp != NULL; wp = wp->w_next) {
+    if (wp->w_p_diff) {
+      redraw_win_later(wp, SOME_VALID);
+      if (dofold && foldmethodIsDiff(wp)) {
+        foldUpdateAll(wp);
+      }
+
+      /* A change may have made filler lines invalid, need to take care
+       * of that for other windows. */
+      int n = diff_check(wp, wp->w_topline);
+
+      if (((wp != curwin) && (wp->w_topfill > 0)) || (n > 0)) {
+        if (wp->w_topfill > n) {
+          wp->w_topfill = (n < 0 ? 0 : n);
+        } else if ((n > 0) && (n > wp->w_topfill)) {
+          wp->w_topfill = n;
+        }
+      }
+    }
+  }
+}
+
+/// Write buffer "buf" to file "name".
+///
+/// Always use 'fileformat' set to "unix".
+///
+/// @param buf
+/// @param fname
+///
+/// @return FAIL for failure
+static int diff_write(buf_T *buf, char_u *fname)
+{
+  char_u *save_ff = buf->b_p_ff;
+  buf->b_p_ff = vim_strsave((char_u *)FF_UNIX);
+  int r = buf_write(buf, fname, NULL, (linenr_T)1, buf->b_ml.ml_line_count,
+                    NULL, FALSE, FALSE, FALSE, TRUE);
+  free_string_option(buf->b_p_ff);
+  buf->b_p_ff = save_ff;
+  return r;
+}
+
+/// Completely update the diffs for the buffers involved.
+///
+/// This uses the ordinary "diff" command.
+/// The buffers are written to a file, also for unmodified buffers (the file
+/// could have been produced by autocommands, e.g. the netrw plugin).
+///
+/// @param eap can be NULL
+void ex_diffupdate(exarg_T *eap)
+{
+  // Delete all diffblocks.
+  diff_clear(curtab);
+  curtab->tp_diff_invalid = FALSE;
+
+  // Use the first buffer as the original text.
+  int idx_orig;
+  for (idx_orig = 0; idx_orig < DB_COUNT; ++idx_orig) {
+    if (curtab->tp_diffbuf[idx_orig] != NULL) {
+      break;
+    }
+  }
+
+  if (idx_orig == DB_COUNT) {
+    return;
+  }
+
+  // Only need to do something when there is another buffer.
+  int idx_new;
+  for (idx_new = idx_orig + 1; idx_new < DB_COUNT; ++idx_new) {
+    if (curtab->tp_diffbuf[idx_new] != NULL) {
+      break;
+    }
+  }
+
+  if (idx_new == DB_COUNT) {
+    return;
+  }
+
+  // We need three temp file names.
+  char_u *tmp_orig = vim_tempname('o');
+  char_u *tmp_new = vim_tempname('n');
+  char_u *tmp_diff = vim_tempname('d');
+
+  if ((tmp_orig == NULL) || (tmp_new == NULL) || (tmp_diff == NULL)) {
+    goto theend;
+  }
+
+  // Do a quick test if "diff" really works.  Otherwise it looks like there
+  // are no differences.  Can't use the return value, it's non-zero when
+  // there are differences.
+  // May try twice, first with "-a" and then without.
+  int io_error = FALSE;
+  int ok = FALSE;
+  for (;;) {
+    ok = FALSE;
+    FILE *fd = mch_fopen((char *)tmp_orig, "w");
+
+    if (fd == NULL) {
+      io_error = TRUE;
+    } else {
+      if (fwrite("line1\n", (size_t)6, (size_t)1, fd) != 1) {
+        io_error = TRUE;
+      }
+      fclose(fd);
+      fd = mch_fopen((char *)tmp_new, "w");
+
+      if (fd == NULL) {
+        io_error = TRUE;
+      } else {
+        if (fwrite("line2\n", (size_t)6, (size_t)1, fd) != 1) {
+          io_error = TRUE;
+        }
+        fclose(fd);
+        diff_file(tmp_orig, tmp_new, tmp_diff);
+        fd = mch_fopen((char *)tmp_diff, "r");
+
+        if (fd == NULL) {
+          io_error = TRUE;
+        } else {
+          char_u linebuf[LBUFLEN];
+
+          for (;;) {
+            // There must be a line that contains "1c1".
+            if (tag_fgets(linebuf, LBUFLEN, fd)) {
+              break;
+            }
+
+            if (STRNCMP(linebuf, "1c1", 3) == 0) {
+              ok = TRUE;
+            }
+          }
+          fclose(fd);
+        }
+        os_remove((char *)tmp_diff);
+        os_remove((char *)tmp_new);
+      }
+      os_remove((char *)tmp_orig);
+    }
+
+    // When using 'diffexpr' break here.
+    if (*p_dex != NUL) {
+      break;
+    }
+
+    // If we checked if "-a" works already, break here.
+    if (diff_a_works != MAYBE) {
+      break;
+    }
+    diff_a_works = ok;
+
+    // If "-a" works break here, otherwise retry without "-a".
+    if (ok) {
+      break;
+    }
+  }
+
+  if (!ok) {
+    if (io_error) {
+      EMSG(_("E810: Cannot read or write temp files"));
+    }
+    EMSG(_("E97: Cannot create diffs"));
+    diff_a_works = MAYBE;
+    goto theend;
+  }
+
+  // :diffupdate!
+  if ((eap != NULL) && eap->forceit) {
+    for (idx_new = idx_orig; idx_new < DB_COUNT; ++idx_new) {
+      buf_T *buf = curtab->tp_diffbuf[idx_new];
+      if (buf_valid(buf)) {
+        buf_check_timestamp(buf, FALSE);
+      }
+    }
+  }
+
+  // Write the first buffer to a tempfile.
+  buf_T *buf = curtab->tp_diffbuf[idx_orig];
+  if (diff_write(buf, tmp_orig) == FAIL) {
+    goto theend;
+  }
+
+  // Make a difference between the first buffer and every other.
+  for (idx_new = idx_orig + 1; idx_new < DB_COUNT; ++idx_new) {
+    buf_T *buf = curtab->tp_diffbuf[idx_new];
+    if (buf == NULL) {
+      continue;
+    }
+
+    if (diff_write(buf, tmp_new) == FAIL) {
+      continue;
+    }
+    diff_file(tmp_orig, tmp_new, tmp_diff);
+
+    // Read the diff output and add each entry to the diff list.
+    diff_read(idx_orig, idx_new, tmp_diff);
+    os_remove((char *)tmp_diff);
+    os_remove((char *)tmp_new);
+  }
+  os_remove((char *)tmp_orig);
+
+  // force updating cursor position on screen
+  curwin->w_valid_cursor.lnum = 0;
+
+  diff_redraw(TRUE);
+
+theend:
+  free(tmp_orig);
+  free(tmp_new);
+  free(tmp_diff);
+}
+
+/// Make a diff between files "tmp_orig" and "tmp_new", results in "tmp_diff".
+///
+/// @param tmp_orig
+/// @param tmp_new
+/// @param tmp_diff
+static void diff_file(char_u *tmp_orig, char_u *tmp_new, char_u *tmp_diff)
+{
+  if (*p_dex != NUL) {
+    // Use 'diffexpr' to generate the diff file.
+    eval_diff(tmp_orig, tmp_new, tmp_diff);
+  } else {
+    size_t len = STRLEN(tmp_orig) + STRLEN(tmp_new) + STRLEN(tmp_diff)
+        + STRLEN(p_srr) + 27;
+    char_u *cmd = xmalloc(len);
+
+    /* We don't want $DIFF_OPTIONS to get in the way. */
+    if (os_getenv("DIFF_OPTIONS")) {
+      vim_setenv((char_u *)"DIFF_OPTIONS", (char_u *)"");
+    }
+
+    /* Build the diff command and execute it.  Always use -a, binary
+     * differences are of no use.  Ignore errors, diff returns
+     * non-zero when differences have been found. */
+    vim_snprintf((char *)cmd, len, "diff %s%s%s%s%s %s",
+                 diff_a_works == FALSE ? "" : "-a ",
+                 "",
+                 (diff_flags & DIFF_IWHITE) ? "-b " : "",
+                 (diff_flags & DIFF_ICASE) ? "-i " : "",
+                 tmp_orig, tmp_new);
+    append_redir(cmd, (int)len, p_srr, tmp_diff);
+    block_autocmds(); /* Avoid ShellCmdPost stuff */
+    (void)call_shell(
+        cmd,
+        kShellOptFilter | kShellOptSilent | kShellOptDoOut,
+        NULL
+        );
+    unblock_autocmds();
+    free(cmd);
+  }
+}
+
+/// Create a new version of a file from the current buffer and a diff file.
+///
+/// The buffer is written to a file, also for unmodified buffers (the file
+/// could have been produced by autocommands, e.g. the netrw plugin).
+///
+/// @param eap
+void ex_diffpatch(exarg_T *eap)
+{
+  char_u *buf = NULL;
+  win_T *old_curwin = curwin;
+  char_u *newname = NULL; // name of patched file buffer
+
+#ifdef UNIX
+  char_u dirbuf[MAXPATHL];
+  char_u *fullname = NULL;
+#endif  // ifdef UNIX
+  // We need two temp file names.
+  // Name of original temp file.
+  char_u *tmp_orig = vim_tempname('o');
+  // Name of patched temp file.
+  char_u *tmp_new = vim_tempname('n');
+
+  if ((tmp_orig == NULL) || (tmp_new == NULL)) {
+    goto theend;
+  }
+
+  // Write the current buffer to "tmp_orig".
+  if (buf_write(curbuf, tmp_orig, NULL,
+                (linenr_T)1, curbuf->b_ml.ml_line_count,
+                NULL, FALSE, FALSE, FALSE, TRUE) == FAIL) {
+    goto theend;
+  }
+
+#ifdef UNIX
+  // Get the absolute path of the patchfile, changing directory below.
+  fullname = FullName_save(eap->arg, FALSE);
+#endif  // ifdef UNIX
+
+#ifdef UNIX
+  size_t buflen = STRLEN(tmp_orig)
+      + (fullname != NULL ? STRLEN(fullname) : STRLEN(eap->arg))
+      + STRLEN(tmp_new) + 16;
+#else
+  size_t buflen = STRLEN(tmp_orig) + (STRLEN(eap->arg)) + STRLEN(tmp_new) + 16;
+#endif  // ifdef UNIX
+
+  buf = xmalloc(buflen);
+
+#ifdef UNIX
+
+  // Temporarily chdir to /tmp, to avoid patching files in the current
+  // directory when the patch file contains more than one patch.  When we
+  // have our own temp dir use that instead, it will be cleaned up when we
+  // exit (any .rej files created).  Don't change directory if we can't
+  // return to the current.
+  if ((os_dirname(dirbuf, MAXPATHL) != OK)
+      || (os_chdir((char *)dirbuf) != 0)) {
+    dirbuf[0] = NUL;
+  } else {
+# ifdef TEMPDIRNAMES
+    if (vim_tempdir != NULL) {
+      ignored = os_chdir((char *)vim_tempdir);
+    } else {
+      ignored = os_chdir("/tmp");
+    }
+# else
+    ignored = os_chdir("/tmp");
+# endif  // ifdef TEMPDIRNAMES
+    shorten_fnames(TRUE);
+  }
+#endif  // ifdef UNIX
+
+  if (*p_pex != NUL) {
+    // Use 'patchexpr' to generate the new file.
+#ifdef UNIX
+    eval_patch(tmp_orig, fullname != NULL ? fullname : eap->arg, tmp_new);
+#else
+    eval_patch(tmp_orig, eap->arg, tmp_new);
+#endif  // ifdef UNIX
+  } else {
+    // Build the patch command and execute it. Ignore errors. Switch to
+    // cooked mode to allow the user to respond to prompts.
+#ifdef UNIX
+    vim_snprintf((char *)buf, buflen, "patch -o %s %s < \"%s\"",
+                 tmp_new, tmp_orig, fullname != NULL ? fullname : eap->arg);
+#else
+    vim_snprintf((char *)buf, buflen, "patch -o %s %s < \"%s\"",
+                 tmp_new, tmp_orig, eap->arg);
+#endif  // ifdef UNIX
+    // Avoid ShellCmdPost stuff
+    block_autocmds();
+    (void)call_shell(buf, kShellOptFilter | kShellOptCooked, NULL);
+    unblock_autocmds();
+  }
+
+#ifdef UNIX
+  if (dirbuf[0] != NUL) {
+    if (os_chdir((char *)dirbuf) != 0) {
+      EMSG(_(e_prev_dir));
+    }
+    shorten_fnames(TRUE);
+  }
+#endif  // ifdef UNIX
+
+  // patch probably has written over the screen
+  redraw_later(CLEAR);
+
+  // Delete any .orig or .rej file created.
+  STRCPY(buf, tmp_new);
+  STRCAT(buf, ".orig");
+  os_remove((char *)buf);
+  STRCPY(buf, tmp_new);
+  STRCAT(buf, ".rej");
+  os_remove((char *)buf);
+
+  // Only continue if the output file was created.
+  off_t file_size;
+  bool file_size_success = os_get_file_size((char *)tmp_new, &file_size);
+  if (!file_size_success || file_size == 0) {
+    EMSG(_("E816: Cannot read patch output"));
+  } else {
+    if (curbuf->b_fname != NULL) {
+      newname = vim_strnsave(curbuf->b_fname,
+                             (int)(STRLEN(curbuf->b_fname) + 4));
+
+      if (newname != NULL) {
+        STRCAT(newname, ".new");
+      }
+    }
+
+    // don't use a new tab page, each tab page has its own diffs
+    cmdmod.tab = 0;
+
+    if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL) {
+      // Pretend it was a ":split fname" command
+      eap->cmdidx = CMD_split;
+      eap->arg = tmp_new;
+      do_exedit(eap, old_curwin);
+
+      // check that split worked and editing tmp_new
+      if ((curwin != old_curwin) && win_valid(old_curwin)) {
+        // Set 'diff', 'scrollbind' on and 'wrap' off.
+        diff_win_options(curwin, TRUE);
+        diff_win_options(old_curwin, TRUE);
+
+        if (newname != NULL) {
+          // do a ":file filename.new" on the patched buffer
+          eap->arg = newname;
+          ex_file(eap);
+
+          // Do filetype detection with the new name.
+          if (au_has_group((char_u *)"filetypedetect")) {
+            do_cmdline_cmd((char_u *)":doau filetypedetect BufRead");
+          }
+        }
+      }
+    }
+  }
+
+theend:
+  if (tmp_orig != NULL) {
+    os_remove((char *)tmp_orig);
+  }
+  free(tmp_orig);
+
+  if (tmp_new != NULL) {
+    os_remove((char *)tmp_new);
+  }
+  free(tmp_new);
+  free(newname);
+  free(buf);
+#ifdef UNIX
+  free(fullname);
+#endif  // ifdef UNIX
+}
+
+/// Split the window and edit another file, setting options to show the diffs.
+///
+/// @param eap
+void ex_diffsplit(exarg_T *eap)
+{
+  win_T *old_curwin = curwin;
+
+  // don't use a new tab page, each tab page has its own diffs
+  cmdmod.tab = 0;
+
+  if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL) {
+    // Pretend it was a ":split fname" command
+    eap->cmdidx = CMD_split;
+    curwin->w_p_diff = TRUE;
+    do_exedit(eap, old_curwin);
+
+    // split must have worked
+    if (curwin != old_curwin) {
+      // Set 'diff', 'scrollbind' on and 'wrap' off.
+      diff_win_options(curwin, TRUE);
+      diff_win_options(old_curwin, TRUE);
+    }
+  }
+}
+
+// Set options to show diffs for the current window.
+void ex_diffthis(exarg_T *eap)
+{
+  // Set 'diff', 'scrollbind' on and 'wrap' off.
+  diff_win_options(curwin, TRUE);
+}
+
+/// Set options in window "wp" for diff mode.
+///
+/// @param addbuf Add buffer to diff.
+void diff_win_options(win_T *wp, int addbuf)
+{
+  win_T *old_curwin = curwin;
+
+  // close the manually opened folds
+  curwin = wp;
+  newFoldLevel();
+  curwin = old_curwin;
+
+  wp->w_p_diff = TRUE;
+
+  // Use 'scrollbind' and 'cursorbind' when available
+  if (!wp->w_p_diff_saved) {
+    wp->w_p_scb_save = wp->w_p_scb;
+  }
+  wp->w_p_scb = TRUE;
+
+  if (!wp->w_p_diff_saved) {
+    wp->w_p_crb_save = wp->w_p_crb;
+  }
+  wp->w_p_crb = TRUE;
+
+  if (!wp->w_p_diff_saved) {
+    wp->w_p_wrap_save = wp->w_p_wrap;
+  }
+  wp->w_p_wrap = FALSE;
+  curwin = wp;
+  curbuf = curwin->w_buffer;
+
+  if (!wp->w_p_diff_saved) {
+    wp->w_p_fdm_save = vim_strsave(wp->w_p_fdm);
+  }
+  set_string_option_direct((char_u *)"fdm", -1, (char_u *)"diff",
+                           OPT_LOCAL | OPT_FREE, 0);
+  curwin = old_curwin;
+  curbuf = curwin->w_buffer;
+
+  if (!wp->w_p_diff_saved) {
+    wp->w_p_fdc_save = wp->w_p_fdc;
+    wp->w_p_fen_save = wp->w_p_fen;
+    wp->w_p_fdl_save = wp->w_p_fdl;
+  }
+  wp->w_p_fdc = diff_foldcolumn;
+  wp->w_p_fen = TRUE;
+  wp->w_p_fdl = 0;
+  foldUpdateAll(wp);
+
+  // make sure topline is not halfway a fold
+  changed_window_setting_win(wp);
+  if (vim_strchr(p_sbo, 'h') == NULL) {
+    do_cmdline_cmd((char_u *)"set sbo+=hor");
+  }
+
+  // Saved the current values, to be restored in ex_diffoff().
+  wp->w_p_diff_saved = TRUE;
+
+  if (addbuf) {
+    diff_buf_add(wp->w_buffer);
+  }