Fossil

*******************************************************************************
**
** This file implements the undo/redo functionality.
*/
#include "config.h"
#include "undo.h"

#if INTERFACE
/*
** Possible return values from the undo_maybe_save() routine.
*/
#define UNDO_NONE     (0) /* Placeholder only used to initialize vars. */
#define UNDO_SAVED_OK (1) /* The specified file was saved succesfully. */
#define UNDO_DISABLED (2) /* File not saved, subsystem is disabled. */
#define UNDO_INACTIVE (3) /* File not saved, subsystem is not active. */
#define UNDO_TOOBIG   (4) /* File not saved, it exceeded a size limit. */
#endif

/*
** Undo the change to the file zPathname.  zPathname is the pathname
** of the file relative to the root of the repository.  If redoFlag is
** true the redo a change.  If there is nothing to undo (or redo) then
** this routine is a noop.
*/

    old_exists = db_column_int(&q, 1);
    old_exe = db_column_int(&q, 2);
    if( old_exists ){
      db_ephemeral_blob(&q, 0, &new);
    }
    if( old_exists ){
      if( new_exists ){
        fossil_print("%s   %s\n", redoFlag ? "REDO" : "UNDO", zPathname);
      }else{
        fossil_print("NEW    %s\n", zPathname);
      }
      create_symlink_or_file(new_exists, old_link, new_link, &new, zFullname);
      file_wd_setexe(zFullname, old_exe);
    }else{
      fossil_print("DELETE %s\n", zPathname);
      file_delete(zFullname);
    }

/*
** Save the current content of the file zPathname so that it
** will be undoable.  The name is relative to the root of the
** tree.
*/
void undo_save(const char *zPathname){
  if( undoDisable ) return;
  if( undo_maybe_save(zPathname, -1)!=UNDO_SAVED_OK ){
    fossil_panic("failed to save undo information for path: %s",
                 zPathname);
  }
}

/*
** Possibly save the current content of the file zPathname so
** that it will be undoable.  The name is relative to the root
** of the tree.  The limit argument may be used to specify the
** maximum size for the file to be saved.  If the size of the
** specified file exceeds this size limit (in bytes), it will
** not be saved and an appropriate code will be returned.
**
** WARNING: Please do NOT call this function with a limit
**          value less than zero, call the undo_save()
**          function instead.
**
** The return value of this function will always be one of the
** following codes:
**
** UNDO_SAVED_OK: The specified file was saved succesfully.
**
** UNDO_DISABLED: The specified file was NOT saved, because the
**                "undo subsystem" is disabled.  This error may
**                indicate that a call to undo_disable() was
**                issued.
**
** UNDO_INACTIVE: The specified file was NOT saved, because the
**                "undo subsystem" is not active.  This error
**                may indicate that a call to undo_begin() is
**                missing.
**
**   UNDO_TOOBIG: The specified file was NOT saved, because it
**                exceeded the specified size limit.  It is
**                impossible for this value to be returned if
**                the specified size limit is less than zero
**                (i.e. unlimited).
*/
int undo_maybe_save(const char *zPathname, i64 limit){
  char *zFullname;


  i64 size;
  int result;


  if( undoDisable ) return UNDO_DISABLED;
  if( !undoActive ) return UNDO_INACTIVE;
  zFullname = mprintf("%s%s", g.zLocalRoot, zPathname);
  size = file_wd_size(zFullname);
  if( limit<0 || size<=limit ){
    int existsFlag = (size>=0);
    int isLink = file_wd_islink(zFullname);
    Stmt q;
    Blob content;
    db_prepare(&q,
      "INSERT OR IGNORE INTO"
      "   undo(pathname,redoflag,existsflag,isExe,isLink,content)"
      " VALUES(%Q,0,%d,%d,%d,:c)",
      zPathname, existsFlag, file_wd_isexe(zFullname), isLink
    );
    if( existsFlag ){
      if( isLink ){
        blob_read_link(&content, zFullname);
      }else{
        blob_read_from_file(&content, zFullname);
      }
      db_bind_blob(&q, ":c", &content);
    }

    db_step(&q);
    db_finalize(&q);
    if( existsFlag ){
      blob_reset(&content);
    }
    undoNeedRollback = 1;
    result = UNDO_SAVED_OK;
  }else{
    result = UNDO_TOOBIG;
  }
  free(zFullname);
  return result;
}

/*
** Returns an error message for the undo_maybe_save() return code.
** Currently, this function assumes that the caller is using the
** returned error message in a context prefixed with "because".
*/
const char *undo_save_message(int rc){
  static char zRc[32];

  switch( rc ){
    case UNDO_NONE:     return "undo is disabled for this operation";
    case UNDO_SAVED_OK: return "the save operation was successful";
    case UNDO_DISABLED: return "the undo subsystem is disabled";
    case UNDO_INACTIVE: return "the undo subsystem is inactive";
    case UNDO_TOOBIG:   return "the file is too big";
    default: {
      sqlite3_snprintf(sizeof(zRc), zRc, "of error code %d", rc);
    }
  }
  return zRc;
}

/*
** Make the current state of stashid undoable.
*/
void undo_save_stash(int stashid){
  const char *zDb = db_name("localdb");

** Undo the changes to the working checkout caused by the most recent
** of the following operations:
**
**    (1) fossil update             (5) fossil stash apply
**    (2) fossil merge              (6) fossil stash drop
**    (3) fossil revert             (7) fossil stash goto
**    (4) fossil stash pop
**
** The "fossil clean" operation can also be undone; however, this is
** currently limited to files that are less than 10MiB in size.
**
** If FILENAME is specified then restore the content of the named
** file(s) but otherwise leave the update or merge or revert in effect.
** The redo command undoes the effect of the most recent undo.
**
** If the -n|--dry-run option is present, no changes are made and instead
** the undo or redo command explains what actions the undo or redo would

      int i;
      if( undo_available==0 ){
        fossil_fatal("nothing to %s", zCmd);
      }
      for(i=2; i<g.argc; i++){
        const char *zFile = g.argv[i];
        Blob path;
        file_tree_name(zFile, &path, 0, 1);
        undo_one(blob_str(&path), isRedo);
        blob_reset(&path);
      }
    }
    vid2 = db_lget_int("checkout", 0);
    if( vid1!=vid2 ){
      fossil_print("--------------------\n");
      show_common_info(vid2, "updated-to:", 1, 0);
    }
  }
  db_end_transaction(0);
}