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File src/merge.c part of check-in [36b96b8616] - Rework the merge algorithm. It now only works for text files. But, it no longer gets confused by line endings (\r\n versus \n) and it reports conflicts. by drh on 2007-11-16 20:42:31. Also file src/merge.c part of check-in [d0305b305a] - Merged mainline into my branch to get the newest application. by aku on 2007-12-05 08:07:46.

/*
** Copyright (c) 2007 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public
** License version 2 as published by the Free Software Foundation.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
** General Public License for more details.
** 
** You should have received a copy of the GNU General Public
** License along with this library; if not, write to the
** Free Software Foundation, Inc., 59 Temple Place - Suite 330,
** Boston, MA  02111-1307, USA.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*******************************************************************************
**
** This file contains code used to merge two or more branches into
** a single tree.
*/
#include "config.h"
#include "merge.h"
#include <assert.h>


/*
** COMMAND: merge
**
** Usage: %fossil merge VERSION
**
** The argument is a version that should be merged into the current
** checkout. 
**
** Only file content is merged.  The result continues to use the
** file and directory names from the current check-out even if those
** names might have been changed in the branch being merged in.
*/
void merge_cmd(void){
  int vid;              /* Current version */
  int mid;              /* Version we are merging against */
  int pid;              /* The pivot version - most recent common ancestor */
  Stmt q;
  int detailFlag;

  detailFlag = find_option("detail",0,0)!=0;
  if( g.argc!=3 ){
    usage("VERSION");
  }
  db_must_be_within_tree();
  vid = db_lget_int("checkout", 0);
  if( vid==0 ){
    fossil_panic("nothing is checked out");
  }
  mid = name_to_rid(g.argv[2]);
  if( mid==0 ){
    fossil_panic("not a version: %s", g.argv[2]);
  }
  if( mid>1 && !db_exists("SELECT 1 FROM plink WHERE cid=%d", mid) ){
    fossil_panic("not a version: %s", g.argv[2]);
  }
  pivot_set_primary(mid);
  pivot_set_secondary(vid);
  db_prepare(&q, "SELECT merge FROM vmerge WHERE id=0");
  while( db_step(&q)==SQLITE_ROW ){
    pivot_set_secondary(db_column_int(&q,0));
  }
  db_finalize(&q);
  pid = pivot_find();
  if( pid<=0 ){
    fossil_panic("cannot find a common ancestor between the current"
                 "checkout and %s", g.argv[2]);
  }
  if( pid>1 && !db_exists("SELECT 1 FROM plink WHERE cid=%d", pid) ){
    fossil_panic("not a version: record #%d", mid);
  }
  vfile_check_signature(vid);
  db_begin_transaction();
  undo_begin();
  load_vfile_from_rid(mid);
  load_vfile_from_rid(pid);

  /*
  ** The vfile.pathname field is used to match files against each other.  The
  ** FV table contains one row for each each unique filename in
  ** in the current checkout, the pivot, and the version being merged.
  */
  db_multi_exec(
    "DROP TABLE IF EXISTS fv;"
    "CREATE TEMP TABLE fv("
    "  fn TEXT PRIMARY KEY,"      /* The filename */
    "  idv INTEGER,"              /* VFILE entry for current version */
    "  idp INTEGER,"              /* VFILE entry for the pivot */
    "  idm INTEGER,"              /* VFILE entry for version merging in */
    "  chnged BOOLEAN,"           /* True if current version has been edited */
    "  ridv INTEGER,"             /* Record ID for current version */
    "  ridp INTEGER,"             /* Record ID for pivot */
    "  ridm INTEGER"              /* Record ID for merge */
    ");"
    "INSERT OR IGNORE INTO fv"
    " SELECT pathname, 0, 0, 0, 0, 0, 0, 0 FROM vfile"
  );
  db_prepare(&q,
    "SELECT id, pathname, rid FROM vfile"
    " WHERE vid=%d", pid
  );
  while( db_step(&q)==SQLITE_ROW ){
    int id = db_column_int(&q, 0);
    const char *fn = db_column_text(&q, 1);
    int rid = db_column_int(&q, 2);
    db_multi_exec(
      "UPDATE fv SET idp=%d, ridp=%d WHERE fn=%Q",
      id, rid, fn
    );
  }
  db_finalize(&q);
  db_prepare(&q,
    "SELECT id, pathname, rid FROM vfile"
    " WHERE vid=%d", mid
  );
  while( db_step(&q)==SQLITE_ROW ){
    int id = db_column_int(&q, 0);
    const char *fn = db_column_text(&q, 1);
    int rid = db_column_int(&q, 2);
    db_multi_exec(
      "UPDATE fv SET idm=%d, ridm=%d WHERE fn=%Q",
      id, rid, fn
    );
  }
  db_finalize(&q);
  db_prepare(&q,
    "SELECT id, pathname, rid, chnged FROM vfile"
    " WHERE vid=%d", vid
  );
  while( db_step(&q)==SQLITE_ROW ){
    int id = db_column_int(&q, 0);
    const char *fn = db_column_text(&q, 1);
    int rid = db_column_int(&q, 2);
    int chnged = db_column_int(&q, 3);
    db_multi_exec(
      "UPDATE fv SET idv=%d, ridv=%d, chnged=%d WHERE fn=%Q",
      id, rid, chnged, fn
    );
  }
  db_finalize(&q);

  /*
  ** Find files in mid and vid but not in pid and report conflicts.
  ** The file in mid will be ignored.  It will be treated as if it
  ** does not exist.
  */
  db_prepare(&q,
    "SELECT idm FROM fv WHERE idp=0 AND idv>0 AND idm>0"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idm = db_column_int(&q, 0);
    char *zName = db_text(0, "SELECT pathname FROM vfile WHERE id=%d", idm);
    printf("WARNING: conflict on %s\n", zName);
    free(zName);
    db_multi_exec("UPDATE fv SET idm=0 WHERE idm=%d", idm);
  }
  db_finalize(&q);

  /*
  ** Add to vid files that are not in pid but are in mid
  */
  db_prepare(&q, 
    "SELECT idm, rowid, fn FROM fv WHERE idp=0 AND idv=0 AND idm>0"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idm = db_column_int(&q, 0);
    int rowid = db_column_int(&q, 1);
    int idv;
    const char *zName;
    db_multi_exec(
      "INSERT INTO vfile(vid,chnged,deleted,rid,mrid,pathname)"
      "  SELECT %d,3,0,rid,mrid,pathname FROM vfile WHERE id=%d",
      vid, idm
    );
    idv = db_last_insert_rowid();
    db_multi_exec("UPDATE fv SET idv=%d WHERE rowid=%d", idv, rowid);
    zName = db_column_text(&q, 2);
    printf("ADDED %s\n", zName);
    undo_save(zName);
    vfile_to_disk(0, idm, 0);
  }
  db_finalize(&q);
  
  /*
  ** Find files that have changed from pid->mid but not pid->vid. 
  ** Copy the mid content over into vid.
  */
  db_prepare(&q,
    "SELECT idv, ridm FROM fv"
    " WHERE idp>0 AND idv>0 AND idm>0"
    "   AND ridm!=ridp AND ridv=ridp AND NOT chnged"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idv = db_column_int(&q, 0);
    int ridm = db_column_int(&q, 1);
    char *zName = db_text(0, "SELECT pathname FROM vfile WHERE id=%d", idv);
    /* Copy content from idm over into idv.  Overwrite idv. */
    printf("UPDATE %s\n", zName);
    undo_save(zName);
    db_multi_exec(
      "UPDATE vfile SET mrid=%d, chnged=2 WHERE id=%d", ridm, idv
    );
    vfile_to_disk(0, idv, 0);
    free(zName);
  }
  db_finalize(&q);

  /*
  ** Do a three-way merge on files that have changes pid->mid and pid->vid
  */
  db_prepare(&q,
    "SELECT ridm, idv, ridp, ridv FROM fv"
    " WHERE idp>0 AND idv>0 AND idm>0"
    "   AND ridm!=ridp AND (ridv!=ridp OR chnged)"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int ridm = db_column_int(&q, 0);
    int idv = db_column_int(&q, 1);
    int ridp = db_column_int(&q, 2);
    int ridv = db_column_int(&q, 3);
    int rc;
    char *zName = db_text(0, "SELECT pathname FROM vfile WHERE id=%d", idv);
    char *zFullPath;
    Blob m, p, v, r;
    /* Do a 3-way merge of idp->idm into idp->idv.  The results go into idv. */
    if( detailFlag ){
      printf("MERGE %s  (pivot=%d v1=%d v2=%d)\n", zName, ridp, ridm, ridv);
    }else{
      printf("MERGE %s\n", zName);
    }
    undo_save(zName);
    zFullPath = mprintf("%s/%s", g.zLocalRoot, zName);
    content_get(ridp, &p);
    content_get(ridm, &m);
    blob_zero(&v);
    blob_read_from_file(&v, zFullPath);
    rc = blob_merge(&p, &m, &v, &r);
    if( rc>=0 ){
      blob_write_to_file(&r, zFullPath);
      if( rc>0 ){
        printf("***** %d merge conflicts in %s\n", rc, zName);
      }
    }else{
      printf("***** Cannot merge binary file %s\n", zName);
    }
    free(zName);
    blob_reset(&p);
    blob_reset(&m);
    blob_reset(&v);
    blob_reset(&r);
    db_multi_exec("INSERT OR IGNORE INTO vmerge(id,merge) VALUES(%d,%d)",
                  idv,ridm);
  }
  db_finalize(&q);

  /*
  ** Drop files from vid that are in pid but not in mid
  */
  db_prepare(&q,
    "SELECT idv FROM fv"
    " WHERE idp>0 AND idv>0 AND idm=0"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idv = db_column_int(&q, 0);
    char *zName = db_text(0, "SELECT pathname FROM vfile WHERE id=%d", idv);
    /* Delete the file idv */
    printf("DELETE %s\n", zName);
    undo_save(zName);
    db_multi_exec(
      "UPDATE vfile SET deleted=1 WHERE id=%d", idv
    );
    free(zName);
  }
  db_finalize(&q);
  
  /*
  ** Clean up the mid and pid VFILE entries.  Then commit the changes.
  */
  db_multi_exec("DELETE FROM vfile WHERE vid!=%d", vid);
  db_multi_exec("INSERT OR IGNORE INTO vmerge(id,merge) VALUES(0,%d)", mid);
  db_end_transaction(0);
}