SQLite

/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.165 2004/06/13 23:07:04 drh Exp $
** $Id: btree.c,v 1.166 2004/06/14 06:03:57 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.

/*
** Return the full pathname of the underlying database file.
*/
const char *sqlite3BtreeGetFilename(Btree *pBt){
  assert( pBt->pPager!=0 );
  return sqlite3pager_filename(pBt->pPager);
}

/*
** Return the pathname of the directory that contains the database file.
*/
const char *sqlite3BtreeGetDirname(Btree *pBt){
  assert( pBt->pPager!=0 );
  return sqlite3pager_dirname(pBt->pPager);
}

/*
** Return the pathname of the journal file for this database. The return
** value of this routine is the same regardless of whether the journal file
** has been created or not.
*/
const char *sqlite3BtreeGetJournalname(Btree *pBt){
  assert( pBt->pPager!=0 );
  return sqlite3pager_journalname(pBt->pPager);
}

/*
** Copy the complete content of pBtFrom into pBtTo.  A transaction
** must be active for both files.
**
** The size of file pBtFrom may be reduced by this operation.
** If anything goes wrong, the transaction on pBtFrom is rolled back.

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite B-Tree file
** subsystem.  See comments in the source code for a detailed description
** of what each interface routine does.
**
** @(#) $Id: btree.h,v 1.53 2004/06/04 06:22:01 danielk1977 Exp $
** @(#) $Id: btree.h,v 1.54 2004/06/14 06:03:57 danielk1977 Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/

int sqlite3BtreeRollbackStmt(Btree*);
int sqlite3BtreeCreateTable(Btree*, int*, int flags);
int sqlite3BtreeIsInTrans(Btree*);
int sqlite3BtreeIsInStmt(Btree*);
int sqlite3BtreeSync(Btree*, const char *zMaster);

const char *sqlite3BtreeGetFilename(Btree *);
const char *sqlite3BtreeGetDirname(Btree *);
const char *sqlite3BtreeGetJournalname(Btree *);
int sqlite3BtreeCopyFile(Btree *, Btree *);

/* The flags parameter to sqlite3BtreeCreateTable can be the bitwise OR
** of the following flags:
*/
#define BTREE_INTKEY     1    /* Table has only 64-bit signed integer keys */
#define BTREE_ZERODATA   2    /* Table has keys only - no data */

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.125 2004/06/14 05:10:43 danielk1977 Exp $
** @(#) $Id: pager.c,v 1.126 2004/06/14 06:03:57 danielk1977 Exp $
*/
#include "os.h"         /* Must be first to enable large file support */
#include "sqliteInt.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

  /* Open the master journal file exclusively in case some other process
  ** is running this routine also. Not that it makes too much difference.
  */
  rc = sqlite3OsOpenExclusive(zMaster, &master, 0);
  if( rc!=SQLITE_OK ) goto delmaster_out;
  master_open = 1;

  rc = sqlite3OsFileSize(&master, &nMasterJournal);
  if( rc!=SQLITE_OK ) goto delmaster_out;

  if( nMasterJournal>0 ){
    char *zDb;
    zMasterJournal = (char *)sqliteMalloc(nMasterJournal);
    char *zJournal;
    char *zMasterPtr;
    int nMasterPtr;   /* Number of bytes allocated at zMasterPtr */

    /* Load the entire master journal file into space obtained from
    ** sqliteMalloc() and pointed to by zMasterJournal. 
    **
    ** Also allocate an extra (strlen(zMaster)+1) bytes. This space is used
    ** to load a master-journal filename from some other journal file to
    ** check if it points at this master journal file.
    */
    nMasterPtr = strlen(zMaster) + 1;
    zMasterJournal = (char *)sqliteMalloc(nMasterJournal) + nMasterPtr;
    if( !zMasterJournal ){
      rc = SQLITE_NOMEM;
      goto delmaster_out;
    }
    zMasterPtr = &zMasterJournal[nMasterJournal];
    rc = sqlite3OsRead(&master, zMasterJournal, nMasterJournal);
    if( rc!=SQLITE_OK ) goto delmaster_out;

    zDb = zMasterJournal;
    while( (zDb-zMasterJournal)<nMasterJournal ){
    zJournal = zMasterJournal;
    while( (zJournal-zMasterJournal)<nMasterJournal ){
      char *zJournal = 0;
      /*** FIX ME:  Store the full journal name in the master journal,
      **** not just the base database name. ***/
      sqlite3SetString(&zJournal, zDb, "-journal", 0);
      if( !zJournal ){
        rc = SQLITE_NOMEM;
        goto delmaster_out;
      }
      if( sqlite3OsFileExists(zJournal) ){
        /* One of the journals pointed to by the master journal exists.
        ** Open it and check if it points at the master journal. If
        ** so, return without deleting the master journal file.
        */
        OsFile journal;
        int nMaster;
        off_t jsz;

        rc = sqlite3OsOpenReadOnly(zJournal, &journal);
        sqliteFree(zJournal);
        if( rc!=SQLITE_OK ){
          sqlite3OsClose(&journal);
          goto delmaster_out;
        }

	/* Check if the file is big enough to be a journal file
        ** with the required master journal name. If not, ignore it.

        ** is stored. Read the master journal name into memory obtained
        ** from malloc.
        */
        rc = sqlite3OsSeek(&journal, 20);
        if( rc!=SQLITE_OK ) goto delmaster_out;
        rc = read32bits(&journal, (u32*)&nMaster);
        if( rc!=SQLITE_OK ) goto delmaster_out;
        if( nMaster>0 && nMaster>=strlen(zMaster)+1 ){
          /*** FIX ME: Consider allocating this space at the same time
          **** space is allocated for holding the text of the master journal */
          char *zMasterPtr = (char *)sqliteMalloc(nMaster);
          if( !zMasterPtr ){
        if( nMaster>=nMasterPtr ){
            rc = SQLITE_NOMEM;
          }
          rc = sqlite3OsRead(&journal, zMasterPtr, nMaster);
          rc = sqlite3OsRead(&journal, zMasterPtr, nMasterPtr);
          if( rc!=SQLITE_OK ){
            sqliteFree(zMasterPtr);
            goto delmaster_out;
          }
          if( 0==strncmp(zMasterPtr, zMaster, nMaster) ){
          if( zMasterPtr[nMasterPtr-1]=='\0' && !strcmp(zMasterPtr, zMaster) ){
            /* We have a match. Do not delete the master journal file. */
            sqliteFree(zMasterPtr);
            goto delmaster_out;
          }
        }
      }
      zDb += (strlen(zDb)+1);
      zJournal += (strlen(zJournal)+1);
    }
  }
  
  sqlite3OsDelete(zMaster);

delmaster_out:
  if( zMasterJournal ){

/*
** Return the full pathname of the database file.
*/
const char *sqlite3pager_filename(Pager *pPager){
  return pPager->zFilename;
}

/*
** Return the directory of the database file.
*/
const char *sqlite3pager_dirname(Pager *pPager){
  return pPager->zDirectory;
}

/*
** Return the full pathname of the journal file.
*/
const char *sqlite3pager_journalname(Pager *pPager){
  return pPager->zJournal;
}

/*
** Set the codec for this pager
*/
void sqlite3pager_set_codec(
  Pager *pPager,
  void (*xCodec)(void*,void*,Pgno,int),

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite page cache
** subsystem.  The page cache subsystem reads and writes a file a page
** at a time and provides a journal for rollback.
**
** @(#) $Id: pager.h,v 1.33 2004/06/09 17:37:28 drh Exp $
** @(#) $Id: pager.h,v 1.34 2004/06/14 06:03:57 danielk1977 Exp $
*/

/*
** The size of a page.
**
** You can change this value to another (reasonable) value you want.
** It need not be a power of two, though the interface to the disk

int sqlite3pager_stmt_commit(Pager*);
int sqlite3pager_stmt_rollback(Pager*);
void sqlite3pager_dont_rollback(void*);
void sqlite3pager_dont_write(Pager*, Pgno);
int *sqlite3pager_stats(Pager*);
void sqlite3pager_set_safety_level(Pager*,int);
const char *sqlite3pager_filename(Pager*);
const char *sqlite3pager_dirname(Pager*);
const char *sqlite3pager_journalname(Pager*);
int sqlite3pager_rename(Pager*, const char *zNewName);
void sqlite3pager_set_codec(Pager*,void(*)(void*,void*,Pgno,int),void*);

#ifdef SQLITE_DEBUG
int sqlite3pager_lockstate(Pager*);
#endif

#ifdef SQLITE_TEST
void sqlite3pager_refdump(Pager*);
int pager3_refinfo_enable;
#endif

    ** still have 'null' as the master journal pointer, so they will roll
    ** back independantly if a failure occurs.
    */
    for(i=0; i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( i==1 ) continue;   /* Ignore the TEMP database */
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        char const *zFile = sqlite3BtreeGetFilename(pBt);
        char const *zFile = sqlite3BtreeGetJournalname(pBt);
        if( zFile[0]==0 ) continue;  /* Ignore :memory: databases */
        rc = sqlite3OsWrite(&master, zFile, strlen(zFile)+1);
        if( rc!=SQLITE_OK ){
          sqlite3OsClose(&master);
          sqlite3OsDelete(zMaster);
          sqliteFree(zMaster);
          return rc;
        }
      }
    }


    /* Sync the master journal file */
    rc = sqlite3OsSync(&master);
    sqlite3OsClose(&master);

    /* FIXME:  Sync the directory that contains the master journal to
    /* Sync the master journal file. Before doing this, open the directory
    ** the master journal file is store in so that it gets synced too.
    */
    zMainFile = sqlite3BtreeGetDirname(db->aDb[0].pBt);
    rc = sqlite3OsOpenDirectory(zMainFile, &master);
    if( rc!=SQLITE_OK ){
      sqlite3OsClose(&master);
      sqlite3OsDelete(zMaster);
      sqliteFree(zMaster);
      return rc;
    }
    rc = sqlite3OsSync(&master);
    ** make sure the i-node is up to date. */

    if( rc!=SQLITE_OK ){
      sqliteFree(zMaster);
      return rc;
    }
    sqlite3OsClose(&master);

    /* Sync all the db files involved in the transaction. The same call
    ** sets the master journal pointer in each individual journal. If
    ** an error occurs here, do not delete the master journal file.
    **
    ** If the error occurs during the first call to sqlite3BtreeSync(),
    ** then there is a chance that the master journal file will be
    ** orphaned. But we cannot delete it, in case the master journal