SQLite

/*
** 2001 September 15
**
** 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 1.83 2003/02/12 14:09:43 drh 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.

** Synchronous is on by default so database corruption is not
** normally a worry.
*/
int sqliteBtreeSetCacheSize(Btree *pBt, int mxPage){
  sqlitepager_set_cachesize(pBt->pPager, mxPage);
  return SQLITE_OK;
}

/*
** Change the way data is synced to disk in order to increase or decrease
** how well the database resists damage due to OS crashes and power
** failures.  Level 1 is the same as asynchronous (no syncs() occur and
** there is a high probability of damage)  Level 2 is the default.  There
** is a very low but non-zero probability of damage.  Level 3 reduces the
** probability of damage to near zero but with a write performance reduction.
*/
int sqliteBtreeSetSafetyLevel(Btree *pBt, int level){
  sqlitepager_set_safety_level(pBt->pPager, level);
  return SQLITE_OK;
}

/*
** Get a reference to page1 of the database file.  This will
** also acquire a readlock on that file.
**
** SQLITE_OK is returned on success.  If the file is not a
** well-formed database file, then SQLITE_CORRUPT is returned.

**    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 1.27 2003/02/12 14:09:44 drh Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

typedef struct Btree Btree;
typedef struct BtCursor BtCursor;

int sqliteBtreeOpen(const char *zFilename, int mode, int nPg, Btree **ppBtree);
int sqliteBtreeClose(Btree*);
int sqliteBtreeSetCacheSize(Btree*, int);
int sqliteBtreeSetSafetyLevel(Btree*, int);

int sqliteBtreeBeginTrans(Btree*);
int sqliteBtreeCommit(Btree*);
int sqliteBtreeRollback(Btree*);
int sqliteBtreeBeginCkpt(Btree*);
int sqliteBtreeCommitCkpt(Btree*);
int sqliteBtreeRollbackCkpt(Btree*);

int sqliteBtreeKey(BtCursor*, int offset, int amt, char *zBuf);
int sqliteBtreeKeyCompare(BtCursor*, const void *pKey, int nKey,
                          int nIgnore, int *pRes);
int sqliteBtreeDataSize(BtCursor*, int *pSize);
int sqliteBtreeData(BtCursor*, int offset, int amt, char *zBuf);
int sqliteBtreeCloseCursor(BtCursor*);

#define SQLITE_N_BTREE_META 10
int sqliteBtreeGetMeta(Btree*, int*);
int sqliteBtreeUpdateMeta(Btree*, int*);

char *sqliteBtreeIntegrityCheck(Btree*, int*, int);

#ifdef SQLITE_TEST
int sqliteBtreePageDump(Btree*, int, int);
int sqliteBtreeCursorDump(BtCursor*, int*);
struct Pager *sqliteBtreePager(Btree*);
int btree_native_byte_order;
#endif

#endif /* _BTREE_H_ */

**     COPY
**     VACUUM
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.129 2003/02/12 14:09:44 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Check to see if the schema for the database needs

    return atoi(z);
  }
  for(i=0; i<sizeof(azTrue)/sizeof(azTrue[0]); i++){
    if( sqliteStrICmp(z,azTrue[i])==0 ) return 1;
  }
  return 0;
}

/*
** Interpret the given string as a safety level.  Return 0 for OFF,
** 1 for ON or NORMAL and 2 for FULL.
**
** Note that the values returned are one less that the values that
** should be passed into sqliteBtreeSetSafetyLevel().  The is done
** to support legacy SQL code.  The safety level used to be boolean
** and older scripts may have used numbers 0 for OFF and 1 for ON.
*/
static int getSafetyLevel(char *z){
  static const struct {
    const char *zWord;
    int val;
  } aKey[] = {
    { "no",    0 },
    { "off",   0 },
    { "false", 0 },
    { "yes",   1 },
    { "on",    1 },
    { "true",  1 },
    { "full",  2 },
  };
  int i;
  if( z[0]==0 ) return 1;
  if( isdigit(z[0]) || (z[0]=='-' && isdigit(z[1])) ){
    return atoi(z);
  }
  for(i=0; i<sizeof(aKey)/sizeof(aKey[0]); i++){
    if( sqliteStrICmp(z,aKey[i].zWord)==0 ) return aKey[i].val;
  }
  return 1;
}

/*
** Process a pragma statement.  
**
** Pragmas are of this form:
**
**      PRAGMA id = value

      db->cache_size = size;
      sqliteBtreeSetCacheSize(db->pBe, db->cache_size);
    }
  }else

  /*
  **  PRAGMA default_synchronous
  **  PRAGMA default_synchronous=ON|OFF|NORMAL|FULL
  **
  ** The first form returns the persistent value of the "synchronous" setting
  ** that is stored in the database.  This is the synchronous setting that
  ** is used whenever the database is opened unless overridden by a separate
  ** "synchronous" pragma.  The second form changes the persistent and the
  ** local synchronous setting to the value given.
  **
  ** If synchronous is OFF, SQLite does not attempt any fsync() systems calls
  ** to make sure data is committed to disk.  Write operations are very fast,

  ** but a power failure can leave the database in an inconsistent state.

  ** If synchronous is ON or NORMAL, SQLite will do an fsync() system call to
  ** make sure data is being written to disk.  The risk of corruption due to




  ** a power loss in this mode is negligible but non-zero.  If synchronous
  ** is FULL, extra fsync()s occur to reduce the risk of corruption to near
  ** zero, but with a write performance penalty.  The default mode is NORMAL.
  */
  if( sqliteStrICmp(zLeft,"default_synchronous")==0 ){
    static VdbeOp getSync[] = {
      { OP_ColumnName,  0, 0,        "synchronous"},
      { OP_ReadCookie,  0, 3,        0},
      { OP_Dup,         0, 0,        0},
      { OP_If,          0, 0,        0},  /* 3 */
      { OP_ReadCookie,  0, 2,        0},
      { OP_Integer,     0, 0,        0},
      { OP_Lt,          0, 5,        0},
      { OP_AddImm,      1, 0,        0},
      { OP_Callback,    1, 0,        0},
      { OP_Halt,        0, 0,        0},
      { OP_AddImm,     -1, 0,        0},  /* 10 */
      { OP_Callback,    1, 0,        0}
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      int addr = sqliteVdbeAddOpList(v, ArraySize(getSync), getSync);
      sqliteVdbeChangeP2(v, addr+3, addr+10);
    }else{
      int addr;
      int size = db->cache_size;
      if( size<0 ) size = -size;
      sqliteBeginWriteOperation(pParse, 0, 0);
      sqliteVdbeAddOp(v, OP_ReadCookie, 0, 2);
      sqliteVdbeAddOp(v, OP_Dup, 0, 0);
      addr = sqliteVdbeAddOp(v, OP_Integer, 0, 0);
      sqliteVdbeAddOp(v, OP_Ne, 0, addr+3);
      sqliteVdbeAddOp(v, OP_AddImm, MAX_PAGES, 0);
      sqliteVdbeAddOp(v, OP_AbsValue, 0, 0);
      db->safety_level = getSafetyLevel(zRight)+1;
      if( db->safety_level==1 ){
        sqliteVdbeAddOp(v, OP_Negative, 0, 0);
        size = -size;
      }
      sqliteVdbeAddOp(v, OP_SetCookie, 0, 2);
      sqliteVdbeAddOp(v, OP_Integer, db->safety_level, 0);
      sqliteVdbeAddOp(v, OP_SetCookie, 0, 3);
      sqliteEndWriteOperation(pParse);
      db->cache_size = size;
      sqliteBtreeSetCacheSize(db->pBe, db->cache_size);
      sqliteBtreeSetSafetyLevel(db->pBe, db->safety_level);
    }
  }else

  /*
  **   PRAGMA synchronous
  **   PRAGMA synchronous=OFF|ON|NORMAL|FULL
  **
  ** Return or set the local value of the synchronous flag.  Changing
  ** the local value does not make changes to the disk file and the
  ** default value will be restored the next time the database is
  ** opened.
  */
  if( sqliteStrICmp(zLeft,"synchronous")==0 ){
    static VdbeOp getSync[] = {
      { OP_ColumnName,  0, 0,        "synchronous"},
      { OP_Callback,    1, 0,        0},
    };
    Vdbe *v = sqliteGetVdbe(pParse);
    if( v==0 ) return;
    if( pRight->z==pLeft->z ){
      sqliteVdbeAddOp(v, OP_Integer, db->safety_level-1, 0);
      sqliteVdbeAddOpList(v, ArraySize(getSync), getSync);
    }else{
      int size = db->cache_size;
      if( size<0 ) size = -size;
      db->safety_level = getSafetyLevel(zRight)+1;
      if( db->safety_level==1 ) size = -size;
      db->cache_size = size;
      sqliteBtreeSetCacheSize(db->pBe, db->cache_size);
      sqliteBtreeSetSafetyLevel(db->pBe, db->safety_level);
    }
  }else

  if( sqliteStrICmp(zLeft, "trigger_overhead_test")==0 ){
    if( getBoolean(zRight) ){
      always_code_trigger_setup = 1;
    }else{

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.113 2003/02/12 14:09:44 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** A pointer to this structure is used to communicate information

  db->schema_cookie = meta[1];
  db->next_cookie = db->schema_cookie;
  db->file_format = meta[2];
  size = meta[3];
  if( size==0 ){ size = MAX_PAGES; }
  db->cache_size = size;
  sqliteBtreeSetCacheSize(db->pBe, size);
  db->safety_level = meta[4];
  if( db->safety_level==0 ) db->safety_level = 2;
  sqliteBtreeSetSafetyLevel(db->pBe, db->safety_level);

  /*
  **     file_format==1    Version 2.1.0.
  **     file_format==2    Version 2.2.0. Add support for INTEGER PRIMARY KEY.
  **     file_format==3    Version 2.6.0. Fix empty-string index bug.
  **     file_format==4    Version 2.7.0. Add support for separate numeric and
  **                       text datatypes.

** 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 1.75 2003/02/12 14:09:44 drh Exp $
*/
#include "os.h"         /* Must be first to enable large file support */
#include "sqliteInt.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

  u8 inJournal;                  /* TRUE if has been written to journal */
  u8 inCkpt;                     /* TRUE if written to the checkpoint journal */
  u8 dirty;                      /* TRUE if we need to write back changes */
  u8 needSync;                   /* Sync journal before writing this page */
  u8 alwaysRollback;             /* Disable dont_rollback() for this page */
  PgHdr *pDirty;                 /* Dirty pages sorted by PgHdr.pgno */
  /* SQLITE_PAGE_SIZE bytes of page data follow this header */
  /* Pager.nExtra bytes of local data follow the page data */
};

/*
** Convert a pointer to a PgHdr into a pointer to its data
** and back again.
*/
#define PGHDR_TO_DATA(P)  ((void*)(&(P)[1]))

}

/*
** Compute and return a checksum for the page of data.
*/
static u32 pager_cksum(Pager *pPager, Pgno pgno, const char *aData){
  u32 cksum = pPager->cksumInit + pgno;




  return cksum;
}

/*
** Read a single page from the journal file opened on file descriptor
** jfd.  Playback this one page.
**

    pPager->noSync = 1;
    mxPage = -mxPage;
  }
  if( mxPage>10 ){
    pPager->mxPage = mxPage;
  }
}

/*
** Adjust the robustness of the database to damage due to OS crashes
** or power failures by changing the number of syncs()s when writing
** the rollback journal.  There are three levels:
**
**    OFF       sqliteOsSync() is never called.  This is the default
**              for temporary and transient files.
**
**    NORMAL    The journal is synced once before writes begin on the
**              database.  This is normally adequate protection, but
**              it is theoretically possible, though very unlikely,
**              that an inopertune power failure could leave the journal
**              in a state which would cause damage to the database
**              when it is rolled back.
**
**    FULL      The journal is synced twice before writes begin on the
**              database (with some additional information being written
**              in between the two syncs.  If we assume that writing a
**              single disk sector is atomic, then this mode provides
**              assurance that the journal will not be corrupted to the
**              point of causing damage to the database during rollback.
**
** Numeric values associated with these states are OFF==1, NORMAL=2,
** and FULL=3.
*/
void sqlitepager_set_safety_level(Pager *pPager, int level){
  pPager->noSync =  level==1 || pPager->tempFile;
  pPager->fullSync = level==3 && !pPager->tempFile;
}

/*
** Open a temporary file.  Write the name of the file into zName
** (zName must be at least SQLITE_TEMPNAME_SIZE bytes long.)  Write
** the file descriptor into *fd.  Return SQLITE_OK on success or some
** other error code if we fail.
**

**    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 1.20 2003/02/12 14:09:44 drh Exp $
*/

/*
** The size of one page
**
** You can change this value to another (reasonable) power of two
** such as 512, 2048, 4096, or 8192 and things will still work.  But

int sqlitepager_isreadonly(Pager*);
int sqlitepager_ckpt_begin(Pager*);
int sqlitepager_ckpt_commit(Pager*);
int sqlitepager_ckpt_rollback(Pager*);
void sqlitepager_dont_rollback(void*);
void sqlitepager_dont_write(Pager*, Pgno);
int *sqlitepager_stats(Pager*);
void sqlitepager_set_safety_level(Pager*,int);

#ifdef SQLITE_TEST
void sqlitepager_refdump(Pager*);
int pager_refinfo_enable;
int journal_format;
#endif

/*
** 2001 September 15
**
** 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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.161 2003/02/12 14:09:44 drh Exp $
*/
#include "config.h"
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"

**     file_format==4    Version 2.7.0. Add support for separate numeric and
**                       text datatypes.
*/
struct sqlite {
  Btree *pBe;                   /* The B*Tree backend */
  Btree *pBeTemp;               /* Backend for session temporary tables */
  int flags;                    /* Miscellanous flags. See below */
  u8 file_format;               /* What file format version is this database? */
  u8 safety_level;              /* How aggressive at synching data to disk */
  int schema_cookie;            /* Magic number that changes with the schema */
  int next_cookie;              /* Value of schema_cookie after commit */
  int cache_size;               /* Number of pages to use in the cache */
  int nTable;                   /* Number of tables in the database */
  void *pBusyArg;               /* 1st Argument to the busy callback */
  int (*xBusyCallback)(void *,const char*,int);  /* The busy callback */
  Hash tblHash;                 /* All tables indexed by name */

# 2001 September 15
#
# 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.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this script is btree database backend
#
# $Id: btree.test,v 1.14 2003/02/12 14:09:45 drh Exp $


set testdir [file dirname $argv0]
source $testdir/tester.tcl

if {[info commands btree_open]!=""} {

  set r   
} {five 5.00 four 4.00 six 6.00 three 3.00 two 2.00}

# Try to read and write meta data
#
do_test btree-5.1 {
  btree_get_meta $::b1
} {0 0 0 0 0 0 0 0 0 0}
do_test btree-5.2 {
  set rc [catch {btree_update_meta $::b1 1 2 3 4 5 6 7 8 9 10} msg]
  lappend rc $msg
} {1 SQLITE_ERROR}
do_test btree-5.3 {
  btree_begin_transaction $::b1
  set rc [catch {btree_update_meta $::b1 1 2 3 4 5 6 7 8 9 10} msg]
  lappend rc $msg
} {0 {}}
do_test btree-5.4 {
  btree_get_meta $::b1
} {0 2 3 4 5 6 7 8 9 10}
do_test btree-5.5 {
  btree_close_cursor $::c1
  btree_rollback $::b1
  btree_get_meta $::b1
} {0 0 0 0 0 0 0 0 0 0}
do_test btree-5.6 {
  btree_begin_transaction $::b1
  btree_update_meta $::b1 999 10 20 30 40 50 60 70 80 90
  btree_commit $::b1
  btree_get_meta $::b1
} {0 10 20 30 40 50 60 70 80 90}

proc select_all {cursor} {
  set r {}
  btree_move_to $cursor {}
  while 1 {
    set key [btree_key $cursor]
    if {$key==""} break

#
# Run this script to generated a fileformat.html output file
#
set rcsid {$Id: fileformat.tcl,v 1.7 2003/02/12 14:09:45 drh Exp $}

puts {<html>
<head>
  <title>SQLite Database File Format</title>
</head>
<body bgcolor="white">
<h1 align="center">

"sqlite_temp_master" instead of "sqlite_master".  Other than the
name change, it works exactly the same.
</p>

<h3>4.4 &nbsp; Schema Version Numbering And Other Meta-Information</h3>

<p>
The nine 32-bit integers that are stored beginning at byte offset
60 of Page 1 in the b-tree layer are passed up into the schema layer
and used for versioning and configuration information.  The meaning
of the first four integers is shown below.  The other five are currently
unused.
</p>

<ol>
<li>The schema version number</li>
<li>The format version number</li>
<li>The recommended pager cache size</li>
<li>The safety level</li>
</ol>

<p>
The first meta-value, the schema version number, is used to detect when
the schema of the database is changed by a CREATE or DROP statement.
Recall that when a database is first opened the sqlite_master table is
scanned and an internal representation of the tables, indices, views,