main.c

最新的sqlite3.6.2源代码

/*
** 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.
**
*************************************************************************
** 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 1.494 2008/08/27 19:01:58 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

#ifdef SQLITE_ENABLE_FTS3
# include "fts3.h"
#endif
#ifdef SQLITE_ENABLE_RTREE
# include "rtree.h"
#endif

/*
** The version of the library
*/
const char sqlite3_version[] = SQLITE_VERSION;
const char *sqlite3_libversion(void){ return sqlite3_version; }
int sqlite3_libversion_number(void){ return SQLITE_VERSION_NUMBER; }
int sqlite3_threadsafe(void){ return SQLITE_THREADSAFE; }

#if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
/*
** If the following function pointer is not NULL and if
** SQLITE_ENABLE_IOTRACE is enabled, then messages describing
** I/O active are written using this function.  These messages
** are intended for debugging activity only.
*/
void (*sqlite3IoTrace)(const char*, ...) = 0;
#endif

/*
** If the following global variable points to a string which is the
** name of a directory, then that directory will be used to store
** temporary files.
**
** See also the "PRAGMA temp_store_directory" SQL command.
*/
char *sqlite3_temp_directory = 0;

/*
** Initialize SQLite.  
**
** This routine must be called to initialize the memory allocation,
** VFS, and mutex subsystems prior to doing any serious work with
** SQLite.  But as long as you do not compile with SQLITE_OMIT_AUTOINIT
** this routine will be called automatically by key routines such as
** sqlite3_open().  
**
** This routine is a no-op except on its very first call for the process,
** or for the first call after a call to sqlite3_shutdown.
**
** The first thread to call this routine runs the initialization to
** completion.  If subsequent threads call this routine before the first
** thread has finished the initialization process, then the subsequent
** threads must block until the first thread finishes with the initialization.
**
** The first thread might call this routine recursively.  Recursive
** calls to this routine should not block, of course.  Otherwise the
** initialization process would never complete.
**
** Let X be the first thread to enter this routine.  Let Y be some other
** thread.  Then while the initial invocation of this routine by X is
** incomplete, it is required that:
**
**    *  Calls to this routine from Y must block until the outer-most
**       call by X completes.
**
**    *  Recursive calls to this routine from thread X return immediately
**       without blocking.
*/
int sqlite3_initialize(void){
  static int inProgress = 0;        /* Prevent recursion */
  sqlite3_mutex *pMaster;           /* The main static mutex */
  int rc;                           /* Result code */

  /* If SQLite is already completely initialized, then this call
  ** to sqlite3_initialize() should be a no-op.  But the initialization
  ** must be complete.  So isInit must not be set until the very end
  ** of this routine.
  */
  if( sqlite3Config.isInit ) return SQLITE_OK;

  /* Make sure the mutex subsystem is initialized.  If unable to 
  ** initialize the mutex subsystem, return early with the error.
  ** If the system is so sick that we are unable to allocate a mutex,
  ** there is not much SQLite is going to be able to do.
  **
  ** The mutex subsystem must take care of serializing its own
  ** initialization.
  */
  rc = sqlite3MutexInit();
  if( rc ) return rc;

  /* Initialize the malloc() system and the recursive pInitMutex mutex.
  ** This operation is protected by the STATIC_MASTER mutex.  Note that
  ** MutexAlloc() is called for a static mutex prior to initializing the
  ** malloc subsystem - this implies that the allocation of a static
  ** mutex must not require support from the malloc subsystem.
  */
  pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(pMaster);
  if( !sqlite3Config.isMallocInit ){
    rc = sqlite3MallocInit();
  }
  if( rc==SQLITE_OK ){
    sqlite3Config.isMallocInit = 1;
    if( !sqlite3Config.pInitMutex ){
      sqlite3Config.pInitMutex = sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
      if( sqlite3Config.bCoreMutex && !sqlite3Config.pInitMutex ){
        rc = SQLITE_NOMEM;
      }
    }
    sqlite3Config.nRefInitMutex++;
  }
  sqlite3_mutex_leave(pMaster);

  /* If unable to initialize the malloc subsystem, then return early.
  ** There is little hope of getting SQLite to run if the malloc
  ** subsystem cannot be initialized.
  */
  if( rc!=SQLITE_OK ){
    return rc;
  }

  /* Do the rest of the initialization under the recursive mutex so
  ** that we will be able to handle recursive calls into
  ** sqlite3_initialize().  The recursive calls normally come through
  ** sqlite3_os_init() when it invokes sqlite3_vfs_register(), but other
  ** recursive calls might also be possible.
  */
  sqlite3_mutex_enter(sqlite3Config.pInitMutex);
  if( sqlite3Config.isInit==0 && inProgress==0 ){
    inProgress = 1;
    memset(&sqlite3GlobalFunctions, 0, sizeof(sqlite3GlobalFunctions));
    sqlite3RegisterGlobalFunctions();
    rc = sqlite3_os_init();
    if( rc==SQLITE_OK ){
      rc = sqlite3PcacheInitialize();
      sqlite3PCacheBufferSetup(sqlite3Config.pPage, sqlite3Config.szPage, 
          sqlite3Config.nPage);
    }
    inProgress = 0;
    sqlite3Config.isInit = (rc==SQLITE_OK ? 1 : 0);
  }
  sqlite3_mutex_leave(sqlite3Config.pInitMutex);

  /* Go back under the static mutex and clean up the recursive
  ** mutex to prevent a resource leak.
  */
  sqlite3_mutex_enter(pMaster);
  sqlite3Config.nRefInitMutex--;
  if( sqlite3Config.nRefInitMutex<=0 ){
    assert( sqlite3Config.nRefInitMutex==0 );
    sqlite3_mutex_free(sqlite3Config.pInitMutex);
    sqlite3Config.pInitMutex = 0;
  }
  sqlite3_mutex_leave(pMaster);

  /* The following is just a sanity check to make sure SQLite has
  ** been compiled correctly.  It is important to run this code, but
  ** we don't want to run it too often and soak up CPU cycles for no
  ** reason.  So we run it once during initialization.
  */
#ifndef NDEBUG
  /* This section of code's only "output" is via assert() statements. */
  if ( rc==SQLITE_OK ){
    u64 x = (((u64)1)<<63)-1;
    double y;
    assert(sizeof(x)==8);
    assert(sizeof(x)==sizeof(y));
    memcpy(&y, &x, 8);
    assert( sqlite3IsNaN(y) );
  }
#endif

  return rc;
}

/*
** Undo the effects of sqlite3_initialize().  Must not be called while
** there are outstanding database connections or memory allocations or
** while any part of SQLite is otherwise in use in any thread.  This
** routine is not threadsafe.  Not by a long shot.
*/
int sqlite3_shutdown(void){
  sqlite3Config.isMallocInit = 0;
  sqlite3PcacheShutdown();
  if( sqlite3Config.isInit ){
    sqlite3_os_end();
  }
  if( sqlite3Config.m.xShutdown ){
    sqlite3MallocEnd();
  }
  if( sqlite3Config.mutex.xMutexEnd ){
    sqlite3MutexEnd();
  }
  sqlite3Config.isInit = 0;
  return SQLITE_OK;
}

/*
** This API allows applications to modify the global configuration of
** the SQLite library at run-time.
**
** This routine should only be called when there are no outstanding
** database connections or memory allocations.  This routine is not
** threadsafe.  Failure to heed these warnings can lead to unpredictable
** behavior.
*/
int sqlite3_config(int op, ...){
  va_list ap;
  int rc = SQLITE_OK;

  /* sqlite3_config() shall return SQLITE_MISUSE if it is invoked while
  ** the SQLite library is in use. */
  if( sqlite3Config.isInit ) return SQLITE_MISUSE;

  va_start(ap, op);
  switch( op ){
    case SQLITE_CONFIG_SINGLETHREAD: {
      /* Disable all mutexing */
      sqlite3Config.bCoreMutex = 0;
      sqlite3Config.bFullMutex = 0;
      break;
    }
    case SQLITE_CONFIG_MULTITHREAD: {
      /* Disable mutexing of database connections */
      /* Enable mutexing of core data structures */
      sqlite3Config.bCoreMutex = 1;
      sqlite3Config.bFullMutex = 0;
      break;
    }
    case SQLITE_CONFIG_SERIALIZED: {
      /* Enable all mutexing */
      sqlite3Config.bCoreMutex = 1;
      sqlite3Config.bFullMutex = 1;
      break;
    }
    case SQLITE_CONFIG_MALLOC: {
      /* Specify an alternative malloc implementation */
      sqlite3Config.m = *va_arg(ap, sqlite3_mem_methods*);
      break;
    }
    case SQLITE_CONFIG_GETMALLOC: {
      /* Retrieve the current malloc() implementation */
      if( sqlite3Config.m.xMalloc==0 ) sqlite3MemSetDefault();
      *va_arg(ap, sqlite3_mem_methods*) = sqlite3Config.m;
      break;
    }
    case SQLITE_CONFIG_MUTEX: {
      /* Specify an alternative mutex implementation */
      sqlite3Config.mutex = *va_arg(ap, sqlite3_mutex_methods*);
      break;
    }
    case SQLITE_CONFIG_GETMUTEX: {
      /* Retrieve the current mutex implementation */
      *va_arg(ap, sqlite3_mutex_methods*) = sqlite3Config.mutex;
      break;
    }
    case SQLITE_CONFIG_MEMSTATUS: {
      /* Enable or disable the malloc status collection */
      sqlite3Config.bMemstat = va_arg(ap, int);
      break;
    }
    case SQLITE_CONFIG_SCRATCH: {
      /* Designate a buffer for scratch memory space */
      sqlite3Config.pScratch = va_arg(ap, void*);
      sqlite3Config.szScratch = va_arg(ap, int);
      sqlite3Config.nScratch = va_arg(ap, int);
      break;
    }
    case SQLITE_CONFIG_PAGECACHE: {
      /* Designate a buffer for scratch memory space */
      sqlite3Config.pPage = va_arg(ap, void*);
      sqlite3Config.szPage = va_arg(ap, int);
      sqlite3Config.nPage = va_arg(ap, int);
      break;
    }

#if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
    case SQLITE_CONFIG_HEAP: {
      /* Designate a buffer for heap memory space */
      sqlite3Config.pHeap = va_arg(ap, void*);
      sqlite3Config.nHeap = va_arg(ap, int);
      sqlite3Config.mnReq = va_arg(ap, int);

      if( sqlite3Config.pHeap==0 ){
        /* If the heap pointer is NULL, then restore the malloc implementation
        ** back to NULL pointers too.  This will cause the malloc to go
        ** back to its default implementation when sqlite3_initialize() is
        ** run.
        */
        memset(&sqlite3Config.m, 0, sizeof(sqlite3Config.m));
      }else{
        /* The heap pointer is not NULL, then install one of the
        ** mem5.c/mem3.c methods. If neither ENABLE_MEMSYS3 nor
        ** ENABLE_MEMSYS5 is defined, return an error.
        ** the default case and return an error.
        */
#ifdef SQLITE_ENABLE_MEMSYS3
        sqlite3Config.m = *sqlite3MemGetMemsys3();
#endif
#ifdef SQLITE_ENABLE_MEMSYS5
        sqlite3Config.m = *sqlite3MemGetMemsys5();
#endif
      }
      break;
    }
#endif

#if defined(SQLITE_ENABLE_MEMSYS6)
    case SQLITE_CONFIG_CHUNKALLOC: {
      sqlite3Config.nSmall = va_arg(ap, int);
      sqlite3Config.m = *sqlite3MemGetMemsys6();
      break;
    }
#endif

    case SQLITE_CONFIG_LOOKASIDE: {
      sqlite3Config.szLookaside = va_arg(ap, int);
      sqlite3Config.nLookaside = va_arg(ap, int);
      break;
    }

    default: {
      rc = SQLITE_ERROR;
      break;
    }
  }
  va_end(ap);
  return rc;
}

/*
** Set up the lookaside buffers for a database connection.
** Return SQLITE_OK on success.  
** If lookaside is already active, return SQLITE_BUSY.
**
** The sz parameter is the number of bytes in each lookaside slot.
** The cnt parameter is the number of slots.  If pStart is NULL the
** space for the lookaside memory is obtained from sqlite3_malloc().
** If pStart is not NULL then it is sz*cnt bytes of memory to use for
** the lookaside memory.
*/
static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
  void *pStart;
  if( db->lookaside.nOut ){
    return SQLITE_BUSY;
  }
  if( sz<0 ) sz = 0;
  if( cnt<0 ) cnt = 0;
  if( pBuf==0 ){
    sz = (sz + 7)&~7;
    sqlite3BeginBenignMalloc();
    pStart = sqlite3Malloc( sz*cnt );
    sqlite3EndBenignMalloc();
  }else{
    sz = sz&~7;
    pStart = pBuf;
  }
  if( db->lookaside.bMalloced ){
    sqlite3_free(db->lookaside.pStart);
  }
  db->lookaside.pStart = pStart;
  db->lookaside.pFree = 0;
  db->lookaside.sz = sz;
  db->lookaside.bMalloced = pBuf==0;
  if( pStart ){
    int i;
    LookasideSlot *p;
    p = (LookasideSlot*)pStart;
    for(i=cnt-1; i>=0; i--){
      p->pNext = db->lookaside.pFree;
      db->lookaside.pFree = p;
      p = (LookasideSlot*)&((u8*)p)[sz];
    }
    db->lookaside.pEnd = p;
    db->lookaside.bEnabled = 1;
  }else{
    db->lookaside.pEnd = 0;
    db->lookaside.bEnabled = 0;
  }
  return SQLITE_OK;
}

/*
** Configuration settings for an individual database connection
*/
int sqlite3_db_config(sqlite3 *db, int op, ...){
  va_list ap;
  int rc;
  va_start(ap, op);
  switch( op ){
    case SQLITE_DBCONFIG_LOOKASIDE: {
      void *pBuf = va_arg(ap, void*);
      int sz = va_arg(ap, int);
      int cnt = va_arg(ap, int);
      rc = setupLookaside(db, pBuf, sz, cnt);
      break;
    }
    default: {
      rc = SQLITE_ERROR;
      break;
    }
  }
  va_end(ap);
  return rc;
}

/*
** Routine needed to support the testcase() macro.
*/
#ifdef SQLITE_COVERAGE_TEST
void sqlite3Coverage(int x){
  static int dummy = 0;
  dummy += x;
}
#endif


/*
** Return true if the buffer z[0..n-1] contains all spaces.
*/
static int allSpaces(const char *z, int n){
  while( n>0 && z[n-1]==' ' ){ n--; }
  return n==0;
}

/*
** This is the default collating function named "BINARY" which is always
** available.
**
** If the padFlag argument is not NULL then space padding at the end
** of strings is ignored.  This implements the RTRIM collation.
*/
static int binCollFunc(
  void *padFlag,
  int nKey1, const void *pKey1,
  int nKey2, const void *pKey2
){
  int rc, n;
  n = nKey1<nKey2 ? nKey1 : nKey2;
  rc = memcmp(pKey1, pKey2, n);
  if( rc==0 ){
    if( padFlag
     && allSpaces(((char*)pKey1)+n, nKey1-n)
     && allSpaces(((char*)pKey2)+n, nKey2-n)
    ){
      /* Leave rc unchanged at 0 */
    }else{
      rc = nKey1 - nKey2;
    }
  }
  return rc;
}

/*
** Another built-in collating sequence: NOCASE. 
**
** This collating sequence is intended to be used for "case independant
** comparison". SQLite's knowledge of upper and lower case equivalents
** extends only to the 26 characters used in the English language.
**
** At the moment there is only a UTF-8 implementation.
*/
static int nocaseCollatingFunc(
  void *NotUsed,
  int nKey1, const void *pKey1,
  int nKey2, const void *pKey2
){
  int r = sqlite3StrNICmp(
      (const char *)pKey1, (const char *)pKey2, (nKey1<nKey2)?nKey1:nKey2);
  if( 0==r ){
    r = nKey1-nKey2;
  }
  return r;
}

/*
** Return the ROWID of the most recent insert
*/
sqlite_int64 sqlite3_last_insert_rowid(sqlite3 *db){
  return db->lastRowid;
}

/*
** Return the number of changes in the most recent call to sqlite3_exec().
*/
int sqlite3_changes(sqlite3 *db){
  return db->nChange;
}

/*
** Return the number of changes since the database handle was opened.
*/
int sqlite3_total_changes(sqlite3 *db){
  return db->nTotalChange;
}

/*
** Close an existing SQLite database