main.c

sqlite 嵌入式数据库的源码

  void *pOld = db->pTraceArg;
  db->xTrace = xTrace;
  db->pTraceArg = pArg;
  return pOld;
}

/*** EXPERIMENTAL ***
**
** Register a function to be invoked when a transaction comments.
** If either function returns non-zero, then the commit becomes a
** rollback.
*/
void *sqlite3_commit_hook(
  sqlite3 *db,              /* Attach the hook to this database */
  int (*xCallback)(void*),  /* Function to invoke on each commit */
  void *pArg                /* Argument to the function */
){
  void *pOld = db->pCommitArg;
  db->xCommitCallback = xCallback;
  db->pCommitArg = pArg;
  return pOld;
}


/*
** This routine is called to create a connection to a database BTree
** driver.  If zFilename is the name of a file, then that file is
** opened and used.  If zFilename is the magic name ":memory:" then
** the database is stored in memory (and is thus forgotten as soon as
** the connection is closed.)  If zFilename is NULL then the database
** is for temporary use only and is deleted as soon as the connection
** is closed.
**
** A temporary database can be either a disk file (that is automatically
** deleted when the file is closed) or a set of red-black trees held in memory,
** depending on the values of the TEMP_STORE compile-time macro and the
** db->temp_store variable, according to the following chart:
**
**       TEMP_STORE     db->temp_store     Location of temporary database
**       ----------     --------------     ------------------------------
**           0               any             file
**           1                1              file
**           1                2              memory
**           1                0              file
**           2                1              file
**           2                2              memory
**           2                0              memory
**           3               any             memory
*/
int sqlite3BtreeFactory(
  const sqlite3 *db,        /* Main database when opening aux otherwise 0 */
  const char *zFilename,    /* Name of the file containing the BTree database */
  int omitJournal,          /* if TRUE then do not journal this file */
  int nCache,               /* How many pages in the page cache */
  Btree **ppBtree           /* Pointer to new Btree object written here */
){
  int btree_flags = 0;
  int rc;
  
  assert( ppBtree != 0);
  if( omitJournal ){
    btree_flags |= BTREE_OMIT_JOURNAL;
  }
  if( db->flags & SQLITE_NoReadlock ){
    btree_flags |= BTREE_NO_READLOCK;
  }
  if( zFilename==0 ){
#if TEMP_STORE==0
    /* Do nothing */
#endif
#ifndef SQLITE_OMIT_MEMORYDB
#if TEMP_STORE==1
    if( db->temp_store==2 ) zFilename = ":memory:";
#endif
#if TEMP_STORE==2
    if( db->temp_store!=1 ) zFilename = ":memory:";
#endif
#if TEMP_STORE==3
    zFilename = ":memory:";
#endif
#endif /* SQLITE_OMIT_MEMORYDB */
  }

  rc = sqlite3BtreeOpen(zFilename, ppBtree, btree_flags);
  if( rc==SQLITE_OK ){
    sqlite3BtreeSetBusyHandler(*ppBtree, (void*)&db->busyHandler);
    sqlite3BtreeSetCacheSize(*ppBtree, nCache);
  }
  return rc;
}

/*
** Return UTF-8 encoded English language explanation of the most recent
** error.
*/
const char *sqlite3_errmsg(sqlite3 *db){
  const char *z;
  if( sqlite3_malloc_failed ){
    return sqlite3ErrStr(SQLITE_NOMEM);
  }
  if( sqlite3SafetyCheck(db) || db->errCode==SQLITE_MISUSE ){
    return sqlite3ErrStr(SQLITE_MISUSE);
  }
  z = sqlite3_value_text(db->pErr);
  if( z==0 ){
    z = sqlite3ErrStr(db->errCode);
  }
  return z;
}

#ifndef SQLITE_OMIT_UTF16
/*
** Return UTF-16 encoded English language explanation of the most recent
** error.
*/
const void *sqlite3_errmsg16(sqlite3 *db){
  /* Because all the characters in the string are in the unicode
  ** range 0x00-0xFF, if we pad the big-endian string with a 
  ** zero byte, we can obtain the little-endian string with
  ** &big_endian[1].
  */
  static const char outOfMemBe[] = {
    0, 'o', 0, 'u', 0, 't', 0, ' ', 
    0, 'o', 0, 'f', 0, ' ', 
    0, 'm', 0, 'e', 0, 'm', 0, 'o', 0, 'r', 0, 'y', 0, 0, 0
  };
  static const char misuseBe [] = {
    0, 'l', 0, 'i', 0, 'b', 0, 'r', 0, 'a', 0, 'r', 0, 'y', 0, ' ', 
    0, 'r', 0, 'o', 0, 'u', 0, 't', 0, 'i', 0, 'n', 0, 'e', 0, ' ', 
    0, 'c', 0, 'a', 0, 'l', 0, 'l', 0, 'e', 0, 'd', 0, ' ', 
    0, 'o', 0, 'u', 0, 't', 0, ' ', 
    0, 'o', 0, 'f', 0, ' ', 
    0, 's', 0, 'e', 0, 'q', 0, 'u', 0, 'e', 0, 'n', 0, 'c', 0, 'e', 0, 0, 0
  };

  const void *z;
  if( sqlite3_malloc_failed ){
    return (void *)(&outOfMemBe[SQLITE_UTF16NATIVE==SQLITE_UTF16LE?1:0]);
  }
  if( sqlite3SafetyCheck(db) || db->errCode==SQLITE_MISUSE ){
    return (void *)(&misuseBe[SQLITE_UTF16NATIVE==SQLITE_UTF16LE?1:0]);
  }
  z = sqlite3_value_text16(db->pErr);
  if( z==0 ){
    sqlite3ValueSetStr(db->pErr, -1, sqlite3ErrStr(db->errCode),
         SQLITE_UTF8, SQLITE_STATIC);
    z = sqlite3_value_text16(db->pErr);
  }
  return z;
}
#endif /* SQLITE_OMIT_UTF16 */

/*
** Return the most recent error code generated by an SQLite routine.
*/
int sqlite3_errcode(sqlite3 *db){
  if( sqlite3_malloc_failed ){
    return SQLITE_NOMEM;
  }
  if( sqlite3SafetyCheck(db) ){
    return SQLITE_MISUSE;
  }
  return db->errCode;
}

/*
** This routine does the work of opening a database on behalf of
** sqlite3_open() and sqlite3_open16(). The database filename "zFilename"  
** is UTF-8 encoded.
*/
static int openDatabase(
  const char *zFilename, /* Database filename UTF-8 encoded */
  sqlite3 **ppDb         /* OUT: Returned database handle */
){
  sqlite3 *db;
  int rc, i;

  /* Allocate the sqlite data structure */
  db = sqliteMalloc( sizeof(sqlite3) );
  if( db==0 ) goto opendb_out;
  db->priorNewRowid = 0;
  db->magic = SQLITE_MAGIC_BUSY;
  db->nDb = 2;
  db->aDb = db->aDbStatic;
  db->enc = SQLITE_UTF8;
  db->autoCommit = 1;
  db->flags |= SQLITE_ShortColNames;
  sqlite3HashInit(&db->aFunc, SQLITE_HASH_STRING, 0);
  sqlite3HashInit(&db->aCollSeq, SQLITE_HASH_STRING, 0);
  for(i=0; i<db->nDb; i++){
    sqlite3HashInit(&db->aDb[i].tblHash, SQLITE_HASH_STRING, 0);
    sqlite3HashInit(&db->aDb[i].idxHash, SQLITE_HASH_STRING, 0);
    sqlite3HashInit(&db->aDb[i].trigHash, SQLITE_HASH_STRING, 0);
    sqlite3HashInit(&db->aDb[i].aFKey, SQLITE_HASH_STRING, 1);
  }
  
  /* Add the default collation sequence BINARY. BINARY works for both UTF-8
  ** and UTF-16, so add a version for each to avoid any unnecessary
  ** conversions. The only error that can occur here is a malloc() failure.
  */
  if( sqlite3_create_collation(db, "BINARY", SQLITE_UTF8, 0,binCollFunc) ||
      sqlite3_create_collation(db, "BINARY", SQLITE_UTF16, 0,binCollFunc) ||
      !(db->pDfltColl = sqlite3FindCollSeq(db, db->enc, "BINARY", 6, 0)) ){
    rc = db->errCode;
    assert( rc!=SQLITE_OK );
    db->magic = SQLITE_MAGIC_CLOSED;
    goto opendb_out;
  }

  /* Also add a UTF-8 case-insensitive collation sequence. */
  sqlite3_create_collation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc);

  /* Open the backend database driver */
  rc = sqlite3BtreeFactory(db, zFilename, 0, MAX_PAGES, &db->aDb[0].pBt);
  if( rc!=SQLITE_OK ){
    sqlite3Error(db, rc, 0);
    db->magic = SQLITE_MAGIC_CLOSED;
    goto opendb_out;
  }

  /* The default safety_level for the main database is 'full'; for the temp
  ** database it is 'NONE'. This matches the pager layer defaults.  
  */
  db->aDb[0].zName = "main";
  db->aDb[0].safety_level = 3;
#ifndef SQLITE_OMIT_TEMPDB
  db->aDb[1].zName = "temp";
  db->aDb[1].safety_level = 1;
#endif


  /* Register all built-in functions, but do not attempt to read the
  ** database schema yet. This is delayed until the first time the database
  ** is accessed.
  */
  sqlite3RegisterBuiltinFunctions(db);
  sqlite3Error(db, SQLITE_OK, 0);
  db->magic = SQLITE_MAGIC_OPEN;

opendb_out:
  if( sqlite3_errcode(db)==SQLITE_OK && sqlite3_malloc_failed ){
    sqlite3Error(db, SQLITE_NOMEM, 0);
  }
  *ppDb = db;
#ifndef SQLITE_OMIT_GLOBALRECOVER
  if( db ){
    sqlite3OsEnterMutex();
    db->pNext = pDbList;
    pDbList = db;
    sqlite3OsLeaveMutex();
  }
#endif
  return sqlite3_errcode(db);
}

/*
** Open a new database handle.
*/
int sqlite3_open(
  const char *zFilename, 
  sqlite3 **ppDb 
){
  return openDatabase(zFilename, ppDb);
}

#ifndef SQLITE_OMIT_UTF16
/*
** Open a new database handle.
*/
int sqlite3_open16(
  const void *zFilename, 
  sqlite3 **ppDb
){
  char const *zFilename8;   /* zFilename encoded in UTF-8 instead of UTF-16 */
  int rc = SQLITE_NOMEM;
  sqlite3_value *pVal;

  assert( ppDb );
  *ppDb = 0;
  pVal = sqlite3ValueNew();
  sqlite3ValueSetStr(pVal, -1, zFilename, SQLITE_UTF16NATIVE, SQLITE_STATIC);
  zFilename8 = sqlite3ValueText(pVal, SQLITE_UTF8);
  if( zFilename8 ){
    rc = openDatabase(zFilename8, ppDb);
    if( rc==SQLITE_OK && *ppDb ){
      sqlite3_exec(*ppDb, "PRAGMA encoding = 'UTF-16'", 0, 0, 0);
    }
  }
  if( pVal ){
    sqlite3ValueFree(pVal);
  }

  return rc;
}
#endif /* SQLITE_OMIT_UTF16 */

/*
** The following routine destroys a virtual machine that is created by
** the sqlite3_compile() routine. The integer returned is an SQLITE_
** success/failure code that describes the result of executing the virtual
** machine.
**
** This routine sets the error code and string returned by
** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
*/
int sqlite3_finalize(sqlite3_stmt *pStmt){
  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    rc = sqlite3VdbeFinalize((Vdbe*)pStmt);
  }
  return rc;
}

/*
** Terminate the current execution of an SQL statement and reset it
** back to its starting state so that it can be reused. A success code from
** the prior execution is returned.
**
** This routine sets the error code and string returned by
** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
*/
int sqlite3_reset(sqlite3_stmt *pStmt){
  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    rc = sqlite3VdbeReset((Vdbe*)pStmt);
    sqlite3VdbeMakeReady((Vdbe*)pStmt, -1, 0, 0, 0, 0);
  }
  return rc;
}

/*
** Register a new collation sequence with the database handle db.
*/
int sqlite3_create_collation(
  sqlite3* db, 
  const char *zName, 
  int enc, 
  void* pCtx,
  int(*xCompare)(void*,int,const void*,int,const void*)
){
  CollSeq *pColl;
  int rc = SQLITE_OK;
  
  if( sqlite3SafetyCheck(db) ){
    return SQLITE_MISUSE;
  }

  /* If SQLITE_UTF16 is specified as the encoding type, transform this
  ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the
  ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally.
  */
  if( enc==SQLITE_UTF16 ){
    enc = SQLITE_UTF16NATIVE;
  }

  if( enc!=SQLITE_UTF8 && enc!=SQLITE_UTF16LE && enc!=SQLITE_UTF16BE ){
    sqlite3Error(db, SQLITE_ERROR, 
        "Param 3 to sqlite3_create_collation() must be one of "
        "SQLITE_UTF8, SQLITE_UTF16, SQLITE_UTF16LE or SQLITE_UTF16BE"
    );
    return SQLITE_ERROR;
  }

  /* Check if this call is removing or replacing an existing collation 
  ** sequence. If so, and there are active VMs, return busy. If there
  ** are no active VMs, invalidate any pre-compiled statements.
  */
  pColl = sqlite3FindCollSeq(db, (u8)enc, zName, strlen(zName), 0);
  if( pColl && pColl->xCmp ){
    if( db->activeVdbeCnt ){
      sqlite3Error(db, SQLITE_BUSY, 
        "Unable to delete/modify collation sequence due to active statements");
      return SQLITE_BUSY;
    }
    sqlite3ExpirePreparedStatements(db);
  }

  pColl = sqlite3FindCollSeq(db, (u8)enc, zName, strlen(zName), 1);
  if( 0==pColl ){
   rc = SQLITE_NOMEM;
  }else{
    pColl->xCmp = xCompare;
    pColl->pUser = pCtx;
    pColl->enc = enc;
  }
  sqlite3Error(db, rc, 0);
  return rc;
}

#ifndef SQLITE_OMIT_UTF16
/*
** Register a new collation sequence with the database handle db.
*/
int sqlite3_create_collation16(
  sqlite3* db, 
  const char *zName, 
  int enc, 
  void* pCtx,
  int(*xCompare)(void*,int,const void*,int,const void*)
){
  char const *zName8;
  sqlite3_value *pTmp;
  if( sqlite3SafetyCheck(db) ){
    return SQLITE_MISUSE;
  }
  pTmp = sqlite3GetTransientValue(db);
  sqlite3ValueSetStr(pTmp, -1, zName, SQLITE_UTF16NATIVE, SQLITE_STATIC);
  zName8 = sqlite3ValueText(pTmp, SQLITE_UTF8);
  return sqlite3_create_collation(db, zName8, enc, pCtx, xCompare);
}
#endif /* SQLITE_OMIT_UTF16 */

/*
** Register a collation sequence factory callback with the database handle
** db. Replace any previously installed collation sequence factory.
*/
int sqlite3_collation_needed(
  sqlite3 *db, 
  void *pCollNeededArg, 
  void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*)
){
  if( sqlite3SafetyCheck(db) ){
    return SQLITE_MISUSE;
  }
  db->xCollNeeded = xCollNeeded;
  db->xCollNeeded16 = 0;
  db->pCollNeededArg = pCollNeededArg;
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_UTF16
/*
** Register a collation sequence factory callback with the database handle
** db. Replace any previously installed collation sequence factory.
*/
int sqlite3_collation_needed16(
  sqlite3 *db, 
  void *pCollNeededArg, 
  void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*)
){
  if( sqlite3SafetyCheck(db) ){
    return SQLITE_MISUSE;
  }
  db->xCollNeeded = 0;
  db->xCollNeeded16 = xCollNeeded16;
  db->pCollNeededArg = pCollNeededArg;
  return SQLITE_OK;
}
#endif /* SQLITE_OMIT_UTF16 */

#ifndef SQLITE_OMIT_GLOBALRECOVER
/*
** This function is called to recover from a malloc failure that occured
** within SQLite. 
**
** This function is *not* threadsafe. Calling this from within a threaded
** application when threads other than the caller have used SQLite is 
** dangerous and will almost certainly result in malfunctions.
*/
int sqlite3_global_recover(){
  int rc = SQLITE_OK;

  if( sqlite3_malloc_failed ){
    sqlite3 *db;
    int i;
    sqlite3_malloc_failed = 0;
    for(db=pDbList; db; db=db->pNext ){
      sqlite3ExpirePreparedStatements(db);
      for(i=0; i<db->nDb; i++){
        Btree *pBt = db->aDb[i].pBt;
        if( pBt && (rc=sqlite3BtreeReset(pBt)) ){
          goto recover_out;
        }
      } 
      db->autoCommit = 1;
    }
  }

recover_out:
  if( rc!=SQLITE_OK ){
    sqlite3_malloc_failed = 1;
  }
  return rc;
}
#endif

/*
** Test to see whether or not the database connection is in autocommit
** mode.  Return TRUE if it is and FALSE if not.  Autocommit mode is on
** by default.  Autocommit is disabled by a BEGIN statement and reenabled
** by the next COMMIT or ROLLBACK.
**
******* THIS IS AN EXPERIMENTAL API AND IS SUBJECT TO CHANGE ******
*/
int sqlite3_get_autocommit(sqlite3 *db){
  return db->autoCommit;
}