tclsqlite.c

sqlite-3.4.1,嵌入式数据库.是一个功能强大的开源数据库,给学习和研发以及小型公司的发展带来了全所未有的好处.

/*
** 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.
**
*************************************************************************
** A TCL Interface to SQLite.  Append this file to sqlite3.c and
** compile the whole thing to build a TCL-enabled version of SQLite.
**
** $Id: tclsqlite.c,v 1.193 2007/06/26 22:55:38 drh Exp $
*/
#include "tcl.h"
#include <errno.h>

/*
** Some additional include files are needed if this file is not
** appended to the amalgamation.
*/
#ifndef SQLITE_AMALGAMATION
# include "sqliteInt.h"
# include "hash.h"
# include <stdlib.h>
# include <string.h>
# include <assert.h>
# include <ctype.h>
#endif

/*
 * Windows needs to know which symbols to export.  Unix does not.
 * BUILD_sqlite should be undefined for Unix.
 */
#ifdef BUILD_sqlite
#undef TCL_STORAGE_CLASS
#define TCL_STORAGE_CLASS DLLEXPORT
#endif /* BUILD_sqlite */

#define NUM_PREPARED_STMTS 10
#define MAX_PREPARED_STMTS 100

/*
** If TCL uses UTF-8 and SQLite is configured to use iso8859, then we
** have to do a translation when going between the two.  Set the 
** UTF_TRANSLATION_NEEDED macro to indicate that we need to do
** this translation.  
*/
#if defined(TCL_UTF_MAX) && !defined(SQLITE_UTF8)
# define UTF_TRANSLATION_NEEDED 1
#endif

/*
** New SQL functions can be created as TCL scripts.  Each such function
** is described by an instance of the following structure.
*/
typedef struct SqlFunc SqlFunc;
struct SqlFunc {
  Tcl_Interp *interp;   /* The TCL interpret to execute the function */
  Tcl_Obj *pScript;     /* The Tcl_Obj representation of the script */
  int useEvalObjv;      /* True if it is safe to use Tcl_EvalObjv */
  char *zName;          /* Name of this function */
  SqlFunc *pNext;       /* Next function on the list of them all */
};

/*
** New collation sequences function can be created as TCL scripts.  Each such
** function is described by an instance of the following structure.
*/
typedef struct SqlCollate SqlCollate;
struct SqlCollate {
  Tcl_Interp *interp;   /* The TCL interpret to execute the function */
  char *zScript;        /* The script to be run */
  SqlCollate *pNext;    /* Next function on the list of them all */
};

/*
** Prepared statements are cached for faster execution.  Each prepared
** statement is described by an instance of the following structure.
*/
typedef struct SqlPreparedStmt SqlPreparedStmt;
struct SqlPreparedStmt {
  SqlPreparedStmt *pNext;  /* Next in linked list */
  SqlPreparedStmt *pPrev;  /* Previous on the list */
  sqlite3_stmt *pStmt;     /* The prepared statement */
  int nSql;                /* chars in zSql[] */
  char zSql[1];            /* Text of the SQL statement */
};

typedef struct IncrblobChannel IncrblobChannel;

/*
** There is one instance of this structure for each SQLite database
** that has been opened by the SQLite TCL interface.
*/
typedef struct SqliteDb SqliteDb;
struct SqliteDb {
  sqlite3 *db;               /* The "real" database structure. MUST BE FIRST */
  Tcl_Interp *interp;        /* The interpreter used for this database */
  char *zBusy;               /* The busy callback routine */
  char *zCommit;             /* The commit hook callback routine */
  char *zTrace;              /* The trace callback routine */
  char *zProfile;            /* The profile callback routine */
  char *zProgress;           /* The progress callback routine */
  char *zAuth;               /* The authorization callback routine */
  char *zNull;               /* Text to substitute for an SQL NULL value */
  SqlFunc *pFunc;            /* List of SQL functions */
  Tcl_Obj *pUpdateHook;      /* Update hook script (if any) */
  Tcl_Obj *pRollbackHook;    /* Rollback hook script (if any) */
  SqlCollate *pCollate;      /* List of SQL collation functions */
  int rc;                    /* Return code of most recent sqlite3_exec() */
  Tcl_Obj *pCollateNeeded;   /* Collation needed script */
  SqlPreparedStmt *stmtList; /* List of prepared statements*/
  SqlPreparedStmt *stmtLast; /* Last statement in the list */
  int maxStmt;               /* The next maximum number of stmtList */
  int nStmt;                 /* Number of statements in stmtList */
  IncrblobChannel *pIncrblob;/* Linked list of open incrblob channels */
};

struct IncrblobChannel {
  sqlite3_blob *pBlob;      /* sqlite3 blob handle */
  SqliteDb *pDb;            /* Associated database connection */
  int iSeek;                /* Current seek offset */
  Tcl_Channel channel;      /* Channel identifier */
  IncrblobChannel *pNext;   /* Linked list of all open incrblob channels */
  IncrblobChannel *pPrev;   /* Linked list of all open incrblob channels */
};

#ifndef SQLITE_OMIT_INCRBLOB
/*
** Close all incrblob channels opened using database connection pDb.
** This is called when shutting down the database connection.
*/
static void closeIncrblobChannels(SqliteDb *pDb){
  IncrblobChannel *p;
  IncrblobChannel *pNext;

  for(p=pDb->pIncrblob; p; p=pNext){
    pNext = p->pNext;

    /* Note: Calling unregister here call Tcl_Close on the incrblob channel, 
    ** which deletes the IncrblobChannel structure at *p. So do not
    ** call Tcl_Free() here.
    */
    Tcl_UnregisterChannel(pDb->interp, p->channel);
  }
}

/*
** Close an incremental blob channel.
*/
static int incrblobClose(ClientData instanceData, Tcl_Interp *interp){
  IncrblobChannel *p = (IncrblobChannel *)instanceData;
  int rc = sqlite3_blob_close(p->pBlob);
  sqlite3 *db = p->pDb->db;

  /* Remove the channel from the SqliteDb.pIncrblob list. */
  if( p->pNext ){
    p->pNext->pPrev = p->pPrev;
  }
  if( p->pPrev ){
    p->pPrev->pNext = p->pNext;
  }
  if( p->pDb->pIncrblob==p ){
    p->pDb->pIncrblob = p->pNext;
  }

  /* Free the IncrblobChannel structure */
  Tcl_Free((char *)p);

  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)sqlite3_errmsg(db), TCL_VOLATILE);
    return TCL_ERROR;
  }
  return TCL_OK;
}

/*
** Read data from an incremental blob channel.
*/
static int incrblobInput(
  ClientData instanceData, 
  char *buf, 
  int bufSize,
  int *errorCodePtr
){
  IncrblobChannel *p = (IncrblobChannel *)instanceData;
  int nRead = bufSize;         /* Number of bytes to read */
  int nBlob;                   /* Total size of the blob */
  int rc;                      /* sqlite error code */

  nBlob = sqlite3_blob_bytes(p->pBlob);
  if( (p->iSeek+nRead)>nBlob ){
    nRead = nBlob-p->iSeek;
  }
  if( nRead<=0 ){
    return 0;
  }

  rc = sqlite3_blob_read(p->pBlob, (void *)buf, nRead, p->iSeek);
  if( rc!=SQLITE_OK ){
    *errorCodePtr = rc;
    return -1;
  }

  p->iSeek += nRead;
  return nRead;
}

/*
** Write data to an incremental blob channel.
*/
static int incrblobOutput(
  ClientData instanceData, 
  CONST char *buf, 
  int toWrite,
  int *errorCodePtr
){
  IncrblobChannel *p = (IncrblobChannel *)instanceData;
  int nWrite = toWrite;        /* Number of bytes to write */
  int nBlob;                   /* Total size of the blob */
  int rc;                      /* sqlite error code */

  nBlob = sqlite3_blob_bytes(p->pBlob);
  if( (p->iSeek+nWrite)>nBlob ){
    *errorCodePtr = EINVAL;
    return -1;
  }
  if( nWrite<=0 ){
    return 0;
  }

  rc = sqlite3_blob_write(p->pBlob, (void *)buf, nWrite, p->iSeek);
  if( rc!=SQLITE_OK ){
    *errorCodePtr = EIO;
    return -1;
  }

  p->iSeek += nWrite;
  return nWrite;
}

/*
** Seek an incremental blob channel.
*/
static int incrblobSeek(
  ClientData instanceData, 
  long offset,
  int seekMode,
  int *errorCodePtr
){
  IncrblobChannel *p = (IncrblobChannel *)instanceData;

  switch( seekMode ){
    case SEEK_SET:
      p->iSeek = offset;
      break;
    case SEEK_CUR:
      p->iSeek += offset;
      break;
    case SEEK_END:
      p->iSeek = sqlite3_blob_bytes(p->pBlob) + offset;
      break;

    default: assert(!"Bad seekMode");
  }

  return p->iSeek;
}


static void incrblobWatch(ClientData instanceData, int mode){ 
  /* NO-OP */ 
}
static int incrblobHandle(ClientData instanceData, int dir, ClientData *hPtr){
  return TCL_ERROR;
}

static Tcl_ChannelType IncrblobChannelType = {
  "incrblob",                        /* typeName                             */
  TCL_CHANNEL_VERSION_2,             /* version                              */
  incrblobClose,                     /* closeProc                            */
  incrblobInput,                     /* inputProc                            */
  incrblobOutput,                    /* outputProc                           */
  incrblobSeek,                      /* seekProc                             */
  0,                                 /* setOptionProc                        */
  0,                                 /* getOptionProc                        */
  incrblobWatch,                     /* watchProc (this is a no-op)          */
  incrblobHandle,                    /* getHandleProc (always returns error) */
  0,                                 /* close2Proc                           */
  0,                                 /* blockModeProc                        */
  0,                                 /* flushProc                            */
  0,                                 /* handlerProc                          */
  0,                                 /* wideSeekProc                         */
};

/*
** Create a new incrblob channel.
*/
static int createIncrblobChannel(
  Tcl_Interp *interp, 
  SqliteDb *pDb, 
  const char *zDb,
  const char *zTable, 
  const char *zColumn, 
  sqlite_int64 iRow,
  int isReadonly
){
  IncrblobChannel *p;
  sqlite3 *db = pDb->db;
  sqlite3_blob *pBlob;
  int rc;
  int flags = TCL_READABLE|(isReadonly ? 0 : TCL_WRITABLE);

  /* This variable is used to name the channels: "incrblob_[incr count]" */
  static int count = 0;
  char zChannel[64];

  rc = sqlite3_blob_open(db, zDb, zTable, zColumn, iRow, !isReadonly, &pBlob);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)sqlite3_errmsg(pDb->db), TCL_VOLATILE);
    return TCL_ERROR;
  }

  p = (IncrblobChannel *)Tcl_Alloc(sizeof(IncrblobChannel));
  p->iSeek = 0;
  p->pBlob = pBlob;

  sqlite3_snprintf(sizeof(zChannel), zChannel, "incrblob_%d", ++count);
  p->channel = Tcl_CreateChannel(&IncrblobChannelType, zChannel, p, flags);
  Tcl_RegisterChannel(interp, p->channel);

  /* Link the new channel into the SqliteDb.pIncrblob list. */
  p->pNext = pDb->pIncrblob;
  p->pPrev = 0;
  if( p->pNext ){
    p->pNext->pPrev = p;
  }
  pDb->pIncrblob = p;
  p->pDb = pDb;

  Tcl_SetResult(interp, (char *)Tcl_GetChannelName(p->channel), TCL_VOLATILE);
  return TCL_OK;
}
#else  /* else clause for "#ifndef SQLITE_OMIT_INCRBLOB" */
  #define closeIncrblobChannels(pDb)
#endif

/*
** Look at the script prefix in pCmd.  We will be executing this script
** after first appending one or more arguments.  This routine analyzes
** the script to see if it is safe to use Tcl_EvalObjv() on the script
** rather than the more general Tcl_EvalEx().  Tcl_EvalObjv() is much
** faster.
**
** Scripts that are safe to use with Tcl_EvalObjv() consists of a
** command name followed by zero or more arguments with no [...] or $
** or {...} or ; to be seen anywhere.  Most callback scripts consist
** of just a single procedure name and they meet this requirement.
*/
static int safeToUseEvalObjv(Tcl_Interp *interp, Tcl_Obj *pCmd){
  /* We could try to do something with Tcl_Parse().  But we will instead
  ** just do a search for forbidden characters.  If any of the forbidden
  ** characters appear in pCmd, we will report the string as unsafe.
  */
  const char *z;
  int n;
  z = Tcl_GetStringFromObj(pCmd, &n);
  while( n-- > 0 ){
    int c = *(z++);
    if( c=='$' || c=='[' || c==';' ) return 0;
  }
  return 1;
}

/*
** Find an SqlFunc structure with the given name.  Or create a new
** one if an existing one cannot be found.  Return a pointer to the
** structure.
*/
static SqlFunc *findSqlFunc(SqliteDb *pDb, const char *zName){
  SqlFunc *p, *pNew;
  int i;
  pNew = (SqlFunc*)Tcl_Alloc( sizeof(*pNew) + strlen(zName) + 1 );
  pNew->zName = (char*)&pNew[1];
  for(i=0; zName[i]; i++){ pNew->zName[i] = tolower(zName[i]); }
  pNew->zName[i] = 0;
  for(p=pDb->pFunc; p; p=p->pNext){ 
    if( strcmp(p->zName, pNew->zName)==0 ){
      Tcl_Free((char*)pNew);
      return p;
    }
  }
  pNew->interp = pDb->interp;
  pNew->pScript = 0;
  pNew->pNext = pDb->pFunc;
  pDb->pFunc = pNew;
  return pNew;
}

/*
** Finalize and free a list of prepared statements
*/
static void flushStmtCache( SqliteDb *pDb ){
  SqlPreparedStmt *pPreStmt;

  while(  pDb->stmtList ){
    sqlite3_finalize( pDb->stmtList->pStmt );
    pPreStmt = pDb->stmtList;
    pDb->stmtList = pDb->stmtList->pNext;
    Tcl_Free( (char*)pPreStmt );
  }
  pDb->nStmt = 0;
  pDb->stmtLast = 0;
}

/*
** TCL calls this procedure when an sqlite3 database command is
** deleted.
*/
static void DbDeleteCmd(void *db){
  SqliteDb *pDb = (SqliteDb*)db;
  flushStmtCache(pDb);