/*
** 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 1.37 2001/09/16 00:13:27 drh Exp $
*/
#include "sqliteInt.h"
#if defined(HAVE_USLEEP) && HAVE_USLEEP
#include <unistd.h>
#endif
/*
** This is the callback routine for the code that initializes the
** database. Each callback contains the following information:
**
** argv[0] = "meta" or "table" or "index"
** argv[1] = table or index name
** argv[2] = root page number for table or index
** argv[3] = SQL create statement for the table or index
**
*/
static int sqliteOpenCb(void *pDb, int argc, char **argv, char **azColName){
sqlite *db = (sqlite*)pDb;
Parse sParse;
int nErr = 0;
assert( argc==4 );
switch( argv[0][0] ){
case 'm': { /* Meta information */
if( strcmp(argv[1],"file-format")==0 ){
db->file_format = atoi(argv[3]);
}else if( strcmp(argv[1],"schema-cookie")==0 ){
db->schema_cookie = atoi(argv[3]);
db->next_cookie = db->schema_cookie;
}
break;
}
case 'i':
case 't': { /* CREATE TABLE and CREATE INDEX statements */
memset(&sParse, 0, sizeof(sParse));
sParse.db = db;
sParse.initFlag = 1;
sParse.newTnum = atoi(argv[2]);
nErr = sqliteRunParser(&sParse, argv[3], 0);
break;
}
default: {
/* This can not happen! */
nErr = 1;
assert( nErr==0 );
}
}
return nErr;
}
/*
** Attempt to read the database schema and initialize internal
** data structures. Return one of the SQLITE_ error codes to
** indicate success or failure.
**
** After the database is initialized, the SQLITE_Initialized
** bit is set in the flags field of the sqlite structure. An
** attempt is made to initialize the database as soon as it
** is opened. If that fails (perhaps because another process
** has the sqlite_master table locked) than another attempt
** is made the first time the database is accessed.
*/
static int sqliteInit(sqlite *db, char **pzErrMsg){
Vdbe *vdbe;
int rc;
/*
** The master database table has a structure like this
*/
static char master_schema[] =
"CREATE TABLE " MASTER_NAME " (\n"
" type text,\n"
" name text,\n"
" tnum integer,\n"
" tbl_name text,\n"
" sql text\n"
")"
;
/* The following program is used to initialize the internal
** structure holding the tables and indexes of the database.
** The database contains a special table named "sqlite_master"
** defined as follows:
**
** CREATE TABLE sqlite_master (
** type text, -- Either "table" or "index" or "meta"
** name text, -- Name of table or index
** tnum integer, -- The integer page number of root page
** tbl_name text, -- Associated table
** sql text -- The CREATE statement for this object
** );
**
** The sqlite_master table contains a single entry for each table
** and each index. The "type" column tells whether the entry is
** a table or index. The "name" column is the name of the object.
** The "tbl_name" is the name of the associated table. For tables,
** the tbl_name column is always the same as name. For indices, the
** tbl_name column contains the name of the table that the index
** indexes. Finally, the "sql" column contains the complete text of
** the CREATE TABLE or CREATE INDEX statement that originally created
** the table or index.
**
** If the "type" column has the value "meta", then the "sql" column
** contains extra information about the database, such as the
** file format version number. All meta information must be processed
** before any tables or indices are constructed.
**
** The following program invokes its callback on the SQL for each
** table then goes back and invokes the callback on the
** SQL for each index. The callback will invoke the
** parser to build the internal representation of the
** database scheme.
*/
static VdbeOp initProg[] = {
{ OP_Open, 0, 2, 0},
{ OP_Rewind, 0, 0, 0},
{ OP_Next, 0, 12, 0}, /* 2 */
{ OP_Column, 0, 0, 0},
{ OP_String, 0, 0, "meta"},
{ OP_Ne, 0, 2, 0},
{ OP_Column, 0, 0, 0},
{ OP_Column, 0, 1, 0},
{ OP_Column, 0, 2, 0},
{ OP_Column, 0, 4, 0},
{ OP_Callback, 4, 0, 0},
{ OP_Goto, 0, 2, 0},
{ OP_Rewind, 0, 0, 0}, /* 12 */
{ OP_Next, 0, 23, 0}, /* 13 */
{ OP_Column, 0, 0, 0},
{ OP_String, 0, 0, "table"},
{ OP_Ne, 0, 13, 0},
{ OP_Column, 0, 0, 0},
{ OP_Column, 0, 1, 0},
{ OP_Column, 0, 2, 0},
{ OP_Column, 0, 4, 0},
{ OP_Callback, 4, 0, 0},
{ OP_Goto, 0, 13, 0},
{ OP_Rewind, 0, 0, 0}, /* 23 */
{ OP_Next, 0, 34, 0}, /* 24 */
{ OP_Column, 0, 0, 0},
{ OP_String, 0, 0, "index"},
{ OP_Ne, 0, 24, 0},
{ OP_Column, 0, 0, 0},
{ OP_Column, 0, 1, 0},
{ OP_Column, 0, 2, 0},
{ OP_Column, 0, 4, 0},
{ OP_Callback, 4, 0, 0},
{ OP_Goto, 0, 24, 0},
{ OP_String, 0, 0, "meta"}, /* 34 */
{ OP_String, 0, 0, "schema-cookie"},
{ OP_String, 0, 0, ""},
{ OP_ReadCookie,0,0, 0},
{ OP_Callback, 4, 0, 0},
{ OP_Close, 0, 0, 0},
{ OP_Halt, 0, 0, 0},
};
/* Create a virtual machine to run the initialization program. Run
** the program. The delete the virtual machine.
*/
vdbe = sqliteVdbeCreate(db);
if( vdbe==0 ){
sqliteSetString(pzErrMsg, "out of memory");
return SQLITE_NOMEM;
}
sqliteVdbeAddOpList(vdbe, sizeof(initProg)/sizeof(initProg[0]), initProg);
rc = sqliteVdbeExec(vdbe, sqliteOpenCb, db, pzErrMsg,
db->pBusyArg, db->xBusyCallback);
sqliteVdbeDelete(vdbe);
if( rc==SQLITE_OK && db->file_format>1 && db->nTable>0 ){
sqliteSetString(pzErrMsg, "unsupported file format", 0);
rc = SQLITE_ERROR;
}
if( rc==SQLITE_OK ){
Table *pTab;
char *azArg[5];
azArg[0] = "table";
azArg[1] = MASTER_NAME;
azArg[2] = "2";
azArg[3] = master_schema;
azArg[4] = 0;
sqliteOpenCb(db, 4, azArg, 0);
pTab = sqliteFindTable(db, MASTER_NAME);
if( pTab ){
pTab->readOnly = 1;
}
db->flags |= SQLITE_Initialized;
sqliteCommitInternalChanges(db);
}
return rc;
}
/*
** The version of the library
*/
const char sqlite_version[] = SQLITE_VERSION;
/*
** Does the library expect data to be encoded as UTF-8 or iso8859? The
** following global constant always lets us know.
*/
#ifdef SQLITE_UTF8
const char sqlite_encoding[] = "UTF-8";
#else
const char sqlite_encoding[] = "iso8859";
#endif
/*
** Open a new SQLite database. Construct an "sqlite" structure to define
** the state of this database and return a pointer to that structure.
**
** An attempt is made to initialize the in-memory data structures that
** hold the database schema. But if this fails (because the schema file
** is locked) then that step is deferred until the first call to
** sqlite_exec().
*/
sqlite *sqlite_open(const char *zFilename, int mode, char **pzErrMsg){
sqlite *db;
int rc;
/* Allocate the sqlite data structure */
db = sqliteMalloc( sizeof(sqlite) );
if( pzErrMsg ) *pzErrMsg = 0;
if( db==0 ) goto no_mem_on_open;
/* Open the backend database driver */
rc = sqliteBtreeOpen(zFilename, mode, MAX_PAGES, &db->pBe);
if( rc!=SQLITE_OK ){
switch( rc ){
default: {
if( pzErrMsg ){
sqliteSetString(pzErrMsg, "unable to open database: ", zFilename, 0);
}
}
}
sqliteFree(db);
sqliteStrRealloc(pzErrMsg);
return 0;
}
/* Assume file format 1 unless the database says otherwise */
db->file_format = 1;
/* Attempt to read the schema */
rc = sqliteInit(db, pzErrMsg);
if( sqlite_malloc_failed ){
goto no_mem_on_open;
}else if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
sqlite_close(db);
sqliteStrRealloc(pzErrMsg);
return 0;
}else /* if( pzErrMsg ) */{
sqliteFree(*pzErrMsg);
*pzErrMsg = 0;
}
return db;
no_mem_on_open:
sqliteSetString(pzErrMsg, "out of memory", 0);
sqliteStrRealloc(pzErrMsg);
return 0;
}
/*
** Erase all schema information from the schema hash table.
**
** The database schema is normally read in once when the database
** is first opened and stored in a hash table in the sqlite structure.
** This routine erases the stored schema. This erasure occurs because
** either the database is being closed or because some other process
** changed the schema and this process needs to reread it.
*/
static void clearHashTable(sqlite *db){
int i;
for(i=0; i<N_HASH; i++){
Table *pNext, *pList = db->apTblHash[i];
db->apTblHash[i] = 0;
while( pList ){
pNext = pList->pHash;
pList->pHash = 0;
sqliteDeleteTable(db, pList);
pList = pNext;
}
}
db->flags &= ~SQLITE_Initialized;
}
/*
** Close an existing SQLite database
*/
void sqlite_close(sqlite *db){
sqliteBtreeClose(db->pBe);
clearHashTable(db);
sqliteFree(db);
}
/*
** Return TRUE if the given SQL string ends in a semicolon.
*/
int sqlite_complete(const char *zSql){
int isComplete = 0;
while( *zSql ){
switch( *zSql ){
case ';': {
isComplete = 1;
break;
}
case ' ':
case '\t':
case '\n':
case '\f': {
break;
}
case '\'': {
isComplete = 0;
zSql++;
while( *zSql && *zSql!='\'' ){ zSql++; }
if( *zSql==0 ) return 0;
break;
}
case '"': {
isComplete = 0;
zSql++;
while( *zSql && *zSql!='"' ){ zSql++; }
if( *zSql==0 ) return 0;
break;
}
case '-': {
if( zSql[1]!='-' ){
isComplete = 0;
break;
}
while( *zSql && *zSql!='\n' ){ zSql++; }
if( *zSql==0 ) return isComplete;
break;
}
default: {
isComplete = 0;
break;
}
}
zSql++;
}
return isComplete;
}
/*
** Execute SQL code. Return one of the SQLITE_ success/failure
** codes. Also write an error message into memory obtained from
** malloc() and make *pzErrMsg point to that message.
**
** If the SQL is a query, then for each row in the query result
** the xCallback() function is called. pArg becomes the first
** argument to xCallback(). If xCallback=NULL then no callback
** is invoked, even for queries.
*/
int sqlite_exec(
sqlite *db, /* The database on which the SQL executes */
char *zSql, /* The SQL to be executed */
sqlite_callback xCallback, /* Invoke this callback routine */
void *pArg, /* First argument to xCallback() */
char **pzErrMsg /* Write error messages here */
){
Parse sParse;
if( pzErrMsg ) *pzErrMsg = 0;
if( (db->flags & SQLITE_Initialized)==0 ){
int rc = sqliteInit(db, pzErrMsg);
if( rc!=SQLITE_OK ){
sqliteStrRealloc(pzErrMsg);
return rc;
}
}
memset(&sParse, 0, sizeof(sParse));
sParse.db = db;
sParse.pBe = db->pBe;
sParse.xCallback = xCallback;
sParse.pArg = pArg;
sqliteRunParser(&sParse, zSql, pzErrMsg);
if( sqlite_malloc_failed ){
sqliteSetString(pzErrMsg, "out of memory", 0);
sParse.rc = SQLITE_NOMEM;
}
sqliteStrRealloc(pzErrMsg);
if( sParse.rc==SQLITE_SCHEMA ){
clearHashTable(db);
}
return sParse.rc;
}
/*
** This routine implements a busy callback that sleeps and tries
** again until a timeout value is reached. The timeout value is
** an integer number of milliseconds passed in as the first
** argument.
*/
static int sqliteDefaultBusyCallback(
void *Timeout, /* Maximum amount of time to wait */
const char *NotUsed, /* The name of the table that is busy */
int count /* Number of times table has been busy */
){
#if defined(HAVE_USLEEP) && HAVE_USLEEP
int delay = 10000;
int prior_delay = 0;
int timeout = (int)Timeout;
int i;
for(i=1; i<count; i++){
prior_delay += delay;
delay = delay*2;
if( delay>=1000000 ){
delay = 1000000;
prior_delay += 1000000*(count - i - 1);
break;
}
}
if( prior_delay + delay > timeout*1000 ){
delay = timeout*1000 - prior_delay;
if( delay<=0 ) return 0;
}
usleep(delay);
return 1;
#else
int timeout = (int)Timeout;
if( (count+1)*1000 > timeout ){
return 0;
}
sleep(1);
return 1;
#endif
}
/*
** This routine sets the busy callback for an Sqlite database to the
** given callback function with the given argument.
*/
void sqlite_busy_handler(
sqlite *db,
int (*xBusy)(void*,const char*,int),
void *pArg
){
db->xBusyCallback = xBusy;
db->pBusyArg = pArg;
}
/*
** This routine installs a default busy handler that waits for the
** specified number of milliseconds before returning 0.
*/
void sqlite_busy_timeout(sqlite *db, int ms){
if( ms>0 ){
sqlite_busy_handler(db, sqliteDefaultBusyCallback, (void*)ms);
}else{
sqlite_busy_handler(db, 0, 0);
}
}
/*
** Cause any pending operation to stop at its earliest opportunity.
*/
void sqlite_interrupt(sqlite *db){
db->flags |= SQLITE_Interrupt;
}