sqlite/src/main.c

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/*
** 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 1.69 2002/04/12 10:08:59 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
/*
** This is the callback routine for the code that initializes the
** database. See sqliteInit() below for additional information.
**
** Each callback contains the following information:
**
** argv[0] = "file-format" or "schema-cookie" or "table" or "index"
** argv[1] = table or index name or meta statement type.
** argv[2] = root page number for table or index. NULL for meta.
** 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;
/* TODO: Do some validity checks on all fields. In particular,
** make sure fields do not contain NULLs. Otherwise we might core
** when attempting to initialize from a corrupt database file. */
assert( argc==4 );
switch( argv[0][0] ){
case 'c': { /* Recommended pager cache size */
int size = atoi(argv[3]);
if( size==0 ){ size = MAX_PAGES; }
db->cache_size = size;
sqliteBtreeSetCacheSize(db->pBe, size);
break;
}
case 'f': { /* File format */
db->file_format = atoi(argv[3]);
break;
}
case 's': { /* Schema cookie */
db->schema_cookie = atoi(argv[3]);
db->next_cookie = db->schema_cookie;
break;
}
case 'v':
case 'i':
case 't': { /* CREATE TABLE, CREATE INDEX, or CREATE VIEW statements */
if( argv[3] && argv[3][0] ){
/* Call the parser to process a CREATE TABLE, INDEX or VIEW.
** But because sParse.initFlag is set to 1, no VDBE code is generated
** or executed. All the parser does is build the internal data
** structures that describe the table, index, or view.
*/
memset(&sParse, 0, sizeof(sParse));
sParse.db = db;
sParse.initFlag = 1;
sParse.newTnum = atoi(argv[2]);
sqliteRunParser(&sParse, argv[3], 0);
}else{
/* If the SQL column is blank it means this is an index that
** was created to be the PRIMARY KEY or to fulfill a UNIQUE
** constraint for a CREATE TABLE. The index should have already
** been created when we processed the CREATE TABLE. All we have
** to do here is record the root page number for that index.
*/
Index *pIndex = sqliteFindIndex(db, argv[1]);
if( pIndex==0 || pIndex->tnum!=0 ){
/* This can occur if there exists an index on a TEMP table which
** has the same name as another index on a permanent index. Since
** the permanent table is hidden by the TEMP table, we can also
** safely ignore the index on the permanent table.
*/
/* Do Nothing */;
}else{
pIndex->tnum = atoi(argv[2]);
}
}
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"
" tbl_name text,\n"
" rootpage integer,\n"
" sql text\n"
")"
;
/* The following VDBE 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
** tbl_name text, -- Associated table
** rootpage integer, -- The integer page number of root page
** 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. The "rootpage" column holds the number of the root page
** for the b-tree for the table or index. Finally, the "sql" column
** contains the complete text of the CREATE TABLE or CREATE INDEX
** statement that originally created the table or index. If an index
** was created to fulfill a PRIMARY KEY or UNIQUE constraint on a table,
** then the "sql" column is NULL.
**
** In format 1, entries in the sqlite_master table are in a random
** order. Two passes must be made through the table to initialize
** internal data structures. The first pass reads table definitions
** and the second pass read index definitions. Having two passes
** insures that indices appear after their tables.
**
** In format 2, entries appear in chronological order. Only a single
** pass needs to be made through the table since everything will be
** in the write order. VIEWs may only occur in format 2.
**
** 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[] = {
/* Send the file format to the callback routine
*/
{ OP_Open, 0, 2, 0},
{ OP_String, 0, 0, "file-format"},
{ OP_String, 0, 0, 0},
{ OP_String, 0, 0, 0},
{ OP_ReadCookie, 0, 1, 0},
{ OP_Callback, 4, 0, 0},
/* Send the recommended pager cache size to the callback routine
*/
{ OP_String, 0, 0, "cache-size"},
{ OP_String, 0, 0, 0},
{ OP_String, 0, 0, 0},
{ OP_ReadCookie, 0, 2, 0},
{ OP_Callback, 4, 0, 0},
/* Send the initial schema cookie to the callback
*/
{ OP_String, 0, 0, "schema_cookie"},
{ OP_String, 0, 0, 0},
{ OP_String, 0, 0, 0},
{ OP_ReadCookie, 0, 0, 0},
{ OP_Callback, 4, 0, 0},
/* Check the file format. If the format number is 2 or more,
** then do a single pass through the SQLITE_MASTER table. For
** a format number of less than 2, jump forward to a different
** algorithm that makes two passes through the SQLITE_MASTER table,
** once for tables and a second time for indices.
*/
{ OP_ReadCookie, 0, 1, 0},
{ OP_Integer, 2, 0, 0},
{ OP_Lt, 0, 28, 0},
/* This is the code for doing a single scan through the SQLITE_MASTER
** table. This code runs for format 2 and greater.
*/
{ OP_Rewind, 0, 26, 0},
{ OP_Column, 0, 0, 0}, /* 20 */
{ OP_Column, 0, 1, 0},
{ OP_Column, 0, 3, 0},
{ OP_Column, 0, 4, 0},
{ OP_Callback, 4, 0, 0},
{ OP_Next, 0, 20, 0},
{ OP_Close, 0, 0, 0}, /* 26 */
{ OP_Halt, 0, 0, 0},
/* This is the code for doing two passes through SQLITE_MASTER. This
** code runs for file format 1.
*/
{ OP_Rewind, 0, 48, 0}, /* 28 */
{ OP_Column, 0, 0, 0}, /* 29 */
{ OP_String, 0, 0, "table"},
{ OP_Ne, 0, 37, 0},
{ OP_Column, 0, 0, 0},
{ OP_Column, 0, 1, 0},
{ OP_Column, 0, 3, 0},
{ OP_Column, 0, 4, 0},
{ OP_Callback, 4, 0, 0},
{ OP_Next, 0, 29, 0}, /* 37 */
{ OP_Rewind, 0, 48, 0}, /* 38 */
{ OP_Column, 0, 0, 0}, /* 39 */
{ OP_String, 0, 0, "index"},
{ OP_Ne, 0, 47, 0},
{ OP_Column, 0, 0, 0},
{ OP_Column, 0, 1, 0},
{ OP_Column, 0, 3, 0},
{ OP_Column, 0, 4, 0},
{ OP_Callback, 4, 0, 0},
{ OP_Next, 0, 39, 0}, /* 47 */
{ OP_Close, 0, 0, 0}, /* 48 */
{ OP_Halt, 0, 0, 0},
};
/* Create a virtual machine to run the initialization program. Run
** the program. Then delete the virtual machine.
*/
vdbe = sqliteVdbeCreate(db);
if( vdbe==0 ){
sqliteSetString(pzErrMsg, "out of memory", 0);
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->nTable==0 ){
db->file_format = 2;
}
if( rc==SQLITE_OK && db->file_format>2 ){
sqliteSetString(pzErrMsg, "unsupported file format", 0);
rc = SQLITE_ERROR;
}
/* The schema for the SQLITE_MASTER table is not stored in the
** database itself. We have to invoke the callback one extra
** time to get it to process the SQLITE_MASTER table defintion.
*/
if( rc==SQLITE_OK ){
Table *pTab;
char *azArg[6];
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;
sqliteHashInit(&db->tblHash, SQLITE_HASH_STRING, 0);
sqliteHashInit(&db->idxHash, SQLITE_HASH_STRING, 0);
sqliteHashInit(&db->tblDrop, SQLITE_HASH_POINTER, 0);
sqliteHashInit(&db->idxDrop, SQLITE_HASH_POINTER, 0);
sqliteHashInit(&db->aFunc, SQLITE_HASH_STRING, 1);
sqliteRegisterBuildinFunctions(db);
db->onError = OE_Default;
db->priorNewRowid = 0;
/* Open the backend database driver */
rc = sqliteBtreeOpen(zFilename, mode, MAX_PAGES, &db->pBe);
if( rc!=SQLITE_OK ){
switch( rc ){
default: {
sqliteSetString(pzErrMsg, "unable to open database: ", zFilename, 0);
}
}
sqliteFree(db);
sqliteStrRealloc(pzErrMsg);
return 0;
}
/* Attempt to read the schema */
rc = sqliteInit(db, pzErrMsg);
if( sqlite_malloc_failed ){
sqlite_close(db);
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. Except
** tables that are created using CREATE TEMPORARY TABLE are preserved
** if the preserveTemps flag is true.
**
** 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 preserveTemps){
HashElem *pElem;
Hash temp1;
assert( sqliteHashFirst(&db->tblDrop)==0 ); /* There can not be uncommitted */
assert( sqliteHashFirst(&db->idxDrop)==0 ); /* DROP TABLEs or DROP INDEXs */
temp1 = db->tblHash;
sqliteHashInit(&db->tblHash, SQLITE_HASH_STRING, 0);
sqliteHashClear(&db->idxHash);
for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
Table *pTab = sqliteHashData(pElem);
if( preserveTemps && pTab->isTemp ){
Index *pIdx;
int nName = strlen(pTab->zName);
Table *pOld = sqliteHashInsert(&db->tblHash, pTab->zName, nName+1, pTab);
if( pOld!=0 ){
assert( pOld==pTab ); /* Malloc failed on the HashInsert */
sqliteDeleteTable(db, pOld);
continue;
}
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int n = strlen(pIdx->zName)+1;
Index *pOldIdx;
pOldIdx = sqliteHashInsert(&db->idxHash, pIdx->zName, n, pIdx);
if( pOld ){
assert( pOldIdx==pIdx );
sqliteUnlinkAndDeleteIndex(db, pOldIdx);
}
}
}else{
sqliteDeleteTable(db, pTab);
}
}
sqliteHashClear(&temp1);
db->flags &= ~SQLITE_Initialized;
}
/*
** Return the ROWID of the most recent insert
*/
int sqlite_last_insert_rowid(sqlite *db){
return db->lastRowid;
}
/*
** Return the number of changes in the most recent call to sqlite_exec().
*/
int sqlite_changes(sqlite *db){
return db->nChange;
}
/*
** Close an existing SQLite database
*/
void sqlite_close(sqlite *db){
HashElem *i;
sqliteBtreeClose(db->pBe);
clearHashTable(db, 0);
if( db->pBeTemp ){
sqliteBtreeClose(db->pBeTemp);
}
for(i=sqliteHashFirst(&db->aFunc); i; i=sqliteHashNext(i)){
FuncDef *pFunc, *pNext;
for(pFunc = (FuncDef*)sqliteHashData(i); pFunc; pFunc=pNext){
pNext = pFunc->pNext;
sqliteFree(pFunc);
}
}
sqliteHashClear(&db->aFunc);
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 '"': {
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 */
const 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;
}
}
if( db->recursionDepth==0 ){ db->nChange = 0; }
db->recursionDepth++;
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;
sqliteBtreeRollback(db->pBe);
if( db->pBeTemp ) sqliteBtreeRollback(db->pBeTemp);
db->flags &= ~SQLITE_InTrans;
clearHashTable(db, 0);
}
sqliteStrRealloc(pzErrMsg);
if( sParse.rc==SQLITE_SCHEMA ){
clearHashTable(db, 1);
}
db->recursionDepth--;
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 SQLITE_MIN_SLEEP_MS==1
int delay = 10;
int prior_delay = 0;
int timeout = (int)Timeout;
int i;
for(i=1; i<count; i++){
prior_delay += delay;
delay = delay*2;
if( delay>=1000 ){
delay = 1000;
prior_delay += 1000*(count - i - 1);
break;
}
}
if( prior_delay + delay > timeout ){
delay = timeout - prior_delay;
if( delay<=0 ) return 0;
}
sqliteOsSleep(delay);
return 1;
#else
int timeout = (int)Timeout;
if( (count+1)*1000 > timeout ){
return 0;
}
sqliteOsSleep(1000);
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;
}
/*
** Windows systems should call this routine to free memory that
** is returned in the in the errmsg parameter of sqlite_open() when
** SQLite is a DLL. For some reason, it does not work to call free()
** directly.
**
** Note that we need to call free() not sqliteFree() here, since every
** string that is exported from SQLite should have already passed through
** sqliteStrRealloc().
*/
void sqlite_freemem(void *p){ free(p); }
/*
** Windows systems need functions to call to return the sqlite_version
** and sqlite_encoding strings.
*/
const char *sqlite_libversion(void){ return sqlite_version; }
const char *sqlite_libencoding(void){ return sqlite_encoding; }
/*
** Create new user-defined functions. The sqlite_create_function()
** routine creates a regular function and sqlite_create_aggregate()
** creates an aggregate function.
**
** Passing a NULL xFunc argument or NULL xStep and xFinalize arguments
** disables the function. Calling sqlite_create_function() with the
** same name and number of arguments as a prior call to
** sqlite_create_aggregate() disables the prior call to
** sqlite_create_aggregate(), and vice versa.
**
** If nArg is -1 it means that this function will accept any number
** of arguments, including 0.
*/
int sqlite_create_function(
sqlite *db, /* Add the function to this database connection */
const char *zName, /* Name of the function to add */
int nArg, /* Number of arguments */
void (*xFunc)(sqlite_func*,int,const char**), /* The implementation */
void *pUserData /* User data */
){
FuncDef *p;
if( db==0 || zName==0 ) return 1;
p = sqliteFindFunction(db, zName, strlen(zName), nArg, 1);
if( p==0 ) return 1;
p->xFunc = xFunc;
p->xStep = 0;
p->xFinalize = 0;
p->pUserData = pUserData;
return 0;
}
int sqlite_create_aggregate(
sqlite *db, /* Add the function to this database connection */
const char *zName, /* Name of the function to add */
int nArg, /* Number of arguments */
void (*xStep)(sqlite_func*,int,const char**), /* The step function */
void (*xFinalize)(sqlite_func*), /* The finalizer */
void *pUserData /* User data */
){
FuncDef *p;
if( db==0 || zName==0 ) return 1;
p = sqliteFindFunction(db, zName, strlen(zName), nArg, 1);
if( p==0 ) return 1;
p->xFunc = 0;
p->xStep = xStep;
p->xFinalize = xFinalize;
p->pUserData = pUserData;
return 0;
}