1 /*
2 ** 2001 September 15
3 **
4 ** The author disclaims copyright to this source code.  In place of
5 ** a legal notice, here is a blessing:
6 **
7 **    May you do good and not evil.
8 **    May you find forgiveness for yourself and forgive others.
9 **    May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 ** Internal interface definitions for SQLite.
13 **
14 ** @(#) $Id: sqliteInt.h,v 1.220.2.1 2004/07/15 13:37:05 drh Exp $
15 */
16 #include "config.h"
17 #include "sqlite.h"
18 #include "hash.h"
19 #include "parse.h"
20 #include "btree.h"
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <assert.h>
25 
26 /*
27 ** The maximum number of in-memory pages to use for the main database
28 ** table and for temporary tables.
29 */
30 #define MAX_PAGES   2000
31 #define TEMP_PAGES   500
32 
33 /*
34 ** If the following macro is set to 1, then NULL values are considered
35 ** distinct for the SELECT DISTINCT statement and for UNION or EXCEPT
36 ** compound queries.  No other SQL database engine (among those tested)
37 ** works this way except for OCELOT.  But the SQL92 spec implies that
38 ** this is how things should work.
39 **
40 ** If the following macro is set to 0, then NULLs are indistinct for
41 ** SELECT DISTINCT and for UNION.
42 */
43 #define NULL_ALWAYS_DISTINCT 0
44 
45 /*
46 ** If the following macro is set to 1, then NULL values are considered
47 ** distinct when determining whether or not two entries are the same
48 ** in a UNIQUE index.  This is the way PostgreSQL, Oracle, DB2, MySQL,
49 ** OCELOT, and Firebird all work.  The SQL92 spec explicitly says this
50 ** is the way things are suppose to work.
51 **
52 ** If the following macro is set to 0, the NULLs are indistinct for
53 ** a UNIQUE index.  In this mode, you can only have a single NULL entry
54 ** for a column declared UNIQUE.  This is the way Informix and SQL Server
55 ** work.
56 */
57 #define NULL_DISTINCT_FOR_UNIQUE 1
58 
59 /*
60 ** The maximum number of attached databases.  This must be at least 2
61 ** in order to support the main database file (0) and the file used to
62 ** hold temporary tables (1).  And it must be less than 256 because
63 ** an unsigned character is used to stored the database index.
64 */
65 #define MAX_ATTACHED 10
66 
67 /*
68 ** The next macro is used to determine where TEMP tables and indices
69 ** are stored.  Possible values:
70 **
71 **   0    Always use a temporary files
72 **   1    Use a file unless overridden by "PRAGMA temp_store"
73 **   2    Use memory unless overridden by "PRAGMA temp_store"
74 **   3    Always use memory
75 */
76 #ifndef TEMP_STORE
77 # define TEMP_STORE 1
78 #endif
79 
80 /*
81 ** When building SQLite for embedded systems where memory is scarce,
82 ** you can define one or more of the following macros to omit extra
83 ** features of the library and thus keep the size of the library to
84 ** a minimum.
85 */
86 /* #define SQLITE_OMIT_AUTHORIZATION  1 */
87 /* #define SQLITE_OMIT_INMEMORYDB     1 */
88 /* #define SQLITE_OMIT_VACUUM         1 */
89 /* #define SQLITE_OMIT_DATETIME_FUNCS 1 */
90 /* #define SQLITE_OMIT_PROGRESS_CALLBACK 1 */
91 
92 /*
93 ** Integers of known sizes.  These typedefs might change for architectures
94 ** where the sizes very.  Preprocessor macros are available so that the
95 ** types can be conveniently redefined at compile-type.  Like this:
96 **
97 **         cc '-DUINTPTR_TYPE=long long int' ...
98 */
99 #ifndef UINT32_TYPE
100 # define UINT32_TYPE unsigned int
101 #endif
102 #ifndef UINT16_TYPE
103 # define UINT16_TYPE unsigned short int
104 #endif
105 #ifndef INT16_TYPE
106 # define INT16_TYPE short int
107 #endif
108 #ifndef UINT8_TYPE
109 # define UINT8_TYPE unsigned char
110 #endif
111 #ifndef INT8_TYPE
112 # define INT8_TYPE signed char
113 #endif
114 #ifndef INTPTR_TYPE
115 # if SQLITE_PTR_SZ==4
116 #   define INTPTR_TYPE int
117 # else
118 #   define INTPTR_TYPE long long
119 # endif
120 #endif
121 typedef UINT32_TYPE u32;           /* 4-byte unsigned integer */
122 typedef UINT16_TYPE u16;           /* 2-byte unsigned integer */
123 typedef INT16_TYPE i16;            /* 2-byte signed integer */
124 typedef UINT8_TYPE u8;             /* 1-byte unsigned integer */
125 typedef UINT8_TYPE i8;             /* 1-byte signed integer */
126 typedef INTPTR_TYPE ptr;           /* Big enough to hold a pointer */
127 typedef unsigned INTPTR_TYPE uptr; /* Big enough to hold a pointer */
128 
129 /*
130 ** Defer sourcing vdbe.h until after the "u8" typedef is defined.
131 */
132 #include "vdbe.h"
133 
134 /*
135 ** Most C compilers these days recognize "long double", don't they?
136 ** Just in case we encounter one that does not, we will create a macro
137 ** for long double so that it can be easily changed to just "double".
138 */
139 #ifndef LONGDOUBLE_TYPE
140 # define LONGDOUBLE_TYPE long double
141 #endif
142 
143 /*
144 ** This macro casts a pointer to an integer.  Useful for doing
145 ** pointer arithmetic.
146 */
147 #define Addr(X)  ((uptr)X)
148 
149 /*
150 ** The maximum number of bytes of data that can be put into a single
151 ** row of a single table.  The upper bound on this limit is 16777215
152 ** bytes (or 16MB-1).  We have arbitrarily set the limit to just 1MB
153 ** here because the overflow page chain is inefficient for really big
154 ** records and we want to discourage people from thinking that
155 ** multi-megabyte records are OK.  If your needs are different, you can
156 ** change this define and recompile to increase or decrease the record
157 ** size.
158 **
159 ** The 16777198 is computed as follows:  238 bytes of payload on the
160 ** original pages plus 16448 overflow pages each holding 1020 bytes of
161 ** data.
162 */
163 #define MAX_BYTES_PER_ROW  1048576
164 /* #define MAX_BYTES_PER_ROW 16777198 */
165 
166 /*
167 ** If memory allocation problems are found, recompile with
168 **
169 **      -DMEMORY_DEBUG=1
170 **
171 ** to enable some sanity checking on malloc() and free().  To
172 ** check for memory leaks, recompile with
173 **
174 **      -DMEMORY_DEBUG=2
175 **
176 ** and a line of text will be written to standard error for
177 ** each malloc() and free().  This output can be analyzed
178 ** by an AWK script to determine if there are any leaks.
179 */
180 #ifdef MEMORY_DEBUG
181 # define sqliteMalloc(X)    sqliteMalloc_(X,1,__FILE__,__LINE__)
182 # define sqliteMallocRaw(X) sqliteMalloc_(X,0,__FILE__,__LINE__)
183 # define sqliteFree(X)      sqliteFree_(X,__FILE__,__LINE__)
184 # define sqliteRealloc(X,Y) sqliteRealloc_(X,Y,__FILE__,__LINE__)
185 # define sqliteStrDup(X)    sqliteStrDup_(X,__FILE__,__LINE__)
186 # define sqliteStrNDup(X,Y) sqliteStrNDup_(X,Y,__FILE__,__LINE__)
187   void sqliteStrRealloc(char**);
188 #else
189 # define sqliteRealloc_(X,Y) sqliteRealloc(X,Y)
190 # define sqliteStrRealloc(X)
191 #endif
192 
193 /*
194 ** This variable gets set if malloc() ever fails.  After it gets set,
195 ** the SQLite library shuts down permanently.
196 */
197 extern int sqlite_malloc_failed;
198 
199 /*
200 ** The following global variables are used for testing and debugging
201 ** only.  They only work if MEMORY_DEBUG is defined.
202 */
203 #ifdef MEMORY_DEBUG
204 extern int sqlite_nMalloc;       /* Number of sqliteMalloc() calls */
205 extern int sqlite_nFree;         /* Number of sqliteFree() calls */
206 extern int sqlite_iMallocFail;   /* Fail sqliteMalloc() after this many calls */
207 #endif
208 
209 /*
210 ** Name of the master database table.  The master database table
211 ** is a special table that holds the names and attributes of all
212 ** user tables and indices.
213 */
214 #define MASTER_NAME       "sqlite_master"
215 #define TEMP_MASTER_NAME  "sqlite_temp_master"
216 
217 /*
218 ** The name of the schema table.
219 */
220 #define SCHEMA_TABLE(x)  (x?TEMP_MASTER_NAME:MASTER_NAME)
221 
222 /*
223 ** A convenience macro that returns the number of elements in
224 ** an array.
225 */
226 #define ArraySize(X)    (sizeof(X)/sizeof(X[0]))
227 
228 /*
229 ** Forward references to structures
230 */
231 typedef struct Column Column;
232 typedef struct Table Table;
233 typedef struct Index Index;
234 typedef struct Instruction Instruction;
235 typedef struct Expr Expr;
236 typedef struct ExprList ExprList;
237 typedef struct Parse Parse;
238 typedef struct Token Token;
239 typedef struct IdList IdList;
240 typedef struct SrcList SrcList;
241 typedef struct WhereInfo WhereInfo;
242 typedef struct WhereLevel WhereLevel;
243 typedef struct Select Select;
244 typedef struct AggExpr AggExpr;
245 typedef struct FuncDef FuncDef;
246 typedef struct Trigger Trigger;
247 typedef struct TriggerStep TriggerStep;
248 typedef struct TriggerStack TriggerStack;
249 typedef struct FKey FKey;
250 typedef struct Db Db;
251 typedef struct AuthContext AuthContext;
252 
253 /*
254 ** Each database file to be accessed by the system is an instance
255 ** of the following structure.  There are normally two of these structures
256 ** in the sqlite.aDb[] array.  aDb[0] is the main database file and
257 ** aDb[1] is the database file used to hold temporary tables.  Additional
258 ** databases may be attached.
259 */
260 struct Db {
261   char *zName;         /* Name of this database */
262   Btree *pBt;          /* The B*Tree structure for this database file */
263   int schema_cookie;   /* Database schema version number for this file */
264   Hash tblHash;        /* All tables indexed by name */
265   Hash idxHash;        /* All (named) indices indexed by name */
266   Hash trigHash;       /* All triggers indexed by name */
267   Hash aFKey;          /* Foreign keys indexed by to-table */
268   u8 inTrans;          /* 0: not writable.  1: Transaction.  2: Checkpoint */
269   u16 flags;           /* Flags associated with this database */
270   void *pAux;          /* Auxiliary data.  Usually NULL */
271   void (*xFreeAux)(void*);  /* Routine to free pAux */
272 };
273 
274 /*
275 ** These macros can be used to test, set, or clear bits in the
276 ** Db.flags field.
277 */
278 #define DbHasProperty(D,I,P)     (((D)->aDb[I].flags&(P))==(P))
279 #define DbHasAnyProperty(D,I,P)  (((D)->aDb[I].flags&(P))!=0)
280 #define DbSetProperty(D,I,P)     (D)->aDb[I].flags|=(P)
281 #define DbClearProperty(D,I,P)   (D)->aDb[I].flags&=~(P)
282 
283 /*
284 ** Allowed values for the DB.flags field.
285 **
286 ** The DB_Locked flag is set when the first OP_Transaction or OP_Checkpoint
287 ** opcode is emitted for a database.  This prevents multiple occurances
288 ** of those opcodes for the same database in the same program.  Similarly,
289 ** the DB_Cookie flag is set when the OP_VerifyCookie opcode is emitted,
290 ** and prevents duplicate OP_VerifyCookies from taking up space and slowing
291 ** down execution.
292 **
293 ** The DB_SchemaLoaded flag is set after the database schema has been
294 ** read into internal hash tables.
295 **
296 ** DB_UnresetViews means that one or more views have column names that
297 ** have been filled out.  If the schema changes, these column names might
298 ** changes and so the view will need to be reset.
299 */
300 #define DB_Locked          0x0001  /* OP_Transaction opcode has been emitted */
301 #define DB_Cookie          0x0002  /* OP_VerifyCookie opcode has been emiited */
302 #define DB_SchemaLoaded    0x0004  /* The schema has been loaded */
303 #define DB_UnresetViews    0x0008  /* Some views have defined column names */
304 
305 
306 /*
307 ** Each database is an instance of the following structure.
308 **
309 ** The sqlite.file_format is initialized by the database file
310 ** and helps determines how the data in the database file is
311 ** represented.  This field allows newer versions of the library
312 ** to read and write older databases.  The various file formats
313 ** are as follows:
314 **
315 **     file_format==1    Version 2.1.0.
316 **     file_format==2    Version 2.2.0. Add support for INTEGER PRIMARY KEY.
317 **     file_format==3    Version 2.6.0. Fix empty-string index bug.
318 **     file_format==4    Version 2.7.0. Add support for separate numeric and
319 **                       text datatypes.
320 **
321 ** The sqlite.temp_store determines where temporary database files
322 ** are stored.  If 1, then a file is created to hold those tables.  If
323 ** 2, then they are held in memory.  0 means use the default value in
324 ** the TEMP_STORE macro.
325 **
326 ** The sqlite.lastRowid records the last insert rowid generated by an
327 ** insert statement.  Inserts on views do not affect its value.  Each
328 ** trigger has its own context, so that lastRowid can be updated inside
329 ** triggers as usual.  The previous value will be restored once the trigger
330 ** exits.  Upon entering a before or instead of trigger, lastRowid is no
331 ** longer (since after version 2.8.12) reset to -1.
332 **
333 ** The sqlite.nChange does not count changes within triggers and keeps no
334 ** context.  It is reset at start of sqlite_exec.
335 ** The sqlite.lsChange represents the number of changes made by the last
336 ** insert, update, or delete statement.  It remains constant throughout the
337 ** length of a statement and is then updated by OP_SetCounts.  It keeps a
338 ** context stack just like lastRowid so that the count of changes
339 ** within a trigger is not seen outside the trigger.  Changes to views do not
340 ** affect the value of lsChange.
341 ** The sqlite.csChange keeps track of the number of current changes (since
342 ** the last statement) and is used to update sqlite_lsChange.
343 */
344 struct sqlite {
345   int nDb;                      /* Number of backends currently in use */
346   Db *aDb;                      /* All backends */
347   Db aDbStatic[2];              /* Static space for the 2 default backends */
348   int flags;                    /* Miscellanous flags. See below */
349   u8 file_format;               /* What file format version is this database? */
350   u8 safety_level;              /* How aggressive at synching data to disk */
351   u8 want_to_close;             /* Close after all VDBEs are deallocated */
352   u8 temp_store;                /* 1=file, 2=memory, 0=compile-time default */
353   u8 onError;                   /* Default conflict algorithm */
354   int next_cookie;              /* Next value of aDb[0].schema_cookie */
355   int cache_size;               /* Number of pages to use in the cache */
356   int nTable;                   /* Number of tables in the database */
357   void *pBusyArg;               /* 1st Argument to the busy callback */
358   int (*xBusyCallback)(void *,const char*,int);  /* The busy callback */
359   void *pCommitArg;             /* Argument to xCommitCallback() */
360   int (*xCommitCallback)(void*);/* Invoked at every commit. */
361   Hash aFunc;                   /* All functions that can be in SQL exprs */
362   int lastRowid;                /* ROWID of most recent insert (see above) */
363   int priorNewRowid;            /* Last randomly generated ROWID */
364   int magic;                    /* Magic number for detect library misuse */
365   int nChange;                  /* Number of rows changed (see above) */
366   int lsChange;                 /* Last statement change count (see above) */
367   int csChange;                 /* Current statement change count (see above) */
368   struct sqliteInitInfo {       /* Information used during initialization */
369     int iDb;                       /* When back is being initialized */
370     int newTnum;                   /* Rootpage of table being initialized */
371     u8 busy;                       /* TRUE if currently initializing */
372   } init;
373   struct Vdbe *pVdbe;           /* List of active virtual machines */
374   void (*xTrace)(void*,const char*);     /* Trace function */
375   void *pTraceArg;                       /* Argument to the trace function */
376 #ifndef SQLITE_OMIT_AUTHORIZATION
377   int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);
378                                 /* Access authorization function */
379   void *pAuthArg;               /* 1st argument to the access auth function */
380 #endif
381 #ifndef SQLITE_OMIT_PROGRESS_CALLBACK
382   int (*xProgress)(void *);     /* The progress callback */
383   void *pProgressArg;           /* Argument to the progress callback */
384   int nProgressOps;             /* Number of opcodes for progress callback */
385 #endif
386 };
387 
388 /*
389 ** Possible values for the sqlite.flags and or Db.flags fields.
390 **
391 ** On sqlite.flags, the SQLITE_InTrans value means that we have
392 ** executed a BEGIN.  On Db.flags, SQLITE_InTrans means a statement
393 ** transaction is active on that particular database file.
394 */
395 #define SQLITE_VdbeTrace      0x00000001  /* True to trace VDBE execution */
396 #define SQLITE_Initialized    0x00000002  /* True after initialization */
397 #define SQLITE_Interrupt      0x00000004  /* Cancel current operation */
398 #define SQLITE_InTrans        0x00000008  /* True if in a transaction */
399 #define SQLITE_InternChanges  0x00000010  /* Uncommitted Hash table changes */
400 #define SQLITE_FullColNames   0x00000020  /* Show full column names on SELECT */
401 #define SQLITE_ShortColNames  0x00000040  /* Show short columns names */
402 #define SQLITE_CountRows      0x00000080  /* Count rows changed by INSERT, */
403                                           /*   DELETE, or UPDATE and return */
404                                           /*   the count using a callback. */
405 #define SQLITE_NullCallback   0x00000100  /* Invoke the callback once if the */
406                                           /*   result set is empty */
407 #define SQLITE_ReportTypes    0x00000200  /* Include information on datatypes */
408                                           /*   in 4th argument of callback */
409 
410 /*
411 ** Possible values for the sqlite.magic field.
412 ** The numbers are obtained at random and have no special meaning, other
413 ** than being distinct from one another.
414 */
415 #define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */
416 #define SQLITE_MAGIC_CLOSED   0x9f3c2d33  /* Database is closed */
417 #define SQLITE_MAGIC_BUSY     0xf03b7906  /* Database currently in use */
418 #define SQLITE_MAGIC_ERROR    0xb5357930  /* An SQLITE_MISUSE error occurred */
419 
420 /*
421 ** Each SQL function is defined by an instance of the following
422 ** structure.  A pointer to this structure is stored in the sqlite.aFunc
423 ** hash table.  When multiple functions have the same name, the hash table
424 ** points to a linked list of these structures.
425 */
426 struct FuncDef {
427   void (*xFunc)(sqlite_func*,int,const char**);  /* Regular function */
428   void (*xStep)(sqlite_func*,int,const char**);  /* Aggregate function step */
429   void (*xFinalize)(sqlite_func*);           /* Aggregate function finializer */
430   signed char nArg;         /* Number of arguments.  -1 means unlimited */
431   signed char dataType;     /* Arg that determines datatype.  -1=NUMERIC, */
432                             /* -2=TEXT. -3=SQLITE_ARGS */
433   u8 includeTypes;          /* Add datatypes to args of xFunc and xStep */
434   void *pUserData;          /* User data parameter */
435   FuncDef *pNext;           /* Next function with same name */
436 };
437 
438 /*
439 ** information about each column of an SQL table is held in an instance
440 ** of this structure.
441 */
442 struct Column {
443   char *zName;     /* Name of this column */
444   char *zDflt;     /* Default value of this column */
445   char *zType;     /* Data type for this column */
446   u8 notNull;      /* True if there is a NOT NULL constraint */
447   u8 isPrimKey;    /* True if this column is part of the PRIMARY KEY */
448   u8 sortOrder;    /* Some combination of SQLITE_SO_... values */
449   u8 dottedName;   /* True if zName contains a "." character */
450 };
451 
452 /*
453 ** The allowed sort orders.
454 **
455 ** The TEXT and NUM values use bits that do not overlap with DESC and ASC.
456 ** That way the two can be combined into a single number.
457 */
458 #define SQLITE_SO_UNK       0  /* Use the default collating type.  (SCT_NUM) */
459 #define SQLITE_SO_TEXT      2  /* Sort using memcmp() */
460 #define SQLITE_SO_NUM       4  /* Sort using sqliteCompare() */
461 #define SQLITE_SO_TYPEMASK  6  /* Mask to extract the collating sequence */
462 #define SQLITE_SO_ASC       0  /* Sort in ascending order */
463 #define SQLITE_SO_DESC      1  /* Sort in descending order */
464 #define SQLITE_SO_DIRMASK   1  /* Mask to extract the sort direction */
465 
466 /*
467 ** Each SQL table is represented in memory by an instance of the
468 ** following structure.
469 **
470 ** Table.zName is the name of the table.  The case of the original
471 ** CREATE TABLE statement is stored, but case is not significant for
472 ** comparisons.
473 **
474 ** Table.nCol is the number of columns in this table.  Table.aCol is a
475 ** pointer to an array of Column structures, one for each column.
476 **
477 ** If the table has an INTEGER PRIMARY KEY, then Table.iPKey is the index of
478 ** the column that is that key.   Otherwise Table.iPKey is negative.  Note
479 ** that the datatype of the PRIMARY KEY must be INTEGER for this field to
480 ** be set.  An INTEGER PRIMARY KEY is used as the rowid for each row of
481 ** the table.  If a table has no INTEGER PRIMARY KEY, then a random rowid
482 ** is generated for each row of the table.  Table.hasPrimKey is true if
483 ** the table has any PRIMARY KEY, INTEGER or otherwise.
484 **
485 ** Table.tnum is the page number for the root BTree page of the table in the
486 ** database file.  If Table.iDb is the index of the database table backend
487 ** in sqlite.aDb[].  0 is for the main database and 1 is for the file that
488 ** holds temporary tables and indices.  If Table.isTransient
489 ** is true, then the table is stored in a file that is automatically deleted
490 ** when the VDBE cursor to the table is closed.  In this case Table.tnum
491 ** refers VDBE cursor number that holds the table open, not to the root
492 ** page number.  Transient tables are used to hold the results of a
493 ** sub-query that appears instead of a real table name in the FROM clause
494 ** of a SELECT statement.
495 */
496 struct Table {
497   char *zName;     /* Name of the table */
498   int nCol;        /* Number of columns in this table */
499   Column *aCol;    /* Information about each column */
500   int iPKey;       /* If not less then 0, use aCol[iPKey] as the primary key */
501   Index *pIndex;   /* List of SQL indexes on this table. */
502   int tnum;        /* Root BTree node for this table (see note above) */
503   Select *pSelect; /* NULL for tables.  Points to definition if a view. */
504   u8 readOnly;     /* True if this table should not be written by the user */
505   u8 iDb;          /* Index into sqlite.aDb[] of the backend for this table */
506   u8 isTransient;  /* True if automatically deleted when VDBE finishes */
507   u8 hasPrimKey;   /* True if there exists a primary key */
508   u8 keyConf;      /* What to do in case of uniqueness conflict on iPKey */
509   Trigger *pTrigger; /* List of SQL triggers on this table */
510   FKey *pFKey;       /* Linked list of all foreign keys in this table */
511 };
512 
513 /*
514 ** Each foreign key constraint is an instance of the following structure.
515 **
516 ** A foreign key is associated with two tables.  The "from" table is
517 ** the table that contains the REFERENCES clause that creates the foreign
518 ** key.  The "to" table is the table that is named in the REFERENCES clause.
519 ** Consider this example:
520 **
521 **     CREATE TABLE ex1(
522 **       a INTEGER PRIMARY KEY,
523 **       b INTEGER CONSTRAINT fk1 REFERENCES ex2(x)
524 **     );
525 **
526 ** For foreign key "fk1", the from-table is "ex1" and the to-table is "ex2".
527 **
528 ** Each REFERENCES clause generates an instance of the following structure
529 ** which is attached to the from-table.  The to-table need not exist when
530 ** the from-table is created.  The existance of the to-table is not checked
531 ** until an attempt is made to insert data into the from-table.
532 **
533 ** The sqlite.aFKey hash table stores pointers to this structure
534 ** given the name of a to-table.  For each to-table, all foreign keys
535 ** associated with that table are on a linked list using the FKey.pNextTo
536 ** field.
537 */
538 struct FKey {
539   Table *pFrom;     /* The table that constains the REFERENCES clause */
540   FKey *pNextFrom;  /* Next foreign key in pFrom */
541   char *zTo;        /* Name of table that the key points to */
542   FKey *pNextTo;    /* Next foreign key that points to zTo */
543   int nCol;         /* Number of columns in this key */
544   struct sColMap {  /* Mapping of columns in pFrom to columns in zTo */
545     int iFrom;         /* Index of column in pFrom */
546     char *zCol;        /* Name of column in zTo.  If 0 use PRIMARY KEY */
547   } *aCol;          /* One entry for each of nCol column s */
548   u8 isDeferred;    /* True if constraint checking is deferred till COMMIT */
549   u8 updateConf;    /* How to resolve conflicts that occur on UPDATE */
550   u8 deleteConf;    /* How to resolve conflicts that occur on DELETE */
551   u8 insertConf;    /* How to resolve conflicts that occur on INSERT */
552 };
553 
554 /*
555 ** SQLite supports many different ways to resolve a contraint
556 ** error.  ROLLBACK processing means that a constraint violation
557 ** causes the operation in process to fail and for the current transaction
558 ** to be rolled back.  ABORT processing means the operation in process
559 ** fails and any prior changes from that one operation are backed out,
560 ** but the transaction is not rolled back.  FAIL processing means that
561 ** the operation in progress stops and returns an error code.  But prior
562 ** changes due to the same operation are not backed out and no rollback
563 ** occurs.  IGNORE means that the particular row that caused the constraint
564 ** error is not inserted or updated.  Processing continues and no error
565 ** is returned.  REPLACE means that preexisting database rows that caused
566 ** a UNIQUE constraint violation are removed so that the new insert or
567 ** update can proceed.  Processing continues and no error is reported.
568 **
569 ** RESTRICT, SETNULL, and CASCADE actions apply only to foreign keys.
570 ** RESTRICT is the same as ABORT for IMMEDIATE foreign keys and the
571 ** same as ROLLBACK for DEFERRED keys.  SETNULL means that the foreign
572 ** key is set to NULL.  CASCADE means that a DELETE or UPDATE of the
573 ** referenced table row is propagated into the row that holds the
574 ** foreign key.
575 **
576 ** The following symbolic values are used to record which type
577 ** of action to take.
578 */
579 #define OE_None     0   /* There is no constraint to check */
580 #define OE_Rollback 1   /* Fail the operation and rollback the transaction */
581 #define OE_Abort    2   /* Back out changes but do no rollback transaction */
582 #define OE_Fail     3   /* Stop the operation but leave all prior changes */
583 #define OE_Ignore   4   /* Ignore the error. Do not do the INSERT or UPDATE */
584 #define OE_Replace  5   /* Delete existing record, then do INSERT or UPDATE */
585 
586 #define OE_Restrict 6   /* OE_Abort for IMMEDIATE, OE_Rollback for DEFERRED */
587 #define OE_SetNull  7   /* Set the foreign key value to NULL */
588 #define OE_SetDflt  8   /* Set the foreign key value to its default */
589 #define OE_Cascade  9   /* Cascade the changes */
590 
591 #define OE_Default  99  /* Do whatever the default action is */
592 
593 /*
594 ** Each SQL index is represented in memory by an
595 ** instance of the following structure.
596 **
597 ** The columns of the table that are to be indexed are described
598 ** by the aiColumn[] field of this structure.  For example, suppose
599 ** we have the following table and index:
600 **
601 **     CREATE TABLE Ex1(c1 int, c2 int, c3 text);
602 **     CREATE INDEX Ex2 ON Ex1(c3,c1);
603 **
604 ** In the Table structure describing Ex1, nCol==3 because there are
605 ** three columns in the table.  In the Index structure describing
606 ** Ex2, nColumn==2 since 2 of the 3 columns of Ex1 are indexed.
607 ** The value of aiColumn is {2, 0}.  aiColumn[0]==2 because the
608 ** first column to be indexed (c3) has an index of 2 in Ex1.aCol[].
609 ** The second column to be indexed (c1) has an index of 0 in
610 ** Ex1.aCol[], hence Ex2.aiColumn[1]==0.
611 **
612 ** The Index.onError field determines whether or not the indexed columns
613 ** must be unique and what to do if they are not.  When Index.onError=OE_None,
614 ** it means this is not a unique index.  Otherwise it is a unique index
615 ** and the value of Index.onError indicate the which conflict resolution
616 ** algorithm to employ whenever an attempt is made to insert a non-unique
617 ** element.
618 */
619 struct Index {
620   char *zName;     /* Name of this index */
621   int nColumn;     /* Number of columns in the table used by this index */
622   int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
623   Table *pTable;   /* The SQL table being indexed */
624   int tnum;        /* Page containing root of this index in database file */
625   u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
626   u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
627   u8 iDb;          /* Index in sqlite.aDb[] of where this index is stored */
628   Index *pNext;    /* The next index associated with the same table */
629 };
630 
631 /*
632 ** Each token coming out of the lexer is an instance of
633 ** this structure.  Tokens are also used as part of an expression.
634 **
635 ** Note if Token.z==0 then Token.dyn and Token.n are undefined and
636 ** may contain random values.  Do not make any assuptions about Token.dyn
637 ** and Token.n when Token.z==0.
638 */
639 struct Token {
640   const char *z;      /* Text of the token.  Not NULL-terminated! */
641   unsigned dyn  : 1;  /* True for malloced memory, false for static */
642   unsigned n    : 31; /* Number of characters in this token */
643 };
644 
645 /*
646 ** Each node of an expression in the parse tree is an instance
647 ** of this structure.
648 **
649 ** Expr.op is the opcode.  The integer parser token codes are reused
650 ** as opcodes here.  For example, the parser defines TK_GE to be an integer
651 ** code representing the ">=" operator.  This same integer code is reused
652 ** to represent the greater-than-or-equal-to operator in the expression
653 ** tree.
654 **
655 ** Expr.pRight and Expr.pLeft are subexpressions.  Expr.pList is a list
656 ** of argument if the expression is a function.
657 **
658 ** Expr.token is the operator token for this node.  For some expressions
659 ** that have subexpressions, Expr.token can be the complete text that gave
660 ** rise to the Expr.  In the latter case, the token is marked as being
661 ** a compound token.
662 **
663 ** An expression of the form ID or ID.ID refers to a column in a table.
664 ** For such expressions, Expr.op is set to TK_COLUMN and Expr.iTable is
665 ** the integer cursor number of a VDBE cursor pointing to that table and
666 ** Expr.iColumn is the column number for the specific column.  If the
667 ** expression is used as a result in an aggregate SELECT, then the
668 ** value is also stored in the Expr.iAgg column in the aggregate so that
669 ** it can be accessed after all aggregates are computed.
670 **
671 ** If the expression is a function, the Expr.iTable is an integer code
672 ** representing which function.  If the expression is an unbound variable
673 ** marker (a question mark character '?' in the original SQL) then the
674 ** Expr.iTable holds the index number for that variable.
675 **
676 ** The Expr.pSelect field points to a SELECT statement.  The SELECT might
677 ** be the right operand of an IN operator.  Or, if a scalar SELECT appears
678 ** in an expression the opcode is TK_SELECT and Expr.pSelect is the only
679 ** operand.
680 */
681 struct Expr {
682   u8 op;                 /* Operation performed by this node */
683   u8 dataType;           /* Either SQLITE_SO_TEXT or SQLITE_SO_NUM */
684   u8 iDb;                /* Database referenced by this expression */
685   u8 flags;              /* Various flags.  See below */
686   Expr *pLeft, *pRight;  /* Left and right subnodes */
687   ExprList *pList;       /* A list of expressions used as function arguments
688                          ** or in "<expr> IN (<expr-list)" */
689   Token token;           /* An operand token */
690   Token span;            /* Complete text of the expression */
691   int iTable, iColumn;   /* When op==TK_COLUMN, then this expr node means the
692                          ** iColumn-th field of the iTable-th table. */
693   int iAgg;              /* When op==TK_COLUMN and pParse->useAgg==TRUE, pull
694                          ** result from the iAgg-th element of the aggregator */
695   Select *pSelect;       /* When the expression is a sub-select.  Also the
696                          ** right side of "<expr> IN (<select>)" */
697 };
698 
699 /*
700 ** The following are the meanings of bits in the Expr.flags field.
701 */
702 #define EP_FromJoin     0x0001  /* Originated in ON or USING clause of a join */
703 
704 /*
705 ** These macros can be used to test, set, or clear bits in the
706 ** Expr.flags field.
707 */
708 #define ExprHasProperty(E,P)     (((E)->flags&(P))==(P))
709 #define ExprHasAnyProperty(E,P)  (((E)->flags&(P))!=0)
710 #define ExprSetProperty(E,P)     (E)->flags|=(P)
711 #define ExprClearProperty(E,P)   (E)->flags&=~(P)
712 
713 /*
714 ** A list of expressions.  Each expression may optionally have a
715 ** name.  An expr/name combination can be used in several ways, such
716 ** as the list of "expr AS ID" fields following a "SELECT" or in the
717 ** list of "ID = expr" items in an UPDATE.  A list of expressions can
718 ** also be used as the argument to a function, in which case the a.zName
719 ** field is not used.
720 */
721 struct ExprList {
722   int nExpr;             /* Number of expressions on the list */
723   int nAlloc;            /* Number of entries allocated below */
724   struct ExprList_item {
725     Expr *pExpr;           /* The list of expressions */
726     char *zName;           /* Token associated with this expression */
727     u8 sortOrder;          /* 1 for DESC or 0 for ASC */
728     u8 isAgg;              /* True if this is an aggregate like count(*) */
729     u8 done;               /* A flag to indicate when processing is finished */
730   } *a;                  /* One entry for each expression */
731 };
732 
733 /*
734 ** An instance of this structure can hold a simple list of identifiers,
735 ** such as the list "a,b,c" in the following statements:
736 **
737 **      INSERT INTO t(a,b,c) VALUES ...;
738 **      CREATE INDEX idx ON t(a,b,c);
739 **      CREATE TRIGGER trig BEFORE UPDATE ON t(a,b,c) ...;
740 **
741 ** The IdList.a.idx field is used when the IdList represents the list of
742 ** column names after a table name in an INSERT statement.  In the statement
743 **
744 **     INSERT INTO t(a,b,c) ...
745 **
746 ** If "a" is the k-th column of table "t", then IdList.a[0].idx==k.
747 */
748 struct IdList {
749   int nId;         /* Number of identifiers on the list */
750   int nAlloc;      /* Number of entries allocated for a[] below */
751   struct IdList_item {
752     char *zName;      /* Name of the identifier */
753     int idx;          /* Index in some Table.aCol[] of a column named zName */
754   } *a;
755 };
756 
757 /*
758 ** The following structure describes the FROM clause of a SELECT statement.
759 ** Each table or subquery in the FROM clause is a separate element of
760 ** the SrcList.a[] array.
761 **
762 ** With the addition of multiple database support, the following structure
763 ** can also be used to describe a particular table such as the table that
764 ** is modified by an INSERT, DELETE, or UPDATE statement.  In standard SQL,
765 ** such a table must be a simple name: ID.  But in SQLite, the table can
766 ** now be identified by a database name, a dot, then the table name: ID.ID.
767 */
768 struct SrcList {
769   i16 nSrc;        /* Number of tables or subqueries in the FROM clause */
770   i16 nAlloc;      /* Number of entries allocated in a[] below */
771   struct SrcList_item {
772     char *zDatabase;  /* Name of database holding this table */
773     char *zName;      /* Name of the table */
774     char *zAlias;     /* The "B" part of a "A AS B" phrase.  zName is the "A" */
775     Table *pTab;      /* An SQL table corresponding to zName */
776     Select *pSelect;  /* A SELECT statement used in place of a table name */
777     int jointype;     /* Type of join between this table and the next */
778     int iCursor;      /* The VDBE cursor number used to access this table */
779     Expr *pOn;        /* The ON clause of a join */
780     IdList *pUsing;   /* The USING clause of a join */
781   } a[1];             /* One entry for each identifier on the list */
782 };
783 
784 /*
785 ** Permitted values of the SrcList.a.jointype field
786 */
787 #define JT_INNER     0x0001    /* Any kind of inner or cross join */
788 #define JT_NATURAL   0x0002    /* True for a "natural" join */
789 #define JT_LEFT      0x0004    /* Left outer join */
790 #define JT_RIGHT     0x0008    /* Right outer join */
791 #define JT_OUTER     0x0010    /* The "OUTER" keyword is present */
792 #define JT_ERROR     0x0020    /* unknown or unsupported join type */
793 
794 /*
795 ** For each nested loop in a WHERE clause implementation, the WhereInfo
796 ** structure contains a single instance of this structure.  This structure
797 ** is intended to be private the the where.c module and should not be
798 ** access or modified by other modules.
799 */
800 struct WhereLevel {
801   int iMem;            /* Memory cell used by this level */
802   Index *pIdx;         /* Index used */
803   int iCur;            /* Cursor number used for this index */
804   int score;           /* How well this indexed scored */
805   int brk;             /* Jump here to break out of the loop */
806   int cont;            /* Jump here to continue with the next loop cycle */
807   int op, p1, p2;      /* Opcode used to terminate the loop */
808   int iLeftJoin;       /* Memory cell used to implement LEFT OUTER JOIN */
809   int top;             /* First instruction of interior of the loop */
810   int inOp, inP1, inP2;/* Opcode used to implement an IN operator */
811   int bRev;            /* Do the scan in the reverse direction */
812 };
813 
814 /*
815 ** The WHERE clause processing routine has two halves.  The
816 ** first part does the start of the WHERE loop and the second
817 ** half does the tail of the WHERE loop.  An instance of
818 ** this structure is returned by the first half and passed
819 ** into the second half to give some continuity.
820 */
821 struct WhereInfo {
822   Parse *pParse;
823   SrcList *pTabList;   /* List of tables in the join */
824   int iContinue;       /* Jump here to continue with next record */
825   int iBreak;          /* Jump here to break out of the loop */
826   int nLevel;          /* Number of nested loop */
827   int savedNTab;       /* Value of pParse->nTab before WhereBegin() */
828   int peakNTab;        /* Value of pParse->nTab after WhereBegin() */
829   WhereLevel a[1];     /* Information about each nest loop in the WHERE */
830 };
831 
832 /*
833 ** An instance of the following structure contains all information
834 ** needed to generate code for a single SELECT statement.
835 **
836 ** The zSelect field is used when the Select structure must be persistent.
837 ** Normally, the expression tree points to tokens in the original input
838 ** string that encodes the select.  But if the Select structure must live
839 ** longer than its input string (for example when it is used to describe
840 ** a VIEW) we have to make a copy of the input string so that the nodes
841 ** of the expression tree will have something to point to.  zSelect is used
842 ** to hold that copy.
843 **
844 ** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
845 ** If there is a LIMIT clause, the parser sets nLimit to the value of the
846 ** limit and nOffset to the value of the offset (or 0 if there is not
847 ** offset).  But later on, nLimit and nOffset become the memory locations
848 ** in the VDBE that record the limit and offset counters.
849 */
850 struct Select {
851   ExprList *pEList;      /* The fields of the result */
852   u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
853   u8 isDistinct;         /* True if the DISTINCT keyword is present */
854   SrcList *pSrc;         /* The FROM clause */
855   Expr *pWhere;          /* The WHERE clause */
856   ExprList *pGroupBy;    /* The GROUP BY clause */
857   Expr *pHaving;         /* The HAVING clause */
858   ExprList *pOrderBy;    /* The ORDER BY clause */
859   Select *pPrior;        /* Prior select in a compound select statement */
860   int nLimit, nOffset;   /* LIMIT and OFFSET values.  -1 means not used */
861   int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
862   char *zSelect;         /* Complete text of the SELECT command */
863 };
864 
865 /*
866 ** The results of a select can be distributed in several ways.
867 */
868 #define SRT_Callback     1  /* Invoke a callback with each row of result */
869 #define SRT_Mem          2  /* Store result in a memory cell */
870 #define SRT_Set          3  /* Store result as unique keys in a table */
871 #define SRT_Union        5  /* Store result as keys in a table */
872 #define SRT_Except       6  /* Remove result from a UNION table */
873 #define SRT_Table        7  /* Store result as data with a unique key */
874 #define SRT_TempTable    8  /* Store result in a trasient table */
875 #define SRT_Discard      9  /* Do not save the results anywhere */
876 #define SRT_Sorter      10  /* Store results in the sorter */
877 #define SRT_Subroutine  11  /* Call a subroutine to handle results */
878 
879 /*
880 ** When a SELECT uses aggregate functions (like "count(*)" or "avg(f1)")
881 ** we have to do some additional analysis of expressions.  An instance
882 ** of the following structure holds information about a single subexpression
883 ** somewhere in the SELECT statement.  An array of these structures holds
884 ** all the information we need to generate code for aggregate
885 ** expressions.
886 **
887 ** Note that when analyzing a SELECT containing aggregates, both
888 ** non-aggregate field variables and aggregate functions are stored
889 ** in the AggExpr array of the Parser structure.
890 **
891 ** The pExpr field points to an expression that is part of either the
892 ** field list, the GROUP BY clause, the HAVING clause or the ORDER BY
893 ** clause.  The expression will be freed when those clauses are cleaned
894 ** up.  Do not try to delete the expression attached to AggExpr.pExpr.
895 **
896 ** If AggExpr.pExpr==0, that means the expression is "count(*)".
897 */
898 struct AggExpr {
899   int isAgg;        /* if TRUE contains an aggregate function */
900   Expr *pExpr;      /* The expression */
901   FuncDef *pFunc;   /* Information about the aggregate function */
902 };
903 
904 /*
905 ** An SQL parser context.  A copy of this structure is passed through
906 ** the parser and down into all the parser action routine in order to
907 ** carry around information that is global to the entire parse.
908 */
909 struct Parse {
910   sqlite *db;          /* The main database structure */
911   int rc;              /* Return code from execution */
912   char *zErrMsg;       /* An error message */
913   Token sErrToken;     /* The token at which the error occurred */
914   Token sFirstToken;   /* The first token parsed */
915   Token sLastToken;    /* The last token parsed */
916   const char *zTail;   /* All SQL text past the last semicolon parsed */
917   Table *pNewTable;    /* A table being constructed by CREATE TABLE */
918   Vdbe *pVdbe;         /* An engine for executing database bytecode */
919   u8 colNamesSet;      /* TRUE after OP_ColumnName has been issued to pVdbe */
920   u8 explain;          /* True if the EXPLAIN flag is found on the query */
921   u8 nameClash;        /* A permanent table name clashes with temp table name */
922   u8 useAgg;           /* If true, extract field values from the aggregator
923                        ** while generating expressions.  Normally false */
924   int nErr;            /* Number of errors seen */
925   int nTab;            /* Number of previously allocated VDBE cursors */
926   int nMem;            /* Number of memory cells used so far */
927   int nSet;            /* Number of sets used so far */
928   int nAgg;            /* Number of aggregate expressions */
929   int nVar;            /* Number of '?' variables seen in the SQL so far */
930   AggExpr *aAgg;       /* An array of aggregate expressions */
931   const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */
932   Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
933   TriggerStack *trigStack;  /* Trigger actions being coded */
934 };
935 
936 /*
937 ** An instance of the following structure can be declared on a stack and used
938 ** to save the Parse.zAuthContext value so that it can be restored later.
939 */
940 struct AuthContext {
941   const char *zAuthContext;   /* Put saved Parse.zAuthContext here */
942   Parse *pParse;              /* The Parse structure */
943 };
944 
945 /*
946 ** Bitfield flags for P2 value in OP_PutIntKey and OP_Delete
947 */
948 #define OPFLAG_NCHANGE   1    /* Set to update db->nChange */
949 #define OPFLAG_LASTROWID 2    /* Set to update db->lastRowid */
950 #define OPFLAG_CSCHANGE  4    /* Set to update db->csChange */
951 
952 /*
953  * Each trigger present in the database schema is stored as an instance of
954  * struct Trigger.
955  *
956  * Pointers to instances of struct Trigger are stored in two ways.
957  * 1. In the "trigHash" hash table (part of the sqlite* that represents the
958  *    database). This allows Trigger structures to be retrieved by name.
959  * 2. All triggers associated with a single table form a linked list, using the
960  *    pNext member of struct Trigger. A pointer to the first element of the
961  *    linked list is stored as the "pTrigger" member of the associated
962  *    struct Table.
963  *
964  * The "step_list" member points to the first element of a linked list
965  * containing the SQL statements specified as the trigger program.
966  */
967 struct Trigger {
968   char *name;             /* The name of the trigger                        */
969   char *table;            /* The table or view to which the trigger applies */
970   u8 iDb;                 /* Database containing this trigger               */
971   u8 iTabDb;              /* Database containing Trigger.table              */
972   u8 op;                  /* One of TK_DELETE, TK_UPDATE, TK_INSERT         */
973   u8 tr_tm;               /* One of TK_BEFORE, TK_AFTER */
974   Expr *pWhen;            /* The WHEN clause of the expresion (may be NULL) */
975   IdList *pColumns;       /* If this is an UPDATE OF <column-list> trigger,
976                              the <column-list> is stored here */
977   int foreach;            /* One of TK_ROW or TK_STATEMENT */
978   Token nameToken;        /* Token containing zName. Use during parsing only */
979 
980   TriggerStep *step_list; /* Link list of trigger program steps             */
981   Trigger *pNext;         /* Next trigger associated with the table */
982 };
983 
984 /*
985  * An instance of struct TriggerStep is used to store a single SQL statement
986  * that is a part of a trigger-program.
987  *
988  * Instances of struct TriggerStep are stored in a singly linked list (linked
989  * using the "pNext" member) referenced by the "step_list" member of the
990  * associated struct Trigger instance. The first element of the linked list is
991  * the first step of the trigger-program.
992  *
993  * The "op" member indicates whether this is a "DELETE", "INSERT", "UPDATE" or
994  * "SELECT" statement. The meanings of the other members is determined by the
995  * value of "op" as follows:
996  *
997  * (op == TK_INSERT)
998  * orconf    -> stores the ON CONFLICT algorithm
999  * pSelect   -> If this is an INSERT INTO ... SELECT ... statement, then
1000  *              this stores a pointer to the SELECT statement. Otherwise NULL.
1001  * target    -> A token holding the name of the table to insert into.
1002  * pExprList -> If this is an INSERT INTO ... VALUES ... statement, then
1003  *              this stores values to be inserted. Otherwise NULL.
1004  * pIdList   -> If this is an INSERT INTO ... (<column-names>) VALUES ...
1005  *              statement, then this stores the column-names to be
1006  *              inserted into.
1007  *
1008  * (op == TK_DELETE)
1009  * target    -> A token holding the name of the table to delete from.
1010  * pWhere    -> The WHERE clause of the DELETE statement if one is specified.
1011  *              Otherwise NULL.
1012  *
1013  * (op == TK_UPDATE)
1014  * target    -> A token holding the name of the table to update rows of.
1015  * pWhere    -> The WHERE clause of the UPDATE statement if one is specified.
1016  *              Otherwise NULL.
1017  * pExprList -> A list of the columns to update and the expressions to update
1018  *              them to. See sqliteUpdate() documentation of "pChanges"
1019  *              argument.
1020  *
1021  */
1022 struct TriggerStep {
1023   int op;              /* One of TK_DELETE, TK_UPDATE, TK_INSERT, TK_SELECT */
1024   int orconf;          /* OE_Rollback etc. */
1025   Trigger *pTrig;      /* The trigger that this step is a part of */
1026 
1027   Select *pSelect;     /* Valid for SELECT and sometimes
1028 			  INSERT steps (when pExprList == 0) */
1029   Token target;        /* Valid for DELETE, UPDATE, INSERT steps */
1030   Expr *pWhere;        /* Valid for DELETE, UPDATE steps */
1031   ExprList *pExprList; /* Valid for UPDATE statements and sometimes
1032 			   INSERT steps (when pSelect == 0)         */
1033   IdList *pIdList;     /* Valid for INSERT statements only */
1034 
1035   TriggerStep * pNext; /* Next in the link-list */
1036 };
1037 
1038 /*
1039  * An instance of struct TriggerStack stores information required during code
1040  * generation of a single trigger program. While the trigger program is being
1041  * coded, its associated TriggerStack instance is pointed to by the
1042  * "pTriggerStack" member of the Parse structure.
1043  *
1044  * The pTab member points to the table that triggers are being coded on. The
1045  * newIdx member contains the index of the vdbe cursor that points at the temp
1046  * table that stores the new.* references. If new.* references are not valid
1047  * for the trigger being coded (for example an ON DELETE trigger), then newIdx
1048  * is set to -1. The oldIdx member is analogous to newIdx, for old.* references.
1049  *
1050  * The ON CONFLICT policy to be used for the trigger program steps is stored
1051  * as the orconf member. If this is OE_Default, then the ON CONFLICT clause
1052  * specified for individual triggers steps is used.
1053  *
1054  * struct TriggerStack has a "pNext" member, to allow linked lists to be
1055  * constructed. When coding nested triggers (triggers fired by other triggers)
1056  * each nested trigger stores its parent trigger's TriggerStack as the "pNext"
1057  * pointer. Once the nested trigger has been coded, the pNext value is restored
1058  * to the pTriggerStack member of the Parse stucture and coding of the parent
1059  * trigger continues.
1060  *
1061  * Before a nested trigger is coded, the linked list pointed to by the
1062  * pTriggerStack is scanned to ensure that the trigger is not about to be coded
1063  * recursively. If this condition is detected, the nested trigger is not coded.
1064  */
1065 struct TriggerStack {
1066   Table *pTab;         /* Table that triggers are currently being coded on */
1067   int newIdx;          /* Index of vdbe cursor to "new" temp table */
1068   int oldIdx;          /* Index of vdbe cursor to "old" temp table */
1069   int orconf;          /* Current orconf policy */
1070   int ignoreJump;      /* where to jump to for a RAISE(IGNORE) */
1071   Trigger *pTrigger;   /* The trigger currently being coded */
1072   TriggerStack *pNext; /* Next trigger down on the trigger stack */
1073 };
1074 
1075 /*
1076 ** The following structure contains information used by the sqliteFix...
1077 ** routines as they walk the parse tree to make database references
1078 ** explicit.
1079 */
1080 typedef struct DbFixer DbFixer;
1081 struct DbFixer {
1082   Parse *pParse;      /* The parsing context.  Error messages written here */
1083   const char *zDb;    /* Make sure all objects are contained in this database */
1084   const char *zType;  /* Type of the container - used for error messages */
1085   const Token *pName; /* Name of the container - used for error messages */
1086 };
1087 
1088 /*
1089  * This global flag is set for performance testing of triggers. When it is set
1090  * SQLite will perform the overhead of building new and old trigger references
1091  * even when no triggers exist
1092  */
1093 extern int always_code_trigger_setup;
1094 
1095 /*
1096 ** Internal function prototypes
1097 */
1098 int sqliteStrICmp(const char *, const char *);
1099 int sqliteStrNICmp(const char *, const char *, int);
1100 int sqliteHashNoCase(const char *, int);
1101 int sqliteIsNumber(const char*);
1102 int sqliteCompare(const char *, const char *);
1103 int sqliteSortCompare(const char *, const char *);
1104 void sqliteRealToSortable(double r, char *);
1105 #ifdef MEMORY_DEBUG
1106   void *sqliteMalloc_(int,int,char*,int);
1107   void sqliteFree_(void*,char*,int);
1108   void *sqliteRealloc_(void*,int,char*,int);
1109   char *sqliteStrDup_(const char*,char*,int);
1110   char *sqliteStrNDup_(const char*, int,char*,int);
1111   void sqliteCheckMemory(void*,int);
1112 #else
1113   void *sqliteMalloc(int);
1114   void *sqliteMallocRaw(int);
1115   void sqliteFree(void*);
1116   void *sqliteRealloc(void*,int);
1117   char *sqliteStrDup(const char*);
1118   char *sqliteStrNDup(const char*, int);
1119 # define sqliteCheckMemory(a,b)
1120 #endif
1121 char *sqliteMPrintf(const char*, ...);
1122 char *sqliteVMPrintf(const char*, va_list);
1123 void sqliteSetString(char **, const char *, ...);
1124 void sqliteSetNString(char **, ...);
1125 void sqliteErrorMsg(Parse*, const char*, ...);
1126 void sqliteDequote(char*);
1127 int sqliteKeywordCode(const char*, int);
1128 int sqliteRunParser(Parse*, const char*, char **);
1129 void sqliteExec(Parse*);
1130 Expr *sqliteExpr(int, Expr*, Expr*, Token*);
1131 void sqliteExprSpan(Expr*,Token*,Token*);
1132 Expr *sqliteExprFunction(ExprList*, Token*);
1133 void sqliteExprDelete(Expr*);
1134 ExprList *sqliteExprListAppend(ExprList*,Expr*,Token*);
1135 void sqliteExprListDelete(ExprList*);
1136 int sqliteInit(sqlite*, char**);
1137 void sqlitePragma(Parse*,Token*,Token*,int);
1138 void sqliteResetInternalSchema(sqlite*, int);
1139 void sqliteBeginParse(Parse*,int);
1140 void sqliteRollbackInternalChanges(sqlite*);
1141 void sqliteCommitInternalChanges(sqlite*);
1142 Table *sqliteResultSetOfSelect(Parse*,char*,Select*);
1143 void sqliteOpenMasterTable(Vdbe *v, int);
1144 void sqliteStartTable(Parse*,Token*,Token*,int,int);
1145 void sqliteAddColumn(Parse*,Token*);
1146 void sqliteAddNotNull(Parse*, int);
1147 void sqliteAddPrimaryKey(Parse*, IdList*, int);
1148 void sqliteAddColumnType(Parse*,Token*,Token*);
1149 void sqliteAddDefaultValue(Parse*,Token*,int);
1150 int sqliteCollateType(const char*, int);
1151 void sqliteAddCollateType(Parse*, int);
1152 void sqliteEndTable(Parse*,Token*,Select*);
1153 void sqliteCreateView(Parse*,Token*,Token*,Select*,int);
1154 int sqliteViewGetColumnNames(Parse*,Table*);
1155 void sqliteDropTable(Parse*, Token*, int);
1156 void sqliteDeleteTable(sqlite*, Table*);
1157 void sqliteInsert(Parse*, SrcList*, ExprList*, Select*, IdList*, int);
1158 IdList *sqliteIdListAppend(IdList*, Token*);
1159 int sqliteIdListIndex(IdList*,const char*);
1160 SrcList *sqliteSrcListAppend(SrcList*, Token*, Token*);
1161 void sqliteSrcListAddAlias(SrcList*, Token*);
1162 void sqliteSrcListAssignCursors(Parse*, SrcList*);
1163 void sqliteIdListDelete(IdList*);
1164 void sqliteSrcListDelete(SrcList*);
1165 void sqliteCreateIndex(Parse*,Token*,SrcList*,IdList*,int,Token*,Token*);
1166 void sqliteDropIndex(Parse*, SrcList*);
1167 void sqliteAddKeyType(Vdbe*, ExprList*);
1168 void sqliteAddIdxKeyType(Vdbe*, Index*);
1169 int sqliteSelect(Parse*, Select*, int, int, Select*, int, int*);
1170 Select *sqliteSelectNew(ExprList*,SrcList*,Expr*,ExprList*,Expr*,ExprList*,
1171                         int,int,int);
1172 void sqliteSelectDelete(Select*);
1173 void sqliteSelectUnbind(Select*);
1174 Table *sqliteSrcListLookup(Parse*, SrcList*);
1175 int sqliteIsReadOnly(Parse*, Table*, int);
1176 void sqliteDeleteFrom(Parse*, SrcList*, Expr*);
1177 void sqliteUpdate(Parse*, SrcList*, ExprList*, Expr*, int);
1178 WhereInfo *sqliteWhereBegin(Parse*, SrcList*, Expr*, int, ExprList**);
1179 void sqliteWhereEnd(WhereInfo*);
1180 void sqliteExprCode(Parse*, Expr*);
1181 int sqliteExprCodeExprList(Parse*, ExprList*, int);
1182 void sqliteExprIfTrue(Parse*, Expr*, int, int);
1183 void sqliteExprIfFalse(Parse*, Expr*, int, int);
1184 Table *sqliteFindTable(sqlite*,const char*, const char*);
1185 Table *sqliteLocateTable(Parse*,const char*, const char*);
1186 Index *sqliteFindIndex(sqlite*,const char*, const char*);
1187 void sqliteUnlinkAndDeleteIndex(sqlite*,Index*);
1188 void sqliteCopy(Parse*, SrcList*, Token*, Token*, int);
1189 void sqliteVacuum(Parse*, Token*);
1190 int sqliteRunVacuum(char**, sqlite*);
1191 int sqliteGlobCompare(const unsigned char*,const unsigned char*);
1192 int sqliteLikeCompare(const unsigned char*,const unsigned char*);
1193 char *sqliteTableNameFromToken(Token*);
1194 int sqliteExprCheck(Parse*, Expr*, int, int*);
1195 int sqliteExprType(Expr*);
1196 int sqliteExprCompare(Expr*, Expr*);
1197 int sqliteFuncId(Token*);
1198 int sqliteExprResolveIds(Parse*, SrcList*, ExprList*, Expr*);
1199 int sqliteExprAnalyzeAggregates(Parse*, Expr*);
1200 Vdbe *sqliteGetVdbe(Parse*);
1201 void sqliteRandomness(int, void*);
1202 void sqliteRollbackAll(sqlite*);
1203 void sqliteCodeVerifySchema(Parse*, int);
1204 void sqliteBeginTransaction(Parse*, int);
1205 void sqliteCommitTransaction(Parse*);
1206 void sqliteRollbackTransaction(Parse*);
1207 int sqliteExprIsConstant(Expr*);
1208 int sqliteExprIsInteger(Expr*, int*);
1209 int sqliteIsRowid(const char*);
1210 void sqliteGenerateRowDelete(sqlite*, Vdbe*, Table*, int, int);
1211 void sqliteGenerateRowIndexDelete(sqlite*, Vdbe*, Table*, int, char*);
1212 void sqliteGenerateConstraintChecks(Parse*,Table*,int,char*,int,int,int,int);
1213 void sqliteCompleteInsertion(Parse*, Table*, int, char*, int, int, int);
1214 int sqliteOpenTableAndIndices(Parse*, Table*, int);
1215 void sqliteBeginWriteOperation(Parse*, int, int);
1216 void sqliteEndWriteOperation(Parse*);
1217 Expr *sqliteExprDup(Expr*);
1218 void sqliteTokenCopy(Token*, Token*);
1219 ExprList *sqliteExprListDup(ExprList*);
1220 SrcList *sqliteSrcListDup(SrcList*);
1221 IdList *sqliteIdListDup(IdList*);
1222 Select *sqliteSelectDup(Select*);
1223 FuncDef *sqliteFindFunction(sqlite*,const char*,int,int,int);
1224 void sqliteRegisterBuiltinFunctions(sqlite*);
1225 void sqliteRegisterDateTimeFunctions(sqlite*);
1226 int sqliteSafetyOn(sqlite*);
1227 int sqliteSafetyOff(sqlite*);
1228 int sqliteSafetyCheck(sqlite*);
1229 void sqliteChangeCookie(sqlite*, Vdbe*);
1230 void sqliteBeginTrigger(Parse*, Token*,int,int,IdList*,SrcList*,int,Expr*,int);
1231 void sqliteFinishTrigger(Parse*, TriggerStep*, Token*);
1232 void sqliteDropTrigger(Parse*, SrcList*);
1233 void sqliteDropTriggerPtr(Parse*, Trigger*, int);
1234 int sqliteTriggersExist(Parse* , Trigger* , int , int , int, ExprList*);
1235 int sqliteCodeRowTrigger(Parse*, int, ExprList*, int, Table *, int, int,
1236                          int, int);
1237 void sqliteViewTriggers(Parse*, Table*, Expr*, int, ExprList*);
1238 void sqliteDeleteTriggerStep(TriggerStep*);
1239 TriggerStep *sqliteTriggerSelectStep(Select*);
1240 TriggerStep *sqliteTriggerInsertStep(Token*, IdList*, ExprList*, Select*, int);
1241 TriggerStep *sqliteTriggerUpdateStep(Token*, ExprList*, Expr*, int);
1242 TriggerStep *sqliteTriggerDeleteStep(Token*, Expr*);
1243 void sqliteDeleteTrigger(Trigger*);
1244 int sqliteJoinType(Parse*, Token*, Token*, Token*);
1245 void sqliteCreateForeignKey(Parse*, IdList*, Token*, IdList*, int);
1246 void sqliteDeferForeignKey(Parse*, int);
1247 #ifndef SQLITE_OMIT_AUTHORIZATION
1248   void sqliteAuthRead(Parse*,Expr*,SrcList*);
1249   int sqliteAuthCheck(Parse*,int, const char*, const char*, const char*);
1250   void sqliteAuthContextPush(Parse*, AuthContext*, const char*);
1251   void sqliteAuthContextPop(AuthContext*);
1252 #else
1253 # define sqliteAuthRead(a,b,c)
1254 # define sqliteAuthCheck(a,b,c,d,e)    SQLITE_OK
1255 # define sqliteAuthContextPush(a,b,c)
1256 # define sqliteAuthContextPop(a)  ((void)(a))
1257 #endif
1258 void sqliteAttach(Parse*, Token*, Token*, Token*);
1259 void sqliteDetach(Parse*, Token*);
1260 int sqliteBtreeFactory(const sqlite *db, const char *zFilename,
1261                        int mode, int nPg, Btree **ppBtree);
1262 int sqliteFixInit(DbFixer*, Parse*, int, const char*, const Token*);
1263 int sqliteFixSrcList(DbFixer*, SrcList*);
1264 int sqliteFixSelect(DbFixer*, Select*);
1265 int sqliteFixExpr(DbFixer*, Expr*);
1266 int sqliteFixExprList(DbFixer*, ExprList*);
1267 int sqliteFixTriggerStep(DbFixer*, TriggerStep*);
1268 double sqliteAtoF(const char *z, const char **);
1269 char *sqlite_snprintf(int,char*,const char*,...);
1270 int sqliteFitsIn32Bits(const char *);
1271