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+/*
+** 2024-02-08
+**
+** 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.
+**
+*************************************************************************
+*/
+
+/*
+** Incremental Integrity-Check Extension
+** -------------------------------------
+**
+** This module contains code to check whether or not an SQLite database
+** is well-formed or corrupt. This is the same task as performed by SQLite's
+** built-in "PRAGMA integrity_check" command. This module differs from
+** "PRAGMA integrity_check" in that:
+**
+** + It is less thorough - this module does not detect certain types
+** of corruption that are detected by the PRAGMA command. However,
+** it does detect all kinds of corruption that are likely to cause
+** errors in SQLite applications.
+**
+** + It is slower. Sometimes up to three times slower.
+**
+** + It allows integrity-check operations to be split into multiple
+** transactions, so that the database does not need to be read-locked
+** for the duration of the integrity-check.
+**
+** One way to use the API to run integrity-check on the "main" database
+** of handle db is:
+**
+** int rc = SQLITE_OK;
+** sqlite3_intck *p = 0;
+**
+** sqlite3_intck_open(db, "main", &p);
+** while( SQLITE_OK==sqlite3_intck_step(p) ){
+** const char *zMsg = sqlite3_intck_message(p);
+** if( zMsg ) printf("corruption: %s\n", zMsg);
+** }
+** rc = sqlite3_intck_error(p, &zErr);
+** if( rc!=SQLITE_OK ){
+** printf("error occured (rc=%d), (errmsg=%s)\n", rc, zErr);
+** }
+** sqlite3_intck_close(p);
+**
+** Usually, the sqlite3_intck object opens a read transaction within the
+** first call to sqlite3_intck_step() and holds it open until the
+** integrity-check is complete. However, if sqlite3_intck_unlock() is
+** called, the read transaction is ended and a new read transaction opened
+** by the subsequent call to sqlite3_intck_step().
+*/
+
+#ifndef _SQLITE_INTCK_H
+#define _SQLITE_INTCK_H
+
+#include "sqlite3.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+** An ongoing incremental integrity-check operation is represented by an
+** opaque pointer of the following type.
+*/
+typedef struct sqlite3_intck sqlite3_intck;
+
+/*
+** Open a new incremental integrity-check object. If successful, populate
+** output variable (*ppOut) with the new object handle and return SQLITE_OK.
+** Or, if an error occurs, set (*ppOut) to NULL and return an SQLite error
+** code (e.g. SQLITE_NOMEM).
+**
+** The integrity-check will be conducted on database zDb (which must be "main",
+** "temp", or the name of an attached database) of database handle db. Once
+** this function has been called successfully, the caller should not use
+** database handle db until the integrity-check object has been destroyed
+** using sqlite3_intck_close().
+*/
+int sqlite3_intck_open(
+ sqlite3 *db, /* Database handle */
+ const char *zDb, /* Database name ("main", "temp" etc.) */
+ sqlite3_intck **ppOut /* OUT: New sqlite3_intck handle */
+);
+
+/*
+** Close and release all resources associated with a handle opened by an
+** earlier call to sqlite3_intck_open(). The results of using an
+** integrity-check handle after it has been passed to this function are
+** undefined.
+*/
+void sqlite3_intck_close(sqlite3_intck *pCk);
+
+/*
+** Do the next step of the integrity-check operation specified by the handle
+** passed as the only argument. This function returns SQLITE_DONE if the
+** integrity-check operation is finished, or an SQLite error code if
+** an error occurs, or SQLITE_OK if no error occurs but the integrity-check
+** is not finished. It is not considered an error if database corruption
+** is encountered.
+**
+** Following a successful call to sqlite3_intck_step() (one that returns
+** SQLITE_OK), sqlite3_intck_message() returns a non-NULL value if
+** corruption was detected in the db.
+**
+** If an error occurs and a value other than SQLITE_OK or SQLITE_DONE is
+** returned, then the integrity-check handle is placed in an error state.
+** In this state all subsequent calls to sqlite3_intck_step() or
+** sqlite3_intck_unlock() will immediately return the same error. The
+** sqlite3_intck_error() method may be used to obtain an English language
+** error message in this case.
+*/
+int sqlite3_intck_step(sqlite3_intck *pCk);
+
+/*
+** If the previous call to sqlite3_intck_step() encountered corruption
+** within the database, then this function returns a pointer to a buffer
+** containing a nul-terminated string describing the corruption in
+** English. If the previous call to sqlite3_intck_step() did not encounter
+** corruption, or if there was no previous call, this function returns
+** NULL.
+*/
+const char *sqlite3_intck_message(sqlite3_intck *pCk);
+
+/*
+** Close any read-transaction opened by an earlier call to
+** sqlite3_intck_step(). Any subsequent call to sqlite3_intck_step() will
+** open a new transaction. Return SQLITE_OK if successful, or an SQLite error
+** code otherwise.
+**
+** If an error occurs, then the integrity-check handle is placed in an error
+** state. In this state all subsequent calls to sqlite3_intck_step() or
+** sqlite3_intck_unlock() will immediately return the same error. The
+** sqlite3_intck_error() method may be used to obtain an English language
+** error message in this case.
+*/
+int sqlite3_intck_unlock(sqlite3_intck *pCk);
+
+/*
+** If an error has occurred in an earlier call to sqlite3_intck_step()
+** or sqlite3_intck_unlock(), then this method returns the associated
+** SQLite error code. Additionally, if pzErr is not NULL, then (*pzErr)
+** may be set to point to a nul-terminated string containing an English
+** language error message. Or, if no error message is available, to
+** NULL.
+**
+** If no error has occurred within sqlite3_intck_step() or
+** sqlite_intck_unlock() calls on the handle passed as the first argument,
+** then SQLITE_OK is returned and (*pzErr) set to NULL.
+*/
+int sqlite3_intck_error(sqlite3_intck *pCk, const char **pzErr);
+
+/*
+** This API is used for testing only. It returns the full-text of an SQL
+** statement used to test object zObj, which may be a table or index.
+** The returned buffer is valid until the next call to either this function
+** or sqlite3_intck_close() on the same sqlite3_intck handle.
+*/
+const char *sqlite3_intck_test_sql(sqlite3_intck *pCk, const char *zObj);
+
+
+#ifdef __cplusplus
+} /* end of the 'extern "C"' block */
+#endif
+
+#endif /* ifndef _SQLITE_INTCK_H */