113 lines
3.2 KiB
Go
113 lines
3.2 KiB
Go
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// Copyright (C) 2019 G.J.R. Timmer <gjr.timmer@gmail.com>.
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// Copyright (C) 2018 segment.com <friends@segment.com>
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//
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file.
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// +build sqlite_preupdate_hook
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package sqlite3
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/*
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#cgo CFLAGS: -DSQLITE_ENABLE_PREUPDATE_HOOK
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#cgo LDFLAGS: -lm
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#ifndef USE_LIBSQLITE3
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#include "sqlite3-binding.h"
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#else
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#include <sqlite3.h>
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#endif
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#include <stdlib.h>
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#include <string.h>
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void preUpdateHookTrampoline(void*, sqlite3 *, int, char *, char *, sqlite3_int64, sqlite3_int64);
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*/
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import "C"
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import (
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"errors"
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"unsafe"
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)
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// RegisterPreUpdateHook sets the pre-update hook for a connection.
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//
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// The callback is passed a SQLitePreUpdateData struct with the data for
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// the update, as well as methods for fetching copies of impacted data.
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//
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// If there is an existing preupdate hook for this connection, it will be
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// removed. If callback is nil the existing hook (if any) will be removed
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// without creating a new one.
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func (c *SQLiteConn) RegisterPreUpdateHook(callback func(SQLitePreUpdateData)) {
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if callback == nil {
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C.sqlite3_preupdate_hook(c.db, nil, nil)
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} else {
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C.sqlite3_preupdate_hook(c.db, (*[0]byte)(unsafe.Pointer(C.preUpdateHookTrampoline)), unsafe.Pointer(newHandle(c, callback)))
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}
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}
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// Depth returns the source path of the write, see sqlite3_preupdate_depth()
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func (d *SQLitePreUpdateData) Depth() int {
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return int(C.sqlite3_preupdate_depth(d.Conn.db))
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}
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// Count returns the number of columns in the row
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func (d *SQLitePreUpdateData) Count() int {
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return int(C.sqlite3_preupdate_count(d.Conn.db))
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}
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func (d *SQLitePreUpdateData) row(dest []interface{}, new bool) error {
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for i := 0; i < d.Count() && i < len(dest); i++ {
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var val *C.sqlite3_value
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var src interface{}
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// Initially I tried making this just a function pointer argument, but
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// it's absurdly complicated to pass C function pointers.
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if new {
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C.sqlite3_preupdate_new(d.Conn.db, C.int(i), &val)
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} else {
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C.sqlite3_preupdate_old(d.Conn.db, C.int(i), &val)
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}
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switch C.sqlite3_value_type(val) {
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case C.SQLITE_INTEGER:
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src = int64(C.sqlite3_value_int64(val))
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case C.SQLITE_FLOAT:
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src = float64(C.sqlite3_value_double(val))
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case C.SQLITE_BLOB:
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len := C.sqlite3_value_bytes(val)
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blobptr := C.sqlite3_value_blob(val)
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src = C.GoBytes(blobptr, len)
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case C.SQLITE_TEXT:
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len := C.sqlite3_value_bytes(val)
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cstrptr := unsafe.Pointer(C.sqlite3_value_text(val))
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src = C.GoBytes(cstrptr, len)
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case C.SQLITE_NULL:
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src = nil
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}
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err := convertAssign(&dest[i], src)
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if err != nil {
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return err
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}
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}
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return nil
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}
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// Old populates dest with the row data to be replaced. This works similar to
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// database/sql's Rows.Scan()
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func (d *SQLitePreUpdateData) Old(dest ...interface{}) error {
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if d.Op == SQLITE_INSERT {
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return errors.New("There is no old row for INSERT operations")
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}
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return d.row(dest, false)
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}
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// New populates dest with the replacement row data. This works similar to
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// database/sql's Rows.Scan()
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func (d *SQLitePreUpdateData) New(dest ...interface{}) error {
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if d.Op == SQLITE_DELETE {
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return errors.New("There is no new row for DELETE operations")
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}
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return d.row(dest, true)
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}
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