1// Copyright (C) 2019 G.J.R. Timmer <gjr.timmer@gmail.com>. 2// Copyright (C) 2018 segment.com <friends@segment.com> 3// 4// Use of this source code is governed by an MIT-style 5// license that can be found in the LICENSE file. 6 7// +build sqlite_preupdate_hook 8 9package sqlite3 10 11/* 12#cgo CFLAGS: -DSQLITE_ENABLE_PREUPDATE_HOOK 13#cgo LDFLAGS: -lm 14 15#ifndef USE_LIBSQLITE3 16#include <sqlite3-binding.h> 17#else 18#include <sqlite3.h> 19#endif 20#include <stdlib.h> 21#include <string.h> 22 23void preUpdateHookTrampoline(void*, sqlite3 *, int, char *, char *, sqlite3_int64, sqlite3_int64); 24*/ 25import "C" 26import ( 27 "errors" 28 "unsafe" 29) 30 31// RegisterPreUpdateHook sets the pre-update hook for a connection. 32// 33// The callback is passed a SQLitePreUpdateData struct with the data for 34// the update, as well as methods for fetching copies of impacted data. 35// 36// If there is an existing update hook for this connection, it will be 37// removed. If callback is nil the existing hook (if any) will be removed 38// without creating a new one. 39func (c *SQLiteConn) RegisterPreUpdateHook(callback func(SQLitePreUpdateData)) { 40 if callback == nil { 41 C.sqlite3_preupdate_hook(c.db, nil, nil) 42 } else { 43 C.sqlite3_preupdate_hook(c.db, (*[0]byte)(unsafe.Pointer(C.preUpdateHookTrampoline)), unsafe.Pointer(newHandle(c, callback))) 44 } 45} 46 47// Depth returns the source path of the write, see sqlite3_preupdate_depth() 48func (d *SQLitePreUpdateData) Depth() int { 49 return int(C.sqlite3_preupdate_depth(d.Conn.db)) 50} 51 52// Count returns the number of columns in the row 53func (d *SQLitePreUpdateData) Count() int { 54 return int(C.sqlite3_preupdate_count(d.Conn.db)) 55} 56 57func (d *SQLitePreUpdateData) row(dest []interface{}, new bool) error { 58 for i := 0; i < d.Count() && i < len(dest); i++ { 59 var val *C.sqlite3_value 60 var src interface{} 61 62 // Initially I tried making this just a function pointer argument, but 63 // it's absurdly complicated to pass C function pointers. 64 if new { 65 C.sqlite3_preupdate_new(d.Conn.db, C.int(i), &val) 66 } else { 67 C.sqlite3_preupdate_old(d.Conn.db, C.int(i), &val) 68 } 69 70 switch C.sqlite3_value_type(val) { 71 case C.SQLITE_INTEGER: 72 src = int64(C.sqlite3_value_int64(val)) 73 case C.SQLITE_FLOAT: 74 src = float64(C.sqlite3_value_double(val)) 75 case C.SQLITE_BLOB: 76 len := C.sqlite3_value_bytes(val) 77 blobptr := C.sqlite3_value_blob(val) 78 src = C.GoBytes(blobptr, len) 79 case C.SQLITE_TEXT: 80 len := C.sqlite3_value_bytes(val) 81 cstrptr := unsafe.Pointer(C.sqlite3_value_text(val)) 82 src = C.GoBytes(cstrptr, len) 83 case C.SQLITE_NULL: 84 src = nil 85 } 86 87 err := convertAssign(&dest[i], src) 88 if err != nil { 89 return err 90 } 91 } 92 93 return nil 94} 95 96// Old populates dest with the row data to be replaced. This works similar to 97// database/sql's Rows.Scan() 98func (d *SQLitePreUpdateData) Old(dest ...interface{}) error { 99 if d.Op == SQLITE_INSERT { 100 return errors.New("There is no old row for INSERT operations") 101 } 102 return d.row(dest, false) 103} 104 105// New populates dest with the replacement row data. This works similar to 106// database/sql's Rows.Scan() 107func (d *SQLitePreUpdateData) New(dest ...interface{}) error { 108 if d.Op == SQLITE_DELETE { 109 return errors.New("There is no new row for DELETE operations") 110 } 111 return d.row(dest, true) 112} 113