1/*
2** 2008 Jan 22
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**
13** This file contains code to support the concept of "benign"
14** malloc failures (when the xMalloc() or xRealloc() method of the
15** sqlite3_mem_methods structure fails to allocate a block of memory
16** and returns 0).
17**
18** Most malloc failures are non-benign. After they occur, SQLite
19** abandons the current operation and returns an error code (usually
20** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily
21** fatal. For example, if a malloc fails while resizing a hash table, this
22** is completely recoverable simply by not carrying out the resize. The
23** hash table will continue to function normally. So a malloc failure
24** during a hash table resize is a benign fault.
25*/
26
27#include "sqliteInt.h"
28
29#ifndef SQLITE_UNTESTABLE
30
31/*
32** Global variables.
33*/
34typedef struct BenignMallocHooks BenignMallocHooks;
35static SQLITE_WSD struct BenignMallocHooks {
36 void (*xBenignBegin)(void);
37 void (*xBenignEnd)(void);
38} sqlite3Hooks = { 0, 0 };
39
40/* The "wsdHooks" macro will resolve to the appropriate BenignMallocHooks
41** structure. If writable static data is unsupported on the target,
42** we have to locate the state vector at run-time. In the more common
43** case where writable static data is supported, wsdHooks can refer directly
44** to the "sqlite3Hooks" state vector declared above.
45*/
46#ifdef SQLITE_OMIT_WSD
47# define wsdHooksInit \
48 BenignMallocHooks *x = &GLOBAL(BenignMallocHooks,sqlite3Hooks)
49# define wsdHooks x[0]
50#else
51# define wsdHooksInit
52# define wsdHooks sqlite3Hooks
53#endif
54
55
56/*
57** Register hooks to call when sqlite3BeginBenignMalloc() and
58** sqlite3EndBenignMalloc() are called, respectively.
59*/
60void sqlite3BenignMallocHooks(
61 void (*xBenignBegin)(void),
62 void (*xBenignEnd)(void)
63){
64 wsdHooksInit;
65 wsdHooks.xBenignBegin = xBenignBegin;
66 wsdHooks.xBenignEnd = xBenignEnd;
67}
68
69/*
70** This (sqlite3EndBenignMalloc()) is called by SQLite code to indicate that
71** subsequent malloc failures are benign. A call to sqlite3EndBenignMalloc()
72** indicates that subsequent malloc failures are non-benign.
73*/
74void sqlite3BeginBenignMalloc(void){
75 wsdHooksInit;
76 if( wsdHooks.xBenignBegin ){
77 wsdHooks.xBenignBegin();
78 }
79}
80void sqlite3EndBenignMalloc(void){
81 wsdHooksInit;
82 if( wsdHooks.xBenignEnd ){
83 wsdHooks.xBenignEnd();
84 }
85}
86
87#endif /* #ifndef SQLITE_UNTESTABLE */
88