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 ** $Id: fault.c,v 1.11 2008/09/02 00:52:52 drh Exp $ 14 */ 15 16 /* 17 ** This file contains code to support the concept of "benign" 18 ** malloc failures (when the xMalloc() or xRealloc() method of the 19 ** sqlite3_mem_methods structure fails to allocate a block of memory 20 ** and returns 0). 21 ** 22 ** Most malloc failures are non-benign. After they occur, SQLite 23 ** abandons the current operation and returns an error code (usually 24 ** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily 25 ** fatal. For example, if a malloc fails while resizing a hash table, this 26 ** is completely recoverable simply by not carrying out the resize. The 27 ** hash table will continue to function normally. So a malloc failure 28 ** during a hash table resize is a benign fault. 29 */ 30 31 #include "sqliteInt.h" 32 33 #ifndef SQLITE_OMIT_BUILTIN_TEST 34 35 /* 36 ** Global variables. 37 */ 38 typedef struct BenignMallocHooks BenignMallocHooks; 39 static SQLITE_WSD struct BenignMallocHooks { 40 void (*xBenignBegin)(void); 41 void (*xBenignEnd)(void); 42 } sqlite3Hooks = { 0, 0 }; 43 44 /* The "wsdHooks" macro will resolve to the appropriate BenignMallocHooks 45 ** structure. If writable static data is unsupported on the target, 46 ** we have to locate the state vector at run-time. In the more common 47 ** case where writable static data is supported, wsdHooks can refer directly 48 ** to the "sqlite3Hooks" state vector declared above. 49 */ 50 #ifdef SQLITE_OMIT_WSD 51 # define wsdHooksInit \ 52 BenignMallocHooks *x = &GLOBAL(BenignMallocHooks,sqlite3Hooks) 53 # define wsdHooks x[0] 54 #else 55 # define wsdHooksInit 56 # define wsdHooks sqlite3Hooks 57 #endif 58 59 60 /* 61 ** Register hooks to call when sqlite3BeginBenignMalloc() and 62 ** sqlite3EndBenignMalloc() are called, respectively. 63 */ 64 void sqlite3BenignMallocHooks( 65 void (*xBenignBegin)(void), 66 void (*xBenignEnd)(void) 67 ){ 68 wsdHooksInit; 69 wsdHooks.xBenignBegin = xBenignBegin; 70 wsdHooks.xBenignEnd = xBenignEnd; 71 } 72 73 /* 74 ** This (sqlite3EndBenignMalloc()) is called by SQLite code to indicate that 75 ** subsequent malloc failures are benign. A call to sqlite3EndBenignMalloc() 76 ** indicates that subsequent malloc failures are non-benign. 77 */ 78 void sqlite3BeginBenignMalloc(void){ 79 wsdHooksInit; 80 if( wsdHooks.xBenignBegin ){ 81 wsdHooks.xBenignBegin(); 82 } 83 } 84 void sqlite3EndBenignMalloc(void){ 85 wsdHooksInit; 86 if( wsdHooks.xBenignEnd ){ 87 wsdHooks.xBenignEnd(); 88 } 89 } 90 91 #endif /* #ifndef SQLITE_OMIT_BUILTIN_TEST */ 92