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 */