[sql] Import reference version of SQLite 3.10.2.

third_party/sqlite/sqlite-src-3100200/src/os.c

 /*
 ** 2005 November 29
 **
 ** The author disclaims copyright to this source code.  In place of
 ** a legal notice, here is a blessing:
 **
 **    May you do good and not evil.
 **    May you find forgiveness for yourself and forgive others.
 **    May you share freely, never taking more than you give.
 **
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 ** Register a VFS with the system.  It is harmless to register the same
 ** VFS multiple times.  The new VFS becomes the default if makeDflt is
 ** true.
 */
 int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
   MUTEX_LOGIC(sqlite3_mutex *mutex;)
 #ifndef SQLITE_OMIT_AUTOINIT
   int rc = sqlite3_initialize();
   if( rc ) return rc;
 #endif
+#ifdef SQLITE_ENABLE_API_ARMOR
+  if( pVfs==0 ) return SQLITE_MISUSE_BKPT;
+#endif
+
   MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
   sqlite3_mutex_enter(mutex);
   vfsUnlink(pVfs);
   if( makeDflt || vfsList==0 ){
     pVfs->pNext = vfsList;
     vfsList = pVfs;
   }else{
     pVfs->pNext = vfsList->pNext;
     vfsList->pNext = pVfs;
   }
   assert(vfsList);
   sqlite3_mutex_leave(mutex);
   return SQLITE_OK;
 }
 
 /*
 ** Unregister a VFS so that it is no longer accessible.
 */
 int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
 #if SQLITE_THREADSAFE
   sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
 #endif
   sqlite3_mutex_enter(mutex);
   vfsUnlink(pVfs);
   sqlite3_mutex_leave(mutex);
   return SQLITE_OK;
 }