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#import "FMDatabase+InMemoryOnDiskIO.h"
#import <sqlite3.h>
// http://www.sqlite.org/backup.html
static
int loadOrSaveDb(sqlite3 *pInMemory, const char *zFilename, int isSave)
{
int rc; /* Function return code */
sqlite3 *pFile; /* Database connection opened on zFilename */
sqlite3_backup *pBackup; /* Backup object used to copy data */
sqlite3 *pTo; /* Database to copy to (pFile or pInMemory) */
sqlite3 *pFrom; /* Database to copy from (pFile or pInMemory) */
/* Open the database file identified by zFilename. Exit early if this fails
** for any reason. */
rc = sqlite3_open(zFilename, &pFile);
if( rc==SQLITE_OK ){
/* If this is a 'load' operation (isSave==0), then data is copied
** from the database file just opened to database pInMemory.
** Otherwise, if this is a 'save' operation (isSave==1), then data
** is copied from pInMemory to pFile. Set the variables pFrom and
** pTo accordingly. */
pFrom = (isSave ? pInMemory : pFile);
pTo = (isSave ? pFile : pInMemory);
/* Set up the backup procedure to copy from the "main" database of
** connection pFile to the main database of connection pInMemory.
** If something goes wrong, pBackup will be set to NULL and an error
** code and message left in connection pTo.
**
** If the backup object is successfully created, call backup_step()
** to copy data from pFile to pInMemory. Then call backup_finish()
** to release resources associated with the pBackup object. If an
** error occurred, then an error code and message will be left in
** connection pTo. If no error occurred, then the error code belonging
** to pTo is set to SQLITE_OK.
*/
pBackup = sqlite3_backup_init(pTo, "main", pFrom, "main");
if( pBackup ){
(void)sqlite3_backup_step(pBackup, -1);
(void)sqlite3_backup_finish(pBackup);
}
rc = sqlite3_errcode(pTo);
}
/* Close the database connection opened on database file zFilename
** and return the result of this function. */
(void)sqlite3_close(pFile);
return rc;
}
@implementation FMDatabase (InMemoryOnDiskIO)
- (BOOL)readFromFile:(NSString*)filePath
{
// only attempt to load an on-disk representation for an in-memory database
if ( [self databasePath] != nil )
{
NSLog(@"Database is not an in-memory representation." );
return NO;
}
// and only if the database is open
if ( [self sqliteHandle] == nil )
{
NSLog(@"Invalid database connection." );
return NO;
}
return ( SQLITE_OK == loadOrSaveDb( [self sqliteHandle], [filePath fileSystemRepresentation], false ) );
}
- (BOOL)writeToFile:(NSString *)filePath
{
// only attempt to save an on-disk representation for an in-memory database
if ( [self databasePath] != nil )
{
NSLog(@"Database is not an in-memory representation." );
return NO;
}
// and only if the database is open
if ( [self sqliteHandle] == nil )
{
NSLog(@"Invalid database connection." );
return NO;
}
// save the in-memory representation
return ( SQLITE_OK == loadOrSaveDb( [self sqliteHandle], [filePath fileSystemRepresentation], true ) );
}
@end
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