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Bug 385871 - DM needs to have schema checking. r=mano

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sdwilsh@shawnwilsher.com 2007-07-03 14:04:54 -07:00
parent f7a000c5ad
commit 74aba047ce
1 changed files with 71 additions and 1 deletions
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72
toolkit/components/downloads/src/nsDownloadManager.cpp
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@ -90,6 +90,10 @@ static const PRInt64 gUpdateInterval = 400 * PR_USEC_PER_MSEC;
static PRInt32 gRefCnt = 0;
#define DM_SCHEMA_VERSION 1
#define DM_DB_NAME NS_LITERAL_STRING("downloads.sqlite")
#define DM_DB_CORRUPT_FILENAME NS_LITERAL_STRING("downloads.sqlite.corrupt")
///////////////////////////////////////////////////////////////////////////////
// nsDownloadManager
@ -166,7 +170,7 @@ nsDownloadManager::InitDB(PRBool *aDoImport)
rv = NS_GetSpecialDirectory(NS_APP_USER_PROFILE_50_DIR,
getter_AddRefs(dbFile));
NS_ENSURE_SUCCESS(rv, rv);
rv = dbFile->Append(NS_LITERAL_STRING("downloads.sqlite"));
rv = dbFile->Append(DM_DB_NAME);
NS_ENSURE_SUCCESS(rv, rv);
rv = storage->OpenDatabase(dbFile, getter_AddRefs(mDBConn));
@ -185,6 +189,69 @@ nsDownloadManager::InitDB(PRBool *aDoImport)
*aDoImport = PR_TRUE;
rv = CreateTable();
NS_ENSURE_SUCCESS(rv, rv);
} else {
// Checking the database schema now
PRInt32 schemaVersion;
rv = mDBConn->GetSchemaVersion(&schemaVersion);
NS_ENSURE_SUCCESS(rv, rv);
if (0 == schemaVersion) {
NS_WARNING("Could not get downlaod's database schema version!");
// The table may still be usable - someone may have just messed with the
// schema version, so let's just treat this like a downgrade and verify
// that the needed columns are there. If they aren't there, we'll drop
// the table anyway.
rv = mDBConn->SetSchemaVersion(DM_SCHEMA_VERSION);
NS_ENSURE_SUCCESS(rv, rv);
// setting it to a large number so we execute a downgrade. This may
// seem odd, but downgrading checks to see if we have the correct
// columns in our table. At this point we've established that we have
// a table, but no schema version, so we want to check this.
schemaVersion = DM_SCHEMA_VERSION + 1;
}
if (schemaVersion != DM_SCHEMA_VERSION) {
// Changing the database? Be sure to do these two things!
// 1) Increment DM_SCHEMA_VERSION
// 2) Implement the proper downgrade/upgrade code for the current version
if (schemaVersion > DM_SCHEMA_VERSION) {
// Downgrading
// If columns have been added to the table, we can still use the ones we
// understand safely. If columns have been deleted or alterd, we just
// drop the table and start from scratch. If you change how a column
// should be interpreted, make sure you also change its name so this
// check will catch it.
nsCOMPtr<mozIStorageStatement> stmt;
rv = mDBConn->CreateStatement(NS_LITERAL_CSTRING(
"SELECT id, name, source, target, iconURL, startTime, endTime, state "
"FROM moz_downloads"), getter_AddRefs(stmt));
if (NS_FAILED(rv)) {
// if the statement fails, that means all the columns were not there.
// First we backup the database
nsCOMPtr<nsIFile> backup;
rv = mDBConn->BackupDB(DM_DB_CORRUPT_FILENAME, nsnull,
getter_AddRefs(backup));
NS_ENSURE_SUCCESS(rv, rv);
// Then we dump it
rv = mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
"DROP TABLE moz_downloads"));
NS_ENSURE_SUCCESS(rv, rv);
rv = CreateTable();
NS_ENSURE_SUCCESS(rv, rv);
}
} else {
// Upgrading
// Every time you increment the database schema, you need to implement
// the upgrading code from the previous version to the new one.
// Also, don't forget to make a unit test to test your upgradeing code!
}
}
}
return NS_OK;
@ -193,6 +260,9 @@ nsDownloadManager::InitDB(PRBool *aDoImport)
nsresult
nsDownloadManager::CreateTable()
{
nsresult rv = mDBConn->SetSchemaVersion(DM_SCHEMA_VERSION);
if (NS_FAILED(rv)) return rv;
return mDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
"CREATE TABLE moz_downloads ("
"id INTEGER PRIMARY KEY, name TEXT, source TEXT, target TEXT,"