[sql] Remove mmap before Raze().
On Windows, file truncation silently fails when the file is memory
mapped. Modify Raze() to disable memory mapping before truncating.
BUG=none
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Review-Url: https://codereview.chromium.org/2830263002
Cr-Commit-Position: refs/heads/master@{#466555}
diff --git a/sql/connection.cc b/sql/connection.cc
index 0511e11..c80758f 100644
--- a/sql/connection.cc
+++ b/sql/connection.cc
@@ -1112,6 +1112,15 @@
// page_size" can be used to query such a database.
ScopedWritableSchema writable_schema(db_);
+#if defined(OS_WIN)
+ // On Windows, truncate silently fails when applied to memory-mapped files.
+ // Disable memory-mapping so that the truncate succeeds. Note that other
+ // connections may have memory-mapped the file, so this may not entirely
+ // prevent the problem.
+ // [Source: <https://sqlite.org/mmap.html> plus experiments.]
+ ignore_result(Execute("PRAGMA mmap_size = 0"));
+#endif
+
const char* kMain = "main";
int rc = BackupDatabase(null_db.db_, db_, kMain);
UMA_HISTOGRAM_SPARSE_SLOWLY("Sqlite.RazeDatabase",rc);
