[sql] Recovery code for "Top Sites" database.

Port recovery code from thumbnail_database.cc to
top_sites_database.cc.  Also retry Init() in case the recovery code
fixes things (a quarter to a third of databases have problems detected
during open).

Extend sql::Recovery::AutoRecoverTable() to handle DOUBLE columns.

Abstract out sql::test::CorruptTableOrIndex() to ease writing
corruption tests.

IWYU pass on various files.

BUG=321852

Review URL: https://codereview.chromium.org/86653002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239377 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 105 insertions, 0 deletions

diff --git a/sql/test/test_helpers.cc b/sql/test/test_helpers.cc
index 6e12b04..8d56140 100644
--- a/sql/test/test_helpers.cc
+++ b/sql/test/test_helpers.cc
@@ -21,6 +21,26 @@ size_t CountSQLItemsOfType(sql::Connection* db, const char* type) {
   return s.ColumnInt(0);
 }
 
+// Get page size for the database.
+bool GetPageSize(sql::Connection* db, int* page_size) {
+  sql::Statement s(db->GetUniqueStatement("PRAGMA page_size"));
+  if (!s.Step())
+    return false;
+  *page_size = s.ColumnInt(0);
+  return true;
+}
+
+// Get |name|'s root page number in the database.
+bool GetRootPage(sql::Connection* db, const char* name, int* page_number) {
+  const char kPageSql[] = "SELECT rootpage FROM sqlite_master WHERE name = ?";
+  sql::Statement s(db->GetUniqueStatement(kPageSql));
+  s.BindString(0, name);
+  if (!s.Step())
+    return false;
+  *page_number = s.ColumnInt(0);
+  return true;
+}
+
 // Helper for reading a number from the SQLite header.
 // See net/base/big_endian.h.
 unsigned ReadBigEndian(unsigned char* buf, size_t bytes) {
@@ -88,6 +108,70 @@ bool CorruptSizeInHeader(const base::FilePath& db_path) {
   return true;
 }
 
+bool CorruptTableOrIndex(const base::FilePath& db_path,
+                         const char* tree_name,
+                         const char* update_sql) {
+  sql::Connection db;
+  if (!db.Open(db_path))
+    return false;
+
+  int page_size = 0;
+  if (!GetPageSize(&db, &page_size))
+    return false;
+
+  int page_number = 0;
+  if (!GetRootPage(&db, tree_name, &page_number))
+    return false;
+
+  // SQLite uses 1-based page numbering.
+  const long int page_ofs = (page_number - 1) * page_size;
+  scoped_ptr<char[]> page_buf(new char[page_size]);
+
+  // Get the page into page_buf.
+  file_util::ScopedFILE file(base::OpenFile(db_path, "rb+"));
+  if (!file.get())
+    return false;
+  if (0 != fseek(file.get(), page_ofs, SEEK_SET))
+    return false;
+  if (1u != fread(page_buf.get(), page_size, 1, file.get()))
+    return false;
+
+  // Require the page to be a leaf node.  A multilevel tree would be
+  // very hard to restore correctly.
+  if (page_buf[0] != 0xD && page_buf[0] != 0xA)
+    return false;
+
+  // The update has to work, and make changes.
+  if (!db.Execute(update_sql))
+    return false;
+  if (db.GetLastChangeCount() == 0)
+    return false;
+
+  // Ensure that the database is fully flushed.
+  db.Close();
+
+  // Check that the stored page actually changed.  This catches usage
+  // errors where |update_sql| is not related to |tree_name|.
+  scoped_ptr<char[]> check_page_buf(new char[page_size]);
+  // The on-disk data should have changed.
+  if (0 != fflush(file.get()))
+    return false;
+  if (0 != fseek(file.get(), page_ofs, SEEK_SET))
+    return false;
+  if (1u != fread(check_page_buf.get(), page_size, 1, file.get()))
+    return false;
+  if (!memcmp(check_page_buf.get(), page_buf.get(), page_size))
+    return false;
+
+  // Put the original page back.
+  if (0 != fseek(file.get(), page_ofs, SEEK_SET))
+    return false;
+  if (1u != fwrite(page_buf.get(), page_size, 1, file.get()))
+    return false;
+
+  return true;
+}
+
 size_t CountSQLTables(sql::Connection* db) {
   return CountSQLItemsOfType(db, "table");
 }
diff --git a/sql/test/test_helpers.h b/sql/test/test_helpers.h
index b9d5e9b..d9dda22 100644
--- a/sql/test/test_helpers.h
+++ b/sql/test/test_helpers.h
@@ -9,6 +9,7 @@
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/files/file_path.h"
 
 // Collection of test-only convenience functions.
 
@@ -33,6 +34,26 @@ namespace test {
 // Returns false if any error occurs accessing the file.
 bool CorruptSizeInHeader(const base::FilePath& db_path) WARN_UNUSED_RESULT;
 
+// Frequently corruption is a result of failure to atomically update
+// pages in different structures.  For instance, if an index update
+// takes effect but the corresponding table update does not.  This
+// helper restores the prior version of a b-tree root after running an
+// update which changed that b-tree.  The named b-tree must exist and
+// must be a leaf node (either index or table).  Returns true if the
+// on-disk file is successfully modified, and the restored page
+// differs from the updated page.
+//
+// The resulting database should be possible to open, and many
+// statements should work.  SQLITE_CORRUPT will be thrown if a query
+// through the index finds the row missing in the table.
+//
+// TODO(shess): It would be very helpful to allow a parameter to the
+// sql statement.  Perhaps a version with a string parameter would be
+// sufficient, given affinity rules?
+bool CorruptTableOrIndex(const base::FilePath& db_path,
+                         const char* tree_name,
+                         const char* update_sql) WARN_UNUSED_RESULT;
+
 // Return the number of tables in sqlite_master.
 size_t CountSQLTables(sql::Connection* db) WARN_UNUSED_RESULT;