Revert 235595 "Revert 235492 "[sql] Recover Favicons v5 database..."

> Revert 235492 "[sql] Recover Favicons v5 databases, with more re..."
> 
> Speculative revert to find the cause for Mac size regression
> (will revert this revert later)
> 
> > [sql] Recover Favicons v5 databases, with more recovery automation.
> > 
> > An entirely automated recovery system runs afoul of questions about
> > whether the corrupt database's schema can be trusted.
> > sql::Recovery::AutoRecoverTable() uses a schema created by the caller
> > to construct the recovery virtual table and then copies the data over.
> > 
> > sql::Recovery::SetupMeta() and GetMetaVersionNumber() simplify
> > accessing meta-table info in the corrupt database.
> > 
> > sql::test::IntegrityCheck() and CorruptSizeInHeader() helpers to
> > simplify common testing operations.
> > 
> > Rewrite ThumbnailDatabase v6 and v7 recovery code and tests using
> > these changes, and add a v5 recovery path.  Additionally handle
> > deprecated versions.
> > 
> > BUG=240396,109482
> > 
> > Review URL: https://codereview.chromium.org/50493012
> 
> TBR=shess@chromium.org
> 
> Review URL: https://codereview.chromium.org/74933002

TBR=kinuko@chromium.org

Review URL: https://codereview.chromium.org/74953002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235604 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 88 insertions, 0 deletions

diff --git a/sql/test/test_helpers.cc b/sql/test/test_helpers.cc
index de3e8f8..5438bd6 100644
--- a/sql/test/test_helpers.cc
+++ b/sql/test/test_helpers.cc
@@ -21,11 +21,73 @@ size_t CountSQLItemsOfType(sql::Connection* db, const char* type) {
   return s.ColumnInt(0);
 }
 
+// Helper for reading a number from the SQLite header.
+// See net/base/big_endian.h.
+unsigned ReadBigEndian(unsigned char* buf, size_t bytes) {
+  unsigned r = buf[0];
+  for (size_t i = 1; i < bytes; i++) {
+    r <<= 8;
+    r |= buf[i];
+  }
+  return r;
+}
+
+// Helper for writing a number to the SQLite header.
+void WriteBigEndian(unsigned val, unsigned char* buf, size_t bytes) {
+  for (size_t i = 0; i < bytes; i++) {
+    buf[bytes - i - 1] = (val & 0xFF);
+    val >>= 8;
+  }
+}
+
 }  // namespace
 
 namespace sql {
 namespace test {
 
+bool CorruptSizeInHeader(const base::FilePath& db_path) {
+  // See http://www.sqlite.org/fileformat.html#database_header
+  const size_t kHeaderSize = 100;
+  const size_t kPageSizeOffset = 16;
+  const size_t kFileChangeCountOffset = 24;
+  const size_t kPageCountOffset = 28;
+  const size_t kVersionValidForOffset = 92;  // duplicate kFileChangeCountOffset
+
+  unsigned char header[kHeaderSize];
+
+  file_util::ScopedFILE file(file_util::OpenFile(db_path, "rb+"));
+  if (!file.get())
+    return false;
+
+  if (0 != fseek(file.get(), 0, SEEK_SET))
+    return false;
+  if (1u != fread(header, sizeof(header), 1, file.get()))
+    return false;
+
+  int64 db_size = 0;
+  if (!file_util::GetFileSize(db_path, &db_size))
+    return false;
+
+  const unsigned page_size = ReadBigEndian(header + kPageSizeOffset, 2);
+
+  // One larger than the expected size.
+  const unsigned page_count = (db_size + page_size) / page_size;
+  WriteBigEndian(page_count, header + kPageCountOffset, 4);
+
+  // Update change count so outstanding readers know the info changed.
+  // Both spots must match for the page count to be considered valid.
+  unsigned change_count = ReadBigEndian(header + kFileChangeCountOffset, 4);
+  WriteBigEndian(change_count + 1, header + kFileChangeCountOffset, 4);
+  WriteBigEndian(change_count + 1, header + kVersionValidForOffset, 4);
+
+  if (0 != fseek(file.get(), 0, SEEK_SET))
+    return false;
+  if (1u != fwrite(header, sizeof(header), 1, file.get()))
+    return false;
+
+  return true;
+}
+
 size_t CountSQLTables(sql::Connection* db) {
   return CountSQLItemsOfType(db, "table");
 }
@@ -91,5 +153,14 @@ bool CreateDatabaseFromSQL(const base::FilePath& db_path,
   return db.Execute(sql.c_str());
 }
 
+std::string IntegrityCheck(sql::Connection* db) {
+  sql::Statement statement(db->GetUniqueStatement("PRAGMA integrity_check"));
+
+  // SQLite should always return a row of data.
+  EXPECT_TRUE(statement.Step());
+
+  return statement.ColumnString(0);
+}
+
 }  // namespace test
 }  // namespace sql
diff --git a/sql/test/test_helpers.h b/sql/test/test_helpers.h
index 330f59a..b9d5e9b 100644
--- a/sql/test/test_helpers.h
+++ b/sql/test/test_helpers.h
@@ -5,6 +5,8 @@
 #ifndef SQL_TEST_TEST_HELPERS_H_
 #define SQL_TEST_TEST_HELPERS_H_
 
+#include <string>
+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 
@@ -21,6 +23,16 @@ class Connection;
 namespace sql {
 namespace test {
 
+// SQLite stores the database size in the header, and if the actual
+// OS-derived size is smaller, the database is considered corrupt.
+// [This case is actually a common form of corruption in the wild.]
+// This helper sets the in-header size to one page larger than the
+// actual file size.  The resulting file will return SQLITE_CORRUPT
+// for most operations unless PRAGMA writable_schema is turned ON.
+//
+// Returns false if any error occurs accessing the file.
+bool CorruptSizeInHeader(const base::FilePath& db_path) WARN_UNUSED_RESULT;
+
 // Return the number of tables in sqlite_master.
 size_t CountSQLTables(sql::Connection* db) WARN_UNUSED_RESULT;
 
@@ -43,6 +55,11 @@ bool CountTableRows(sql::Connection* db, const char* table, size_t* count);
 bool CreateDatabaseFromSQL(const base::FilePath& db_path,
                            const base::FilePath& sql_path) WARN_UNUSED_RESULT;
 
+// Return the results of running "PRAGMA integrity_check" on |db|.
+// TODO(shess): sql::Connection::IntegrityCheck() is basically the
+// same, but not as convenient for testing.  Maybe combine.
+std::string IntegrityCheck(sql::Connection* db) WARN_UNUSED_RESULT;
+
 }  // namespace test
 }  // namespace sql