Drop support for reading PrefixSet v1.

chrome/browser/safe_browsing/prefix_set.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/safe_browsing/prefix_set.h"
 
 #include <algorithm>
 #include <math.h>
 
 #include "base/file_util.h"
@@ skipping 11 matching lines @@
 static uint32 kMagic = 0x864088dd;
 
 // Version history:
 // Version 1: b6cb7cfe/r74487 by shess@chromium.org on 2011-02-10
 // Version 2: 2b59b0a6/r253924 by shess@chromium.org on 2014-02-27
 // Version 3: ????????/r?????? by shess@chromium.org on 2014-04-??
 
 // Version 2 layout is identical to version 1.  The sort order of |index_|
 // changed from |int32| to |uint32| to match the change of |SBPrefix|.
 // Version 3 adds storage for full hashes.
-static uint32 kVersion = 0x3;
+static uint32 kVersion = 3;
+static uint32 kDeprecatedVersion = 1;  // And lower.
 
 typedef struct {
   uint32 magic;
   uint32 version;
   uint32 index_size;
   uint32 deltas_size;
 } FileHeader_v2;
 
 typedef struct {
   uint32 magic;
@@ skipping 145 matching lines @@
   base::MD5Init(&context);
   base::MD5Update(&context, base::StringPiece(reinterpret_cast<char*>(&header),
                                               sizeof(header)));
 
   if (header.magic != kMagic)
     return scoped_ptr<PrefixSet>();
 
   // Track version read to inform removal of support for older versions.
   UMA_HISTOGRAM_SPARSE_SLOWLY("SB2.PrefixSetVersionRead", header.version);
 
-  // TODO(shess): Version 1 and 2 use the same file structure, with version 1
-  // data using a signed sort.  For M-35, the data is re-sorted before return.
-  // After M-36, just drop v1 support. <http://crbug.com/346405>
   // TODO(shess): <http://crbug.com/368044> for removing v2 support.
   size_t header_size = sizeof(header);
-  if (header.version == 2 || header.version == 1) {
+  if (header.version <= kDeprecatedVersion) {
+    return scoped_ptr<PrefixSet>();
+  } else if (header.version == 2) {
     // Rewind the file and restart building the digest with the old header
     // structure.
     FileHeader_v2 v2_header;
     if (0 != fseek(file.get(), 0, SEEK_SET))
       return scoped_ptr<PrefixSet>();
 
     size_t read = fread(&v2_header, sizeof(v2_header), 1, file.get());
     if (read != 1)
       return scoped_ptr<PrefixSet>();
 
@@ skipping 71 matching lines @@
   base::MD5Final(&calculated_digest, &context);
 
   base::MD5Digest file_digest;
   read = fread(&file_digest, sizeof(file_digest), 1, file.get());
   if (read != 1)
     return scoped_ptr<PrefixSet>();
 
   if (0 != memcmp(&file_digest, &calculated_digest, sizeof(file_digest)))
     return scoped_ptr<PrefixSet>();
 
-  // For version 1, fetch the prefixes and re-sort.
-  if (header.version == 1) {
-    std::vector<SBPrefix> prefixes;
-    PrefixSet(&index, &deltas, &full_hashes).GetPrefixes(&prefixes);
-    std::sort(prefixes.begin(), prefixes.end());
-
-    // v1 cannot have full hashes, so no need to propagate a copy here.
-    return PrefixSetBuilder(prefixes).GetPrefixSetNoHashes().Pass();
-  }
-
   // Steals vector contents using swap().
   return scoped_ptr<PrefixSet>(new PrefixSet(&index, &deltas, &full_hashes));
 }
 
 bool PrefixSet::WriteFile(const base::FilePath& filter_name) const {
   FileHeader header;
   header.magic = kMagic;
   header.version = kVersion;
   header.index_size = static_cast<uint32>(index_.size());
   header.deltas_size = static_cast<uint32>(deltas_.size());
@@ skipping 168 matching lines @@
   }
   buffer_.push_back(prefix);
 
   // Flush buffer when a run can be constructed.  +1 for the index item, and +1
   // to leave at least one item in the buffer for dropping duplicates.
   if (buffer_.size() > PrefixSet::kMaxRun + 2)
     EmitRun();
 }
 
 }  // namespace safe_browsing