Create CrashReportDatabase interface, a test, and a Mac implementation.

util/mac/xattr.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #include "util/mac/xattr.h"
 
+#include <errno.h>
 #include <stdint.h>
 #include <sys/xattr.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/string_number_conversions.h"
 
 namespace crashpad {
 
+bool HasXattr(const base::FilePath& file, const base::StringPiece& name) {
+  if (getxattr(file.value().c_str(), name.data(), nullptr, 0, 0, 0) < 0) {

[Mark Mentovai, 2015/01/08 22:38:10]

Especially since you just wind up calling getxattr() twice on the same file for
the same attribute. Seems unnecessary.

+    PLOG_IF(ERROR, errno != ENOATTR)
+        << "getxattr exists " << name << " on file " << file.value();
+    return false;
+  }
+  return true;
+}
+
 bool ReadXattr(const base::FilePath& file,
                const base::StringPiece& name,
                std::string* value) {
   // First get the size of the attribute value.
   ssize_t buffer_size = getxattr(file.value().c_str(), name.data(), nullptr,
                                  0, 0, 0);
   if (buffer_size < 0) {
     PLOG(ERROR) << "getxattr size " << name << " on file " << file.value();
     return false;
   }
@@ skipping 95 matching lines @@
 }
 
 bool WriteXattrTimeT(const base::FilePath& file,
                      const base::StringPiece& name,
                      time_t value) {
   std::string tmp = base::StringPrintf("%ld", value);
   return WriteXattr(file, name, tmp);
 }
 
 }  // namespace crashpad