Add wrappers around getxattr() and setxattr().

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 <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 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;
+  }
+
+  // Resize the buffer and read into it.
+  value->resize(buffer_size);
+  ssize_t bytes_read = getxattr(file.value().c_str(), name.data(),
+                                &(*value)[0], value->size(),
+                                0, 0);
+  if (bytes_read < 0) {
+    PLOG(ERROR) << "getxattr " << name << " on file " << file.value();
+    return false;
+  }
+  DCHECK_EQ(bytes_read, buffer_size);
+
+  return true;
+}
+
+bool WriteXattr(const base::FilePath& file,
+                const base::StringPiece& name,
+                const std::string& value) {
+  int rv = setxattr(file.value().c_str(), name.data(), value.c_str(),
+      value.length(), 0, 0);
+  PLOG_IF(ERROR, rv != 0) << "setxattr " << name << " on file "
+                          << file.value();
+  return rv == 0;
+}
+
+bool ReadXattrBool(const base::FilePath& file,
+                   const base::StringPiece& name,
+                   bool* value) {
+  std::string tmp;
+  if (!ReadXattr(file, name, &tmp))
+    return false;
+  if (tmp == "1") {
+    *value = true;
+    return true;
+  } else if (tmp == "0") {
+    *value = false;
+    return true;
+  } else {
+    LOG(ERROR) << "ReadXattrBool " << name << " on file " << file.value()
+               << " could not be interpreted as boolean";
+    return false;
+  }
+}
+
+bool WriteXattrBool(const base::FilePath& file,
+                    const base::StringPiece& name,
+                    bool value) {
+  return WriteXattr(file, name, (value ? "1" : "0"));
+}
+
+bool ReadXattrInt(const base::FilePath& file,
+                  const base::StringPiece& name,
+                  int* value) {
+  std::string tmp;
+  if (!ReadXattr(file, name, &tmp))
+    return false;
+  if (!base::StringToInt(tmp, value)) {
+    LOG(ERROR) << "ReadXattrInt " << name << " on file " << file.value()
+               << " could not be converted to an int";
+    return false;
+  }
+  return true;
+}
+
+bool WriteXattrInt(const base::FilePath& file,
+                   const base::StringPiece& name,
+                   int value) {
+  std::string tmp = base::StringPrintf("%d", value);
+  return WriteXattr(file, name, tmp);
+}
+
+bool ReadXattrTimeT(const base::FilePath& file,
+                    const base::StringPiece& name,
+                    time_t* value) {
+  // time_t on OS X is defined as a long, but it will be read into an
+  // int64_t here, since there is no string conversion method for long.
+  std::string tmp;
+  if (!ReadXattr(file, name, &tmp))
+    return false;
+
+  int64_t encoded_value;
+  if (!base::StringToInt64(tmp, &encoded_value)) {
+    LOG(ERROR) << "ReadXattrTimeT " << name << " on file " << file.value()
+               << " could not be converted to an int";
+    return false;
+  }
+
+  *value = base::saturated_cast<time_t>(encoded_value);
+  if (!base::IsValueInRangeForNumericType<time_t>(encoded_value)) {
+    LOG(ERROR) << "ReadXattrTimeT " << name << " on file " << file.value()
+               << " read over-sized value and will saturate";
+    return false;
+  }
+
+  return true;
+}
+
+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