Add a tri-state enum to return the result of Xattr operations.

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 ReadXattr(const base::FilePath& file,
-               const base::StringPiece& name,
-               std::string* value) {
+XattrStatus 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) {
+    if (errno == ENOATTR)
+      return XattrStatus::kNoAttribute;
     PLOG(ERROR) << "getxattr size " << name << " on file " << file.value();
-    return false;
+    return XattrStatus::kOtherError;
   }
 
   // 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;
+    return XattrStatus::kOtherError;
   }
   DCHECK_EQ(bytes_read, buffer_size);
 
-  return true;
+  return XattrStatus::kOK;
 }
 
 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) {
+XattrStatus ReadXattrBool(const base::FilePath& file,
+                          const base::StringPiece& name,
+                          bool* value) {
   std::string tmp;
-  if (!ReadXattr(file, name, &tmp))
-    return false;
+  XattrStatus status;
+  if ((status = ReadXattr(file, name, &tmp)) != XattrStatus::kOK)
+    return status;
   if (tmp == "1") {
     *value = true;
-    return true;
+    return XattrStatus::kOK;
   } else if (tmp == "0") {
     *value = false;
-    return true;
+    return XattrStatus::kOK;
   } else {
     LOG(ERROR) << "ReadXattrBool " << name << " on file " << file.value()
                << " could not be interpreted as boolean";
-    return false;
+    return XattrStatus::kOtherError;
   }
 }
 
 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) {
+XattrStatus ReadXattrInt(const base::FilePath& file,
+                         const base::StringPiece& name,
+                         int* value) {
   std::string tmp;
-  if (!ReadXattr(file, name, &tmp))
-    return false;
+  XattrStatus status;
+  if ((status = ReadXattr(file, name, &tmp)) != XattrStatus::kOK)
+    return status;
   if (!base::StringToInt(tmp, value)) {
     LOG(ERROR) << "ReadXattrInt " << name << " on file " << file.value()
                << " could not be converted to an int";
-    return false;
+    return XattrStatus::kOtherError;
   }
-  return true;
+  return XattrStatus::kOK;
 }
 
 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) {
+XattrStatus 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;
+  XattrStatus status;
+  if ((status = ReadXattr(file, name, &tmp)) != XattrStatus::kOK)
+    return status;
 
   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;
+    return XattrStatus::kOtherError;
   }
 
   *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 XattrStatus::kOtherError;
   }
 
-  return true;
+  return XattrStatus::kOK;
 }
 
 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