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

R=mark@chromium.org
TEST=util_test --gtest_filter=Xattr\*

Review URL: https://codereview.chromium.org/842223003

util/mac/xattr.cc

@@ -14,6 +14,7 @@
 
 #include "util/mac/xattr.h"
 
+#include <errno.h>
 #include <stdint.h>
 #include <sys/xattr.h>
 
@@ -25,15 +26,17 @@
 
 namespace crashpad {
 
-bool ReadXattr(const base::FilePath& file,
+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.
@@ -43,11 +46,11 @@ bool ReadXattr(const base::FilePath& file,
                                 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,
@@ -60,22 +63,23 @@ bool WriteXattr(const base::FilePath& file,
   return rv == 0;
 }
 
-bool ReadXattrBool(const base::FilePath& file,
+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;
   }
 }
 
@@ -85,18 +89,19 @@ bool WriteXattrBool(const base::FilePath& file,
   return WriteXattr(file, name, (value ? "1" : "0"));
 }
 
-bool ReadXattrInt(const base::FilePath& file,
+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,
@@ -106,30 +111,31 @@ bool WriteXattrInt(const base::FilePath& file,
   return WriteXattr(file, name, tmp);
 }
 
-bool ReadXattrTimeT(const base::FilePath& file,
+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,

util/mac/xattr.h

@@ -24,15 +24,26 @@
 
 namespace crashpad {
 
+//! \brief The result code for a ReadXattr operation.
+enum class XattrStatus {
+  //! \brief No error occured. No message is logged.
+  kOK = 0,
+
+  //! \brief The attribute does not exist. No message is logged.
+  kNoAttribute,
+
+  //! \brief An error occurred and an error message was logged.
+  kOtherError,
+};
+
 //! \brief Reads an extended attribute on a file.
 //!
 //! \param[in] file The path to the file.
 //! \param[in] name The name of the extended attribute to read.
 //! \param[out] value The value of the attribute.
 //!
-//! \return `true` if the read was successful, with \a value filled in. `false`
-//!     on error, with a message logged.
-bool ReadXattr(const base::FilePath& file,
+//! \return XattrStatus
+XattrStatus ReadXattr(const base::FilePath& file,
                       const base::StringPiece& name,
                       std::string* value);
 
@@ -52,7 +63,7 @@ bool WriteXattr(const base::FilePath& file,
 //!
 //! Only the values `"0"` and `"1"`, for `false` and `true` respectively, are
 //! valid conversions.
-bool ReadXattrBool(const base::FilePath& file,
+XattrStatus ReadXattrBool(const base::FilePath& file,
                           const base::StringPiece& name,
                           bool* value);
 
@@ -62,7 +73,7 @@ bool WriteXattrBool(const base::FilePath& file,
                     bool value);
 
 //! \copydoc ReadXattr
-bool ReadXattrInt(const base::FilePath& file,
+XattrStatus ReadXattrInt(const base::FilePath& file,
                          const base::StringPiece& name,
                          int* value);
 
@@ -72,7 +83,7 @@ bool WriteXattrInt(const base::FilePath& file,
                    int value);
 
 //! \copydoc ReadXattr
-bool ReadXattrTimeT(const base::FilePath& file,
+XattrStatus ReadXattrTimeT(const base::FilePath& file,
                            const base::StringPiece& name,
                            time_t* value);
 

util/mac/xattr_test.cc

@@ -57,7 +57,7 @@ const char kKey[] = "com.google.crashpad.test";
 
 TEST_F(Xattr, ReadNonExistentXattr) {
   std::string value;
-  EXPECT_FALSE(ReadXattr(path(), kKey, &value));
+  EXPECT_EQ(XattrStatus::kNoAttribute, ReadXattr(path(), kKey, &value));
 }
 
 TEST_F(Xattr, WriteAndReadString) {
@@ -65,7 +65,7 @@ TEST_F(Xattr, WriteAndReadString) {
   EXPECT_TRUE(WriteXattr(path(), kKey, value));
 
   std::string actual;
-  EXPECT_TRUE(ReadXattr(path(), kKey, &actual));
+  EXPECT_EQ(XattrStatus::kOK, ReadXattr(path(), kKey, &actual));
   EXPECT_EQ(value, actual);
 }
 
@@ -74,18 +74,18 @@ TEST_F(Xattr, WriteAndReadVeryLongString) {
   EXPECT_TRUE(WriteXattr(path(), kKey, value));
 
   std::string actual;
-  EXPECT_TRUE(ReadXattr(path(), kKey, &actual));
+  EXPECT_EQ(XattrStatus::kOK, ReadXattr(path(), kKey, &actual));
   EXPECT_EQ(value, actual);
 }
 
 TEST_F(Xattr, WriteAndReadBool) {
   EXPECT_TRUE(WriteXattrBool(path(), kKey, true));
   bool actual = false;
-  EXPECT_TRUE(ReadXattrBool(path(), kKey, &actual));
+  EXPECT_EQ(XattrStatus::kOK, ReadXattrBool(path(), kKey, &actual));
   EXPECT_TRUE(actual);
 
   EXPECT_TRUE(WriteXattrBool(path(), kKey, false));
-  EXPECT_TRUE(ReadXattrBool(path(), kKey, &actual));
+  EXPECT_EQ(XattrStatus::kOK, ReadXattrBool(path(), kKey, &actual));
   EXPECT_FALSE(actual);
 }
 
@@ -94,12 +94,12 @@ TEST_F(Xattr, WriteAndReadInt) {
   int actual;
 
   EXPECT_TRUE(WriteXattrInt(path(), kKey, expected));
-  EXPECT_TRUE(ReadXattrInt(path(), kKey, &actual));
+  EXPECT_EQ(XattrStatus::kOK, ReadXattrInt(path(), kKey, &actual));
   EXPECT_EQ(expected, actual);
 
   expected = std::numeric_limits<int>::max();
   EXPECT_TRUE(WriteXattrInt(path(), kKey, expected));
-  EXPECT_TRUE(ReadXattrInt(path(), kKey, &actual));
+  EXPECT_EQ(XattrStatus::kOK, ReadXattrInt(path(), kKey, &actual));
   EXPECT_EQ(expected, actual);
 }
 
@@ -108,12 +108,12 @@ TEST_F(Xattr, WriteAndReadTimeT) {
   time_t actual;
 
   EXPECT_TRUE(WriteXattrTimeT(path(), kKey, expected));
-  EXPECT_TRUE(ReadXattrTimeT(path(), kKey, &actual));
+  EXPECT_EQ(XattrStatus::kOK, ReadXattrTimeT(path(), kKey, &actual));
   EXPECT_EQ(expected, actual);
 
   expected = std::numeric_limits<time_t>::max();
   EXPECT_TRUE(WriteXattrTimeT(path(), kKey, expected));
-  EXPECT_TRUE(ReadXattrTimeT(path(), kKey, &actual));
+  EXPECT_EQ(XattrStatus::kOK, ReadXattrTimeT(path(), kKey, &actual));
   EXPECT_EQ(expected, actual);
 }