--- a/hotspot/src/share/vm/logging/log.cpp	Thu Sep 08 15:28:05 2016 +0200
+++ b/hotspot/src/share/vm/logging/log.cpp	Thu Sep 08 15:43:20 2016 +0200
@@ -50,72 +50,6 @@
 #define assert_char_not_in(c, s) \
   assert(strchr(s, c) == NULL, "Expected '%s' to *not* contain character '%c'", s, c)
 
-// Read a complete line from fp and return it as a resource allocated string.
-// Returns NULL on EOF.
-static char* read_line(FILE* fp) {
-  assert(fp != NULL, "bad fp");
-  int buflen = 512;
-  char* buf = NEW_RESOURCE_ARRAY(char, buflen);
-  long pos = ftell(fp);
-
-  char* ret = fgets(buf, buflen, fp);
-  while (ret != NULL && buf[strlen(buf) - 1] != '\n' && !feof(fp)) {
-    // retry with a larger buffer
-    buf = REALLOC_RESOURCE_ARRAY(char, buf, buflen, buflen * 2);
-    buflen *= 2;
-    // rewind to beginning of line
-    fseek(fp, pos, SEEK_SET);
-    // retry read with new buffer
-    ret = fgets(buf, buflen, fp);
-  }
-  return ret;
-}
-
-static size_t number_of_lines_with_substring_in_file(const char* filename,
-                                                     const char* substr) {
-  FILE* fp = fopen(filename, "r");
-  assert(fp != NULL, "error opening file %s: %s", filename, strerror(errno));
-
-  size_t ret = 0;
-  for (;;) {
-    ResourceMark rm;
-    char* line = read_line(fp);
-    if (line == NULL) {
-      break;
-    }
-    if (strstr(line, substr) != NULL) {
-      ret++;
-    }
-  }
-
-  fclose(fp);
-  return ret;
-}
-
-static bool file_exists(const char* filename) {
-  struct stat st;
-  return os::stat(filename, &st) == 0;
-}
-
-static void delete_file(const char* filename) {
-  if (!file_exists(filename)) {
-    return;
-  }
-  int ret = remove(filename);
-  assert(ret == 0, "failed to remove file '%s': %s", filename, strerror(errno));
-}
-
-static void create_directory(const char* name) {
-  assert(!file_exists(name), "can't create directory: %s already exists", name);
-  bool failed;
-#ifdef _WINDOWS
-  failed = !CreateDirectory(name, NULL);
-#else
-  failed = mkdir(name, 0777);
-#endif
-  assert(!failed, "failed to create directory %s", name);
-}
-
 class TestLogFile {
  private:
   char file_name[256];
@@ -201,77 +135,6 @@
   assert_str_eq("all=off", stdoutput->config_string());
 }
 
-static const char* ExpectedLine = "a (hopefully) unique log line for testing";
-
-static void init_file(const char* filename, const char* options = "") {
-  LogConfiguration::parse_log_arguments(filename, "logging=trace", "", options,
-                                        Log(logging)::error_stream());
-  log_debug(logging)("%s", ExpectedLine);
-  LogConfiguration::parse_log_arguments(filename, "all=off", "", "",
-                                        Log(logging)::error_stream());
-}
-
-void Test_log_file_startup_rotation() {
-  ResourceMark rm;
-  const size_t rotations = 5;
-  const char* filename = "start-rotate-test";
-  char* rotated_file[rotations];
-  for (size_t i = 0; i < rotations; i++) {
-    size_t len = strlen(filename) + 3;
-    rotated_file[i] = NEW_RESOURCE_ARRAY(char, len);
-    jio_snprintf(rotated_file[i], len, "%s." SIZE_FORMAT, filename, i);
-    delete_file(rotated_file[i]);
-  };
-
-  delete_file(filename);
-  init_file(filename);
-  assert(file_exists(filename),
-         "configured logging to file '%s' but file was not found", filename);
-
-  // Initialize the same file a bunch more times to trigger rotations
-  for (size_t i = 0; i < rotations; i++) {
-    init_file(filename);
-    assert(file_exists(rotated_file[i]), "existing file was not rotated");
-  }
-
-  // Remove a file and expect its slot to be re-used
-  delete_file(rotated_file[1]);
-  init_file(filename);
-  assert(file_exists(rotated_file[1]), "log file not properly rotated");
-
-  // Clean up after test
-  delete_file(filename);
-  for (size_t i = 0; i < rotations; i++) {
-    delete_file(rotated_file[i]);
-  }
-}
-
-void Test_log_file_startup_truncation() {
-  ResourceMark rm;
-  const char* filename = "start-truncate-test";
-  const char* archived_filename = "start-truncate-test.0";
-
-  delete_file(filename);
-  delete_file(archived_filename);
-
-  // Use the same log file twice and expect it to be overwritten/truncated
-  init_file(filename, "filecount=0");
-  assert(file_exists(filename), "couldn't find log file: %s", filename);
-
-  init_file(filename, "filecount=0");
-  assert(file_exists(filename), "couldn't find log file: %s", filename);
-  assert(!file_exists(archived_filename),
-         "existing log file %s was not properly truncated when filecount was 0",
-         filename);
-
-  // Verify that the file was really truncated and not just appended
-  assert(number_of_lines_with_substring_in_file(filename, ExpectedLine) == 1,
-         "log file %s appended rather than truncated", filename);
-
-  delete_file(filename);
-  delete_file(archived_filename);
-}
-
 static int Test_logconfiguration_subscribe_triggered = 0;
 
 static void Test_logconfiguration_subscribe_helper() {
@@ -608,20 +471,4 @@
   Test_logtargethandle_off();
 }
 
-void Test_invalid_log_file() {
-  ResourceMark rm;
-  stringStream ss;
-  const char* target_name = "tmplogdir";
-
-  // Attempt to log to a directory (existing log not a regular file)
-  create_directory(target_name);
-  LogFileOutput bad_file("file=tmplogdir");
-  assert(bad_file.initialize("", &ss) == false, "file was initialized "
-         "when there was an existing directory with the same name");
-  assert(strstr(ss.as_string(), "tmplogdir is not a regular file") != NULL,
-         "missing expected error message, received msg: %s", ss.as_string());
-  ss.reset();
-  remove(target_name);
-}
-
 #endif // PRODUCT

--- a/hotspot/src/share/vm/utilities/internalVMTests.cpp	Thu Sep 08 15:28:05 2016 +0200
+++ b/hotspot/src/share/vm/utilities/internalVMTests.cpp	Thu Sep 08 15:43:20 2016 +0200
@@ -67,9 +67,6 @@
   run_unit_test(Test_logconfiguration_subscribe);
   run_unit_test(Test_log_prefix);
   run_unit_test(Test_log_big);
-  run_unit_test(Test_log_file_startup_rotation);
-  run_unit_test(Test_log_file_startup_truncation);
-  run_unit_test(Test_invalid_log_file);
   run_unit_test(DirectivesParser_test);
 #if INCLUDE_VM_STRUCTS
   run_unit_test(VMStructs_test);

--- a/hotspot/test/native/logging/logTestUtils.inline.hpp	Thu Sep 08 15:28:05 2016 +0200
+++ b/hotspot/test/native/logging/logTestUtils.inline.hpp	Thu Sep 08 15:43:20 2016 +0200
@@ -48,6 +48,26 @@
       << os::strerror(errno) << " (" << errno << ")";
 }
 
+static inline void create_directory(const char* name) {
+  assert(!file_exists(name), "can't create directory: %s already exists", name);
+  bool failed;
+#ifdef _WINDOWS
+  failed = !CreateDirectory(name, NULL);
+#else
+  failed = mkdir(name, 0777);
+#endif
+  assert(!failed, "failed to create directory %s", name);
+}
+
+static inline void init_log_file(const char* filename, const char* options = "") {
+  LogStreamHandle(Error, logging) stream;
+  bool success = LogConfiguration::parse_log_arguments(filename, "logging=trace", "", options, &stream);
+  guarantee(success, "Failed to initialize log file '%s' with options '%s'", filename, options);
+  log_debug(logging)("%s", LOG_TEST_STRING_LITERAL);
+  success = LogConfiguration::parse_log_arguments(filename, "all=off", "", "", &stream);
+  guarantee(success, "Failed to disable logging to file '%s'", filename);
+}
+
 // Read a complete line from fp and return it as a resource allocated string.
 // Returns NULL on EOF.
 static inline char* read_line(FILE* fp) {

--- a/hotspot/test/native/logging/test_logFileOutput.cpp	Thu Sep 08 15:28:05 2016 +0200
+++ b/hotspot/test/native/logging/test_logFileOutput.cpp	Thu Sep 08 15:43:20 2016 +0200
@@ -22,6 +22,7 @@
  *
  */
 #include "precompiled.hpp"
+#include "logTestUtils.inline.hpp"
 #include "logging/logFileOutput.hpp"
 #include "memory/resourceArea.hpp"
 #include "runtime/os.hpp"
@@ -101,3 +102,82 @@
   LogFileOutput fo(name);
   EXPECT_FALSE(fo.initialize(buf, &ss)) << "Accepted filesize that overflows";
 }
+
+TEST(LogFileOutput, startup_rotation) {
+  const size_t rotations = 5;
+  const char* filename = "start-rotate-test";
+  char* rotated_file[rotations];
+
+  ResourceMark rm;
+  for (size_t i = 0; i < rotations; i++) {
+    size_t len = strlen(filename) + 3;
+    rotated_file[i] = NEW_RESOURCE_ARRAY(char, len);
+    int ret = jio_snprintf(rotated_file[i], len, "%s." SIZE_FORMAT, filename, i);
+    ASSERT_NE(-1, ret);
+    delete_file(rotated_file[i]);
+  }
+
+  delete_file(filename);
+  init_log_file(filename);
+  ASSERT_TRUE(file_exists(filename))
+    << "configured logging to file '" << filename << "' but file was not found";
+
+  // Initialize the same file a bunch more times to trigger rotations
+  for (size_t i = 0; i < rotations; i++) {
+    init_log_file(filename);
+    EXPECT_TRUE(file_exists(rotated_file[i]));
+  }
+
+  // Remove a file and expect its slot to be re-used
+  delete_file(rotated_file[1]);
+  init_log_file(filename);
+  EXPECT_TRUE(file_exists(rotated_file[1]));
+
+  // Clean up after test
+  delete_file(filename);
+  for (size_t i = 0; i < rotations; i++) {
+    delete_file(rotated_file[i]);
+  }
+}
+
+TEST(LogFileOutput, startup_truncation) {
+  const char* filename = "start-truncate-test";
+  const char* archived_filename = "start-truncate-test.0";
+
+  delete_file(filename);
+  delete_file(archived_filename);
+
+  // Use the same log file twice and expect it to be overwritten/truncated
+  init_log_file(filename, "filecount=0");
+  ASSERT_TRUE(file_exists(filename))
+    << "configured logging to file '" << filename << "' but file was not found";
+
+  init_log_file(filename, "filecount=0");
+  ASSERT_TRUE(file_exists(filename))
+    << "configured logging to file '" << filename << "' but file was not found";
+  EXPECT_FALSE(file_exists(archived_filename))
+    << "existing log file was not properly truncated when filecount was 0";
+
+  // Verify that the file was really truncated and not just appended
+  EXPECT_TRUE(file_contains_substring(filename, LOG_TEST_STRING_LITERAL));
+  const char* repeated[] = { LOG_TEST_STRING_LITERAL, LOG_TEST_STRING_LITERAL };
+  EXPECT_FALSE(file_contains_substrings_in_order(filename, repeated))
+    << "log file " << filename << " appended rather than truncated";
+
+  delete_file(filename);
+  delete_file(archived_filename);
+}
+
+TEST(LogFileOutput, invalid_file) {
+  ResourceMark rm;
+  stringStream ss;
+
+  // Attempt to log to a directory (existing log not a regular file)
+  create_directory("tmplogdir");
+  LogFileOutput bad_file("file=tmplogdir");
+  EXPECT_FALSE(bad_file.initialize("", &ss))
+    << "file was initialized when there was an existing directory with the same name";
+  EXPECT_TRUE(string_contains_substring(ss.as_string(), "tmplogdir is not a regular file"))
+    << "missing expected error message, received msg: %s" << ss.as_string();
+  remove("tmplogdir");
+}