# HG changeset patch
# User andrew
# Date 1560786098 -3600
# Node ID 0f2fe7d37d8c980cf38a4867de068a9e6983229b
# Parent  5d306df084eb74c7df7e02b31e1f0b4a5ea9d3bd
8202353: os::readdir should use readdir instead of readdir_r
Summary: Summary: os::readdir uses POSIX readdir, drop buffer arg, fix JFR uses.
Reviewed-by: coleenp, tschatzl, bsrbnd, shade, phh

diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/aix/vm/os_aix.cpp
--- a/src/os/aix/vm/os_aix.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/aix/vm/os_aix.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -4184,8 +4184,7 @@
 
   /* Scan the directory */
   bool result = true;
-  char buf[sizeof(struct dirent) + MAX_PATH];
-  while (result && (ptr = ::readdir(dir)) != NULL) {
+  while (result && (ptr = readdir(dir)) != NULL) {
     if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
       result = false;
     }
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/aix/vm/os_aix.inline.hpp
--- a/src/os/aix/vm/os_aix.inline.hpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/aix/vm/os_aix.inline.hpp	Mon Jun 17 16:41:38 2019 +0100
@@ -92,19 +92,6 @@
 
 inline const int os::default_file_open_flags() { return 0;}
 
-inline DIR* os::opendir(const char* dirname)
-{
-  assert(dirname != NULL, "just checking");
-  return ::opendir(dirname);
-}
-
-inline int os::readdir_buf_size(const char *path)
-{
-  // according to aix sys/limits, NAME_MAX must be retrieved at runtime. */
-  const long my_NAME_MAX = pathconf(path, _PC_NAME_MAX);
-  return my_NAME_MAX + sizeof(dirent) + 1;
-}
-
 inline jlong os::lseek(int fd, jlong offset, int whence) {
   return (jlong) ::lseek64(fd, offset, whence);
 }
@@ -121,28 +108,6 @@
   return ::ftruncate64(fd, length);
 }
 
-inline struct dirent* os::readdir(DIR* dirp, dirent *dbuf)
-{
-  dirent* p;
-  int status;
-  assert(dirp != NULL, "just checking");
-
-  // NOTE: Linux readdir_r (on RH 6.2 and 7.2 at least) is NOT like the POSIX
-  // version. Here is the doc for this function:
-  // http://www.gnu.org/manual/glibc-2.2.3/html_node/libc_262.html
-
-  if((status = ::readdir_r(dirp, dbuf, &p)) != 0) {
-    errno = status;
-    return NULL;
-  } else
-    return p;
-}
-
-inline int os::closedir(DIR *dirp) {
-  assert(dirp != NULL, "argument is NULL");
-  return ::closedir(dirp);
-}
-
 // macros for restartable system calls
 
 #define RESTARTABLE(_cmd, _result) do { \
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/aix/vm/perfMemory_aix.cpp
--- a/src/os/aix/vm/perfMemory_aix.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/aix/vm/perfMemory_aix.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -612,9 +612,8 @@
   // to determine the user name for the process id.
   //
   struct dirent* dentry;
-  char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
   errno = 0;
-  while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
+  while ((dentry = os::readdir(tmpdirp)) != NULL) {
 
     // check if the directory entry is a hsperfdata file
     if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
@@ -648,9 +647,8 @@
     }
 
     struct dirent* udentry;
-    char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
     errno = 0;
-    while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
+    while ((udentry = os::readdir(subdirp)) != NULL) {
 
       if (filename_to_pid(udentry->d_name) == vmid) {
         struct stat statbuf;
@@ -694,11 +692,9 @@
       }
     }
     os::closedir(subdirp);
-    FREE_C_HEAP_ARRAY(char, udbuf, mtInternal);
     FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
   }
   os::closedir(tmpdirp);
-  FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal);
 
   return(oldest_user);
 }
@@ -774,10 +770,8 @@
   // loop under these conditions is dependent upon the implementation of
   // opendir/readdir.
   struct dirent* entry;
-  char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
-
   errno = 0;
-  while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
+  while ((entry = os::readdir(dirp)) != NULL) {
 
     pid_t pid = filename_to_pid(entry->d_name);
 
@@ -816,7 +810,6 @@
   // Close the directory and reset the current working directory.
   close_directory_secure_cwd(dirp, saved_cwd_fd);
 
-  FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
 }
 
 // Make the user specific temporary directory. Returns true if
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/bsd/vm/os_bsd.cpp
--- a/src/os/bsd/vm/os_bsd.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/bsd/vm/os_bsd.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -3957,8 +3957,7 @@
 
   /* Scan the directory */
   bool result = true;
-  char buf[sizeof(struct dirent) + MAX_PATH];
-  while (result && (ptr = ::readdir(dir)) != NULL) {
+  while (result && (ptr = readdir(dir)) != NULL) {
     if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
       result = false;
     }
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/bsd/vm/os_bsd.inline.hpp
--- a/src/os/bsd/vm/os_bsd.inline.hpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/bsd/vm/os_bsd.inline.hpp	Mon Jun 17 16:41:38 2019 +0100
@@ -95,17 +95,6 @@
 
 inline const int os::default_file_open_flags() { return 0;}
 
-inline DIR* os::opendir(const char* dirname)
-{
-  assert(dirname != NULL, "just checking");
-  return ::opendir(dirname);
-}
-
-inline int os::readdir_buf_size(const char *path)
-{
-  return NAME_MAX + sizeof(dirent) + 1;
-}
-
 inline jlong os::lseek(int fd, jlong offset, int whence) {
   return (jlong) ::lseek(fd, offset, whence);
 }
@@ -122,28 +111,6 @@
   return ::ftruncate(fd, length);
 }
 
-inline struct dirent* os::readdir(DIR* dirp, dirent *dbuf)
-{
-  dirent* p;
-  int status;
-  assert(dirp != NULL, "just checking");
-
-  // NOTE: Bsd readdir_r (on RH 6.2 and 7.2 at least) is NOT like the POSIX
-  // version. Here is the doc for this function:
-  // http://www.gnu.org/manual/glibc-2.2.3/html_node/libc_262.html
-
-  if((status = ::readdir_r(dirp, dbuf, &p)) != 0) {
-    errno = status;
-    return NULL;
-  } else
-    return p;
-}
-
-inline int os::closedir(DIR *dirp) {
-  assert(dirp != NULL, "argument is NULL");
-  return ::closedir(dirp);
-}
-
 // macros for restartable system calls
 
 #define RESTARTABLE(_cmd, _result) do { \
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/bsd/vm/perfMemory_bsd.cpp
--- a/src/os/bsd/vm/perfMemory_bsd.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/bsd/vm/perfMemory_bsd.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -533,9 +533,8 @@
   // to determine the user name for the process id.
   //
   struct dirent* dentry;
-  char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
   errno = 0;
-  while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
+  while ((dentry = os::readdir(tmpdirp)) != NULL) {
 
     // check if the directory entry is a hsperfdata file
     if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
@@ -557,9 +556,8 @@
     }
 
     struct dirent* udentry;
-    char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
     errno = 0;
-    while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
+    while ((udentry = os::readdir(subdirp)) != NULL) {
 
       if (filename_to_pid(udentry->d_name) == vmid) {
         struct stat statbuf;
@@ -603,11 +601,9 @@
       }
     }
     os::closedir(subdirp);
-    FREE_C_HEAP_ARRAY(char, udbuf, mtInternal);
     FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
   }
   os::closedir(tmpdirp);
-  FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal);
 
   return(oldest_user);
 }
@@ -686,10 +682,8 @@
   // opendir/readdir.
   //
   struct dirent* entry;
-  char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
-
   errno = 0;
-  while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
+  while ((entry = os::readdir(dirp)) != NULL) {
 
     pid_t pid = filename_to_pid(entry->d_name);
 
@@ -729,7 +723,6 @@
   // close the directory and reset the current working directory
   close_directory_secure_cwd(dirp, saved_cwd_fd);
 
-  FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
 }
 
 // make the user specific temporary directory. Returns true if
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/linux/vm/os_linux.cpp
--- a/src/os/linux/vm/os_linux.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/linux/vm/os_linux.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -5501,8 +5501,7 @@
 
   /* Scan the directory */
   bool result = true;
-  char buf[sizeof(struct dirent) + MAX_PATH];
-  while (result && (ptr = ::readdir(dir)) != NULL) {
+  while (result && (ptr = readdir(dir)) != NULL) {
     if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
       result = false;
     }
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/linux/vm/os_linux.inline.hpp
--- a/src/os/linux/vm/os_linux.inline.hpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/linux/vm/os_linux.inline.hpp	Mon Jun 17 16:41:38 2019 +0100
@@ -87,17 +87,6 @@
 
 inline const int os::default_file_open_flags() { return 0;}
 
-inline DIR* os::opendir(const char* dirname)
-{
-  assert(dirname != NULL, "just checking");
-  return ::opendir(dirname);
-}
-
-inline int os::readdir_buf_size(const char *path)
-{
-  return NAME_MAX + sizeof(dirent) + 1;
-}
-
 inline jlong os::lseek(int fd, jlong offset, int whence) {
   return (jlong) ::lseek64(fd, offset, whence);
 }
@@ -114,28 +103,6 @@
   return ::ftruncate64(fd, length);
 }
 
-inline struct dirent* os::readdir(DIR* dirp, dirent *dbuf)
-{
-  dirent* p;
-  int status;
-  assert(dirp != NULL, "just checking");
-
-  // NOTE: Linux readdir_r (on RH 6.2 and 7.2 at least) is NOT like the POSIX
-  // version. Here is the doc for this function:
-  // http://www.gnu.org/manual/glibc-2.2.3/html_node/libc_262.html
-
-  if((status = ::readdir_r(dirp, dbuf, &p)) != 0) {
-    errno = status;
-    return NULL;
-  } else
-    return p;
-}
-
-inline int os::closedir(DIR *dirp) {
-  assert(dirp != NULL, "argument is NULL");
-  return ::closedir(dirp);
-}
-
 // macros for restartable system calls
 
 #define RESTARTABLE(_cmd, _result) do { \
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/linux/vm/perfMemory_linux.cpp
--- a/src/os/linux/vm/perfMemory_linux.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/linux/vm/perfMemory_linux.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -533,9 +533,8 @@
   // to determine the user name for the process id.
   //
   struct dirent* dentry;
-  char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
   errno = 0;
-  while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
+  while ((dentry = os::readdir(tmpdirp)) != NULL) {
 
     // check if the directory entry is a hsperfdata file
     if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
@@ -569,9 +568,8 @@
     }
 
     struct dirent* udentry;
-    char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
     errno = 0;
-    while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
+    while ((udentry = os::readdir(subdirp)) != NULL) {
 
       if (filename_to_pid(udentry->d_name) == vmid) {
         struct stat statbuf;
@@ -615,11 +613,9 @@
       }
     }
     os::closedir(subdirp);
-    FREE_C_HEAP_ARRAY(char, udbuf, mtInternal);
     FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
   }
   os::closedir(tmpdirp);
-  FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal);
 
   return(oldest_user);
 }
@@ -698,10 +694,8 @@
   // opendir/readdir.
   //
   struct dirent* entry;
-  char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
-
   errno = 0;
-  while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
+  while ((entry = os::readdir(dirp)) != NULL) {
 
     pid_t pid = filename_to_pid(entry->d_name);
 
@@ -738,8 +732,6 @@
 
   // close the directory and reset the current working directory
   close_directory_secure_cwd(dirp, saved_cwd_fd);
-
-  FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
 }
 
 // make the user specific temporary directory. Returns true if
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/posix/vm/os_posix.cpp
--- a/src/os/posix/vm/os_posix.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/posix/vm/os_posix.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -302,6 +302,21 @@
   return ::fdopen(fd, mode);
 }
 
+DIR* os::opendir(const char* dirname) {
+  assert(dirname != NULL, "just checking");
+  return ::opendir(dirname);
+}
+
+struct dirent* os::readdir(DIR* dirp) {
+  assert(dirp != NULL, "just checking");
+  return ::readdir(dirp);
+}
+
+int os::closedir(DIR *dirp) {
+  assert(dirp != NULL, "just checking");
+  return ::closedir(dirp);
+}
+
 // Builds a platform dependent Agent_OnLoad_<lib_name> function name
 // which is used to find statically linked in agents.
 // Parameters:
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/solaris/vm/os_solaris.cpp
--- a/src/os/solaris/vm/os_solaris.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/solaris/vm/os_solaris.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -5163,9 +5163,7 @@
 
   /* Scan the directory */
   bool result = true;
-  char buf[sizeof(struct dirent) + MAX_PATH];
-  struct dirent *dbuf = (struct dirent *) buf;
-  while (result && (ptr = readdir(dir, dbuf)) != NULL) {
+  while (result && (ptr = readdir(dir)) != NULL) {
     if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
       result = false;
     }
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/solaris/vm/os_solaris.inline.hpp
--- a/src/os/solaris/vm/os_solaris.inline.hpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/solaris/vm/os_solaris.inline.hpp	Mon Jun 17 16:41:38 2019 +0100
@@ -71,37 +71,6 @@
 }
 inline void os::dll_unload(void *lib) { ::dlclose(lib); }
 
-inline DIR* os::opendir(const char* dirname) {
-  assert(dirname != NULL, "just checking");
-  return ::opendir(dirname);
-}
-
-inline int os::readdir_buf_size(const char *path) {
-  int size = pathconf(path, _PC_NAME_MAX);
-  return (size < 0 ? MAXPATHLEN : size) + sizeof(dirent) + 1;
-}
-
-inline struct dirent* os::readdir(DIR* dirp, dirent* dbuf) {
-  assert(dirp != NULL, "just checking");
-#if defined(_LP64) || defined(_GNU_SOURCE) || _FILE_OFFSET_BITS==64
-  dirent* p;
-  int status;
-
-  if((status = ::readdir_r(dirp, dbuf, &p)) != 0) {
-    errno = status;
-    return NULL;
-  } else
-    return p;
-#else  // defined(_LP64) || defined(_GNU_SOURCE) || _FILE_OFFSET_BITS==64
-  return ::readdir_r(dirp, dbuf);
-#endif // defined(_LP64) || defined(_GNU_SOURCE) || _FILE_OFFSET_BITS==64
-}
-
-inline int os::closedir(DIR *dirp) {
-  assert(dirp != NULL, "argument is NULL");
-  return ::closedir(dirp);
-}
-
 //////////////////////////////////////////////////////////////////////////////
 ////////////////////////////////////////////////////////////////////////////////
 
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/solaris/vm/perfMemory_solaris.cpp
--- a/src/os/solaris/vm/perfMemory_solaris.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/solaris/vm/perfMemory_solaris.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -524,9 +524,8 @@
   // to determine the user name for the process id.
   //
   struct dirent* dentry;
-  char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
   errno = 0;
-  while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
+  while ((dentry = os::readdir(tmpdirp)) != NULL) {
 
     // check if the directory entry is a hsperfdata file
     if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
@@ -560,9 +559,8 @@
     }
 
     struct dirent* udentry;
-    char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
     errno = 0;
-    while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
+    while ((udentry = os::readdir(subdirp)) != NULL) {
 
       if (filename_to_pid(udentry->d_name) == vmid) {
         struct stat statbuf;
@@ -606,11 +604,9 @@
       }
     }
     os::closedir(subdirp);
-    FREE_C_HEAP_ARRAY(char, udbuf, mtInternal);
     FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
   }
   os::closedir(tmpdirp);
-  FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal);
 
   return(oldest_user);
 }
@@ -737,10 +733,8 @@
   // opendir/readdir.
   //
   struct dirent* entry;
-  char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
-
   errno = 0;
-  while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
+  while ((entry = os::readdir(dirp)) != NULL) {
 
     pid_t pid = filename_to_pid(entry->d_name);
 
@@ -780,7 +774,6 @@
   // close the directory and reset the current working directory
   close_directory_secure_cwd(dirp, saved_cwd_fd);
 
-  FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
 }
 
 // make the user specific temporary directory. Returns true if
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/windows/vm/os_windows.cpp
--- a/src/os/windows/vm/os_windows.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/windows/vm/os_windows.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -1172,14 +1172,12 @@
     return dirp;
 }
 
-/* parameter dbuf unused on Windows */
-
 struct dirent *
-os::readdir(DIR *dirp, dirent *dbuf)
+os::readdir(DIR *dirp)
 {
     assert(dirp != NULL, "just checking");      // hotspot change
     if (dirp->handle == INVALID_HANDLE_VALUE) {
-        return 0;
+        return NULL;
     }
 
     strcpy(dirp->dirent.d_name, dirp->find_data.cFileName);
@@ -1187,7 +1185,7 @@
     if (!FindNextFile(dirp->handle, &dirp->find_data)) {
         if (GetLastError() == ERROR_INVALID_HANDLE) {
             errno = EBADF;
-            return 0;
+            return NULL;
         }
         FindClose(dirp->handle);
         dirp->handle = INVALID_HANDLE_VALUE;
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/windows/vm/os_windows.inline.hpp
--- a/src/os/windows/vm/os_windows.inline.hpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/windows/vm/os_windows.inline.hpp	Mon Jun 17 16:41:38 2019 +0100
@@ -65,14 +65,6 @@
   return true;
 }
 
-inline int os::readdir_buf_size(const char *path)
-{
-  /* As Windows doesn't use the directory entry buffer passed to
-     os::readdir() this can be as short as possible */
-
-  return 1;
-}
-
 // Bang the shadow pages if they need to be touched to be mapped.
 inline void os::bang_stack_shadow_pages() {
   // Write to each page of our new frame to force OS mapping.
diff -r 5d306df084eb -r 0f2fe7d37d8c src/os/windows/vm/perfMemory_windows.cpp
--- a/src/os/windows/vm/perfMemory_windows.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/os/windows/vm/perfMemory_windows.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -316,9 +316,8 @@
   // to determine the user name for the process id.
   //
   struct dirent* dentry;
-  char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
   errno = 0;
-  while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
+  while ((dentry = os::readdir(tmpdirp)) != NULL) {
 
     // check if the directory entry is a hsperfdata file
     if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
@@ -351,9 +350,8 @@
     }
 
     struct dirent* udentry;
-    char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
     errno = 0;
-    while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
+    while ((udentry = os::readdir(subdirp)) != NULL) {
 
       if (filename_to_pid(udentry->d_name) == vmid) {
         struct stat statbuf;
@@ -405,11 +403,9 @@
       }
     }
     os::closedir(subdirp);
-    FREE_C_HEAP_ARRAY(char, udbuf, mtInternal);
     FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
   }
   os::closedir(tmpdirp);
-  FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal);
 
   return(latest_user);
 }
@@ -639,9 +635,8 @@
   // opendir/readdir.
   //
   struct dirent* entry;
-  char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
   errno = 0;
-  while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
+  while ((entry = os::readdir(dirp)) != NULL) {
 
     int pid = filename_to_pid(entry->d_name);
 
@@ -682,7 +677,6 @@
     errno = 0;
   }
   os::closedir(dirp);
-  FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
 }
 
 // create a file mapping object with the requested name, and size
diff -r 5d306df084eb -r 0f2fe7d37d8c src/share/vm/runtime/arguments.cpp
--- a/src/share/vm/runtime/arguments.cpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/share/vm/runtime/arguments.cpp	Mon Jun 17 16:41:38 2019 +0100
@@ -556,8 +556,7 @@
 
   /* Scan the directory for jars/zips, appending them to path. */
   struct dirent *entry;
-  char *dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(directory), mtInternal);
-  while ((entry = os::readdir(dir, (dirent *) dbuf)) != NULL) {
+  while ((entry = os::readdir(dir)) != NULL) {
     const char* name = entry->d_name;
     const char* ext = name + strlen(name) - 4;
     bool isJarOrZip = ext > name &&
@@ -571,7 +570,6 @@
       FREE_C_HEAP_ARRAY(char, jarpath, mtInternal);
     }
   }
-  FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
   os::closedir(dir);
   return path;
 }
@@ -3485,14 +3483,12 @@
   if (dir == NULL) return false;
 
   struct dirent *entry;
-  char *dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(directory), mtInternal);
   bool hasJarFile = false;
-  while (!hasJarFile && (entry = os::readdir(dir, (dirent *) dbuf)) != NULL) {
+  while (!hasJarFile && (entry = os::readdir(dir)) != NULL) {
     const char* name = entry->d_name;
     const char* ext = name + strlen(name) - 4;
     hasJarFile = ext > name && (os::file_name_strcmp(ext, ".jar") == 0);
   }
-  FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
   os::closedir(dir);
   return hasJarFile ;
 }
@@ -3574,8 +3570,7 @@
   if (dir != NULL) {
     int num_ext_jars = 0;
     struct dirent *entry;
-    char *dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(extDir), mtInternal);
-    while ((entry = os::readdir(dir, (dirent *) dbuf)) != NULL) {
+    while ((entry = os::readdir(dir)) != NULL) {
       const char* name = entry->d_name;
       const char* ext = name + strlen(name) - 4;
       if (ext > name && (os::file_name_strcmp(ext, ".jar") == 0)) {
@@ -3594,7 +3589,6 @@
         }
       }
     }
-    FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
     os::closedir(dir);
     if (num_ext_jars > 0) {
       nonEmptyDirs += 1;
diff -r 5d306df084eb -r 0f2fe7d37d8c src/share/vm/runtime/os.hpp
--- a/src/share/vm/runtime/os.hpp	Tue Apr 30 14:49:19 2019 +0200
+++ b/src/share/vm/runtime/os.hpp	Mon Jun 17 16:41:38 2019 +0100
@@ -561,8 +561,7 @@
 
   // Reading directories.
   static DIR*           opendir(const char* dirname);
-  static int            readdir_buf_size(const char *path);
-  static struct dirent* readdir(DIR* dirp, dirent* dbuf);
+  static struct dirent* readdir(DIR* dirp);
   static int            closedir(DIR* dirp);
 
   // Dynamic library extension