RFR: 8179887 - Build failure with glibc >= 2.24: error: 'int readdir_r(DIR*, dirent*, dirent**)' is deprecated

[Alan Bateman]

On 20/06/2018 11:08, Pengfei Li wrote:
> Hi
>
> I have tried the patch ( http://mail.openjdk.java.net/pipermail/core-libs-dev/2018-May/052991.html ) on Ubuntu 18.04 machines (x86_64 & aarch64) with glibc=2.26.1 and build is OK.
>
> There's a small issue within the following code in src/java.base/unix/native/libnio/fs/UnixNativeDispatcher.c
> Unlike readdir_r(), readdir() does not return int value. The value of res is always 0 before #ifdef.
>
>   727     /* EINTR not listed as a possible error */
>   728     errno = 0;
>   729     ptr = readdir64(dirp);
>   730     res = errno;
>   731
>   732 #ifdef _AIX
>   733     /* On AIX, readdir() returns EBADF (i.e. '9') and sets 'result' to NULL for the */
>   734     /* directory stream end. Otherwise, 'errno' will contain the error code. */
>   735     if (res != 0) {
>   736         res = (ptr == NULL && res == EBADF) ? 0 : errno;
>   737     }
>   738 #endif
>
> May I know that if this core-libs change going to be merged recently, or more platforms needs to be explored?
>
I see your other mail looking to to add #pragma GCC ... to avoid using 
configure --disable-warnings-as-errors.

I think it would be better to just replace the usage readdir_r usage in 
that native method. I've tested the patch below on macOS, Linux and 
Solaris.  The SAP folks maintain the AIX port and would need to test it 
on that platform as it eliminates the AIX specific code for dealing with 
end of stream that should be needed when using readdir.

-Alan

diff -r 9d62da00bf15 -r 5e67e87bd6fa 
src/java.base/unix/native/libnio/fs/UnixNativeDispatcher.c
--- a/src/java.base/unix/native/libnio/fs/UnixNativeDispatcher.c Sat May 
26 06:59:49 2018 +0200
+++ b/src/java.base/unix/native/libnio/fs/UnixNativeDispatcher.c Mon Jun 
25 14:17:03 2018 +0100
@@ -1,5 +1,5 @@
  /*
- * Copyright (c) 2008, 2017, Oracle and/or its affiliates. All rights 
reserved.
+ * Copyright (c) 2008, 2018, Oracle and/or its affiliates. All rights 
reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
@@ -72,7 +72,7 @@
  #define fstat64 fstat
  #define lstat64 lstat
  #define dirent64 dirent
-#define readdir64_r readdir_r
+#define readdir64 readdir
  #endif

  #include "jni.h"
@@ -720,41 +720,23 @@

  JNIEXPORT jbyteArray JNICALL
  Java_sun_nio_fs_UnixNativeDispatcher_readdir(JNIEnv* env, jclass this, 
jlong value) {
-    struct dirent64* result;
-    struct {
-        struct dirent64 buf;
-        char name_extra[PATH_MAX + 1 - sizeof result->d_name];
-    } entry;
-    struct dirent64* ptr = &entry.buf;
-    int res;
      DIR* dirp = jlong_to_ptr(value);
+    struct dirent64* ptr;

-    /* EINTR not listed as a possible error */
-    /* TDB: reentrant version probably not required here */
-    res = readdir64_r(dirp, ptr, &result);
-
-#ifdef _AIX
-    /* On AIX, readdir_r() returns EBADF (i.e. '9') and sets 'result' 
to NULL for the */
-    /* directory stream end. Otherwise, 'errno' will contain the error 
code. */
-    if (res != 0) {
-        res = (result == NULL && res == EBADF) ? 0 : errno;
-    }
-#endif
-
-    if (res != 0) {
-        throwUnixException(env, res);
+    errno = 0;
+    ptr = readdir64(dirp);
+    if (ptr == NULL) {
+        if (errno != 0) {
+            throwUnixException(env, errno);
+        }
          return NULL;
      } else {
-        if (result == NULL) {
-            return NULL;
-        } else {
-            jsize len = strlen(ptr->d_name);
-            jbyteArray bytes = (*env)->NewByteArray(env, len);
-            if (bytes != NULL) {
-                (*env)->SetByteArrayRegion(env, bytes, 0, len, 
(jbyte*)(ptr->d_name));
-            }
-            return bytes;
+        jsize len = strlen(ptr->d_name);
+        jbyteArray bytes = (*env)->NewByteArray(env, len);
+        if (bytes != NULL) {
+            (*env)->SetByteArrayRegion(env, bytes, 0, len, 
(jbyte*)(ptr->d_name));
          }
+        return bytes;
      }
  }