Disable readdir_r and readdir64_r on glibc >= 2.24

DESCRIPTION
       This function is deprecated; use readdir(3) instead.

       The  readdir_r()  function was invented as a reentrant version of read-
       dir(3).  It reads the next directory entry from  the  directory  stream
       dirp,  and  returns  it  in  the  caller-allocated buffer pointed to by
       entry.  For details of the dirent structure, see readdir(3).

       A pointer to the returned buffer is placed in *result; if  the  end  of
       the  directory stream was encountered, then NULL is instead returned in
       *result.

       It is recommended that applications use  readdir(3)  instead  of  read-
       dir_r().   Furthermore,  since  version  2.24,  glibc  deprecates read-
       dir_r().  The reasons are as follows:

       *  On systems where NAME_MAX is undefined, calling readdir_r()  may  be
          unsafe  because  the  interface does not allow the caller to specify
          the length of the buffer used for the returned directory entry.

       *  On some systems, readdir_r() can't read directory entries with  very
          long  names.   When the glibc implementation encounters such a name,
          readdir_r() fails with the error ENAMETOOLONG after the final direc-
          tory  entry  has  been read.  On some other systems, readdir_r() may
          return a success status, but the returned d_name field  may  not  be
          null terminated or may be truncated.

       *  In  the  current POSIX.1 specification (POSIX.1-2008), readdir(3) is
          not required to be thread-safe.  However, in modern  implementations
          (including the glibc implementation), concurrent calls to readdir(3)
          that specify different directory streams  are  thread-safe.   There-
          fore,  the  use  of  readdir_r()  is generally unnecessary in multi-
          threaded programs.  In cases where multiple threads must  read  from
          the  same  directory stream, using readdir(3) with external synchro-
          nization is still preferable to the use of readdir_r(), for the rea-
          sons given in the points above.

       *  It  is  expected  that  a  future version of POSIX.1 will make read-
          dir_r() obsolete, and require that readdir(3)  be  thread-safe  when
          concurrently employed on different directory streams.

1 files changed, 5 insertions, 0 deletions

diff --git a/reentr.h b/reentr.h
index c268851922..b1f3c80615 100644
--- a/reentr.h
+++ b/reentr.h
@@ -56,6 +56,11 @@
 #   define NETDB_R_OBSOLETE
 #endif
 
+#if defined(__GLIBC__) && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 24))
+#   undef HAS_READDIR_R
+#   undef HAS_READDIR64_R
+#endif
+
 /*
  * As of OpenBSD 3.7, reentrant functions are now working, they just are
  * incompatible with everyone else.  To make OpenBSD happy, we have to