[Guile-commits] 02/03: Use readdir instead of readdir_r

[Andy Wingo]

wingo pushed a commit to branch master
in repository guile.

commit 7ff3d3834d7d1c0cf7887468187fb5ee200fbdc0
Author: Andy Wingo <address@hidden>
Date:   Tue Dec 6 23:02:28 2016 +0100

    Use readdir instead of readdir_r
    
    * libguile/filesys.c:
    * configure.ac: Remove readdir_r / readdir64_r checks and usage.
      glibc's impls are thread-safe, the _r variants are squirrely and now
      deprecated in glibc, and it is expected that POSIX will mandate that
      readdir{,64} be thread-safe already.  See
      https://sourceware.org/ml/libc-alpha/2016-02/msg00093.html.
---
 configure.ac       |    2 +-
 libguile/filesys.c |   75 ++++++++--------------------------------------------
 2 files changed, 12 insertions(+), 65 deletions(-)

diff --git a/configure.ac b/configure.ac
index db0511d..ab4f1f7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -773,7 +773,7 @@ AC_CHECK_HEADERS([assert.h crt_externs.h])
 AC_CHECK_FUNCS([DINFINITY DQNAN cexp chsize clog clog10 ctermid                
\
   fesetround ftime ftruncate fchown fchmod getcwd geteuid getsid       \
   gettimeofday getuid getgid gmtime_r ioctl lstat mkdir mknod nice     \
-  readdir_r readdir64_r readlink rename rmdir setegid seteuid          \
+  readlink rename rmdir setegid seteuid                                        
\
   setlocale setuid setgid setpgid setsid sigaction siginterrupt stat64 \
   strptime symlink sync sysconf tcgetpgrp tcsetpgrp uname waitpid      \
   strdup system usleep atexit on_exit chown link fcntl ttyname getpwent        
\
diff --git a/libguile/filesys.c b/libguile/filesys.c
index 0bc3669..cccb397 100644
--- a/libguile/filesys.c
+++ b/libguile/filesys.c
@@ -26,9 +26,6 @@
 
 /* See stime.c for comments on why _POSIX_C_SOURCE is not always defined. */
 #define _LARGEFILE64_SOURCE      /* ask for stat64 etc */
-#ifdef __hpux
-#define _POSIX_C_SOURCE 199506L  /* for readdir_r */
-#endif
 
 #ifdef HAVE_CONFIG_H
 #  include <config.h>
@@ -1723,12 +1720,6 @@ SCM_DEFINE (scm_opendir, "opendir", 1, 0, 0,
 #undef FUNC_NAME
 
 
-/* FIXME: The glibc manual has a portability note that readdir_r may not
-   null-terminate its return string.  The circumstances outlined for this
-   are not clear, nor is it clear what should be done about it.  Lets use
-   NAMLEN and worry about what else should be done if/when someone can
-   figure it out.  */
-
 SCM_DEFINE (scm_readdir, "readdir", 1, 0, 0,
            (SCM port),
            "Return (as a string) the next directory entry from the directory 
stream\n"
@@ -1736,70 +1727,26 @@ SCM_DEFINE (scm_readdir, "readdir", 1, 0, 0,
            "end of file object is returned.")
 #define FUNC_NAME s_scm_readdir
 {
+  SCM ret;
   struct dirent_or_dirent64 *rdent;
 
   SCM_VALIDATE_DIR (1, port);
   if (!SCM_DIR_OPEN_P (port))
     SCM_MISC_ERROR ("Directory ~S is not open.", scm_list_1 (port));
 
-#if HAVE_READDIR_R
-  /* As noted in the glibc manual, on various systems (such as Solaris)
-     the d_name[] field is only 1 char and you're expected to size the
-     dirent buffer for readdir_r based on NAME_MAX.  The MAX expressions
-     below effectively give either sizeof(d_name) or NAME_MAX+1,
-     whichever is bigger.
-
-     On solaris 10 there's no NAME_MAX constant, it's necessary to use
-     pathconf().  We prefer NAME_MAX though, since it should be a constant
-     and will therefore save a system call.  We also prefer it since dirfd()
-     is not available everywhere.
-
-     An alternative to dirfd() would be to open() the directory and then use
-     fdopendir(), if the latter is available.  That'd let us hold the fd
-     somewhere in the smob, or just the dirent size calculated once.  */
-  {
-    struct dirent_or_dirent64 de; /* just for sizeof */
-    DIR    *ds = (DIR *) SCM_SMOB_DATA_1 (port);
-#ifdef NAME_MAX
-    char   buf [MAX (sizeof (de),
-                     sizeof (de) - sizeof (de.d_name) + NAME_MAX + 1)];
-#else
-    char   *buf;
-    long   name_max = fpathconf (dirfd (ds), _PC_NAME_MAX);
-    if (name_max == -1)
-      SCM_SYSERROR;
-    buf = alloca (MAX (sizeof (de),
-                       sizeof (de) - sizeof (de.d_name) + name_max + 1));
-#endif
-
-    errno = 0;
-    SCM_SYSCALL (readdir_r_or_readdir64_r (ds, (struct dirent_or_dirent64 *) 
buf, &rdent));
-    if (errno != 0)
-      SCM_SYSERROR;
-    if (! rdent)
-      return SCM_EOF_VAL;
-
-    return (rdent ? scm_from_locale_stringn (rdent->d_name, NAMLEN (rdent))
-           : SCM_EOF_VAL);
-  }
-#else
-  {
-    SCM ret;
-    scm_dynwind_begin (0);
-    scm_i_dynwind_pthread_mutex_lock (&scm_i_misc_mutex);
+  scm_dynwind_begin (0);
+  scm_i_dynwind_pthread_mutex_lock (&scm_i_misc_mutex);
 
-    errno = 0;
-    SCM_SYSCALL (rdent = readdir_or_readdir64 ((DIR *) SCM_SMOB_DATA_1 
(port)));
-    if (errno != 0)
-      SCM_SYSERROR;
+  errno = 0;
+  SCM_SYSCALL (rdent = readdir_or_readdir64 ((DIR *) SCM_SMOB_DATA_1 (port)));
+  if (errno != 0)
+    SCM_SYSERROR;
 
-    ret = (rdent ? scm_from_locale_stringn (rdent->d_name, NAMLEN (rdent))
-          : SCM_EOF_VAL);
+  ret = (rdent ? scm_from_locale_stringn (rdent->d_name, NAMLEN (rdent))
+         : SCM_EOF_VAL);
 
-    scm_dynwind_end ();
-    return ret;
-  }
-#endif
+  scm_dynwind_end ();
+  return ret;
 }
 #undef FUNC_NAME