* configure.in: check dup3.

* io.c (rb_cloexec_dup2): use dup3 if available.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@33561 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Sun Oct 30 07:47:10 2011  Tanaka Akira  <akr@fsij.org>
+
+	* configure.in: check dup3.
+
+	* io.c (rb_cloexec_dup2): use dup3 if available.
+
 Sat Oct 29 22:06:37 2011  Tanaka Akira  <akr@fsij.org>
 
 	* include/ruby/intern.h (rb_cloexec_dup2): declared.

configure.in

@@ -1351,7 +1351,8 @@ AC_CHECK_FUNCS(fmod killpg wait4 waitpid fork spawnv syscall __syscall chroot ge
 	      setsid telldir seekdir fchmod cosh sinh tanh log2 round\
 	      setuid setgid daemon select_large_fdset setenv unsetenv\
               mktime timegm gmtime_r clock_gettime gettimeofday poll ppoll\
-              pread sendfile shutdown sigaltstack dl_iterate_phdr)
+              pread sendfile shutdown sigaltstack dl_iterate_phdr\
+              dup3)
 
 AC_CACHE_CHECK(for unsetenv returns a value, rb_cv_unsetenv_return_value,
   [AC_TRY_COMPILE([

io.c

@@ -232,7 +232,22 @@ rb_cloexec_dup2(int oldfd, int newfd)
 {
     int ret;
 
+#if defined(HAVE_DUP3) && defined(O_CLOEXEC)
+    static int try_dup3 = 1;
+    if (try_dup3) {
+        ret = dup3(oldfd, newfd, O_CLOEXEC);
+        /* dup3 is available since Linux 2.6.27. */
+        if (ret == -1 && errno == ENOSYS) {
+            try_dup3 = 0;
             ret = dup2(oldfd, newfd);
+        }
+    }
+    else {
+        ret = dup2(oldfd, newfd);
+    }
+#else
+    ret = dup2(oldfd, newfd);
+#endif
     if (ret == -1) return -1;
     fd_set_cloexec(ret);
     return ret;