* io.c (io_reopen): avoid dup2() equal handles not to close itself and

  to get rid of a msvcrt bug.  [ruby-dev:20919]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@4177 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 29 insertions, 24 deletions

diff --git a/io.c b/io.c
index debb94a7cd..d9db70401e 100644
--- a/io.c
+++ b/io.c
@@ -2351,7 +2351,7 @@ io_reopen(io, nfile)
 {
     OpenFile *fptr, *orig;
     char *mode;
-    int fd;
+    int fd, fd2;
     off_t pos = 0;
 
     nfile = rb_io_get_io(nfile);
@@ -2386,36 +2386,41 @@ io_reopen(io, nfile)
 
     mode = rb_io_mode_string(fptr);
     fd = fileno(fptr->f);
-    if (fptr->f == stdin || fptr->f == stdout || fptr->f == stderr) {
-	clearerr(fptr->f);
-	/* need to keep stdio objects */
-	if (dup2(fileno(orig->f), fd) < 0)
-	    rb_sys_fail(orig->path);
-    }
-    else {
-	fclose(fptr->f);
-	if (dup2(fileno(orig->f), fd) < 0)
-	    rb_sys_fail(orig->path);
-	fptr->f = rb_fdopen(fd, mode);
-    }
-    rb_thread_fd_close(fd);
-    if ((orig->mode & FMODE_READABLE) && pos >= 0) {
-	io_seek(fptr, pos, SEEK_SET);
-	io_seek(orig, pos, SEEK_SET);
+    fd2 = fileno(orig->f);
+    if (fd != fd2) {
+	if (fptr->f == stdin || fptr->f == stdout || fptr->f == stderr) {
+	    clearerr(fptr->f);
+	    /* need to keep stdio objects */
+	    if (dup2(fd2, fd) < 0)
+		rb_sys_fail(orig->path);
+	}
+	else {
+	    fclose(fptr->f);
+	    if (dup2(fd2, fd) < 0)
+		rb_sys_fail(orig->path);
+	    fptr->f = rb_fdopen(fd, mode);
+	}
+	rb_thread_fd_close(fd);
+	if ((orig->mode & FMODE_READABLE) && pos >= 0) {
+	    io_seek(fptr, pos, SEEK_SET);
+	    io_seek(orig, pos, SEEK_SET);
+	}
     }
 
     if (fptr->f2 && fd != fileno(fptr->f2)) {
 	fd = fileno(fptr->f2);
-	fclose(fptr->f2);
-	rb_thread_fd_close(fd);
-	if (orig->f2) {
-	    if (dup2(fileno(orig->f2), fd) < 0)
+	if (!orig->f2) {
+	    fclose(fptr->f2);
+	    rb_thread_fd_close(fd);
+	    fptr->f2 = 0;
+	}
+	else if (fd != (fd2 = fileno(orig->f2))) {
+	    fclose(fptr->f2);
+	    rb_thread_fd_close(fd);
+	    if (dup2(fd2, fd) < 0)
 		rb_sys_fail(orig->path);
 	    fptr->f2 = rb_fdopen(fd, "w");
 	}
-	else {
-	    fptr->f2 = 0;
-	}
     }
 
     if (fptr->mode & FMODE_BINMODE) {