ptsname_r: new module

For now, this replacement focuses solely on compilation
compatibility, and assumes that isatty() and ttyname_r() work
on a master side pty; if this assumption fails, or if
thread-safety is also required, then a later patch can follow
the lead of strerror_r.c in wrapping the system ptsname()
with a lock.

* modules/ptsname_r: New module.
* m4/ptsname_r.m4 (gl_FUNC_PTSNAME_R): New file.
* lib/ptsname.c (__ptsname_r): Split...
* lib/ptsname_r.c: ...into new file.
* m4/stdlib_h.m4 (gl_STDLIB_H): Check for decl.
(gl_STDLIB_H_DEFAULTS): Set witness defaults.
* modules/stdlib (Makefile.am): Substitute witnesses.
* lib/stdlib.in.h (ptsname_r): Declare it.
* doc/glibc-functions/ptsname_r.texi (ptsname_r): Document it.
* MODULES.html.sh (Misc): Likewise.
* modules/ptsname (Depends-on): Alter dependency.
* doc/posix-functions/ptsname.texi (ptsname): Mention new module.

Signed-off-by: Eric Blake <eblake@redhat.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/lib/ptsname_r.c b/lib/ptsname_r.c
new file mode 100644
index 0000000000..e7f2d5b9ef
--- /dev/null
+++ b/lib/ptsname_r.c
@@ -0,0 +1,85 @@
+/* Determine name of the slave side of a pseudo-terminal.
+   Copyright (C) 1998, 2002, 2010-2011 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include <stdlib.h>
+
+#include <errno.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#ifdef _LIBC
+# include <paths.h>
+#else
+# ifndef _PATH_TTY
+#  define _PATH_TTY "/dev/tty"
+# endif
+# ifndef _PATH_DEV
+#  define _PATH_DEV "/dev/"
+# endif
+
+# define __set_errno(e) errno = (e)
+# define __isatty isatty
+# define __stat stat
+# define __ttyname_r ttyname_r
+# define __ptsname_r ptsname_r
+
+#endif
+
+
+/* Store at most BUFLEN characters of the pathname of the slave pseudo
+   terminal associated with the master FD is open on in BUF.
+   Return 0 on success, otherwise an error number.  */
+int
+__ptsname_r (int fd, char *buf, size_t buflen)
+{
+  int save_errno = errno;
+  int err;
+  struct stat st;
+
+  if (buf == NULL)
+    {
+      __set_errno (EINVAL);
+      return EINVAL;
+    }
+
+  if (!__isatty (fd))
+    /* We rely on isatty to set errno properly (i.e. EBADF or ENOTTY).  */
+    return errno;
+
+  if (buflen < strlen (_PATH_TTY) + 3)
+    {
+      __set_errno (ERANGE);
+      return ERANGE;
+    }
+
+  err = __ttyname_r (fd, buf, buflen);
+  if (err != 0)
+    {
+      __set_errno (err);
+      return errno;
+    }
+
+  buf[sizeof (_PATH_DEV) - 1] = 't';
+
+  if (__stat (buf, &st) < 0)
+    return errno;
+
+  __set_errno (save_errno);
+  return 0;
+}