Re: ptsname_r

[Eric Blake <eblake at redhat dot com>]

On 11/07/2011 01:46 PM, Eric Blake wrote:
> > Thanks. Also, even with your patches of today, ptsname() is still not
> > thread-safe; should we be sticking that in a thread-local buffer rather
> > than in static storage, similar to how other functions like strerror()
> > are thread-safe?

I didn't tackle that,

> Also, should we have an efault handler in syscalls.cc ptsname_r(),
> similar to ttyname_r(), so as to gracefully reject invalid buffers
> rather than faulting?

but I had this additional code in my sandbox right before your commit 
hit CVS; should I add a ChangeLog and make it a formal patch submission?

diff --git a/winsup/cygwin/include/cygwin/stdlib.h 
b/winsup/cygwin/include/cygwin/stdlib.h
index d2dfe4c..20358ef 100644
--- a/winsup/cygwin/include/cygwin/stdlib.h
+++ b/winsup/cygwin/include/cygwin/stdlib.h
@@ -1,6 +1,6 @@
 /* stdlib.h

-   Copyright 2005, 2006, 2007, 2008, 2009 Red Hat Inc.
+   Copyright 2005, 2006, 2007, 2008, 2009, 2011 Red Hat Inc.

 This file is part of Cygwin.

diff --git a/winsup/cygwin/libc/bsdlib.cc b/winsup/cygwin/libc/bsdlib.cc
index 3b6e7e4..c4398d3 100644
--- a/winsup/cygwin/libc/bsdlib.cc
+++ b/winsup/cygwin/libc/bsdlib.cc
@@ -108,7 +108,7 @@ openpty (int *amaster, int *aslave, char *name, 
const struct termios *termp,
     {
       grantpt (master);
       unlockpt (master);
-      strcpy (pts, ptsname (master));
+      ptsname_r (master, pts, sizeof pts);
       revoke (pts);
       if ((slave = open (pts, O_RDWR | O_NOCTTY)) >= 0)
 	{
diff --git a/winsup/cygwin/posix.sgml b/winsup/cygwin/posix.sgml
index ef27fde..5c510ed 100644
--- a/winsup/cygwin/posix.sgml
+++ b/winsup/cygwin/posix.sgml
@@ -1131,6 +1131,7 @@ also IEEE Std 1003.1-2008 (POSIX.1-2008).</para>
     pow10f
     ppoll
     pthread_getattr_np
+    ptsname_r
     removexattr
     setxattr
     strchrnul
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 514d458..68dec59 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -2913,16 +2913,24 @@ ptsname (int fd)
 extern "C" int
 ptsname_r (int fd, char *buf, size_t buflen)
 {
-  if (!buf)
+  int ret = 0;
+  myfault efault;
+  if (efault.faulted ())
+    ret = EFAULT;
+  else
     {
-      set_errno (EINVAL);
-      return EINVAL;
+      cygheap_fdget cfd (fd, true);
+      if (cfd < 0)
+	ret = EBADF;
+      else if (!buf)
+        ret = EINVAL;
+      else
+	ret = cfd->ptsname_r (buf, buflen);
     }
-
-  cygheap_fdget cfd (fd);
-  if (cfd < 0)
-    return 0;
-  return cfd->ptsname_r (buf, buflen);
+  if (ret)
+    set_errno (ret);
+  debug_printf ("returning %d pts: %s", ret, ret ? "NULL" : buf);
+  return ret;
 }

 static int __stdcall

--
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org