1 files changed, 89 insertions, 0 deletions
diff --git a/login/pututline_r.c b/login/pututline_r.c
new file mode 100644
index 0000000000..365a37672e
--- /dev/null
+++ b/login/pututline_r.c
@@ -0,0 +1,89 @@
+/* Copyright (C) 1996 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+#include <alloca.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <utmp.h>
+#include <sys/file.h>
+
+
+int
+pututline_r (const struct utmp *utmp_ptr, struct utmp_data *utmp_data)
+{
+  /* Open utmp file if not already done.  */
+  if (utmp_data->ut_fd == -1)
+    {
+      setutent_r (utmp_data);
+      if (utmp_data->ut_fd == -1)
+	return -1;
+    }
+
+  /* Seek position to write.  */
+  if (utmp_data->ubuf.ut_type != utmp_ptr->ut_type)
+    {
+      /* We must not overwrite the data in UTMP_DATA.  */
+      struct utmp_data *data_tmp = alloca (sizeof (utmp_data));
+      struct utmp *dummy;
+
+      memcpy (data_tmp, utmp_data, sizeof (utmp_data));
+      utmp_data = data_tmp;
+      
+      if (getutid_r (utmp_ptr, &dummy, utmp_data) < 0)
+	{
+	  if (errno != ESRCH)
+	    return -1;
+
+	  utmp_data->loc_utmp = lseek (utmp_data->ut_fd, 0, SEEK_END);
+	  if (utmp_data->loc_utmp == -1)
+	    return -1;
+	}
+    }
+
+  /* Position file correctly.  */
+  if (utmp_data->loc_utmp > 0
+      && lseek (utmp_data->ut_fd, utmp_data->loc_utmp - sizeof (struct utmp),
+		SEEK_SET) < 0)
+    return -1;
+
+  /* XXX An alternative solution would be to call an SUID root program
+     which write the new value.  */
+  
+  /* Try to lock the file.  */
+  if (flock (utmp_data->ut_fd, LOCK_EX | LOCK_NB) < 0 && errno != ENOSYS)
+    {
+      /* Oh, oh.  The file is already locked.  Wait a bit and try again.  */
+      sleep (1);
+
+      /* This time we ignore the error.  */
+      (void) flock (utmp_data->ut_fd, LOCK_EX | LOCK_NB);
+    }
+  
+  /* Write the new data.  */
+  if (write (utmp_data->ut_fd, &utmp_data->ubuf, sizeof (struct utmp))
+      != sizeof (struct utmp))
+    return -1;
+
+  /* And unlock the file.  */
+  (void) flock (utmp_data->ut_fd, LOCK_UN);
+
+  return 0;
+}