1 files changed, 90 insertions, 0 deletions
diff --git a/sysdeps/unix/getlogin.c b/sysdeps/unix/getlogin.c
new file mode 100644
index 0000000000..504a7aa4c0
--- /dev/null
+++ b/sysdeps/unix/getlogin.c
@@ -0,0 +1,90 @@
+/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+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., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <stddef.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+#include <limits.h>
+#include <fcntl.h>
+
+#include <utmp.h>
+
+/* Defined in ttyname.c.  */
+extern char *__ttyname;
+
+/* Return the login name of the user, or NULL if it can't be determined.
+   The returned pointer, if not NULL, is good only until the next call.  */
+
+char *
+DEFUN_VOID(getlogin)
+{
+  char save_tty_pathname[2 + 2 * NAME_MAX];
+  char *save_ttyname;
+  char *real_tty_path;
+  char *result = NULL;
+  FILE *f;
+  static struct utmp ut;
+
+  if (__ttyname == NULL)
+    save_ttyname = NULL;
+  else
+    save_ttyname = strcpy (save_tty_pathname, __ttyname);
+
+  {
+    int err;
+    int d = __open ("/dev/tty", 0);
+    if (d < 0)
+      return NULL;
+
+    real_tty_path = ttyname (d);
+    err = errno;
+    (void) close (d);
+
+    if (real_tty_path == NULL)
+      {
+	errno = err;
+	return NULL;
+      }
+  }
+
+  real_tty_path += 5;		/* Remove "/dev/".  */
+
+  f = fopen ("/etc/utmp", "r");
+  if (f != NULL)
+    {
+      while (fread ((PTR) &ut, sizeof(ut), 1, f) == 1)
+	if (!strncmp (ut.ut_line, real_tty_path, sizeof (ut.ut_line)))
+	  {
+	    result = ut.ut_name;
+	    /* The name is not null-terminated if
+	       it is as long as sizeof (ut.ut_name).  */
+	    result[sizeof (ut.ut_name)] = '\0';
+	    break;
+	  }
+      (void) fclose (f);
+    }
+
+  if (save_ttyname != NULL)
+    strcpy (__ttyname, save_ttyname);
+  if (result == NULL)
+    errno = ENOENT;
+  return result;
+}