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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/unix/getlogin.c
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initial import
Diffstat (limited to 'sysdeps/unix/getlogin.c')
-rw-r--r--sysdeps/unix/getlogin.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/sysdeps/unix/getlogin.c b/sysdeps/unix/getlogin.c
new file mode 100644
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--- /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;
+}