about summary refs log tree commit diff
path: root/login/login.c
blob: ede02d7938f0bbbb3df98a6766e274c0897971a8 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
/* 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 <errno.h>
#include <limits.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <utmp.h>

/* Return the result of ttyname in the buffer pointed to by TTY, which should
   be of length BUF_LEN.  If it is too long to fit in this buffer, a
   sufficiently long buffer is allocated using malloc, and returned in TTY.
   0 is returned upon success, -1 otherwise.  */
static int
tty_name (int fd, char **tty, size_t buf_len)
{
  int rv;			/* Return value.  0 = success.  */
  char *buf = *tty;		/* Buffer for ttyname, initially the user's. */

  for (;;)
    {
      char *new_buf;

      if (buf_len)
	{
	  rv = ttyname_r (fd, buf, buf_len);

	  if (rv < 0 || memchr (buf, '\0', buf_len))
	    /* We either got an error, or we succeeded and the returned name fit
	       in the buffer.  */
	    break;

	  /* Try again with a longer buffer.  */
	  buf_len += buf_len;	/* Double it */
	}
      else
	/* No initial buffer; start out by mallocing one.  */
	buf_len = 128;		/* First time guess.  */

      if (buf != *tty)
	/* We've already malloced another buffer at least once.  */
	new_buf = realloc (buf, buf_len);
      else
	new_buf = malloc (buf_len);
      if (! new_buf)
	{
	  rv = -1;
	  errno = ENOMEM;
	  break;
	}
    }

  if (rv == 0)
    *tty = buf;			/* Return buffer to the user.  */
  else if (buf != *tty)
    free (buf);			/* Free what we malloced when returning an error.  */

  return rv;
}

void
login (const struct utmp *ut)
{
#ifdef PATH_MAX
  char _tty[PATH_MAX + UT_LINESIZE];
#else
  char _tty[512 + UT_LINESIZE];
#endif
  char *tty = _tty;
  int found_tty;
  const char *ttyp;
  struct utmp_data data;

  /* Seek tty.  */
  found_tty = tty_name (STDIN_FILENO, &tty, sizeof (_tty));
  if (found_tty < 0)
    found_tty = tty_name (STDOUT_FILENO, &tty, sizeof (_tty));
  if (found_tty < 0)
    found_tty = tty_name (STDERR_FILENO, &tty, sizeof (_tty));

  if (found_tty >= 0)
    {
      /* Tell that we want to use the UTMP file.  */
      if (utmpname (_PATH_UTMP) != 0)
	{
	  struct utmp tmp;
	  struct utmp *old;

	  /* Open UTMP file.  */
	  setutent_r (&data);

	  /* We only want to insert the name of the tty without path.  */
	  ttyp = basename (tty);

	  /* Position to record for this tty.  */
#if _HAVE_UT_TYPE - 0
	  tmp.ut_type = USER_PROCESS;
#endif
	  strncpy (tmp.ut_line, ttyp, UT_LINESIZE);

	  /* Read the record.  */
	  if (getutline_r (&tmp, &old, &data) >= 0 || errno == ESRCH)
	    {
#if _HAVE_UT_TYPE - 0
	      /* We have to fake the old entry because this `login'
		 function does not fit well into the UTMP file
		 handling scheme.  */
	      old->ut_type = ut->ut_type;
#endif
	      pututline_r (ut, &data);
	    }

	  /* Close UTMP file.  */
	  endutent_r (&data);
	}

      if (tty != _tty)
	free (tty);		/* Free buffer malloced by tty_name.  */
    }

  /* Update the WTMP file.  Here we have to add a new entry.  */
  if (utmpname (_PATH_WTMP) != 0)
    {
      /* Open the WTMP file.  */
      setutent_r (&data);

      /* Position at end of file.  */
      data.loc_utmp = lseek (data.ut_fd, 0, SEEK_END);
      if (data.loc_utmp != -1)
	{
#if _HAVE_UT_TYPE - 0
	  /* We have to fake the old entry because this `login'
	     function does not fit well into the UTMP file handling
	     scheme.  */
	  data.ubuf.ut_type = ut->ut_type;
#endif
	  pututline_r (ut, &data);
	}

      /* Close WTMP file.  */
      endutent_r (&data);
    }
}