File: login.c

package info (click to toggle)
glibc 2.30-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, sid
  • size: 270,900 kB
  • sloc: ansic: 1,012,501; asm: 257,517; makefile: 11,622; sh: 10,353; python: 9,001; cpp: 5,081; awk: 1,956; perl: 514; yacc: 290; pascal: 182; sed: 73
file content (139 lines) | stat: -rw-r--r-- 3,838 bytes parent folder | download | duplicates (4)
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
/* Copyright (C) 1996-2019 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <assert.h>
#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;
	  __set_errno (ENOMEM);
	  break;
	}
      buf = new_buf;
    }

  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 copy = *ut;

  /* Fill in those fields we supply.  */
  copy.ut_type = USER_PROCESS;
  copy.ut_pid = getpid ();

  /* 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)
    {
      /* We only want to insert the name of the tty without path.
	 But take care of name like /dev/pts/3.  */
      if (strncmp (tty, "/dev/", 5) == 0)
	ttyp = tty + 5;		/* Skip the "/dev/".  */
      else
	ttyp = basename (tty);

      /* Position to record for this tty.  */
      strncpy (copy.ut_line, ttyp, UT_LINESIZE);

      /* Tell that we want to use the UTMP file.  */
      if (utmpname (_PATH_UTMP) == 0)
	{
	  /* Open UTMP file.  */
	  setutent ();

	  /* Write the entry.  */
	  pututline (&copy);

	  /* Close UTMP file.  */
	  endutent ();
	}

      if (tty != _tty)
	free (tty);		/* Free buffer malloced by tty_name.  */
    }
  else
    /* We provide a default value so that the output does not contain
       an random bytes in this field.  */
    strncpy (copy.ut_line, "???", UT_LINESIZE);

  /* Update the WTMP file.  Here we have to add a new entry.  */
  updwtmp (_PATH_WTMP, &copy);
}