Line data Source code
1 : /* GNU's read utmp module.
2 :
3 : Copyright (C) 1992-2001, 2003, 2004, 2005, 2006 Free Software
4 : Foundation, Inc.
5 :
6 : This program is free software: you can redistribute it and/or modify
7 : it under the terms of the GNU General Public License as published by
8 : the Free Software Foundation; either version 3 of the License, or
9 : (at your option) any later version.
10 :
11 : This program is distributed in the hope that it will be useful,
12 : but WITHOUT ANY WARRANTY; without even the implied warranty of
13 : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 : GNU General Public License for more details.
15 :
16 : You should have received a copy of the GNU General Public License
17 : along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 :
19 : /* Written by jla; revised by djm */
20 :
21 : #include <config.h>
22 :
23 : #include "readutmp.h"
24 :
25 : #include <errno.h>
26 : #include <stdio.h>
27 :
28 : #include <sys/types.h>
29 : #include <sys/stat.h>
30 : #include <signal.h>
31 : #include <stdbool.h>
32 : #include <string.h>
33 : #include <stdlib.h>
34 :
35 : #include "xalloc.h"
36 :
37 : #if USE_UNLOCKED_IO
38 : # include "unlocked-io.h"
39 : #endif
40 :
41 : #ifndef SIZE_MAX
42 : # define SIZE_MAX ((size_t) -1)
43 : #endif
44 :
45 : /* Copy UT->ut_name into storage obtained from malloc. Then remove any
46 : trailing spaces from the copy, NUL terminate it, and return the copy. */
47 :
48 : char *
49 0 : extract_trimmed_name (const STRUCT_UTMP *ut)
50 : {
51 : char *p, *trimmed_name;
52 :
53 0 : trimmed_name = xmalloc (sizeof (UT_USER (ut)) + 1);
54 0 : strncpy (trimmed_name, UT_USER (ut), sizeof (UT_USER (ut)));
55 : /* Append a trailing NUL. Some systems pad names shorter than the
56 : maximum with spaces, others pad with NULs. Remove any trailing
57 : spaces. */
58 0 : trimmed_name[sizeof (UT_USER (ut))] = '\0';
59 0 : for (p = trimmed_name + strlen (trimmed_name);
60 0 : trimmed_name < p && p[-1] == ' ';
61 0 : *--p = '\0')
62 0 : continue;
63 0 : return trimmed_name;
64 : }
65 :
66 : /* Is the utmp entry U desired by the user who asked for OPTIONS? */
67 :
68 : static inline bool
69 0 : desirable_utmp_entry (STRUCT_UTMP const *u, int options)
70 : {
71 0 : bool user_proc = IS_USER_PROCESS (u);
72 0 : if ((options & READ_UTMP_USER_PROCESS) && !user_proc)
73 0 : return false;
74 0 : if ((options & READ_UTMP_CHECK_PIDS)
75 0 : && user_proc
76 0 : && (UT_PID (u) <= 0
77 0 : || (kill (UT_PID (u), 0) < 0 && errno == ESRCH)))
78 0 : return false;
79 0 : return true;
80 : }
81 :
82 : /* Read the utmp entries corresponding to file FILE into freshly-
83 : malloc'd storage, set *UTMP_BUF to that pointer, set *N_ENTRIES to
84 : the number of entries, and return zero. If there is any error,
85 : return -1, setting errno, and don't modify the parameters.
86 : If OPTIONS & READ_UTMP_CHECK_PIDS is nonzero, omit entries whose
87 : process-IDs do not currently exist. */
88 :
89 : #ifdef UTMP_NAME_FUNCTION
90 :
91 : int
92 79 : read_utmp (char const *file, size_t *n_entries, STRUCT_UTMP **utmp_buf,
93 : int options)
94 : {
95 79 : size_t n_read = 0;
96 79 : size_t n_alloc = 0;
97 79 : STRUCT_UTMP *utmp = NULL;
98 : STRUCT_UTMP *u;
99 :
100 : /* Ignore the return value for now.
101 : Solaris' utmpname returns 1 upon success -- which is contrary
102 : to what the GNU libc version does. In addition, older GNU libc
103 : versions are actually void. */
104 79 : UTMP_NAME_FUNCTION (file);
105 :
106 79 : SET_UTMP_ENT ();
107 :
108 158 : while ((u = GET_UTMP_ENT ()) != NULL)
109 0 : if (desirable_utmp_entry (u, options))
110 : {
111 0 : if (n_read == n_alloc)
112 0 : utmp = x2nrealloc (utmp, &n_alloc, sizeof *utmp);
113 :
114 0 : utmp[n_read++] = *u;
115 : }
116 :
117 79 : END_UTMP_ENT ();
118 :
119 79 : *n_entries = n_read;
120 79 : *utmp_buf = utmp;
121 :
122 79 : return 0;
123 : }
124 :
125 : #else
126 :
127 : int
128 : read_utmp (char const *file, size_t *n_entries, STRUCT_UTMP **utmp_buf,
129 : int options)
130 : {
131 : size_t n_read = 0;
132 : size_t n_alloc = 0;
133 : STRUCT_UTMP *utmp = NULL;
134 : int saved_errno;
135 : FILE *f = fopen (file, "r");
136 :
137 : if (! f)
138 : return -1;
139 :
140 : for (;;)
141 : {
142 : if (n_read == n_alloc)
143 : utmp = x2nrealloc (utmp, &n_alloc, sizeof *utmp);
144 : if (fread (&utmp[n_read], sizeof utmp[n_read], 1, f) == 0)
145 : break;
146 : n_read += desirable_utmp_entry (&utmp[n_read], options);
147 : }
148 :
149 : saved_errno = ferror (f) ? errno : 0;
150 : if (fclose (f) != 0)
151 : saved_errno = errno;
152 : if (saved_errno != 0)
153 : {
154 : free (utmp);
155 : errno = saved_errno;
156 : return -1;
157 : }
158 :
159 : *n_entries = n_read;
160 : *utmp_buf = utmp;
161 :
162 : return 0;
163 : }
164 :
165 : #endif
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