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/* GNU's users.
Copyright (C) 1992-2023 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by jla; revised by djm */
#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include "system.h"
#include "long-options.h"
#include "quote.h"
#include "readutmp.h"
/* The official name of this program (e.g., no 'g' prefix). */
#define PROGRAM_NAME "users"
#define AUTHORS \
proper_name ("Joseph Arceneaux"), \
proper_name ("David MacKenzie")
static int
userid_compare (const void *v_a, const void *v_b)
{
char **a = (char **) v_a;
char **b = (char **) v_b;
return strcmp (*a, *b);
}
static void
list_entries_users (idx_t n, struct gl_utmp const *this)
{
char **u = xinmalloc (n, sizeof *u);
idx_t i;
idx_t n_entries = 0;
while (n--)
{
if (IS_USER_PROCESS (this))
{
char *trimmed_name;
trimmed_name = extract_trimmed_name (this);
u[n_entries] = trimmed_name;
++n_entries;
}
this++;
}
qsort (u, n_entries, sizeof (u[0]), userid_compare);
for (i = 0; i < n_entries; i++)
{
char c = (i < n_entries - 1 ? ' ' : '\n');
fputs (u[i], stdout);
putchar (c);
}
for (i = 0; i < n_entries; i++)
free (u[i]);
free (u);
}
/* Display a list of users on the system, according to utmp file FILENAME.
Use read_utmp OPTIONS to read FILENAME. */
static void
users (char const *filename, int options)
{
idx_t n_users;
struct gl_utmp *utmp_buf;
options |= READ_UTMP_USER_PROCESS;
if (read_utmp (filename, &n_users, &utmp_buf, options) != 0)
error (EXIT_FAILURE, errno, "%s", quotef (filename));
list_entries_users (n_users, utmp_buf);
free (utmp_buf);
}
void
usage (int status)
{
if (status != EXIT_SUCCESS)
emit_try_help ();
else
{
printf (_("Usage: %s [OPTION]... [FILE]\n"), program_name);
printf (_("\
Output who is currently logged in according to FILE.\n\
If FILE is not specified, use %s. %s as FILE is common.\n\
\n\
"),
UTMP_FILE, WTMP_FILE);
fputs (HELP_OPTION_DESCRIPTION, stdout);
fputs (VERSION_OPTION_DESCRIPTION, stdout);
emit_ancillary_info (PROGRAM_NAME);
}
exit (status);
}
int
main (int argc, char **argv)
{
initialize_main (&argc, &argv);
set_program_name (argv[0]);
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
atexit (close_stdout);
parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
Version, true, usage, AUTHORS,
(char const *) nullptr);
switch (argc - optind)
{
case 0: /* users */
users (UTMP_FILE, READ_UTMP_CHECK_PIDS);
break;
case 1: /* users <utmp file> */
users (argv[optind], 0);
break;
default: /* lose */
error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
usage (EXIT_FAILURE);
}
return EXIT_SUCCESS;
}
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