| /* GNU's read utmp module. |
| |
| Copyright (C) 1992-2001, 2003-2006, 2009-2020 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 "readutmp.h" |
| |
| #include <errno.h> |
| #include <stdio.h> |
| |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include <signal.h> |
| #include <stdbool.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <stdint.h> |
| |
| #include "xalloc.h" |
| |
| #if USE_UNLOCKED_IO |
| # include "unlocked-io.h" |
| #endif |
| |
| #if 8 <= __GNUC__ |
| # pragma GCC diagnostic ignored "-Wsizeof-pointer-memaccess" |
| #endif |
| |
| /* Copy UT->ut_name into storage obtained from malloc. Then remove any |
| trailing spaces from the copy, NUL terminate it, and return the copy. */ |
| |
| char * |
| extract_trimmed_name (const STRUCT_UTMP *ut) |
| { |
| char *p, *trimmed_name; |
| |
| trimmed_name = xmalloc (sizeof (UT_USER (ut)) + 1); |
| strncpy (trimmed_name, UT_USER (ut), sizeof (UT_USER (ut))); |
| /* Append a trailing NUL. Some systems pad names shorter than the |
| maximum with spaces, others pad with NULs. Remove any trailing |
| spaces. */ |
| trimmed_name[sizeof (UT_USER (ut))] = '\0'; |
| for (p = trimmed_name + strlen (trimmed_name); |
| trimmed_name < p && p[-1] == ' '; |
| *--p = '\0') |
| continue; |
| return trimmed_name; |
| } |
| |
| /* Is the utmp entry U desired by the user who asked for OPTIONS? */ |
| |
| static bool |
| desirable_utmp_entry (STRUCT_UTMP const *u, int options) |
| { |
| bool user_proc = IS_USER_PROCESS (u); |
| if ((options & READ_UTMP_USER_PROCESS) && !user_proc) |
| return false; |
| if ((options & READ_UTMP_CHECK_PIDS) |
| && user_proc |
| && 0 < UT_PID (u) |
| && (kill (UT_PID (u), 0) < 0 && errno == ESRCH)) |
| return false; |
| return true; |
| } |
| |
| /* Read the utmp entries corresponding to file FILE into freshly- |
| malloc'd storage, set *UTMP_BUF to that pointer, set *N_ENTRIES to |
| the number of entries, and return zero. If there is any error, |
| return -1, setting errno, and don't modify the parameters. |
| If OPTIONS & READ_UTMP_CHECK_PIDS is nonzero, omit entries whose |
| process-IDs do not currently exist. */ |
| |
| #ifdef UTMP_NAME_FUNCTION |
| |
| int |
| read_utmp (char const *file, size_t *n_entries, STRUCT_UTMP **utmp_buf, |
| int options) |
| { |
| size_t n_read = 0; |
| size_t n_alloc = 0; |
| STRUCT_UTMP *utmp = NULL; |
| STRUCT_UTMP *u; |
| |
| /* Ignore the return value for now. |
| Solaris' utmpname returns 1 upon success -- which is contrary |
| to what the GNU libc version does. In addition, older GNU libc |
| versions are actually void. */ |
| UTMP_NAME_FUNCTION ((char *) file); |
| |
| SET_UTMP_ENT (); |
| |
| while ((u = GET_UTMP_ENT ()) != NULL) |
| if (desirable_utmp_entry (u, options)) |
| { |
| if (n_read == n_alloc) |
| utmp = x2nrealloc (utmp, &n_alloc, sizeof *utmp); |
| |
| utmp[n_read++] = *u; |
| } |
| |
| END_UTMP_ENT (); |
| |
| *n_entries = n_read; |
| *utmp_buf = utmp; |
| |
| return 0; |
| } |
| |
| #else |
| |
| int |
| read_utmp (char const *file, size_t *n_entries, STRUCT_UTMP **utmp_buf, |
| int options) |
| { |
| size_t n_read = 0; |
| size_t n_alloc = 0; |
| STRUCT_UTMP *utmp = NULL; |
| int saved_errno; |
| FILE *f = fopen (file, "r"); |
| |
| if (! f) |
| return -1; |
| |
| for (;;) |
| { |
| if (n_read == n_alloc) |
| utmp = x2nrealloc (utmp, &n_alloc, sizeof *utmp); |
| if (fread (&utmp[n_read], sizeof utmp[n_read], 1, f) == 0) |
| break; |
| n_read += desirable_utmp_entry (&utmp[n_read], options); |
| } |
| |
| saved_errno = ferror (f) ? errno : 0; |
| if (fclose (f) != 0) |
| saved_errno = errno; |
| if (saved_errno != 0) |
| { |
| free (utmp); |
| errno = saved_errno; |
| return -1; |
| } |
| |
| *n_entries = n_read; |
| *utmp_buf = utmp; |
| |
| return 0; |
| } |
| |
| #endif |