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* Mandos plugin runner - Run Mandos plugins
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* Copyright © 2008,2009 Teddy Hogeborn
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* Copyright © 2008,2009 Björn Påhlsson
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful, but
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* Copyright © 2008-2020 Teddy Hogeborn
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* Copyright © 2008-2020 Björn Påhlsson
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* This file is part of Mandos.
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* Mandos is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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* Mandos is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see
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* <http://www.gnu.org/licenses/>.
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* along with Mandos. If not, see <http://www.gnu.org/licenses/>.
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* Contact the authors at <mandos@fukt.bsnet.se>.
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* Contact the authors at <mandos@recompile.se>.
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#define _GNU_SOURCE /* TEMP_FAILURE_RETRY(), getline(),
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asprintf(), O_CLOEXEC */
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#include <stddef.h> /* size_t, NULL */
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#include <stdlib.h> /* malloc(), exit(), EXIT_SUCCESS,
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#include <stdlib.h> /* malloc(), reallocarray(), realloc(),
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EXIT_SUCCESS, exit() */
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#include <stdbool.h> /* bool, true, false */
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#include <stdio.h> /* fileno(), fprintf(),
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stderr, STDOUT_FILENO */
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#include <sys/types.h> /* DIR, fdopendir(), stat(), struct
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stat, waitpid(), WIFEXITED(),
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WEXITSTATUS(), wait(), pid_t,
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uid_t, gid_t, getuid(), getgid(),
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stderr, STDOUT_FILENO, fclose() */
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#include <sys/types.h> /* fstat(), struct stat, waitpid(),
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WIFEXITED(), WEXITSTATUS(), wait(),
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pid_t, uid_t, gid_t, getuid(),
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#include <sys/select.h> /* fd_set, select(), FD_ZERO(),
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FD_SET(), FD_ISSET(), FD_CLR */
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#include <sys/wait.h> /* wait(), waitpid(), WIFEXITED(),
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WEXITSTATUS(), WTERMSIG(),
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#include <sys/stat.h> /* struct stat, stat(), S_ISREG() */
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WEXITSTATUS(), WTERMSIG() */
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#include <sys/stat.h> /* struct stat, fstat(), S_ISREG() */
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#include <iso646.h> /* and, or, not */
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#include <dirent.h> /* DIR, struct dirent, fdopendir(),
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readdir(), closedir(), dirfd() */
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#include <unistd.h> /* struct stat, stat(), S_ISREG(),
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fcntl(), setuid(), setgid(),
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F_GETFD, F_SETFD, FD_CLOEXEC,
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access(), pipe(), fork(), close()
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dup2(), STDOUT_FILENO, _exit(),
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execv(), write(), read(),
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#include <dirent.h> /* struct dirent, scandirat() */
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#include <unistd.h> /* fcntl(), F_GETFD, F_SETFD,
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FD_CLOEXEC, write(), STDOUT_FILENO,
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struct stat, fstat(), close(),
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setgid(), setuid(), S_ISREG(),
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faccessat() pipe2(), fork(),
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_exit(), dup2(), fexecve(), read(),
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#include <fcntl.h> /* fcntl(), F_GETFD, F_SETFD,
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#include <string.h> /* strsep, strlen(), asprintf(),
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strsignal(), strcmp(), strncmp() */
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FD_CLOEXEC, openat(), scandirat(),
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#include <string.h> /* strsep, strlen(), strsignal(),
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strcmp(), strncmp() */
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#include <errno.h> /* errno */
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#include <argp.h> /* struct argp_option, struct
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argp_state, struct argp,
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plugin *p = getplugin(arg);
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p->disabled = false;
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case 128: /* --plugin-dir */
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plugindir = strdup(arg);
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if(plugindir != NULL){
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case 129: /* --config-file */
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/* This is already done by parse_opt_config_file() */
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case 130: /* --userid */
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tmpmax = strtoimax(arg, &tmp, 10);
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tmp_id = strtoimax(arg, &tmp, 10);
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if(errno != 0 or tmp == arg or *tmp != '\0'
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or tmpmax != (uid_t)tmpmax){
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or tmp_id != (uid_t)tmp_id){
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argp_error(state, "Bad user ID number: \"%s\", using %"
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PRIdMAX, arg, (intmax_t)uid);
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case 131: /* --groupid */
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tmpmax = strtoimax(arg, &tmp, 10);
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tmp_id = strtoimax(arg, &tmp, 10);
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if(errno != 0 or tmp == arg or *tmp != '\0'
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or tmpmax != (gid_t)tmpmax){
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or tmp_id != (gid_t)tmp_id){
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argp_error(state, "Bad group ID number: \"%s\", using %"
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PRIdMAX, arg, (intmax_t)gid);
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case 132: /* --debug */
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case 133: /* --plugin-helper-dir */
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free(pluginhelperdir);
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pluginhelperdir = strdup(arg);
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if(pluginhelperdir != NULL){
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* These reproduce what we would get without ARGP_NO_HELP
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case '?': /* --help */
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state->flags &= ~(unsigned int)ARGP_NO_EXIT; /* force exit */
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argp_state_help(state, state->out_stream, ARGP_HELP_STD_HELP);
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__builtin_unreachable();
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case -3: /* --usage */
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state->flags &= ~(unsigned int)ARGP_NO_EXIT; /* force exit */
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argp_state_help(state, state->out_stream,
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ARGP_HELP_USAGE | ARGP_HELP_EXIT_OK);
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__builtin_unreachable();
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case 'V': /* --version */
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fprintf(state->out_stream, "%s\n", argp_program_version);
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exit(EXIT_SUCCESS);
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/* Strip permissions down to nobody */
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/* Work around Debian bug #633582:
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<https://bugs.debian.org/633582> */
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int plugindir_fd = open(/* plugindir or */ PDIR, O_RDONLY);
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if(plugindir_fd == -1){
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error(0, errno, "open(\"" PDIR "\")");
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ret = (int)TEMP_FAILURE_RETRY(fstat(plugindir_fd, &st));
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error(0, errno, "fstat");
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if(S_ISDIR(st.st_mode) and st.st_uid == 0 and st.st_gid == 0){
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ret = fchown(plugindir_fd, uid, gid);
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error(0, errno, "fchown");
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/* Work around Debian bug #981302
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<https://bugs.debian.org/981302> */
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if(lstat("/dev/fd", &st) != 0 and errno == ENOENT){
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ret = symlink("/proc/self/fd", "/dev/fd");
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error(0, errno, "Failed to create /dev/fd symlink");
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/* Lower permissions */
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error(0, errno, "setgid");
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ret = set_cloexec_flag(dir_fd);
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error(0, errno, "set_cloexec_flag");
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TEMP_FAILURE_RETRY(close(dir_fd));
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exitstatus = EX_OSERR;
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#endif /* O_CLOEXEC */
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dir = fdopendir(dir_fd);
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error(0, errno, "Could not open plugin dir");
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TEMP_FAILURE_RETRY(close(dir_fd));
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exitstatus = EX_OSERR;
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int good_name(const struct dirent * const dirent){
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const char * const patterns[] = { ".*", "#*#", "*~", "*.dpkg-new",
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"*.dpkg-old", "*.dpkg-bak",
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"*.dpkg-divert", NULL };
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wcast-qual"
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for(const char **pat = (const char **)patterns;
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*pat != NULL; pat++){
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#pragma GCC diagnostic pop
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if(fnmatch(*pat, dirent->d_name, FNM_FILE_NAME | FNM_PERIOD)
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fprintf(stderr, "Ignoring plugin dir entry \"%s\""
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" matching pattern %s\n", dirent->d_name, *pat);
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int numplugins = scandirat(dir_fd, ".", &direntries, good_name,
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if(numplugins == -1){
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error(0, errno, "Could not scan plugin dir");
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exitstatus = EX_OSERR;
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FD_ZERO(&rfds_all);
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/* Read and execute any executable in the plugin directory*/
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dirst = readdir(dir);
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} while(dirst == NULL and errno == EINTR);
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/* All directory entries have been processed */
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error(0, errno, "readdir");
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exitstatus = EX_IOERR;
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d_name_len = strlen(dirst->d_name);
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/* Ignore dotfiles, backup files and other junk */
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bool bad_name = false;
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const char const *bad_prefixes[] = { ".", "#", NULL };
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const char const *bad_suffixes[] = { "~", "#", ".dpkg-new",
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".dpkg-divert", NULL };
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for(const char **pre = bad_prefixes; *pre != NULL; pre++){
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size_t pre_len = strlen(*pre);
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if((d_name_len >= pre_len)
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and strncmp((dirst->d_name), *pre, pre_len) == 0){
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fprintf(stderr, "Ignoring plugin dir entry \"%s\""
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" with bad prefix %s\n", dirst->d_name, *pre);
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for(const char **suf = bad_suffixes; *suf != NULL; suf++){
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size_t suf_len = strlen(*suf);
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if((d_name_len >= suf_len)
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and (strcmp((dirst->d_name) + d_name_len-suf_len, *suf)
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fprintf(stderr, "Ignoring plugin dir entry \"%s\""
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" with bad suffix %s\n", dirst->d_name, *suf);
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if(plugindir == NULL){
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ret = (int)TEMP_FAILURE_RETRY(asprintf(&filename, PDIR "/%s",
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ret = (int)TEMP_FAILURE_RETRY(asprintf(&filename, "%s/%s",
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error(0, errno, "asprintf");
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for(int i = 0; i < numplugins; i++){
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int plugin_fd = openat(dir_fd, direntries[i]->d_name, O_RDONLY);
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error(0, errno, "Could not open plugin");
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ret = (int)TEMP_FAILURE_RETRY(stat(filename, &st));
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ret = (int)TEMP_FAILURE_RETRY(fstat(plugin_fd, &st));
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error(0, errno, "stat");
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/* Ignore non-executable files */
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if(not S_ISREG(st.st_mode)
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or (TEMP_FAILURE_RETRY(access(filename, X_OK)) != 0)){
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or (TEMP_FAILURE_RETRY(faccessat(dir_fd, direntries[i]->d_name,
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fprintf(stderr, "Ignoring plugin dir entry \"%s\""
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" with bad type or mode\n", filename);
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fprintf(stderr, "Ignoring plugin dir entry \"%s/%s\""
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" with bad type or mode\n",
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plugindir != NULL ? plugindir : PDIR,
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direntries[i]->d_name);
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plugin *p = getplugin(dirst->d_name);
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plugin *p = getplugin(direntries[i]->d_name);
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error(0, errno, "getplugin");
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fprintf(stderr, "Ignoring disabled plugin \"%s\"\n",
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direntries[i]->d_name);
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_exit(EX_OSERR);
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/* If dir has no file descriptor, we could not set FD_CLOEXEC
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above and must now close it manually here. */
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if(p->environ[0] == NULL){
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if(execv(filename, p->argv) < 0){
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error(0, errno, "execv");
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if(execve(filename, p->argv, p->environ) < 0){
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error(0, errno, "execve");
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if(fexecve(plugin_fd, p->argv,
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(p->environ[0] != NULL) ? p->environ : environ) < 0){
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error(0, errno, "fexecve for %s/%s",
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plugindir != NULL ? plugindir : PDIR,
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direntries[i]->d_name);
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/* no return */
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/* Parent process */
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TEMP_FAILURE_RETRY(close(pipefd[1])); /* Close unused write end of
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plugin *new_plugin = getplugin(dirst->d_name);
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close(pipefd[1]); /* Close unused write end of pipe */
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plugin *new_plugin = getplugin(direntries[i]->d_name);
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if(new_plugin == NULL){
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error(0, errno, "getplugin");
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ret = (int)(TEMP_FAILURE_RETRY