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/* -*- coding: utf-8 -*- */
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* Mandos plugin runner - Run Mandos plugins
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* Copyright © 2007-2008 Teddy Hogeborn & 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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* 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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* Contact the authors at <mandos@fukt.bsnet.se>.
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#define _GNU_SOURCE /* TEMP_FAILURE_RETRY() */
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#include <stddef.h> /* size_t, NULL */
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#include <stdlib.h> /* malloc(), exit(), EXIT_FAILURE,
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EXIT_SUCCESS, realloc() */
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#include <stdbool.h> /* bool, true, false */
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#include <stdio.h> /* perror, popen(), fileno(),
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fprintf(), stderr, STDOUT_FILENO */
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#include <sys/types.h> /* DIR, opendir(), 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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#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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#include <sys/stat.h> /* struct stat, stat(), S_ISREG() */
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#include <iso646.h> /* and, or, not */
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#include <dirent.h> /* DIR, struct dirent, opendir(),
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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 <fcntl.h> /* fcntl(), F_GETFD, F_SETFD,
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#include <string.h> /* strtok, strlen(), strcpy(),
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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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argp_parse(), ARGP_ERR_UNKNOWN,
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ARGP_KEY_END, ARGP_KEY_ARG, error_t */
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#include <signal.h> /* struct sigaction, sigemptyset(),
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sigaddset(), sigaction(),
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sigprocmask(), SIG_BLOCK, SIGCHLD,
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SIG_UNBLOCK, kill() */
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#include <errno.h> /* errno, EBADF */
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#define BUFFER_SIZE 256
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const char *argp_program_version = "plugin-runner 1.0";
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const char *argp_program_bug_address = "<mandos@fukt.bsnet.se>";
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typedef struct process{
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typedef struct plugin{
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char *name; /* can be NULL or any plugin name */
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static plugin *getplugin(char *name, plugin **plugin_list){
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for (plugin *p = *plugin_list; p != NULL; p = p->next){
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or (p->name and name and (strcmp(p->name, name) == 0))){
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/* Create a new plugin */
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plugin *new_plugin = malloc(sizeof(plugin));
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if (new_plugin == NULL){
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new_plugin->name = name;
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new_plugin->argv = malloc(sizeof(char *) * 2);
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if (new_plugin->argv == NULL){
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new_plugin->argv[0] = name;
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new_plugin->argv[1] = NULL;
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new_plugin->argc = 1;
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new_plugin->disabled = false;
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new_plugin->next = *plugin_list;
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/* Append the new plugin to the list */
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*plugin_list = new_plugin;
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static void addargument(plugin *p, char *arg){
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p->argv[p->argc] = arg;
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p->argv = realloc(p->argv, sizeof(char *) * (size_t)(p->argc + 2));
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if (p->argv == NULL){
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p->argv[p->argc] = NULL;
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* Based on the example in the GNU LibC manual chapter 13.13 "File
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* *Note File Descriptor Flags:(libc)Descriptor Flags.
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static int set_cloexec_flag(int fd)
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int ret = fcntl(fd, F_GETFD, 0);
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/* If reading the flags failed, return error indication now. */
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/* Store modified flag word in the descriptor. */
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return fcntl(fd, F_SETFD, ret | FD_CLOEXEC);
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process *process_list = NULL;
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/* Mark a process as completed when it exits, and save its exit
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void handle_sigchld(__attribute__((unused)) int sig){
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process *proc = process_list;
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pid_t pid = wait(&status);
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while(proc != NULL and proc->pid != pid){
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/* Process not found in process list */
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proc->status = status;
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proc->completed = true;
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bool print_out_password(const char *buffer, size_t length){
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if(length>0 and buffer[length-1] == '\n'){
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for(size_t written = 0; written < length; written += (size_t)ret){
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ret = TEMP_FAILURE_RETRY(write(STDOUT_FILENO, buffer + written,
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int main(int argc, char *argv[]){
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const char *plugindir = "/lib/mandos/plugins.d";
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struct dirent *dirst;
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int exitstatus = EXIT_SUCCESS;
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struct sigaction old_sigchld_action;
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struct sigaction sigchld_action = { .sa_handler = handle_sigchld,
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.sa_flags = SA_NOCLDSTOP };
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char *plus_options = NULL;
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char **plus_argv = NULL;
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/* Establish a signal handler */
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sigemptyset(&sigchld_action.sa_mask);
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ret = sigaddset(&sigchld_action.sa_mask, SIGCHLD);
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ret = sigaction(SIGCHLD, &sigchld_action, &old_sigchld_action);
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/* The options we understand. */
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struct argp_option options[] = {
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{ .name = "global-options", .key = 'g',
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.arg = "OPTION[,OPTION[,...]]",
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.doc = "Options passed to all plugins" },
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{ .name = "options-for", .key = 'o',
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.arg = "PLUGIN:OPTION[,OPTION[,...]]",
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.doc = "Options passed only to specified plugin" },
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{ .name = "disable", .key = 'd',
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.doc = "Disable a specific plugin", .group = 1 },
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{ .name = "plugin-dir", .key = 128,
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.doc = "Specify a different plugin directory", .group = 2 },
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{ .name = "userid", .key = 129,
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.arg = "ID", .flags = 0,
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.doc = "User ID the plugins will run as", .group = 2 },
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{ .name = "groupid", .key = 130,
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.arg = "ID", .flags = 0,
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.doc = "Group ID the plugins will run as", .group = 2 },
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{ .name = "debug", .key = 131,
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.doc = "Debug mode", .group = 3 },
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error_t parse_opt (int key, char *arg, struct argp_state *state) {
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/* Get the INPUT argument from `argp_parse', which we know is a
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pointer to our plugin list pointer. */
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plugin **plugins = state->input;
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char *p = strtok(arg, ",");
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addargument(getplugin(NULL, plugins), p);
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p = strtok(NULL, ",");
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char *name = strtok(arg, ":");
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char *p = strtok(NULL, ":");
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addargument(getplugin(name, plugins), p);
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p = strtok(NULL, ",");
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getplugin(arg, plugins)->disabled = true;
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uid = (uid_t)strtol(arg, NULL, 10);
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gid = (gid_t)strtol(arg, NULL, 10);
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if(plus_options != NULL or arg == NULL or arg[0] != '+'){
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return ARGP_ERR_UNKNOWN;
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plugin *plugin_list = NULL;
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struct argp argp = { .options = options, .parser = parse_opt,
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.args_doc = "[+PLUS_SEPARATED_OPTIONS]",
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.doc = "Mandos plugin runner -- Run plugins" };
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ret = argp_parse (&argp, argc, argv, 0, 0, &plugin_list);
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if (ret == ARGP_ERR_UNKNOWN){
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fprintf(stderr, "Unknown error while parsing arguments\n");
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exitstatus = EXIT_FAILURE;
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/* This is a mangled argument in the form of
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"+--option+--other-option=parameter+--yet-another-option", etc */
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/* Make new argc and argv vars, and call argp_parse() again. */
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plus_options++; /* skip the first '+' character */
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const char delims[] = "+";
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plus_argv = malloc(sizeof(char*) * 2);
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if(plus_argv == NULL){
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exitstatus = EXIT_FAILURE;
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plus_argv[0] = argv[0];
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arg = strtok(plus_options, delims); /* Get first argument */
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plus_argv = realloc(plus_argv, sizeof(char *)
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* ((unsigned int) new_argc + 1));
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if(plus_argv == NULL){
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exitstatus = EXIT_FAILURE;
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plus_argv[new_argc-1] = arg;
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plus_argv[new_argc] = NULL;
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arg = strtok(NULL, delims); /* Get next argument */
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ret = argp_parse (&argp, new_argc, plus_argv, 0, 0, &plugin_list);
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if (ret == ARGP_ERR_UNKNOWN){
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fprintf(stderr, "Unknown error while parsing arguments\n");
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exitstatus = EXIT_FAILURE;
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for(plugin *p = plugin_list; p != NULL; p=p->next){
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fprintf(stderr, "Plugin: %s has %d arguments\n",
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p->name ? p->name : "Global", p->argc - 1);
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for(char **a = p->argv; *a != NULL; a++){
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fprintf(stderr, "\tArg: %s\n", *a);
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dir = opendir(plugindir);
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perror("Could not open plugin dir");
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exitstatus = EXIT_FAILURE;
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/* Set the FD_CLOEXEC flag on the directory, if possible */
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int dir_fd = dirfd(dir);
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ret = set_cloexec_flag(dir_fd);
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perror("set_cloexec_flag");
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exitstatus = EXIT_FAILURE;
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dirst = readdir(dir);
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// All directory entries have been processed
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exitstatus = EXIT_FAILURE;
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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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char *filename = malloc(d_name_len + strlen(plugindir) + 2);
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if (filename == NULL){
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strcpy(filename, plugindir); /* Spurious warning */
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strcat(filename, "/"); /* Spurious warning */
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strcat(filename, dirst->d_name); /* Spurious warning */
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ret = stat(filename, &st);
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if (not S_ISREG(st.st_mode) or (access(filename, X_OK) != 0)){
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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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if(getplugin(dirst->d_name, &plugin_list)->disabled){
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fprintf(stderr, "Ignoring disabled plugin \"%s\"\n",
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plugin *p = getplugin(dirst->d_name, &plugin_list);
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/* Add global arguments to argument list for this plugin */
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plugin *g = getplugin(NULL, &plugin_list);
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for(char **a = g->argv + 1; *a != NULL; a++){
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exitstatus = EXIT_FAILURE;
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ret = set_cloexec_flag(pipefd[0]);
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perror("set_cloexec_flag");
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exitstatus = EXIT_FAILURE;
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ret = set_cloexec_flag(pipefd[1]);
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perror("set_cloexec_flag");
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exitstatus = EXIT_FAILURE;
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/* Block SIGCHLD until process is safely in process list */
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ret = sigprocmask (SIG_BLOCK, &sigchld_action.sa_mask, NULL);
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perror("sigprocmask");
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exitstatus = EXIT_FAILURE;
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// Starting a new process to be watched
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exitstatus = EXIT_FAILURE;
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/* this is the child process */
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ret = sigaction(SIGCHLD, &old_sigchld_action, NULL);
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ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
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perror("sigprocmask");
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ret = dup2(pipefd[1], STDOUT_FILENO); /* replace our stdout */
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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(execv(filename, p->argv) < 0){
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close(pipefd[1]); /* close unused write end of pipe */
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process *new_process = malloc(sizeof(process));
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if (new_process == NULL){
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ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
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perror("sigprocmask");
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exitstatus = EXIT_FAILURE;
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*new_process = (struct process){ .pid = pid,
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.next = process_list };
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process_list = new_process;
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/* Unblock SIGCHLD so signal handler can be run if this process
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has already completed */
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ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
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perror("sigprocmask");
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exitstatus = EXIT_FAILURE;
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FD_SET(new_process->fd, &rfds_all);
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if (maxfd < new_process->fd){
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maxfd = new_process->fd;
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/* Free the plugin list */
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for(plugin *next; plugin_list != NULL; plugin_list = next){
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next = plugin_list->next;
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free(plugin_list->argv);
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if (process_list == NULL){
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fprintf(stderr, "No plugin processes started. Incorrect plugin"
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fd_set rfds = rfds_all;
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int select_ret = select(maxfd+1, &rfds, NULL, NULL, NULL);
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if (select_ret == -1){
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exitstatus = EXIT_FAILURE;
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/* OK, now either a process completed, or something can be read
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for(process *proc = process_list; proc ; proc = proc->next){
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/* Is this process completely done? */
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if(proc->eof and proc->completed){
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/* Only accept the plugin output if it exited cleanly */
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if(not WIFEXITED(proc->status)
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or WEXITSTATUS(proc->status) != 0){
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/* Bad exit by plugin */
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if(WIFEXITED(proc->status)){
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fprintf(stderr, "Plugin %u exited with status %d\n",
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(unsigned int) (proc->pid),
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WEXITSTATUS(proc->status));
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} else if(WIFSIGNALED(proc->status)) {
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fprintf(stderr, "Plugin %u killed by signal %d\n",
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(unsigned int) (proc->pid),
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WTERMSIG(proc->status));
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} else if(WCOREDUMP(proc->status)){
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fprintf(stderr, "Plugin %d dumped core\n",
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(unsigned int) (proc->pid));
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/* Remove the plugin */
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FD_CLR(proc->fd, &rfds_all);
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/* Block signal while modifying process_list */
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ret = sigprocmask (SIG_BLOCK, &sigchld_action.sa_mask, NULL);
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perror("sigprocmask");
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exitstatus = EXIT_FAILURE;
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/* Delete this process entry from the list */
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if(process_list == proc){
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/* First one - simple */
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process_list = proc->next;
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/* Second one or later */
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for(process *p = process_list; p != NULL; p = p->next){
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p->next = proc->next;
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/* We are done modifying process list, so unblock signal */
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ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask,
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perror("sigprocmask");
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/* We deleted this process from the list, so we can't go
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proc->next. Therefore, start over from the beginning of
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/* This process exited nicely, so print its buffer */
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bool bret = print_out_password(proc->buffer, proc->buffer_length);
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perror("print_out_password");
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exitstatus = EXIT_FAILURE;
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/* This process has not completed. Does it have any output? */
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if(proc->eof or not FD_ISSET(proc->fd, &rfds)){
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/* This process had nothing to say at this time */
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/* Before reading, make the process' data buffer large enough */
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if(proc->buffer_length + BUFFER_SIZE > proc->buffer_size){
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proc->buffer = realloc(proc->buffer, proc->buffer_size
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+ (size_t) BUFFER_SIZE);
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if (proc->buffer == NULL){
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exitstatus = EXIT_FAILURE;
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proc->buffer_size += BUFFER_SIZE;
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/* Read from the process */
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ret = read(proc->fd, proc->buffer + proc->buffer_length,
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/* Read error from this process; ignore the error */
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proc->buffer_length += (size_t) ret;
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if(process_list == NULL or exitstatus != EXIT_SUCCESS){
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/* Fallback if all plugins failed, none are found or an error occured */
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fprintf(stderr, "Going to fallback mode using getpass(3)\n");
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char *passwordbuffer = getpass("Password: ");
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bret = print_out_password(passwordbuffer, strlen(passwordbuffer));
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perror("print_out_password");
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exitstatus = EXIT_FAILURE;
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/* Restore old signal handler */
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sigaction(SIGCHLD, &old_sigchld_action, NULL);
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/* Free the plugin list */
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for(plugin *next; plugin_list != NULL; plugin_list = next){
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next = plugin_list->next;
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free(plugin_list->argv);
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/* Free the process list and kill the processes */
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for(process *next; process_list != NULL; process_list = next){
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next = process_list->next;
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close(process_list->fd);
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ret = kill(process_list->pid, SIGTERM);
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if(ret == -1 and errno != ESRCH){
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/* set-uid proccesses migth not get closed */
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free(process_list->buffer);
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/* Wait for any remaining child processes to terminate */