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* Contact the authors at <mandos@fukt.bsnet.se>.
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#define _GNU_SOURCE /* TEMP_FAILURE_RETRY(), getline() */
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#define _GNU_SOURCE /* TEMP_FAILURE_RETRY(), getline(),
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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 <fcntl.h> /* fcntl(), F_GETFD, F_SETFD,
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#include <string.h> /* strsep, strlen(), strcpy(),
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#include <string.h> /* strsep, strlen(), asprintf() */
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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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ARGP_KEY_END, ARGP_KEY_ARG,
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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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/* 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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char *copy_name = NULL;
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copy_name = strdup(name);
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if(copy_name == NULL){
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*new_plugin = (plugin) { .name = copy_name,
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.next = *plugin_list };
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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[0] = copy_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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new_plugin->environ = malloc(sizeof(char *));
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if(new_plugin->environ == NULL){
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free(new_plugin->argv);
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new_plugin->environ[0] = NULL;
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/* Append the new plugin to the list */
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*plugin_list = new_plugin;
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return 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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/* Helper function for add_argument and add_environment */
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static bool add_to_char_array(const char *new, char ***array,
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/* Resize the pointed-to array to hold one more pointer */
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*array = realloc(*array, sizeof(char *)
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* (size_t) ((*len) + 2));
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/* Make a copy of the new string */
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char *copy = strdup(new);
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/* Insert the copy */
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(*array)[*len] = copy;
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/* Add a new terminating NULL pointer to the last element */
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(*array)[*len] = NULL;
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/* Add to a plugin's argument vector */
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static bool add_argument(plugin *p, const char *arg){
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return add_to_char_array(arg, &(p->argv), &(p->argc));
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/* Add to a plugin's environment */
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static bool add_environment(plugin *p, const char *def){
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return add_to_char_array(def, &(p->environ), &(p->envc));
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* Based on the example in the GNU LibC manual chapter 13.13 "File
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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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/* Mark processes as completed when they exit, and save their 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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process *proc = process_list;
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pid_t pid = waitpid(-1, &status, WNOHANG);
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/* Only still running child processes */
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if (errno != ECHILD){
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/* No child processes */
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/* A child exited, find it in process_list */
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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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char ** addcustomargument(char **argv, int *argc, char *arg){
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char **add_to_argv(char **argv, int *argc, char *arg){
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if (argv == NULL){
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argv = malloc(sizeof(char*) * 2);
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if(argv == NULL){
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argv[0] = NULL; /* Will be set to argv[0] in main before parsing */
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argv[0] = NULL; /* Will be set to argv[0] in main before
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argv[*argc-1] = arg;
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static void free_plugin_list(plugin *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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for(char **arg = plugin_list->argv; *arg != NULL; arg++){
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free(plugin_list->argv);
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for(char **env = plugin_list->environ; *env != NULL; env++){
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free(plugin_list->environ);
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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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const char *argfile = ARGFILE;
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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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perror("sigaddset");
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exitstatus = EXIT_FAILURE;
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ret = sigaction(SIGCHLD, &sigchld_action, &old_sigchld_action);
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perror("sigaction");
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exitstatus = EXIT_FAILURE;
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/* The options we understand. */
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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 = "global-envs", .key = 'e',
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.doc = "Environment variable 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 = "envs-for", .key = 'f',
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.arg = "PLUGIN:ENV=value",
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.doc = "Environment variable passed 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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if(p[0] == '\0'){
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addargument(getplugin(NULL, plugins), p);
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if(not add_argument(getplugin(NULL, plugins), p)){
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perror("add_argument");
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return ARGP_ERR_UNKNOWN;
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char *envdef = strdup(arg);
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if(not add_environment(getplugin(NULL, plugins), envdef)){
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perror("add_environment");
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if (arg != NULL){
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char *name = strsep(&arg, ":");
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char *p_name = strsep(&arg, ":");
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if(p_name[0] == '\0'){
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char *opt = strsep(&arg, ":");
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if(p[0] == '\0'){
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addargument(getplugin(name, plugins), p);
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if(not add_argument(getplugin(p_name, plugins), p)){
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perror("add_argument");
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return ARGP_ERR_UNKNOWN;
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char *envdef = strchr(arg, ':');
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char *p_name = strndup(arg, (size_t) (envdef-arg));
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if(not add_environment(getplugin(p_name, plugins), envdef)){
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perror("add_environment");
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if (arg != NULL){
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getplugin(arg, plugins)->disabled = true;
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plugin *p = getplugin(arg, plugins);
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return ARGP_ERR_UNKNOWN;
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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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conffp = fopen(argfile, "r");
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if(conffp != NULL){
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char *org_line = NULL;
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char *p, *arg, *new_arg, *line;
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char *p, *arg, *new_arg, *line;
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const char whitespace_delims[] = " \r\t\f\v\n";
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const char comment_delim[] = "#";
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new_arg = strdup(p);
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custom_argv = addcustomargument(custom_argv, &custom_argc, new_arg);
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custom_argv = add_to_argv(custom_argv, &custom_argc, new_arg);
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if (custom_argv == NULL){
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perror("addcustomargument");
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perror("add_to_argv");
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exitstatus = EXIT_FAILURE;
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if (errno == EMFILE or errno == ENFILE or errno == ENOMEM){
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exitstatus = EXIT_FAILURE;
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if(custom_argv != NULL){
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custom_argv[0] = argv[0];
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ret = argp_parse (&argp, custom_argc, custom_argv, 0, 0, &plugin_list);
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ret = argp_parse (&argp, custom_argc, custom_argv, 0, 0,
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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(char **a = p->argv; *a != NULL; a++){
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fprintf(stderr, "\tArg: %s\n", *a);
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fprintf(stderr, "...and %u environment variables\n", p->envc);
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for(char **a = p->environ; *a != NULL; a++){
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fprintf(stderr, "\t%s\n", *a);
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char *filename = malloc(d_name_len + strlen(plugindir) + 2);
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if (filename == NULL){
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ret = asprintf(&filename, "%s/%s", plugindir, dirst->d_name);
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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(getplugin(dirst->d_name, &plugin_list)->disabled){
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plugin *p = getplugin(dirst->d_name, &plugin_list);
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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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for(char **a = g->argv + 1; *a != NULL; a++){
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if(not add_argument(p, *a)){
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perror("add_argument");
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/* Add global environment variables */
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for(char **e = g->environ; *e != NULL; e++){
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if(not add_environment(p, *e)){
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perror("add_environment");
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/* If this plugin has any environment variables, we will call
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using execve and need to duplicate the environment from this
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if(p->environ[0] != NULL){
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for(char **e = environ; *e != NULL; e++){
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char *copy = strdup(*e);
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if(not add_environment(p, copy)){
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perror("add_environment");
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ret = pipe(pipefd);
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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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pid_t pid = fork();
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exitstatus = EXIT_FAILURE;
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/* this is the child process */
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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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if(p->environ[0] == NULL){
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if(execv(filename, p->argv) < 0){
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if(execve(filename, p->argv, p->environ) < 0){
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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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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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/* 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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bool bret = print_out_password(proc->buffer,
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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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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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/* Fallback if all plugins failed, none are found or an error
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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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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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ret = sigaction(SIGCHLD, &old_sigchld_action, NULL);
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exitstatus = EXIT_FAILURE;
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if(custom_argv != NULL){
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for(char **arg = custom_argv; *arg != NULL; arg++){
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free_plugin_list(plugin_list);