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* Plymouth - Read a password from Plymouth and output it
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* Copyright © 2010 Teddy Hogeborn
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* Copyright © 2010 Björn Påhlsson
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* Copyright © 2010-2017 Teddy Hogeborn
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* Copyright © 2010-2017 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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* 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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* Contact the authors at <mandos@recompile.se>.
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#define _GNU_SOURCE /* asprintf(), TEMP_FAILURE_RETRY() */
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#include <stddef.h> /* NULL */
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#include <string.h> /* strchr(), memcmp() */
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#include <stdio.h> /* asprintf(), perror(), fopen(),
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fscanf(), vasprintf(), fprintf(),
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#include <unistd.h> /* close(), readlink(), read(),
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fork(), setsid(), chdir(), dup2(),
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STDERR_FILENO, execv(), access() */
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#include <error.h> /* error() */
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#include <errno.h> /* TEMP_FAILURE_RETRY */
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#include <argz.h> /* argz_count(), argz_extract() */
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#include <stdarg.h> /* va_list, va_start(), ... */
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sig_atomic_t interrupted_by_signal = 0;
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const char plymouth_pid[] = "/dev/.initramfs/plymouth.pid";
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/* Used by Ubuntu 11.04 (Natty Narwahl) */
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const char plymouth_old_pid[] = "/dev/.initramfs/plymouth.pid";
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/* Used by Ubuntu 11.10 (Oneiric Ocelot) */
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const char plymouth_pid[] = "/run/initramfs/plymouth.pid";
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const char plymouth_path[] = "/bin/plymouth";
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const char plymouthd_path[] = "/sbin/plymouthd";
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const char *plymouthd_default_argv[] = {"/sbin/plymouthd",
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"--attach-to-session",
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static void termination_handler(__attribute__((unused))int signum){
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interrupted_by_signal = 1;
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/* Function to use when printing errors */
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__attribute__((format (gnu_printf, 3, 4)))
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void error_plus(int status, int errnum, const char *formatstring,
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va_start(ap, formatstring);
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ret = vasprintf(&text, formatstring, ap);
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fprintf(stderr, "Mandos plugin %s: ",
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program_invocation_short_name);
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vfprintf(stderr, formatstring, ap);
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fprintf(stderr, ": ");
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fprintf(stderr, "%s\n", strerror(errnum));
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error(status, errno, "vasprintf while printing error");
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fprintf(stderr, "Mandos plugin ");
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error(status, errnum, "%s", text);
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/* Create prompt string */
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char *makeprompt(void){
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bool become_a_daemon(void){
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int ret = setuid(geteuid());
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error(0, errno, "setuid");
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error_plus(0, errno, "setuid");
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ret = chdir("/");
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error(0, errno, "chdir");
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error_plus(0, errno, "chdir");
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ret = dup2(STDERR_FILENO, STDOUT_FILENO); /* replace our stdout */
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error(0, errno, "dup2");
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error_plus(0, errno, "dup2");
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__attribute__((nonnull (2, 3)))
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bool exec_and_wait(pid_t *pid_return, const char *path,
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const char **argv, bool interruptable,
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const char * const *argv, bool interruptable,
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error(0, errno, "fork");
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error_plus(0, errno, "fork");
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char **new_argv = NULL;
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char **new_argv = malloc(sizeof(const char *));
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if(new_argv == NULL){
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error_plus(0, errno, "malloc");
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for (; argv[i]!=NULL; i++){
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tmp = realloc(new_argv, sizeof(const char *) * ((size_t)i + 1));
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error(0, errno, "realloc");
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for (; argv[i] != NULL; i++){
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tmp = realloc(new_argv, sizeof(const char *) * ((size_t)i + 2));
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error_plus(0, errno, "realloc");
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new_argv[i] = NULL;
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execv(path, (char *const *)new_argv);
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error(0, errno, "execv");
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error_plus(0, errno, "execv");
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_exit(EXIT_FAILURE);
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if(pid_return != NULL){
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error(0, errno, "waitpid");
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error_plus(0, errno, "waitpid");
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if(WIFEXITED(status) and (WEXITSTATUS(status) == 0)){
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__attribute__((nonnull))
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int is_plymouth(const struct dirent *proc_entry){
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maxvalue = strtoumax(proc_entry->d_name, &tmp, 10);
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proc_id = strtoumax(proc_entry->d_name, &tmp, 10);
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if(errno != 0 or *tmp != '\0'
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or maxvalue != (uintmax_t)((pid_t)maxvalue)){
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or proc_id != (uintmax_t)((pid_t)proc_id)){
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char exe_target[sizeof(plymouth_path)];
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char exe_target[sizeof(plymouthd_path)];
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ret = asprintf(&exe_link, "/proc/%s/exe", proc_entry->d_name);
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error(0, errno, "asprintf");
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error_plus(0, errno, "asprintf");
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ssize_t sret = readlink(exe_link, exe_target, sizeof(exe_target));
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if((sret != (ssize_t)sizeof(plymouth_path)-1) or
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(memcmp(plymouth_path, exe_target,
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sizeof(plymouth_path)-1) != 0)){
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if((sret != (ssize_t)sizeof(plymouthd_path)-1) or
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(memcmp(plymouthd_path, exe_target,
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sizeof(plymouthd_path)-1) != 0)){
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pid_t get_pid(void){
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uintmax_t proc_id = 0;
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FILE *pidfile = fopen(plymouth_pid, "r");
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uintmax_t maxvalue = 0;
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/* Try the new pid file location */
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if(pidfile != NULL){
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ret = fscanf(pidfile, "%" SCNuMAX, &maxvalue);
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ret = fscanf(pidfile, "%" SCNuMAX, &proc_id);
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struct dirent **direntries;
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/* Try the old pid file location */
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pidfile = fopen(plymouth_pid, "r");
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ret = fscanf(pidfile, "%" SCNuMAX, &proc_id);
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/* Look for a plymouth process */
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struct dirent **direntries = NULL;
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ret = scandir("/proc", &direntries, is_plymouth, alphasort);
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sscanf(direntries[0]->d_name, "%" SCNuMAX, &maxvalue);
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error_plus(0, errno, "scandir");
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ret = sscanf(direntries[0]->d_name, "%" SCNuMAX, &proc_id);
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error_plus(0, errno, "sscanf");
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/* scandir might preallocate for this variable (man page unclear).
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even if ret == 0, therefore we need to free it. */
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pid = (pid_t)maxvalue;
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if((uintmax_t)pid == maxvalue){
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pid = (pid_t)proc_id;
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if((uintmax_t)pid == proc_id){
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const char **getargv(pid_t pid){
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const char * const * getargv(pid_t pid){
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char *cmdline_filename;
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ret = asprintf(&cmdline_filename, "/proc/%" PRIuMAX "/cmdline",
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error(0, errno, "asprintf");
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error_plus(0, errno, "asprintf");
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if(cmdline_len + blocksize > cmdline_allocated){
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tmp = realloc(cmdline, cmdline_allocated + blocksize);
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error(0, errno, "realloc");
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error_plus(0, errno, "realloc");
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sret = read(cl_fd, cmdline + cmdline_len,
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cmdline_allocated - cmdline_len);
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error(0, errno, "read");
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error_plus(0, errno, "read");
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char **argv = malloc((argz_count(cmdline, cmdline_len) + 1)
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* sizeof(char *)); /* Get number of args */
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if(argv == NULL){
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error(0, errno, "argv = malloc()");
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error_plus(0, errno, "argv = malloc()");
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argz_extract(cmdline, cmdline_len, argv); /* Create argv */
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return (const char **)argv;
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return (const char * const *)argv;
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int main(__attribute__((unused))int argc,
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*sig != 0; sig++){
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ret = sigaddset(&new_action.sa_mask, *sig);
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error(EX_OSERR, errno, "sigaddset");
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error_plus(EX_OSERR, errno, "sigaddset");
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ret = sigaction(*sig, NULL, &old_action);
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error(EX_OSERR, errno, "sigaction");
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error_plus(EX_OSERR, errno, "sigaction");
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if(old_action.sa_handler != SIG_IGN){
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ret = sigaction(*sig, &new_action, NULL);
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error(EX_OSERR, errno, "sigaction");
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error_plus(EX_OSERR, errno, "sigaction");
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ret = asprintf(&prompt_arg, "--prompt=%s", prompt);
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error(EX_OSERR, errno, "asprintf");
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error_plus(EX_OSERR, errno, "asprintf");
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/* plymouth ask-for-password --prompt="$prompt" */
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kill_and_wait(plymouth_command_pid);
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const char **plymouthd_argv;
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const char * const *plymouthd_argv;
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pid_t pid = get_pid();
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error(0, 0, "plymouthd pid not found");
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error_plus(0, 0, "plymouthd pid not found");
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plymouthd_argv = plymouthd_default_argv;
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plymouthd_argv = getargv(pid);