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* Plymouth - Read a password from Plymouth and output it
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* Copyright © 2010-2020 Teddy Hogeborn
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* Copyright © 2010-2020 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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* Copyright © 2010-2011 Teddy Hogeborn
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* Copyright © 2010-2011 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 Mandos. If not, see <http://www.gnu.org/licenses/>.
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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@recompile.se>.
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* Contact the authors at <mandos@fukt.bsnet.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 <stdlib.h> /* free(), EXIT_FAILURE, realloc(),
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EXIT_SUCCESS, malloc(), _exit(),
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getenv(), reallocarray() */
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#include <dirent.h> /* scandir(), alphasort() */
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#include <inttypes.h> /* intmax_t, strtoumax(), SCNuMAX */
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#include <sys/stat.h> /* struct stat, lstat() */
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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 *argp_program_version = "plymouth " VERSION;
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const char *argp_program_bug_address = "<mandos@recompile.se>";
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/* Used by Ubuntu 11.04 (Natty Narwahl) */
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const char plymouth_old_old_pid[] = "/dev/.initramfs/plymouth.pid";
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/* Used by Ubuntu 11.10 (Oneiric Ocelot) */
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const char plymouth_old_pid[] = "/run/initramfs/plymouth.pid";
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/* Used by Debian 9 (stretch) */
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const char plymouth_pid[] = "/run/plymouth/pid";
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const char plymouth_pid[] = "/dev/.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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if(interrupted_by_signal){
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interrupted_by_signal = 1;
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__attribute__((format (gnu_printf, 2, 3), nonnull))
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int fprintf_plus(FILE *stream, const char *format, ...){
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va_start (ap, format);
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fprintf(stream, "Mandos plugin %s: ", program_invocation_short_name);
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return vfprintf(stream, format, ap);
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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_plus(0, errno, "setuid");
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error(0, errno, "setuid");
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ret = chdir("/");
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error_plus(0, errno, "chdir");
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error(0, errno, "chdir");
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ret = dup2(STDERR_FILENO, STDOUT_FILENO); /* replace our stdout */
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error_plus(0, errno, "dup2");
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error(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 * const * const argv, bool interruptable,
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const char **argv, bool interruptable,
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for(const char * const *arg = argv; *arg != NULL; arg++){
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fprintf_plus(stderr, "exec_and_wait arg: %s\n", *arg);
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fprintf_plus(stderr, "exec_and_wait end of args\n");
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error_plus(0, errno, "fork");
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error(0, errno, "fork");
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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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char **new_argv = NULL;
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for (; argv[i] != NULL; i++){
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#if defined(__GLIBC_PREREQ) and __GLIBC_PREREQ(2, 26)
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tmp = reallocarray(new_argv, ((size_t)i + 2),
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sizeof(const char *));
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if(((size_t)i + 2) > (SIZE_MAX / sizeof(const char *))){
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tmp = realloc(new_argv, ((size_t)i + 2) * sizeof(const char *));
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error_plus(0, errno, "reallocarray");
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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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new_argv[i] = NULL;
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execv(path, (char *const *)new_argv);
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error_plus(0, errno, "execv");
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error(0, errno, "execv");
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_exit(EXIT_FAILURE);
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if(pid_return != NULL){
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and ((not interrupted_by_signal)
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or (not interruptable)));
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if(interrupted_by_signal and interruptable){
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fprintf_plus(stderr, "Interrupted by signal\n");
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error_plus(0, errno, "waitpid");
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error(0, errno, "waitpid");
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if(WIFEXITED(status)){
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fprintf_plus(stderr, "exec_and_wait exited: %d\n",
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WEXITSTATUS(status));
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} else if(WIFSIGNALED(status)) {
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fprintf_plus(stderr, "exec_and_wait signaled: %d\n",
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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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proc_id = strtoumax(proc_entry->d_name, &tmp, 10);
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maxvalue = strtoumax(proc_entry->d_name, &tmp, 10);
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if(errno != 0 or *tmp != '\0'
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or proc_id != (uintmax_t)((pid_t)proc_id)){
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or maxvalue != (uintmax_t)((pid_t)maxvalue)){
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ret = asprintf(&exe_link, "/proc/%s/exe", proc_entry->d_name);
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error_plus(0, errno, "asprintf");
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error(0, errno, "asprintf");
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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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/* Try the new pid file location */
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uintmax_t maxvalue = 0;
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if(pidfile != NULL){
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ret = fscanf(pidfile, "%" SCNuMAX, &proc_id);
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ret = fscanf(pidfile, "%" SCNuMAX, &maxvalue);
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/* Try the old pid file location */
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pidfile = fopen(plymouth_old_pid, "r");
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ret = fscanf(pidfile, "%" SCNuMAX, &proc_id);
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/* Try the old old pid file location */
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pidfile = fopen(plymouth_old_old_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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struct dirent **direntries;
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ret = scandir("/proc", &direntries, is_plymouth, alphasort);
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error_plus(0, errno, "scandir");
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error(0, errno, "scandir");
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for(int i = ret-1; i >= 0; i--){
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ret = sscanf(direntries[i]->d_name, "%" SCNuMAX, &proc_id);
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error_plus(0, errno, "sscanf");
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ret = sscanf(direntries[0]->d_name, "%" SCNuMAX, &maxvalue);
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error(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)proc_id;
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if((uintmax_t)pid == proc_id){
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pid = (pid_t)maxvalue;
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if((uintmax_t)pid == maxvalue){
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char **getargv(pid_t pid){
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const char **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_plus(0, errno, "asprintf");
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error(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_plus(0, errno, "realloc");
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error(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_plus(0, errno, "read");
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error(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_plus(0, errno, "argv = malloc()");
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error(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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int main(__attribute__((unused))int argc,
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__attribute__((unused))char **argv){
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char *prompt_arg;
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pid_t plymouth_command_pid;
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struct argp_option options[] = {
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{ .name = "prompt", .key = 128, .arg = "PROMPT",
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.doc = "The prompt to show" },
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{ .name = "debug", .key = 129,
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.doc = "Debug mode" },
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__attribute__((nonnull(3)))
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error_t parse_opt (int key, char *arg, __attribute__((unused))
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struct argp_state *state){
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case 128: /* --prompt */
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fprintf_plus(stderr, "Custom prompt \"%s\"\n", prompt);
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case 129: /* --debug */
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return ARGP_ERR_UNKNOWN;
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struct argp argp = { .options = options, .parser = parse_opt,
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.doc = "Mandos plymouth -- Read and"
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" output a password" };
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ret = argp_parse(&argp, argc, argv, ARGP_IN_ORDER, NULL, NULL);
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error_plus(0, errno, "argp_parse");
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error_plus(0, errno, "argp_parse");
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/* test -x /bin/plymouth */
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ret = access(plymouth_path, X_OK);
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/* Plymouth is probably not installed. Don't print an error
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message, just exit. */
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fprintf_plus(stderr, "Plymouth (%s) not found\n",
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exit(EX_UNAVAILABLE);
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361
*sig != 0; sig++){
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ret = sigaddset(&new_action.sa_mask, *sig);
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error_plus(EX_OSERR, errno, "sigaddset");
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error(EX_OSERR, errno, "sigaddset");
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ret = sigaction(*sig, NULL, &old_action);
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error_plus(EX_OSERR, errno, "sigaction");
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error(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_plus(EX_OSERR, errno, "sigaction");
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error(EX_OSERR, errno, "sigaction");
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/* Plymouth is probably not running. Don't print an error
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message, just exit. */
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fprintf_plus(stderr, "Plymouth not running\n");
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exit(EX_UNAVAILABLE);
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ret = asprintf(&prompt_arg, "--prompt=%s", prompt);
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char *made_prompt = makeprompt();
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ret = asprintf(&prompt_arg, "--prompt=%s", made_prompt);
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prompt = makeprompt();
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ret = asprintf(&prompt_arg, "--prompt=%s", prompt);
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error_plus(EX_OSERR, errno, "asprintf");
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error(EX_OSERR, errno, "asprintf");
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/* plymouth ask-for-password --prompt="$prompt" */
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fprintf_plus(stderr, "Prompting for password via Plymouth\n");
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bret = exec_and_wait(&plymouth_command_pid,
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plymouth_path, (const char *[])
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{ plymouth_path, "ask-for-password",
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kill_and_wait(plymouth_command_pid);
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char **plymouthd_argv = NULL;
417
const char **plymouthd_argv;
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pid_t pid = get_pid();
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error_plus(0, 0, "plymouthd pid not found");
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error(0, 0, "plymouthd pid not found");
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plymouthd_argv = plymouthd_default_argv;
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plymouthd_argv = getargv(pid);
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{ plymouth_path, "quit", NULL },
602
if(plymouthd_argv != NULL){
603
free(*plymouthd_argv);
604
free(plymouthd_argv);
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430
exit(EXIT_FAILURE);
608
bret = exec_and_wait(NULL, plymouthd_path,
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(plymouthd_argv != NULL)
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? (const char * const *)plymouthd_argv
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: plymouthd_default_argv,
432
bret = exec_and_wait(NULL, plymouthd_path, plymouthd_argv,
613
if(plymouthd_argv != NULL){
614
free(*plymouthd_argv);
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free(plymouthd_argv);
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exit(EXIT_FAILURE);
added
removed
plugins.d/plymouth.c
