/**
* mds — A micro-display server
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mds-server.h"
#include "config.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <limits.h>
#include <unistd.h>
#include <pwd.h>
#include <errno.h>
#include <pthread.h>
#include <sys/socket.h>
/**
* Number of elements in `argv`
*/
static int argc;
/**
* Command line arguments
*/
static char** argv;
/**
* The program run state, 1 when running,
* 0 when shutting down
*/
static volatile int running = 1;
/**
* The number of running slaves
*/
static int running_slaves = 0;
/**
* Mutex for slave counter
*/
static pthread_mutex_t slave_mutex;
/**
* Condition for slave counter
*/
static pthread_cond_t slave_cond;
/* TODO make the server update without all slaves dying on SIGUSR1 */
/**
* Entry point of the server
*
* @param argc_ Number of elements in `argv_`
* @param argv_ Command line arguments
* @return Non-zero on error
*/
int main(int argc_, char** argv_)
{
int is_respawn = -1;
int socket_fd = -1;
int unparsed_args_ptr = 1;
char* unparsed_args[ARGC_LIMIT + LIBEXEC_ARGC_EXTRA_LIMIT + 1];
int i;
pid_t pid;
pthread_t _slave_thread;
argc = argc_;
argv = argv_;
/* Drop privileges like it's hot. */
if ((geteuid() == getuid() ? 0 : seteuid(getuid())) ||
(getegid() == getgid() ? 0 : setegid(getgid())))
{
perror(*argv);
return 1;
}
/* Sanity check the number of command line arguments. */
if (argc > ARGC_LIMIT + LIBEXEC_ARGC_EXTRA_LIMIT)
{
fprintf(stderr,
"%s: that number of arguments is ridiculous, I will not allow it.\n",
*argv);
return 1;
}
/* Parse command line arguments. */
for (i = 1; i < argc; i++)
{
char* arg = argv[i];
if (!strcmp(arg, "--initial-spawn")) /* Initial spawn? */
if (is_respawn == 1)
{
fprintf(stderr,
"%s: conflicting arguments %s and %s cannot be combined.\n",
*argv, "--initial-spawn", "--respawn");
return 1;
}
else
is_respawn = 0;
else if (!strcmp(arg, "--respawn")) /* Respawning after crash? */
if (is_respawn == 0)
{
fprintf(stderr,
"%s: conflicting arguments %s and %s cannot be combined.\n",
*argv, "--initial-spawn", "--respawn");
return 1;
}
else
is_respawn = 1;
else if (strstr(arg, "--socket-fd=") == arg) /* Socket file descriptor. */
{
long int r;
char* endptr;
if (socket_fd != -1)
{
fprintf(stderr, "%s: duplicate declaration of %s.\n", *argv, "--socket-fd");
return -1;
}
arg += strlen("--socket-fd=");
r = strtol(arg, &endptr, 10);
if ((*argv == '\0') || isspace(*argv) ||
(endptr - arg != (ssize_t)strlen(arg))
|| (r < 0) || (r > INT_MAX))
{
fprintf(stderr, "%s: invalid value for %s: %s.\n", *argv, "--socket-fd", arg);
return 1;
}
socket_fd = (int)r;
}
else
/* Not recognised, it is probably for another server. */
unparsed_args[unparsed_args_ptr++] = arg;
}
unparsed_args[unparsed_args_ptr] = NULL;
/* Check that manditory arguments have been specified. */
if (is_respawn < 0)
{
fprintf(stderr,
"%s: missing state argument, require either %s or %s.\n",
*argv, "--initial-spawn", "--respawn");
return 1;
}
if (socket_fd < 0)
{
fprintf(stderr, "%s: missing socket file descriptor argument.\n", *argv);
return 1;
}
if (is_respawn == 0)
{
/* Run mdsinitrc. */
pid = fork();
if (pid == (pid_t)-1)
{
perror(*argv);
return 1;
}
if (pid == 0) /* Child process exec:s, the parent continues without waiting for it. */
{
run_initrc(unparsed_args);
return 1;
}
}
/* Create mutex and condition for slave counter. */
pthread_mutex_init(&slave_mutex, NULL);
pthread_cond_init(&slave_cond, NULL);
/* Accepting incoming connections. */
while (running)
{
/* Accept connection. */
int client_fd = accept(socket_fd, NULL, NULL);
/* Handle errors and shutdown. */
if (client_fd == -1)
{
switch (errno)
{
case EINTR:
/* Interrupted. */
break;
case ECONNABORTED:
case EINVAL:
/* Closing. */
running = 0;
break;
default:
/* Error. */
perror(*argv);
break;
}
continue;
}
/* Increase number of running slaves. */
pthread_mutex_lock(&slave_mutex);
running_slaves++;
pthread_mutex_unlock(&slave_mutex);
/* Start slave thread. */
errno = pthread_create(&_slave_thread, NULL, slave_loop, (void*)(intptr_t)client_fd);
if (errno)
{
perror(*argv);
pthread_mutex_lock(&slave_mutex);
running_slaves--;
pthread_mutex_unlock(&slave_mutex);
}
}
/* Wait for all slaves to close. */
pthread_mutex_lock(&slave_mutex);
while (running_slaves > 0)
pthread_cond_wait(&slave_cond, &slave_mutex);
pthread_mutex_unlock(&slave_mutex);
return 0;
}
/**
* Master function for slave threads
*
* @param data Input data
* @return Outout data
*/
void* slave_loop(void* data)
{
int socket_fd = (int)(intptr_t)data;
/* TODO */
/* Close socket. */
close(socket_fd);
/* Decrease the slave count. */
pthread_mutex_lock(&slave_mutex);
running_slaves--;
pthread_cond_signal(&slave_cond);
pthread_mutex_unlock(&slave_mutex);
return NULL;
}
/**
* Read an environment variable, but handle it as undefined if empty
*
* @param var The environment variable's name
* @return The environment variable's value, `NULL` if empty or not defined
*/
char* getenv_nonempty(const char* var)
{
char* rc = getenv(var);
if ((rc == NULL) || (*rc == '\0'))
return NULL;
return rc;
}
/**
* Exec into the mdsinitrc script
*
* @param args The arguments to the child process
*/
void run_initrc(char** args)
{
char pathname[PATH_MAX];
struct passwd* pwd;
char* env;
char* home;
args[0] = pathname;
/* Test $XDG_CONFIG_HOME. */
if ((env = getenv_nonempty("XDG_CONFIG_HOME")) != NULL)
{
snprintf(pathname, sizeof(pathname) / sizeof(char), "%s/.%s", env, INITRC_FILE);
execv(args[0], args);
}
/* Test $HOME. */
if ((env = getenv_nonempty("HOME")) != NULL)
{
snprintf(pathname, sizeof(pathname) / sizeof(char), "%s/.config/%s", env, INITRC_FILE);
execv(args[0], args);
snprintf(pathname, sizeof(pathname) / sizeof(char), "%s/.%s", env, INITRC_FILE);
execv(args[0], args);
}
/* Test ~. */
pwd = getpwuid(getuid()); /* Ignore error. */
if (pwd != NULL)
{
home = pwd->pw_dir;
if ((home != NULL) && (*home != '\0'))
{
snprintf(pathname, sizeof(pathname) / sizeof(char), "%s/.config/%s", home, INITRC_FILE);
execv(args[0], args);
snprintf(pathname, sizeof(pathname) / sizeof(char), "%s/.%s", home, INITRC_FILE);
execv(args[0], args);
}
}
/* Test $XDG_CONFIG_DIRS. */
if ((env = getenv_nonempty("XDG_CONFIG_DIRS")) != NULL)
{
char* begin = env;
char* end;
int len;
for (;;)
{
end = strchrnul(begin, ':');
len = (int)(end - begin);
if (len > 0)
{
snprintf(pathname, sizeof(pathname) / sizeof(char), "%.*s/%s", len, begin, INITRC_FILE);
execv(args[0], args);
}
if (*end == '\0')
break;
begin = end + 1;
}
}
/* Test /etc. */
snprintf(pathname, sizeof(pathname) / sizeof(char), "%s/%s", SYSCONFDIR, INITRC_FILE);
execv(args[0], args);
/* Everything failed. */
fprintf(stderr, "%s: unable to run %s file, you might as well kill me.\n", *argv, INITRC_FILE);
}
