/**
* Copyright © 2015 Mattias Andrée <maandree@member.fsf.org>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#include "common.h"
#include "daemon.h"
#include "daemonise.h"
#include <unistd.h>
#include <errno.h>
#include <pwd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <sys/file.h>
/**
* The size of the backlog on the socket.
*/
#ifndef SATD_BACKLOG
# define SATD_BACKLOG 5
#endif
COMMAND("satd")
USAGE("[-f]")
/**
* Create the socket.
*
* @param address Output parameter for the socket address.
* @return The file descriptor for the socket, -1 on error.
*/
static int
create_socket(struct sockaddr_un *address)
{
int fd = -1, bound = 0;
const void *_cvoid;
const char *dir;
int saved_errno;
/* Get socket address. */
dir = getenv("XDG_RUNTIME_DIR"), dir = (dir ? dir : "/run");
if (strlen(dir) + sizeof("/satd.socket") > sizeof(address->sun_path))
t ((errno = ENAMETOOLONG));
stpcpy(stpcpy(address->sun_path, dir), "/satd.socket");
address->sun_family = AF_UNIX;
/* Check that no living process owns the socket. */
fd = open(address->sun_path, O_RDONLY);
if (fd == -1) {
t (errno != ENOENT);
goto does_not_exist;
} else if (flock(fd, LOCK_EX | LOCK_NB) == -1) {
t (errno != EWOULDBLOCK);
fprintf(stderr, "%s: the daemon's socket file is already in use.\n", argv0);
errno = 0;
goto fail;
}
/* Create socket. */
unlink(address->sun_path);
flock(fd, LOCK_UN);
close(fd), fd = -1;
does_not_exist:
t ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) == -1);
t (fchmod(fd, S_IRWXU) == -1);
t (bind(fd, (const struct sockaddr *)(_cvoid = address), (socklen_t)sizeof(*address)) == -1);
/* EADDRINUSE just means that the file already exists, not that it is actually used. */
bound = 1;
/* Mark the socket as owned by a living process. */
t (flock(fd, LOCK_SH));
return fd;
fail:
saved_errno = errno;
if (fd >= 0)
close(fd);
if (bound)
unlink(address->sun_path);
errno = saved_errno;
return -1;
}
/**
* Construct the pathname for the hook script.
*
* @param env The environment variable to use for the beginning
* of the pathname, `NULL` for the home directory.
* @param suffix The rest of the pathname.
* @return The pathname.
*
* @throws 0 The environment variable is not set, or, if `env` is
* `NULL` the user is root or homeless.
*/
static char *
hookpath(const char *env, const char *suffix)
{
const char *prefix = NULL;
char *path;
struct passwd *pwd;
if (!env) {
if (!getuid())
goto try_next;
pwd = getpwuid(getuid());
prefix = pwd ? pwd->pw_dir : NULL;
} else {
prefix = getenv(env);
}
if (!prefix || !*prefix)
goto try_next;
t (!(path = malloc((strlen(prefix) + strlen(suffix) + 1) * sizeof(char))));
stpcpy(stpcpy(path, prefix), suffix);
return path;
try_next:
errno = 0;
fail:
return NULL;
}
/**
* Duplicate a file descriptor, and
* open /dev/null to the old file descriptor.
* However, if `old` is 3 or greater, it will
* be closed rather than /dev/null.
*
* @param old The old file descriptor.
* @param new The new file descriptor.
* @return `new`, -1 on error.
*/
static int
dup2_and_null(int old, int new)
{
int want, fd = -1;
int saved_errno;
if (old == new) goto done;
t (dup2(old, new) == -1);
close(old), want = old;
if (want >= 3) goto done;
t (fd = open("/dev/null", O_RDWR), fd == -1);
if (fd == want) goto done;
t (dup2(fd, want) == -1);
close(fd), fd = -1;
done:
return new;
fail:
saved_errno = errno;
if (fd >= 0)
close(fd);
errno = saved_errno;
return -1;
}
/**
* The sat daemon initialisation.
*
* @param argc Any value in [0, 2] is accepted.
* @param argv The name of the process, and -f if the process
* shall not be daemonised.
* @return 0 The process was successful.
* @return 1 The process failed queuing the job.
* @return 2 User error, you do not know what you are doing.
*/
int
main(int argc, char *argv[])
{
struct sockaddr_un address;
int sock = -1, state = -1, foreground = 0;
char *path = NULL;
const char *dir;
/* Parse command line. */
if (argc > 0) argv0 = argv[0];
if (argc > 2) usage();
if (argc == 2)
if (!(foreground = !strcmp(argv[1], "-f")))
usage();
/* Get hook-script pathname. */
if (!getenv("SAT_HOOK_PATH")) {
t (path = hookpath("XDG_CONFIG_HOME", "/sat/hook"), !path && errno);
t (path = path ? path : hookpath("HOME", "/.config/sat/hook"), !path && errno);
t (path = path ? path : hookpath(NULL, "/.config/sat/hook"), !path && errno);
t (setenv("SAT_HOOK_PATH", path ? path : "/etc/sat/hook", 1));
free(path), path = NULL;
}
/* Open/create state file. */
dir = getenv("XDG_RUNTIME_DIR"), dir = (dir ? dir : "/run");
t (!(path = malloc(strlen(dir) * sizeof(char) + sizeof("/satd.state"))));
stpcpy(stpcpy(path, dir), "/satd.state");
t (state = open(path, O_RDWR | O_CREAT /* but not O_EXCL */, S_IRWXU), state == -1);
free(path), path = NULL;
/* The state fill shall be on fd STATE_FILENO. */
t (dup2_and_null(state, STATE_FILENO) == -1);
state = STATE_FILENO;
/* Create socket. */
t (sock = create_socket(&address), sock == -1);
/* Socket shall be on fd SOCK_FILENO. */
t (dup2_and_null(sock, SOCK_FILENO) == -1);
sock = SOCK_FILENO;
/* Listen for incoming conections. */
#if SOMAXCONN < SATD_BACKLOG
t (listen(sock, SOMAXCONN));
#else
t (listen(sock, SATD_BACKLOG));
#endif
/* Daemonise. */
t (foreground ? 0 : daemonise("satd", DAEMONISE_KEEP_FDS, sock, -1));
/* Change to a process image without all this initialisation text. */
execl(LIBEXECDIR "/" PACKAGE "/satd-diminished", argv0, address.sun_path, NULL);
fail:
if (errno)
perror(argv0);
free(path);
if (sock >= 0) {
unlink(address.sun_path);
close(sock);
}
if (state >= 0)
close(state);
undaemonise();
return 1;
}
