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Commit 7b1212f6 authored by Niels Möller's avatar Niels Möller
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(daemon_pidfile): Deleted #if:ed out file locking 

code.
(daemon_started_by_init, daemon_started_by_inetd): Made static.
(daemon_detect): New function, split out from daemon_init.
(daemon_dup_null): Likewise.
(getdtablesize): New function, for systems that don't have it in
libc.
(daemon_close_fds): New function.
(daemon_init): New argument with the daemon mode. Split handling
of fd:s to the new functions daemon_dup_null and daemon_close_fds.

Rev: src/daemon.c:1.14
parent 9fe21f61
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Showing with 119 additions and 276 deletions
src/daemon.c
View file @ 7b1212f6
...@@ -67,22 +67,10 @@ ...@@ -67,22 +67,10 @@
#define PID_SUFFIX ".pid" #define PID_SUFFIX ".pid"
#endif #endif
/* /* Creates a pid file for a daemon. For now, only O_EXCL style
** struct lsh_string *daemon_pidfile(const char *name) locking. Returns 1 on success or 0 on failure. */
** int
** Creates a pid file for a daemon and locks it. daemon_pidfile(const char *name)
** The file has one line containing the process id of the daemon.
** The well-known location for the file is defined in PID_DIR
** ("/var/run" by default). The name of the file is the name of
** the daemon (given by the name argument) followed by ".pid".
**
** Returns 1 on success or 0 on failure (with errno set
** appropriately). Reasons for failure are: ENAMETOOLONG If the pid
** file's path is longer than the system path limit. open(2).
** fcntl(2). write(2). */
int daemon_pidfile(const char *name)
{ {
int fd; int fd;
...@@ -100,90 +88,9 @@ int daemon_pidfile(const char *name) ...@@ -100,90 +88,9 @@ int daemon_pidfile(const char *name)
return 0; return 0;
} }
/* FIXME: We could try to detect and ignore stale pid files. */
werror("Pid file '%z' already exists.\n", name); werror("Pid file '%z' already exists.\n", name);
return 0; return 0;
/* FIXME: Various trickery to detect and ignore stale pid files.
* Disabled for now. */
#if 0
/* Attempt to lock and read the file */
{
struct flock lock;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
int fd = open(name, O_RDWR);
if (fcntl(fd, F_SETLK, &lock) < 0)
{
werror("pid file '%z' exists and is locked.\n");
return 0;
}
}
fd = open(name, O_RDONLY);
if (fd < 0)
{
werror("Pid file '%z' already exists, and is unreadable %e\n",
name, errno);
return 0;
}
{
/* Read some characters */
#define BUF_SIZE 20
char buffer[BUF_SIZE];
int length = read(fd, buffer, BUF_SIZE);
close(fd);
if (length < 0)
{
werror("Pid file '%z' already exists, but read failed %e\n",
name, errno);
return 0;
}
if ( !length|| !buffer[0] || (length == BUF_SIZE) )
{
werror("Pid file '%z' already exists, but contents is garbled.\n",
name);
return 0;
}
buffer[length] = '\0';
{
long other;
char *end;
/* FIXME: strtol is somewhat inconvenient, too forgiving,
* and possibly locale dependent. */
other = strtol(buffer, &end, 10);
errno = 0;
if ( (errno == ERANGE) || (end != buffer + length)
|| (other <= 0) || (other != (pid_t) other))
{
werror("Pid file '%z' already exists, but contents is garbled.\n",
name);
return 0;
}
if ( (kill((pid_t) other, 0) < 0)
&& (errno == SRCH))
{
werror("pid lock '%z' owned by process %i, which appear to be dead.\n",
name, other);
/* We could try to be clever and delete the file in this
* case, but then we get into race conditions if two
* processes tries to do that simultaneously. */
}
else
werror("pid lock '%z' owned by process %i, which appears to be alive.\n");
return 0;
}
}
#endif
} }
else else
{ {
...@@ -211,32 +118,23 @@ int daemon_pidfile(const char *name) ...@@ -211,32 +118,23 @@ int daemon_pidfile(const char *name)
} }
} }
/* /* Determines whether or not this process was started by init(8). If
** int daemon_started_by_init(void) it was, we might be getting respawned so fork(2) and exit(2) would
** be a big mistake. */
** Determines whether or not this process was started by init(8). static int
** If it was, we might be getting respawned so fork(2) and exit(2) daemon_started_by_init(void)
** would be a big mistake.
*/
int daemon_started_by_init(void)
{ {
return (getppid() == 1); return (getppid() == 1);
} }
/* /* Determines whether or not this process was started by inetd(8). If
** int daemon_started_by_inetd(void) it was, stdin, stdout and stderr would be opened to a socket.
** Closing stdin and stdout. We also wouldn't need to fork(2) and
** Determines whether or not this process was started by inetd(8). exec(2) because there isn't a controlling terminal in sight. */
** If it was, stdin, stdout and stderr would be opened to a socket.
** Closing them would be a big mistake. We also wouldn't need to
** fork(2) and exec(2) because there isn't a controlling terminal
** in sight.
*/
/* FIXME: Do we need to detect if the socket is listening or connected /* FIXME: Do we need to detect if the socket is listening or connected
* to a peer? */ * to a peer? */
int static int
daemon_started_by_inetd(void) daemon_started_by_inetd(void)
{ {
int optval; int optval;
...@@ -247,6 +145,17 @@ daemon_started_by_inetd(void) ...@@ -247,6 +145,17 @@ daemon_started_by_inetd(void)
return res == 0; return res == 0;
} }
enum daemon_mode
daemon_detect(void)
{
if (daemon_started_by_init())
return DAEMON_INIT;
else if (daemon_started_by_inetd())
return DAEMON_INETD;
else
return DAEMON_NORMAL;
}
/* Disable core files */ /* Disable core files */
int int
daemon_disable_core(void) daemon_disable_core(void)
...@@ -268,51 +177,89 @@ daemon_disable_core(void) ...@@ -268,51 +177,89 @@ daemon_disable_core(void)
return 1; return 1;
} }
/* int
** int daemon_init(void) daemon_dup_null(int fd)
**
** Initialises a daemon:
** Disables core files to prevent security holes.
** If the process wasn't started by init(8) or inetd(8):
** Backgrounds the process to lose process group leadership.
** Becomes a process session leader.
** When SVR4 is defined:
** Backgrounds the process again to lose process group leadership.
** This prevents the process from gaining a controlling terminal.
** Under BSD, you must still include O_NOCTTY when opening terminals
** to prevent the process from gaining a controlling terminal.
** Changes directory to the root directory so as not to hamper umounts.
** Clears the umask to enable explicit file modes.
** If the process wasn't started by inetd(8):
** Closes all files (as determined by sysconf(2)).
** Opens stdin, stdout and stderr to /dev/null in case something needs them.
** If the hup parameter is non-null,
** Registers a SIGHUP handler.
** If the term parameter is non-null,
** Registers a SIGTERM handler.
** If the name parameter is non-null,
** Places the process id in the file system and locks it.
**
** Returns DAEMON_NORMAL, DAEMON_INIT or DAEMON_INETD on success, 0 on
** error (with errno set appropriately).
**
** Reasons for failure are: getrlimit(2), setrlimit(2), fork(2), chdir(2),
** sysconf(2), open(2), dup2(2), daemon_pidfile(), sigemptyset(2),
** sigaddset(2), sigaction(2). */
int daemon_init(void)
{ {
int mode = DAEMON_NORMAL; int null = open("/dev/null", O_RDWR);
if (null < 0)
{
werror("Opening /dev/null failed: %e\n", errno);
return 0;
}
if (dup2(null, fd) < 0)
{
werror("Failed to redirect fd %i to /dev/null: %e\n", errno);
close(null);
return 0;
}
if (daemon_started_by_init()) close(null);
mode = DAEMON_INIT; return 1;
else if (daemon_started_by_inetd()) }
mode = DAEMON_INETD;
#if !HAVE_GETDTABLESIZE
/* #define MAX_CLOSE_FD 1024;
** Don't setup a daemon-friendly process context int
** if started by init(8) or inetd(8). getdtablesize(void)
*/ {
long open_max = sysconf(_SC_OPEN_MAX);
if (open_max < 0 || open_max > MAX_INT)
{
werror("No limit on number of openfiles. Some high fd:s might be left open.\n");
return MAX_CLOSE_FD;
}
else
return open_max;
}
#endif /* !HAVE_GETDTABLESIZE */
/* Try to close all fd:s above stderr. There shouldn't be any open
file descriptors left over by startup scripts and the like, but if
there are anyway, they should be closed so that they aren't
inherited by user processes started by lshd. */
void
daemon_close_fds(void)
{
int fd = getdtablesize();
while (--fd > 2)
{
int res;
do
res = close(fd);
while (res < 0 && errno == EINTR);
if (res == 0)
werror("Closed spurious fd %i\n", fd);
else if (errno != EBADF)
werror("Closing spurious fd %i failed: %e\n", fd, errno);
}
}
/* Initialises a daemon:
If the process wasn't started by init(8) or inetd(8):
Backgrounds the process to lose process group leadership.
Becomes a process session leader.
Backgrounds the process again to lose process group leadership.
This prevents the process from gaining a controlling terminal.
Under BSD, you must still include O_NOCTTY when opening terminals
to prevent the process from gaining a controlling terminal.
Changes directory to the root directory so as not to hamper umounts.
Clears the umask to enable explicit file modes.
*/
int
daemon_init(enum daemon_mode mode)
{
/* Don't setup a daemon-friendly process context if started by
init(8) or inetd(8). */
if (mode == DAEMON_NORMAL) if (mode == DAEMON_NORMAL)
{ {
...@@ -334,17 +281,16 @@ int daemon_init(void) ...@@ -334,17 +281,16 @@ int daemon_init(void)
/* Parent */ /* Parent */
exit(0); exit(0);
} }
/* /* Become a process session leader. */
** Become a process session leader.
*/
if (setsid() < 0) if (setsid() < 0)
fatal("daemon_init: setsid failed.\n"); {
werror("daemon_init: setsid failed.\n");
return 0;
}
/* /* Lose process session leadership to prevent gaining a
** Lose process session leadership controlling terminal in SVR4.
** to prevent gaining a controlling
** terminal in SVR4.
*/ */
switch (child = fork()) switch (child = fork())
{ {
...@@ -378,123 +324,20 @@ int daemon_init(void) ...@@ -378,123 +324,20 @@ int daemon_init(void)
} }
} }
/* /* Enter the root directory to prevent hampering umounts. */
** Enter the root directory to prevent hampering umounts.
*/
if (chdir(ROOT_DIR) == -1) if (chdir(ROOT_DIR) == -1)
return 0; return 0;
/* /* Clear umask to enable explicit file modes. */
** Clear umask to enable explicit file modes.
*/
umask(0); umask(0);
{
int fd;
fd = open("/dev/null", O_RDWR);
if (fd < 0)
return 0;
/* Don't close stdin if we are started from inetd. */
if ( (mode != DAEMON_INETD)
&& (dup2(fd, STDIN_FILENO) < 0))
{
werror("daemon_init: Failed to redirect stdin to /dev/null.\n");
close(fd);
return 0;
}
if ( (dup2(fd, STDOUT_FILENO) < 0)
|| (dup2(fd, STDERR_FILENO) < 0) )
{
werror("daemon_init: Failed to redirect stdout and stderr to /dev/null.\n");
close(fd);
return 0;
}
close(fd);
/* It seems unfriendly to try toclose all fds (and on some
* systems, e.g. the HURD, there are no limits to the number of
* open files. It should be good enough to take care of stdio. */
#if 0
/*
** Close all open files.
** Don't forget to open any future
** tty devices with O_NOCTTY so as
** to prevent gaining a controlling
** terminal (not necessary with SVR4).
*/
if ((nopen = limit_open()) == -1)
return -1;
for (fd = 0; fd < nopen; ++fd)
close(fd);
/*
** Open stdin, stdout and stderr to /dev/null
** just in case someone expects them to be open.
*/
if ((fd = open("/dev/null", O_RDWR)) == -1)
return -1;
/*
** This is only needed for very strange
** (hypothetical) posix implementations
** where STDIN_FILENO != 0 or STDOUT_FILE != 1
** or STERR_FILENO != 2 (yeah, right).
*/
if (fd != STDIN_FILENO)
{
if (dup2(fd, STDIN_FILENO) == -1)
return -1;
close(fd);
}
if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1)
return -1;
if (dup2(STDIN_FILENO, STDERR_FILENO) == -1)
return -1;
#endif
}
#if 0
/*
** Register a SIGHUP handler, if required.
*/
if (hup && signal_set_handler(SIGHUP, 0, hup) == -1)
return -1;
/*
** Register a SIGTERM handler, if required.
*/
if (term && signal_set_handler(SIGTERM, 0, term) == -1)
return -1;
#endif
return 1; return 1;
} }
/* /* Unlinks the daemon's (locked) process id file. */
** int daemon_close() int
** daemon_close(const char *name)
** Unlinks the daemon's (locked) process id file.
*/
int daemon_close(const char *name)
{ {
if (unlink(name) < 0) if (unlink(name) < 0)
{ {
......
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