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start-stop-daemon: create pidfile before parent exits, closes 8596

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This removes DAEMON_DOUBLE_FORK flag from bb_daemonize_or_rexec(),
as SSD was the only user.

Also includes fix for -S: now works without -a and -x,
does not print pids
(compat with "start-stop-daemon (OpenRC) 0.34.11 (Gentoo Linux)").

function                                             old     new   delta
start_stop_daemon_main                              1018    1084     +66
add_interface                                         99     103      +4
fail_hunk                                            139     136      -3
bb_daemonize_or_rexec                                205     183     -22
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/2 up/down: 70/-25)             Total: 45 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2019-01-14 14:45:18 +01:00
parent b67d900395
commit 088fec36fe
4 changed files with 62 additions and 35 deletions
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66
debianutils/start_stop_daemon.c
View File

@ -409,7 +409,7 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
{ {
unsigned opt; unsigned opt;
char *signame; char *signame;
char *startas; char *startas = NULL;
char *chuid; char *chuid;
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY #if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
// char *retry_arg = NULL; // char *retry_arg = NULL;
@ -425,10 +425,11 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
/* -K or -S is required; they are mutually exclusive */ /* -K or -S is required; they are mutually exclusive */
/* -p is required if -m is given */ /* -p is required if -m is given */
/* -xpun (at least one) is required if -K is given */ /* -xpun (at least one) is required if -K is given */
/* -xa (at least one) is required if -S is given */ // /* -xa (at least one) is required if -S is given */
//WRONG: "start-stop-daemon -S -- sleep 5" is a valid invocation
/* -q turns off -v */ /* -q turns off -v */
"\0" "\0"
"K:S:K--S:S--K:m?p:K?xpun:S?xa" "K:S:K--S:S--K:m?p:K?xpun"
IF_FEATURE_START_STOP_DAEMON_FANCY("q-v"), IF_FEATURE_START_STOP_DAEMON_FANCY("q-v"),
LONGOPTS LONGOPTS
&startas, &cmdname, &signame, &userspec, &chuid, &execname, &pidfile &startas, &cmdname, &signame, &userspec, &chuid, &execname, &pidfile
@ -442,21 +443,34 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
if (signal_nr < 0) bb_show_usage(); if (signal_nr < 0) bb_show_usage();
} }
if (!(opt & OPT_a)) //argc -= optind;
startas = execname; argv += optind;
if (!execname) /* in case -a is given and -x is not */ // ARGS contains zeroth arg if -x/-a is not given, else it starts with 1st arg.
// These will try to execute "[/bin/]sleep 5":
// "start-stop-daemon -S -- sleep 5"
// "start-stop-daemon -S -x /bin/sleep -- 5"
// "start-stop-daemon -S -a sleep -- 5"
// NB: -n option does _not_ behave in this way: this will try to execute "5":
// "start-stop-daemon -S -n sleep -- 5"
if (!execname) { /* -x is not given */
execname = startas; execname = startas;
if (execname) { if (!execname) { /* neither -x nor -a is given */
G.execname_sizeof = strlen(execname) + 1; execname = argv[0];
G.execname_cmpbuf = xmalloc(G.execname_sizeof + 1); if (!execname)
bb_show_usage();
argv++;
}
} }
if (!startas) /* -a is not given: use -x EXECUTABLE or argv[0] */
startas = execname;
*--argv = startas;
G.execname_sizeof = strlen(execname) + 1;
G.execname_cmpbuf = xmalloc(G.execname_sizeof + 1);
// IF_FEATURE_START_STOP_DAEMON_FANCY( // IF_FEATURE_START_STOP_DAEMON_FANCY(
// if (retry_arg) // if (retry_arg)
// retries = xatoi_positive(retry_arg); // retries = xatoi_positive(retry_arg);
// ) // )
//argc -= optind;
argv += optind;
if (userspec) { if (userspec) {
user_id = bb_strtou(userspec, NULL, 10); user_id = bb_strtou(userspec, NULL, 10);
@ -473,7 +487,7 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
if (G.found_procs) { if (G.found_procs) {
if (!QUIET) if (!QUIET)
printf("%s is already running\n%u\n", execname, (unsigned)G.found_procs->pid); printf("%s is already running\n", execname);
return !(opt & OPT_OKNODO); return !(opt & OPT_OKNODO);
} }
@ -482,30 +496,37 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
xstat(execname, &G.execstat); xstat(execname, &G.execstat);
#endif #endif
*--argv = startas;
if (opt & OPT_BACKGROUND) { if (opt & OPT_BACKGROUND) {
#if BB_MMU
bb_daemonize(DAEMON_DEVNULL_STDIO + DAEMON_CLOSE_EXTRA_FDS + DAEMON_DOUBLE_FORK);
/* DAEMON_DEVNULL_STDIO is superfluous -
* it's always done by bb_daemonize() */
#else
/* Daemons usually call bb_daemonize_or_rexec(), but SSD can do /* Daemons usually call bb_daemonize_or_rexec(), but SSD can do
* without: SSD is not itself a daemon, it _execs_ a daemon. * without: SSD is not itself a daemon, it _execs_ a daemon.
* The usual NOMMU problem of "child can't run indefinitely, * The usual NOMMU problem of "child can't run indefinitely,
* it must exec" does not bite us: we exec anyway. * it must exec" does not bite us: we exec anyway.
*
* bb_daemonize(DAEMON_DEVNULL_STDIO | DAEMON_CLOSE_EXTRA_FDS | DAEMON_DOUBLE_FORK)
* can be used on MMU systems, but use of vfork()
* is preferable since we want to create pidfile
* _before_ parent returns, and vfork() on Linux
* ensures that (by blocking parent until exec in the child).
*/ */
pid_t pid = xvfork(); pid_t pid = xvfork();
if (pid != 0) { if (pid != 0) {
/* parent */ /* Parent */
/* why _exit? the child may have changed the stack, /* why _exit? the child may have changed the stack,
* so "return 0" may do bad things */ * so "return 0" may do bad things
*/
_exit(EXIT_SUCCESS); _exit(EXIT_SUCCESS);
} }
/* Child */ /* Child */
setsid(); /* detach from controlling tty */ setsid(); /* detach from controlling tty */
/* Redirect stdio to /dev/null, close extra FDs */ /* Redirect stdio to /dev/null, close extra FDs */
bb_daemon_helper(DAEMON_DEVNULL_STDIO + DAEMON_CLOSE_EXTRA_FDS); bb_daemon_helper(DAEMON_DEVNULL_STDIO + DAEMON_CLOSE_EXTRA_FDS);
#endif /* On Linux, session leader can acquire ctty
* unknowingly, by opening a tty.
* Prevent this: stop being a session leader.
*/
pid = xvfork();
if (pid != 0)
_exit(EXIT_SUCCESS); /* Parent */
} }
if (opt & OPT_MAKEPID) { if (opt & OPT_MAKEPID) {
/* User wants _us_ to make the pidfile */ /* User wants _us_ to make the pidfile */
@ -534,6 +555,7 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
} }
} }
#endif #endif
execvp(startas, argv); //bb_error_msg("HERE %d '%s'%s'", __LINE__, argv[0], argv[1]);
execvp(argv[0], argv);
bb_perror_msg_and_die("can't execute '%s'", startas); bb_perror_msg_and_die("can't execute '%s'", startas);
} }

10
include/libbb.h
View File

@ -1201,11 +1201,11 @@ void set_task_comm(const char *comm) FAST_FUNC;
* to /dev/null if they are not. * to /dev/null if they are not.
*/ */
enum { enum {
DAEMON_CHDIR_ROOT = 1, DAEMON_CHDIR_ROOT = 1 << 0,
DAEMON_DEVNULL_STDIO = 2, DAEMON_DEVNULL_STDIO = 1 << 1,
DAEMON_CLOSE_EXTRA_FDS = 4, DAEMON_CLOSE_EXTRA_FDS = 1 << 2,
DAEMON_ONLY_SANITIZE = 8, /* internal use */ DAEMON_ONLY_SANITIZE = 1 << 3, /* internal use */
DAEMON_DOUBLE_FORK = 16, /* double fork to avoid controlling tty */ //DAEMON_DOUBLE_FORK = 1 << 4, /* double fork to avoid controlling tty */
}; };
#if BB_MMU #if BB_MMU
enum { re_execed = 0 }; enum { re_execed = 0 };

16
libbb/vfork_daemon_rexec.c
View File

@ -292,14 +292,14 @@ void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
dup2(fd, 0); dup2(fd, 0);
dup2(fd, 1); dup2(fd, 1);
dup2(fd, 2); dup2(fd, 2);
if (flags & DAEMON_DOUBLE_FORK) { // if (flags & DAEMON_DOUBLE_FORK) {
/* On Linux, session leader can acquire ctty // /* On Linux, session leader can acquire ctty
* unknowingly, by opening a tty. // * unknowingly, by opening a tty.
* Prevent this: stop being a session leader. // * Prevent this: stop being a session leader.
*/ // */
if (fork_or_rexec(argv)) // if (fork_or_rexec(argv))
_exit(EXIT_SUCCESS); /* parent */ // _exit(EXIT_SUCCESS); /* parent */
} // }
} }
while (fd > 2) { while (fd > 2) {
close(fd--); close(fd--);

5
testsuite/start-stop-daemon.tests
View File

@ -16,4 +16,9 @@ testing "start-stop-daemon -a without -x" \
"1\n" \ "1\n" \
"" "" "" ""
testing "start-stop-daemon without -x and -a" \
'start-stop-daemon -S false 2>&1; echo $?' \
"1\n" \
"" ""
exit $FAILCOUNT exit $FAILCOUNT