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088fec36f

Denys Vlasenko
Denys Vlasenko
2019-01-14
SUCCESS Duration: 150s

Subject

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

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

debianutils/start_stop_daemon.c +44 -22include/libbb.h +5 -5libbb/vfork_daemon_rexec.c +8 -8testsuite/start-stop-daemon.tests +5 -0
debianutils/start_stop_daemon.c+44 -22
@@ -409,7 +409,7 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
{
unsigned opt;
char *signame;
- char *startas;
+ char *startas = NULL;
char *chuid;
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
// 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 */
/* -p is required if -m 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 */
"\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"),
LONGOPTS
&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 (!(opt & OPT_a))
- startas = execname;
- if (!execname) /* in case -a is given and -x is not */
+ //argc -= optind;
+ argv += optind;
+// 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;
- if (execname) {
- G.execname_sizeof = strlen(execname) + 1;
- G.execname_cmpbuf = xmalloc(G.execname_sizeof + 1);
+ if (!execname) { /* neither -x nor -a is given */
+ execname = argv[0];
+ 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 (retry_arg)
// retries = xatoi_positive(retry_arg);
// )
- //argc -= optind;
- argv += optind;
if (userspec) {
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 (!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);
}
@@ -482,30 +496,37 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
xstat(execname, &G.execstat);
#endif
- *--argv = startas;
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
* without: SSD is not itself a daemon, it _execs_ a daemon.
* The usual NOMMU problem of "child can't run indefinitely,
* 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();
if (pid != 0) {
- /* parent */
+ /* Parent */
/* 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);
}
/* Child */
setsid(); /* detach from controlling tty */
/* Redirect stdio to /dev/null, 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) {
/* User wants _us_ to make the pidfile */
@@ -534,6 +555,7 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
}
}
#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);
}
include/libbb.h+5 -5
@@ -1201,11 +1201,11 @@ void set_task_comm(const char *comm) FAST_FUNC;
* to /dev/null if they are not.
*/
enum {
- DAEMON_CHDIR_ROOT = 1,
- DAEMON_DEVNULL_STDIO = 2,
- DAEMON_CLOSE_EXTRA_FDS = 4,
- DAEMON_ONLY_SANITIZE = 8, /* internal use */
- DAEMON_DOUBLE_FORK = 16, /* double fork to avoid controlling tty */
+ DAEMON_CHDIR_ROOT = 1 << 0,
+ DAEMON_DEVNULL_STDIO = 1 << 1,
+ DAEMON_CLOSE_EXTRA_FDS = 1 << 2,
+ DAEMON_ONLY_SANITIZE = 1 << 3, /* internal use */
+ //DAEMON_DOUBLE_FORK = 1 << 4, /* double fork to avoid controlling tty */
};
#if BB_MMU
enum { re_execed = 0 };
libbb/vfork_daemon_rexec.c+8 -8
@@ -292,14 +292,14 @@ void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
- if (flags & DAEMON_DOUBLE_FORK) {
- /* On Linux, session leader can acquire ctty
- * unknowingly, by opening a tty.
- * Prevent this: stop being a session leader.
- */
- if (fork_or_rexec(argv))
- _exit(EXIT_SUCCESS); /* parent */
- }
+// if (flags & DAEMON_DOUBLE_FORK) {
+// /* On Linux, session leader can acquire ctty
+// * unknowingly, by opening a tty.
+// * Prevent this: stop being a session leader.
+// */
+// if (fork_or_rexec(argv))
+// _exit(EXIT_SUCCESS); /* parent */
+// }
}
while (fd > 2) {
close(fd--);
testsuite/start-stop-daemon.tests+5 -0
@@ -16,4 +16,9 @@ testing "start-stop-daemon -a without -x" \
"1\n" \
"" ""
+testing "start-stop-daemon without -x and -a" \
+ 'start-stop-daemon -S false 2>&1; echo $?' \
+ "1\n" \
+ "" ""
+
exit $FAILCOUNT