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authorMike Gilbert <floppym@gentoo.org>2022-10-29 12:38:43 -0400
committerWilliam Hubbs <w.d.hubbs@gmail.com>2022-12-07 17:12:24 -0600
commit1364e6631c7f266484981d88be43f9b039f76b6a (patch)
tree9d563d117489a9d0c43d36113c5da6ef15be7bae /src/start-stop-daemon
parent953172c6c670d10d36ea3917243079b86ecc102d (diff)
start-stop-daemon: use a pipe to sync parent/child processes
This fixes #557.
Diffstat (limited to 'src/start-stop-daemon')
-rw-r--r--src/start-stop-daemon/start-stop-daemon.c23
1 files changed, 22 insertions, 1 deletions
diff --git a/src/start-stop-daemon/start-stop-daemon.c b/src/start-stop-daemon/start-stop-daemon.c
index e439388f..d3f6fd4d 100644
--- a/src/start-stop-daemon/start-stop-daemon.c
+++ b/src/start-stop-daemon/start-stop-daemon.c
@@ -354,6 +354,9 @@ int main(int argc, char **argv)
#ifdef PR_SET_NO_NEW_PRIVS
bool no_new_privs = false;
#endif
+ int pipefd[2];
+ char readbuf[1];
+ ssize_t ss;
applet = basename_c(argv[0]);
atexit(cleanup);
@@ -864,12 +867,17 @@ int main(int argc, char **argv)
if (background)
signal_setup(SIGCHLD, handle_signal);
+ /* Use a pipe to sync the parent/child processes. */
+ if (pipe2(pipefd, O_CLOEXEC) == -1)
+ eerrorx("%s: pipe2: %s", applet, strerror(errno));
+
if ((pid = fork()) == -1)
eerrorx("%s: fork: %s", applet, strerror(errno));
/* Child process - lets go! */
if (pid == 0) {
pid_t mypid = getpid();
+ close(pipefd[0]); /* Close the read end of the pipe. */
umask(numask);
#ifdef TIOCNOTTY
@@ -1097,7 +1105,8 @@ int main(int argc, char **argv)
dup2(stderr_fd, STDERR_FILENO);
for (i = getdtablesize() - 1; i >= 3; --i)
- close(i);
+ if (i != pipefd[1])
+ close(i);
if (scheduler != NULL) {
int scheduler_index;
@@ -1140,6 +1149,18 @@ int main(int argc, char **argv)
}
/* Parent process */
+
+ close(pipefd[1]); /* Close the write end of the pipe. */
+
+ /* The child never writes to the pipe, so this read will block until
+ * the child calls exec or exits. */
+ while ((ss = read(pipefd[0], readbuf, 1)) == -1 && errno == EINTR);
+ if (ss == -1)
+ eerrorx("%s: failed to read from pipe: %s",
+ applet, strerror(errno));
+
+ close(pipefd[0]);
+
if (!background) {
/* As we're not backgrounding the process, wait for our pid
* to return */