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authorKenny Levinsen <kl@kl.wtf>2021-08-06 00:06:44 +0200
committerKenny Levinsen <kl@kl.wtf>2021-08-06 01:29:52 +0200
commit1e98727ae9dfdb23316249a4f32b3169d956e417 (patch)
tree9d886b4708cf7d9bfac266fc7a494c0f5b4cd347 /seatd-launch
parentc8b3a22d4ef0f69c3d22f0ec1170b89c93ef1dc3 (diff)
seatd-launch: Add seatd launch wrapper
This launch wrapper is used to conveniently start a new seatd instance, wait for it to be ready, and launch a target application.
Diffstat (limited to 'seatd-launch')
-rw-r--r--seatd-launch/seatd-launch.c123
1 files changed, 123 insertions, 0 deletions
diff --git a/seatd-launch/seatd-launch.c b/seatd-launch/seatd-launch.c
new file mode 100644
index 0000000..ffa6cc6
--- /dev/null
+++ b/seatd-launch/seatd-launch.c
@@ -0,0 +1,123 @@
+#include <errno.h>
+#include <poll.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[]) {
+ (void)argc;
+ char sockbuf[256];
+
+ sprintf(sockbuf, "/tmp/seatd.%d.sock", getpid());
+ unlink(sockbuf);
+
+ int fds[2];
+ if (pipe(fds) == -1) {
+ perror("Could not create pipe");
+ goto error;
+ }
+
+ pid_t seatd_child = fork();
+ if (seatd_child == -1) {
+ perror("Could not fork seatd process");
+ goto error;
+ } else if (seatd_child == 0) {
+ close(fds[0]);
+
+ char pipebuf[8];
+ sprintf(pipebuf, "%d", fds[1]);
+ struct passwd *user = getpwuid(getuid());
+
+ // TODO: Make seatd accept the numeric UID
+ execlp("seatd", "seatd", "-n", pipebuf, "-u", user->pw_name, "-s", sockbuf, NULL);
+ perror("Could not start seatd");
+ goto error;
+ }
+ close(fds[1]);
+
+ // Drop privileges
+ if (setgid(getgid()) == -1) {
+ perror("Could not set gid to drop privileges");
+ goto error_seatd;
+ }
+ if (setuid(getuid()) == -1) {
+ perror("Could not set uid to drop privileges");
+ goto error_seatd;
+ }
+
+ char buf[1] = {0};
+ while (true) {
+ pid_t p = waitpid(seatd_child, NULL, WNOHANG);
+ if (p == seatd_child) {
+ fprintf(stderr, "seatd exited prematurely\n");
+ goto error_seatd;
+ } else if (p == -1 && (errno != EINTR && errno != ECHILD)) {
+ perror("Could not wait for seatd process");
+ goto error_seatd;
+ }
+
+ struct pollfd fd = {
+ .fd = fds[0],
+ .events = POLLIN,
+ };
+
+ // We poll with timeout to avoid a racing on a blocking read
+ if (poll(&fd, 1, 1000) == -1) {
+ if (errno == EAGAIN || errno == EINTR) {
+ continue;
+ } else {
+ perror("Could not poll notification fd");
+ goto error_seatd;
+ }
+ }
+
+ if (fd.revents & POLLIN) {
+ ssize_t n = read(fds[0], buf, 1);
+ if (n == -1 && errno != EINTR) {
+ perror("Could not read from pipe");
+ goto error_seatd;
+ } else if (n > 0) {
+ break;
+ }
+ }
+ }
+ close(fds[0]);
+
+ pid_t child = fork();
+ if (child == -1) {
+ perror("Could not fork target process");
+ goto error_seatd;
+ } else if (child == 0) {
+ setenv("SEATD_SOCK", sockbuf, 1);
+ execv(argv[1], &argv[1]);
+ perror("Could not start target");
+ goto error_seatd;
+ }
+
+ while (true) {
+ pid_t p = waitpid(child, NULL, 0);
+ if (p == child) {
+ break;
+ } else if (p == -1 && errno != EINTR) {
+ perror("Could not wait for target process");
+ goto error_seatd;
+ }
+ }
+
+ unlink(sockbuf);
+ kill(seatd_child, SIGTERM);
+ return 0;
+
+error_seatd:
+ unlink(sockbuf);
+ kill(seatd_child, SIGTERM);
+error:
+ return 1;
+}