Ensure "tinc start" knows if the daemon really started succesfully.

[tinc] / src / tincctl.c

diff --git a/src/tincctl.c b/src/tincctl.c
index 46bf5bd..c6d4aac 100644 (file)
--- a/src/tincctl.c
+++ b/src/tincctl.c
@@ -853,6 +853,13 @@ static int cmd_start(int argc, char *argv[]) {
        }
        return status;
 #else
+       int pfd[2] = {-1, -1};
+       if(pipe(pfd)) {
+               fprintf(stderr, "Could not create umbilical pipe: %s\n", strerror(errno));
+               free(nargv);
+               return 1;
+       }
+
        pid_t pid = fork();
        if(pid == -1) {
                fprintf(stderr, "Could not fork: %s\n", strerror(errno));
@@ -860,8 +867,15 @@ static int cmd_start(int argc, char *argv[]) {
                return 1;
        }
 
-       if(!pid)
+       if(!pid) {
+               close(pfd[0]);
+               char buf[100] = "";
+               snprintf(buf, sizeof buf, "%d", pfd[1]);
+               setenv("TINC_UMBILICAL", buf, true);
                exit(execvp(c, nargv));
+       } else {
+               close(pfd[1]);
+       }
 
        free(nargv);
 
@@ -869,12 +883,33 @@ static int cmd_start(int argc, char *argv[]) {
 #ifdef SIGINT
        signal(SIGINT, SIG_IGN);
 #endif
+
+       // Pass all log messages from the umbilical to stderr.
+       // A nul-byte right before closure means tincd started succesfully.
+       bool failure = true;
+       char buf[1024];
+       ssize_t len;
+
+       while((len = read(pfd[0], buf, sizeof buf)) > 0) {
+               failure = buf[len - 1];
+               if(!failure)
+                       len--;
+               write(2, buf, len);
+       }
+
+       if(len)
+               failure = true;
+
+       close(pfd[0]);
+
+       // Make sure the child process is really gone.
        result = waitpid(pid, &status, 0);
+
 #ifdef SIGINT
        signal(SIGINT, SIG_DFL);
 #endif
 
-       if(result != pid || !WIFEXITED(status) || WEXITSTATUS(status)) {
+       if(failure || result != pid || !WIFEXITED(status) || WEXITSTATUS(status)) {
                fprintf(stderr, "Error starting %s\n", c);
                return 1;
        }