add some more code

This adds a basic "worker" program.

You can now do something like

    ./server &
    ./worker &
    ./client ci_run URL REV

and the server should pass a message to worker, after which it should
clone the repository at URL, checkout REV, and try to run the CI script.

It's extremely unfinished: I need to sort out the graceful shutdown, how
the server manages workers, etc.

1 files changed, 46 insertions, 0 deletions

diff --git a/src/process.c b/src/process.c
new file mode 100644
index 0000000..9d95037
--- /dev/null
+++ b/src/process.c
@@ -0,0 +1,46 @@
+#include "process.h"
+#include "log.h"
+
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+static int wait_for_child(pid_t pid, int *ec)
+{
+	int status;
+
+	pid_t ret = waitpid(pid, &status, 0);
+	if (ret < 0) {
+		print_errno("waitpid");
+		return ret;
+	}
+
+	if (WIFEXITED(status))
+		*ec = WEXITSTATUS(status);
+	else
+		*ec = -1;
+
+	return 0;
+}
+
+int proc_spawn(const char *args[], int *ec)
+{
+	int ret = 0;
+
+	pid_t child_pid = fork();
+	if (child_pid < 0) {
+		print_errno("fork");
+		return child_pid;
+	}
+
+	if (child_pid)
+		return wait_for_child(child_pid, ec);
+
+	ret = execv(args[0], (char *const *)args);
+	if (ret < 0) {
+		print_errno("execv");
+		exit(ret);
+	}
+
+	return 0;
+}