term: break out fork+exec functionality to a separate file

spawn.c

@@ -0,0 +1,72 @@
+#include "spawn.h"
+
+#include <unistd.h>
+#include <errno.h>
+#include <assert.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#define LOG_MODULE "spawn"
+#define LOG_ENABLE_DBG 0
+#include "log.h"
+
+bool
+spawn(struct reaper *reaper, const char *cwd, char *const argv[])
+{
+    int pipe_fds[2] = {-1, -1};
+    if (pipe2(pipe_fds, O_CLOEXEC) < 0) {
+        LOG_ERRNO("failed to create pipe");
+        goto err;
+    }
+
+    pid_t pid = fork();
+    if (pid < 0) {
+        LOG_ERRNO("failed to fork");
+        goto err;
+    }
+
+    if (pid == 0) {
+        /* Child */
+        close(pipe_fds[0]);
+        if ((cwd != NULL && chdir(cwd) < 0) ||
+            //execlp(term->foot_exe, term->foot_exe, NULL) < 0)
+            execvp(argv[0], argv) < 0)
+        {
+            (void)!write(pipe_fds[1], &errno, sizeof(errno));
+            _exit(errno);
+        }
+        assert(false);
+        _exit(errno);
+    }
+
+    /* Parent */
+    close(pipe_fds[1]);
+
+    int _errno;
+    static_assert(sizeof(_errno) == sizeof(errno), "errno size mismatch");
+
+    ssize_t ret = read(pipe_fds[0], &_errno, sizeof(_errno));
+    close(pipe_fds[0]);
+
+    if (ret == 0) {
+        reaper_add(reaper, pid);
+        return true;
+    } else if (ret < 0) {
+        LOG_ERRNO("failed to read from pipe");
+        return false;
+    } else {
+        LOG_ERRNO_P("%s: failed to spawn", _errno, argv[0]);
+        errno = _errno;
+        waitpid(pid, NULL, 0);
+        return false;
+    }
+
+err:
+    if (pipe_fds[0] != -1)
+        close(pipe_fds[0]);
+    if (pipe_fds[1] != -1)
+        close(pipe_fds[1]);
+    return false;
+}