Add helper to spawn process with stdin connected to a pipe

1 files changed, 57 insertions, 0 deletions

diff --git a/src/rc/rc-pipes.c b/src/rc/rc-pipes.c
new file mode 100644
index 00000000..55f3ff8d
--- /dev/null
+++ b/src/rc/rc-pipes.c
@@ -0,0 +1,57 @@
+/*
+ * rc-pipes.c
+ * Helper to handle spawning processes and connecting them to pipes.
+ */
+
+/*
+ * Copyright (c) 2018 The OpenRC Authors.
+ * See the Authors file at the top-level directory of this distribution and
+ * https://github.com/OpenRC/openrc/blob/master/AUTHORS
+ *
+ * This file is part of OpenRC. It is subject to the license terms in
+ * the LICENSE file found in the top-level directory of this
+ * distribution and at https://github.com/OpenRC/openrc/blob/master/LICENSE
+ * This file may not be copied, modified, propagated, or distributed
+ *    except according to the terms contained in the LICENSE file.
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "rc-pipe-command.h"
+
+static const int pipe_read_end = 0;
+static const int pipe_write_end = 1;
+
+/*
+ * Starts a command with stdin redirected from a pipe
+ * Returns the write end of the pipe or -1
+ */
+int rc_pipe_command(char *cmd)
+{
+	int pfd[2];
+	pid_t pid;
+
+	if (pipe(pfd) < 0)
+		return -1;
+
+	pid = fork();
+	if (pid < 0)
+		return -1;
+	else if (pid > 0) {
+		/* parent */
+		close(pfd[0]);
+		return pfd[pipe_write_end];
+	} else if (pid == 0) {
+		/* child */
+		close(pfd[pipe_write_end]);
+		if (pfd[0] != STDIN_FILENO) {
+			if (dup2(pfd[0], STDIN_FILENO) < 0)
+				exit(1);
+			close(pfd[0]);
+		}
+		execl("/bin/sh", "sh", "-c", cmd, NULL);
+		exit(1);
+	}
+}