Introduce helper functions for safe fork+exec of processes

In some situations, we want to execute an external shell command
in a non-blocking way.  Similar to 'system', but without waiting for
the child to complete.  We also want to close all file descriptors
ahead of the exec() and filter + modify the environment.

Change-Id: Ib24ac8a083db32e55402ce496a5eabd8749cc888
Related: OS#4332

1 files changed, 28 insertions, 0 deletions

diff --git a/include/osmocom/core/exec.h b/include/osmocom/core/exec.h
new file mode 100644
index 00000000..6bbd352c
--- /dev/null
+++ b/include/osmocom/core/exec.h
@@ -0,0 +1,28 @@
+#pragma once
+/* (C) 2019 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+extern const char *osmo_environment_whitelist[];
+
+int osmo_environment_filter(char **out, size_t out_len, char **in, const char **whitelist);
+int osmo_environment_append(char **out, size_t out_len, char **in);
+int osmo_close_all_fds_above(int last_fd_to_keep);
+int osmo_system_nowait(const char *command, const char **env_whitelist, char **addl_env);