process-util: Move Xwayland fork helpers to shared

We'll want to reuse these inside desktop-shell as well as the Weston
frontend.

(Based on the work from
 https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/954)

Bug-AGL: SPEC-4510

Signed-off-by: Daniel Stone <daniel.stone@collabora.com>
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: Ife13dce545928cf53e4f49a657b756ed88ee742f

1 files changed, 94 insertions, 0 deletions

diff --git a/shared/process-util.h b/shared/process-util.h
new file mode 100644
index 0000000..05543f6
--- /dev/null
+++ b/shared/process-util.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2022 Collabora, Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <wayland-util.h>
+
+#include "os-compatibility.h"
+#include "string-helpers.h"
+
+/**
+ * A container for file descriptors and their string representations, designed
+ * to be used when forking child processes.
+ *
+ * fds[0] is generally used as the file descriptor held within the parent
+ * process to communicate with the child, and fds[1] as the child's counterpart.
+ *
+ * str1[] is used as a string representation of fds[1].
+ */
+struct fdstr {
+	char str1[12];
+	int fds[2];
+};
+
+void
+fdstr_update_str1(struct fdstr *s);
+
+void
+fdstr_set_fd1(struct fdstr *s, int fd);
+
+bool
+fdstr_clear_cloexec_fd1(struct fdstr *s);
+
+void
+fdstr_close_all(struct fdstr *s);
+
+
+/**
+ * A container for environment variables and/or process arguments, designed to
+ * be used when forking child processes, as setenv() and anything which
+ * allocates memory cannot be used between fork() and exec().
+ */
+struct custom_env {
+	struct wl_array envp;
+	bool env_finalized;
+	struct wl_array argp;
+	bool arg_finalized;
+};
+
+void
+custom_env_init_from_environ(struct custom_env *env);
+
+void
+custom_env_fini(struct custom_env *env);
+
+void
+custom_env_set_env_var(struct custom_env *env, const char *name, const char *value);
+
+void
+custom_env_add_arg(struct custom_env *env, const char *arg);
+
+void
+custom_env_add_from_exec_string(struct custom_env *env, const char *exec_str);
+
+char *const *
+custom_env_get_envp(struct custom_env *env);
+
+char *const *
+custom_env_get_argp(struct custom_env *env);