From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/um/os-Linux/helper.c | 164 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100644 arch/um/os-Linux/helper.c

(limited to 'arch/um/os-Linux/helper.c')

diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
new file mode 100644
index 000000000..e3ee4a51e
--- /dev/null
+++ b/arch/um/os-Linux/helper.c
@@ -0,0 +1,164 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sched.h>
+#include <linux/limits.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <kern_util.h>
+#include <os.h>
+#include <um_malloc.h>
+
+struct helper_data {
+	void (*pre_exec)(void*);
+	void *pre_data;
+	char **argv;
+	int fd;
+	char *buf;
+};
+
+static int helper_child(void *arg)
+{
+	struct helper_data *data = arg;
+	char **argv = data->argv;
+	int err, ret;
+
+	if (data->pre_exec != NULL)
+		(*data->pre_exec)(data->pre_data);
+	err = execvp_noalloc(data->buf, argv[0], argv);
+
+	/* If the exec succeeds, we don't get here */
+	CATCH_EINTR(ret = write(data->fd, &err, sizeof(err)));
+
+	return 0;
+}
+
+/* Returns either the pid of the child process we run or -E* on failure. */
+int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv)
+{
+	struct helper_data data;
+	unsigned long stack, sp;
+	int pid, fds[2], ret, n;
+
+	stack = alloc_stack(0, __cant_sleep());
+	if (stack == 0)
+		return -ENOMEM;
+
+	ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
+	if (ret < 0) {
+		ret = -errno;
+		printk(UM_KERN_ERR "run_helper : pipe failed, errno = %d\n",
+		       errno);
+		goto out_free;
+	}
+
+	ret = os_set_exec_close(fds[1]);
+	if (ret < 0) {
+		printk(UM_KERN_ERR "run_helper : setting FD_CLOEXEC failed, "
+		       "ret = %d\n", -ret);
+		goto out_close;
+	}
+
+	sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
+	data.pre_exec = pre_exec;
+	data.pre_data = pre_data;
+	data.argv = argv;
+	data.fd = fds[1];
+	data.buf = __cant_sleep() ? uml_kmalloc(PATH_MAX, UM_GFP_ATOMIC) :
+					uml_kmalloc(PATH_MAX, UM_GFP_KERNEL);
+	pid = clone(helper_child, (void *) sp, CLONE_VM, &data);
+	if (pid < 0) {
+		ret = -errno;
+		printk(UM_KERN_ERR "run_helper : clone failed, errno = %d\n",
+		       errno);
+		goto out_free2;
+	}
+
+	close(fds[1]);
+	fds[1] = -1;
+
+	/*
+	 * Read the errno value from the child, if the exec failed, or get 0 if
+	 * the exec succeeded because the pipe fd was set as close-on-exec.
+	 */
+	n = read(fds[0], &ret, sizeof(ret));
+	if (n == 0) {
+		ret = pid;
+	} else {
+		if (n < 0) {
+			n = -errno;
+			printk(UM_KERN_ERR "run_helper : read on pipe failed, "
+			       "ret = %d\n", -n);
+			ret = n;
+		}
+		CATCH_EINTR(waitpid(pid, NULL, __WCLONE));
+	}
+
+out_free2:
+	kfree(data.buf);
+out_close:
+	if (fds[1] != -1)
+		close(fds[1]);
+	close(fds[0]);
+out_free:
+	free_stack(stack, 0);
+	return ret;
+}
+
+int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
+		      unsigned long *stack_out)
+{
+	unsigned long stack, sp;
+	int pid, status, err;
+
+	stack = alloc_stack(0, __cant_sleep());
+	if (stack == 0)
+		return -ENOMEM;
+
+	sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
+	pid = clone(proc, (void *) sp, flags, arg);
+	if (pid < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "run_helper_thread : clone failed, "
+		       "errno = %d\n", errno);
+		return err;
+	}
+	if (stack_out == NULL) {
+		CATCH_EINTR(pid = waitpid(pid, &status, __WCLONE));
+		if (pid < 0) {
+			err = -errno;
+			printk(UM_KERN_ERR "run_helper_thread - wait failed, "
+			       "errno = %d\n", errno);
+			pid = err;
+		}
+		if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
+			printk(UM_KERN_ERR "run_helper_thread - thread "
+			       "returned status 0x%x\n", status);
+		free_stack(stack, 0);
+	} else
+		*stack_out = stack;
+	return pid;
+}
+
+int helper_wait(int pid)
+{
+	int ret, status;
+	int wflags = __WCLONE;
+
+	CATCH_EINTR(ret = waitpid(pid, &status, wflags));
+	if (ret < 0) {
+		printk(UM_KERN_ERR "helper_wait : waitpid process %d failed, "
+		       "errno = %d\n", pid, errno);
+		return -errno;
+	} else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+		printk(UM_KERN_ERR "helper_wait : process %d exited with "
+		       "status 0x%x\n", pid, status);
+		return -ECHILD;
+	} else
+		return 0;
+}
-- 
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