5 files changed, 169 insertions, 6 deletions

diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index 0b761a08f0df..b83ac8e21c35 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -3,10 +3,11 @@
 # Licensed under the GPL
 #
 
-obj-y = aio.o elf_aux.o file.o main.o mem.o process.o signal.o start_up.o \
-	time.o tt.o tty.o uaccess.o user_syms.o drivers/ sys-$(SUBARCH)/
+obj-y = aio.o elf_aux.o file.o helper.o main.o mem.o process.o signal.o \
+	start_up.o time.o tt.o tty.o uaccess.o user_syms.o drivers/ \
+	sys-$(SUBARCH)/
 
-USER_OBJS := aio.o elf_aux.o file.o main.o mem.o process.o signal.o \
+USER_OBJS := aio.o elf_aux.o file.o helper.o main.o mem.o process.o signal.o \
 	start_up.o time.o tt.o tty.o uaccess.o
 
 elf_aux.o: $(ARCH_DIR)/kernel-offsets.h
diff --git a/arch/um/os-Linux/aio.c b/arch/um/os-Linux/aio.c
index 41cfb0944201..ffa759addd3c 100644
--- a/arch/um/os-Linux/aio.c
+++ b/arch/um/os-Linux/aio.c
@@ -10,7 +10,6 @@
 #include <sched.h>
 #include <sys/syscall.h>
 #include "os.h"
-#include "helper.h"
 #include "aio.h"
 #include "init.h"
 #include "user.h"
diff --git a/arch/um/os-Linux/drivers/ethertap_user.c b/arch/um/os-Linux/drivers/ethertap_user.c
index cd4d6544da71..901b85e8a1c6 100644
--- a/arch/um/os-Linux/drivers/ethertap_user.c
+++ b/arch/um/os-Linux/drivers/ethertap_user.c
@@ -19,7 +19,6 @@
 #include "user_util.h"
 #include "net_user.h"
 #include "etap.h"
-#include "helper.h"
 #include "os.h"
 
 #define MAX_PACKET ETH_MAX_PACKET
diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c
index 4ba9b17adf13..52945338b64d 100644
--- a/arch/um/os-Linux/drivers/tuntap_user.c
+++ b/arch/um/os-Linux/drivers/tuntap_user.c
@@ -20,7 +20,6 @@
 #include "kern_util.h"
 #include "user_util.h"
 #include "user.h"
-#include "helper.h"
 #include "os.h"
 
 #define MAX_PACKET ETH_MAX_PACKET
diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
new file mode 100644
index 000000000000..36cc8475bcda
--- /dev/null
+++ b/arch/um/os-Linux/helper.c
@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sched.h>
+#include <sys/signal.h>
+#include <sys/wait.h>
+#include "user.h"
+#include "kern_util.h"
+#include "user_util.h"
+#include "os.h"
+
+struct helper_data {
+	void (*pre_exec)(void*);
+	void *pre_data;
+	char **argv;
+	int fd;
+};
+
+/* Debugging aid, changed only from gdb */
+int helper_pause = 0;
+
+static void helper_hup(int sig)
+{
+}
+
+static int helper_child(void *arg)
+{
+	struct helper_data *data = arg;
+	char **argv = data->argv;
+	int errval;
+
+	if(helper_pause){
+		signal(SIGHUP, helper_hup);
+		pause();
+	}
+	if(data->pre_exec != NULL)
+		(*data->pre_exec)(data->pre_data);
+	execvp(argv[0], argv);
+	errval = errno;
+	printk("execvp of '%s' failed - errno = %d\n", argv[0], errno);
+	os_write_file(data->fd, &errval, sizeof(errval));
+	kill(os_getpid(), SIGKILL);
+	return(0);
+}
+
+/* Returns either the pid of the child process we run or -E* on failure.
+ * XXX The alloc_stack here breaks if this is called in the tracing thread */
+int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
+	       unsigned long *stack_out)
+{
+	struct helper_data data;
+	unsigned long stack, sp;
+	int pid, fds[2], ret, n;
+
+	if((stack_out != NULL) && (*stack_out != 0))
+		stack = *stack_out;
+	else stack = alloc_stack(0, um_in_interrupt());
+	if(stack == 0)
+		return(-ENOMEM);
+
+	ret = os_pipe(fds, 1, 0);
+	if(ret < 0){
+		printk("run_helper : pipe failed, ret = %d\n", -ret);
+		goto out_free;
+	}
+
+	ret = os_set_exec_close(fds[1], 1);
+	if(ret < 0){
+		printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n",
+		       -ret);
+		goto out_close;
+	}
+
+	sp = stack + page_size() - sizeof(void *);
+	data.pre_exec = pre_exec;
+	data.pre_data = pre_data;
+	data.argv = argv;
+	data.fd = fds[1];
+	pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data);
+	if(pid < 0){
+		ret = -errno;
+		printk("run_helper : clone failed, errno = %d\n", errno);
+		goto out_close;
+	}
+
+	close(fds[1]);
+	fds[1] = -1;
+
+	/*Read the errno value from the child.*/
+	n = os_read_file(fds[0], &ret, sizeof(ret));
+	if(n < 0){
+		printk("run_helper : read on pipe failed, ret = %d\n", -n);
+		ret = n;
+		kill(pid, SIGKILL);
+		CATCH_EINTR(waitpid(pid, NULL, 0));
+	}
+	else if(n != 0){
+		CATCH_EINTR(n = waitpid(pid, NULL, 0));
+		ret = -errno;
+	} else {
+		ret = pid;
+	}
+
+out_close:
+	if (fds[1] != -1)
+		close(fds[1]);
+	close(fds[0]);
+out_free:
+	if(stack_out == NULL)
+		free_stack(stack, 0);
+	else *stack_out = stack;
+	return(ret);
+}
+
+int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
+		      unsigned long *stack_out, int stack_order)
+{
+	unsigned long stack, sp;
+	int pid, status, err;
+
+	stack = alloc_stack(stack_order, um_in_interrupt());
+	if(stack == 0) return(-ENOMEM);
+
+	sp = stack + (page_size() << stack_order) - sizeof(void *);
+	pid = clone(proc, (void *) sp, flags | SIGCHLD, arg);
+	if(pid < 0){
+		err = -errno;
+		printk("run_helper_thread : clone failed, errno = %d\n",
+		       errno);
+		return err;
+	}
+	if(stack_out == NULL){
+		CATCH_EINTR(pid = waitpid(pid, &status, 0));
+		if(pid < 0){
+			err = -errno;
+			printk("run_helper_thread - wait failed, errno = %d\n",
+			       errno);
+			pid = err;
+		}
+		if(!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
+			printk("run_helper_thread - thread returned status "
+			       "0x%x\n", status);
+		free_stack(stack, stack_order);
+	}
+	else *stack_out = stack;
+	return(pid);
+}
+
+int helper_wait(int pid)
+{
+	int ret;
+
+	CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG));
+	if(ret < 0){
+		ret = -errno;
+		printk("helper_wait : waitpid failed, errno = %d\n", errno);
+	}
+	return(ret);
+}