/*
 * Copyright (c) 2008 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup loader
 * @brief	Loads and runs programs from VFS.
 * @{
 */ 
/**
 * @file
 * @brief	Loads and runs programs from VFS.
 *
 * The program loader is a special init binary. Its image is used
 * to create a new task upon a @c task_spawn syscall. The syscall
 * returns the id of a phone connected to the newly created task.
 *
 * The caller uses this phone to send the pathname and various other
 * information to the loader. This is normally done by the C library
 * and completely hidden from applications.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <bool.h>
#include <fcntl.h>
#include <sys/types.h>
#include <ipc/ipc.h>
#include <ipc/loader.h>
#include <loader/pcb.h>
#include <errno.h>
#include <async.h>
#include <as.h>

#include <elf.h>
#include <elf_load.h>

/** Pathname of the file that will be loaded */
static char *pathname = NULL;

/** The Program control block */
static pcb_t pcb;

/** Number of arguments */
static int argc = 0;
/** Argument vector */
static char **argv = NULL;
/** Buffer holding all arguments */
static char *arg_buf = NULL;

static elf_info_t prog_info;
static elf_info_t interp_info;

static bool is_dyn_linked;


static void loader_get_taskid(ipc_callid_t rid, ipc_call_t *request)
{
	ipc_callid_t callid;
	task_id_t task_id;
	size_t len;

	task_id = task_get_id();

	if (!ipc_data_read_receive(&callid, &len)) {
		ipc_answer_0(callid, EINVAL);
		ipc_answer_0(rid, EINVAL);
		return;
	}

	if (len > sizeof(task_id)) len = sizeof(task_id);

	ipc_data_read_finalize(callid, &task_id, len);
	ipc_answer_0(rid, EOK);
}


/** Receive a call setting pathname of the program to execute.
 *
 * @param rid
 * @param request
 */
static void loader_set_pathname(ipc_callid_t rid, ipc_call_t *request)
{
	ipc_callid_t callid;
	size_t len;
	char *name_buf;

	if (!ipc_data_write_receive(&callid, &len)) {
		ipc_answer_0(callid, EINVAL);
		ipc_answer_0(rid, EINVAL);
		return;
	}

	name_buf = malloc(len + 1);
	if (!name_buf) {
		ipc_answer_0(callid, ENOMEM);
		ipc_answer_0(rid, ENOMEM);
		return;
	}

	ipc_data_write_finalize(callid, name_buf, len);
	ipc_answer_0(rid, EOK);

	if (pathname != NULL) {
		free(pathname);
		pathname = NULL;
	}

	name_buf[len] = '\0';
	pathname = name_buf;
}

/** Receive a call setting arguments of the program to execute.
 *
 * @param rid
 * @param request
 */
static void loader_set_args(ipc_callid_t rid, ipc_call_t *request)
{
	ipc_callid_t callid;
	size_t buf_len, arg_len;
	char *p;
	int n;

	if (!ipc_data_write_receive(&callid, &buf_len)) {
		ipc_answer_0(callid, EINVAL);
		ipc_answer_0(rid, EINVAL);
		return;
	}

	if (arg_buf != NULL) {
		free(arg_buf);
		arg_buf = NULL;
	}

	if (argv != NULL) {
		free(argv);
		argv = NULL;
	}

	arg_buf = malloc(buf_len + 1);
	if (!arg_buf) {
		ipc_answer_0(callid, ENOMEM);
		ipc_answer_0(rid, ENOMEM);
		return;
	}

	ipc_data_write_finalize(callid, arg_buf, buf_len);
	ipc_answer_0(rid, EOK);

	arg_buf[buf_len] = '\0';

	/*
	 * Count number of arguments
	 */
	p = arg_buf;
	n = 0;
	while (p < arg_buf + buf_len) {
		arg_len = strlen(p);
		p = p + arg_len + 1;
		++n;
	}

	/* Allocate argv */
	argv = malloc((n + 1) * sizeof(char *));

	if (argv == NULL) {
		free(arg_buf);
		ipc_answer_0(callid, ENOMEM);
		ipc_answer_0(rid, ENOMEM);
		return;
	}

	/*
	 * Fill argv with argument pointers
	 */
	p = arg_buf;
	n = 0;
	while (p < arg_buf + buf_len) {
		argv[n] = p;

		arg_len = strlen(p);
		p = p + arg_len + 1;
		++n;
	}

	argc = n;
	argv[n] = NULL;
}

/** Load the previously selected program.
 *
 * @param rid
 * @param request
 * @return 0 on success, !0 on error.
 */
static int loader_load(ipc_callid_t rid, ipc_call_t *request)
{
	int rc;

	rc = elf_load_file(pathname, 0, &prog_info);
	if (rc < 0) {
		printf("Failed to load executable '%s'.\n", pathname);
		ipc_answer_0(rid, EINVAL);
		return 1;
	}

	elf_create_pcb(&prog_info, &pcb);

	pcb.argc = argc;
	pcb.argv = argv;

	if (prog_info.interp == NULL) {
		/* Statically linked program */
		is_dyn_linked = false;
		ipc_answer_0(rid, EOK);
		return 0;
	}

	rc = elf_load_file(prog_info.interp, 0, &interp_info);
	if (rc < 0) {
		printf("Failed to load interpreter '%s.'\n", prog_info.interp);
		ipc_answer_0(rid, EINVAL);
		return 1;
	}

	is_dyn_linked = true;
	ipc_answer_0(rid, EOK);

	return 0;
}


/** Run the previously loaded program.
 *
 * @param rid
 * @param request
 * @return 0 on success, !0 on error.
 */
static void loader_run(ipc_callid_t rid, ipc_call_t *request)
{
	if (is_dyn_linked == true) {
		/* Dynamically linked program */
		printf("run dynamic linker\n");
		printf("entry point: 0x%lx\n", interp_info.entry);
		close_console();

		ipc_answer_0(rid, EOK);
		elf_run(&interp_info, &pcb);

	} else {
		/* Statically linked program */
		close_console();
		ipc_answer_0(rid, EOK);
		elf_run(&prog_info, &pcb);
	} 

	/* Not reached */
}

/** Handle loader connection.
 *
 * Receive and carry out commands (of which the last one should be
 * to execute the loaded program).
 */
static void loader_connection(ipc_callid_t iid, ipc_call_t *icall)
{
	ipc_callid_t callid;
	ipc_call_t call;
	int retval;

	/* Ignore parameters, the connection is already open */
	(void)iid; (void)icall;

	while (1) {
		callid = async_get_call(&call);

		switch (IPC_GET_METHOD(call)) {
		case IPC_M_PHONE_HUNGUP:
			exit(0);
		case LOADER_GET_TASKID:
			loader_get_taskid(callid, &call);
			continue;
		case LOADER_SET_PATHNAME:
			loader_set_pathname(callid, &call);
			continue;
		case LOADER_SET_ARGS:
			loader_set_args(callid, &call);
			continue;
		case LOADER_LOAD:
			loader_load(callid, &call);
			continue;
		case LOADER_RUN:
			loader_run(callid, &call);
			/* Not reached */
		default:
			retval = ENOENT;
			break;
		}
		if ((callid & IPC_CALLID_NOTIFICATION) == 0 &&
		    IPC_GET_METHOD(call) != IPC_M_PHONE_HUNGUP) {
			printf("responding EINVAL to method %d\n", 
			    IPC_GET_METHOD(call));
			ipc_answer_0(callid, EINVAL);
		}
	}
}

/** Program loader main function.
 */
int main(int argc, char *argv[])
{
	ipc_callid_t callid;
	ipc_call_t call;
	ipcarg_t phone_hash;

	/* The first call only communicates the incoming phone hash */
	callid = ipc_wait_for_call(&call);

	if (IPC_GET_METHOD(call) != LOADER_HELLO) {
		if (IPC_GET_METHOD(call) != IPC_M_PHONE_HUNGUP)
			ipc_answer_0(callid, EINVAL);
		return 1;
	}

	ipc_answer_0(callid, EOK);
	phone_hash = call.in_phone_hash;

	/* 
	 * Up until now async must not be used as it couldn't
	 * handle incoming requests. (Which means e.g. printf() 
	 * cannot be used)
	 */
	async_new_connection(phone_hash, 0, NULL, loader_connection);
	async_manager();

	/* not reached */
	return 0;
}

/** @}
 */