/*
 * 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 <stdbool.h>
#include <fcntl.h>
#include <sys/types.h>
#include <ipc/services.h>
#include <ipc/loader.h>
#include <ns.h>
#include <loader/pcb.h>
#include <entry_point.h>
#include <errno.h>
#include <async.h>
#include <str.h>
#include <as.h>
#include <elf/elf.h>
#include <elf/elf_load.h>
#include <vfs/vfs.h>

#ifdef CONFIG_RTLD
#include <rtld/rtld.h>
#include <rtld/dynamic.h>
#include <rtld/module.h>

static int ldr_load_dyn_linked(elf_info_t *p_info);
#endif

#define DPRINTF(...)

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

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

/** Current working directory */
static char *cwd = NULL;

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

/** Number of preset files */
static unsigned int filc = 0;

static elf_info_t prog_info;

/** Used to limit number of connections to one. */
static bool connected = false;

#ifdef CONFIG_RTLD
/** State structure of the dynamic linker. */
runtime_env_t dload_re;
static module_t prog_mod;
#endif

static void ldr_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 (!async_data_read_receive(&callid, &len)) {
		async_answer_0(callid, EINVAL);
		async_answer_0(rid, EINVAL);
		return;
	}
	
	if (len > sizeof(task_id))
		len = sizeof(task_id);
	
	async_data_read_finalize(callid, &task_id, len);
	async_answer_0(rid, EOK);
}

/** Receive a call setting the current working directory.
 *
 * @param rid
 * @param request
 */
static void ldr_set_cwd(ipc_callid_t rid, ipc_call_t *request)
{
	char *buf;
	int rc = async_data_write_accept((void **) &buf, true, 0, 0, 0, NULL);
	
	if (rc == EOK) {
		if (cwd != NULL)
			free(cwd);
		
		cwd = buf;
	}
	
	async_answer_0(rid, rc);
}

/** Receive a call setting pathname of the program to execute.
 *
 * @param rid
 * @param request
 */
static void ldr_set_pathname(ipc_callid_t rid, ipc_call_t *request)
{
	char *buf;
	int rc = async_data_write_accept((void **) &buf, true, 0, 0, 0, NULL);
	
	if (rc == EOK) {
		if (pathname != NULL)
			free(pathname);
		
		pathname = buf;
	}
	
	async_answer_0(rid, rc);
}

/** Receive a call setting arguments of the program to execute.
 *
 * @param rid
 * @param request
 */
static void ldr_set_args(ipc_callid_t rid, ipc_call_t *request)
{
	char *buf;
	size_t buf_size;
	int rc = async_data_write_accept((void **) &buf, true, 0, 0, 0, &buf_size);
	
	if (rc == EOK) {
		/*
		 * Count number of arguments
		 */
		char *cur = buf;
		int count = 0;
		
		while (cur < buf + buf_size) {
			size_t arg_size = str_size(cur);
			cur += arg_size + 1;
			count++;
		}
		
		/*
		 * Allocate new argv
		 */
		char **_argv = (char **) malloc((count + 1) * sizeof(char *));
		if (_argv == NULL) {
			free(buf);
			async_answer_0(rid, ENOMEM);
			return;
		}
		
		/*
		 * Fill the new argv with argument pointers
		 */
		cur = buf;
		count = 0;
		while (cur < buf + buf_size) {
			_argv[count] = cur;
			
			size_t arg_size = str_size(cur);
			cur += arg_size + 1;
			count++;
		}
		_argv[count] = NULL;
		
		/*
		 * Copy temporary data to global variables
		 */
		if (arg_buf != NULL)
			free(arg_buf);
		
		if (argv != NULL)
			free(argv);
		
		argc = count;
		arg_buf = buf;
		argv = _argv;
	}
	
	async_answer_0(rid, rc);
}

/** Receive a call setting preset files of the program to execute.
 *
 * @param rid
 * @param request
 */
static void ldr_set_files(ipc_callid_t rid, ipc_call_t *request)
{
	size_t count = IPC_GET_ARG1(*request);

	async_exch_t *vfs_exch = vfs_exchange_begin();

	for (filc = 0; filc < count; filc++) {
		ipc_callid_t callid;
		int fd;

		if (!async_state_change_receive(&callid, NULL, NULL, NULL)) {
			async_answer_0(callid, EINVAL);
			break;
		}
		async_state_change_finalize(callid, vfs_exch);
		fd = fd_wait();
		assert(fd == (int) filc);
	}

	vfs_exchange_end(vfs_exch);

	async_answer_0(rid, EOK);
}

/** Load the previously selected program.
 *
 * @param rid
 * @param request
 * @return 0 on success, !0 on error.
 */
static int ldr_load(ipc_callid_t rid, ipc_call_t *request)
{
	int rc;
	
	rc = elf_load_file(pathname, 0, 0, &prog_info);
	if (rc != EE_OK) {
		DPRINTF("Failed to load executable '%s'.\n", pathname);
		async_answer_0(rid, EINVAL);
		return 1;
	}
	
	elf_create_pcb(&prog_info, &pcb);
	
	pcb.cwd = cwd;
	
	pcb.argc = argc;
	pcb.argv = argv;
	
	pcb.filc = filc;
	
	if (prog_info.interp == NULL) {
		/* Statically linked program */
		async_answer_0(rid, EOK);
		return 0;
	}
	
	DPRINTF("Binary is dynamically linked.\n");
#ifdef CONFIG_RTLD
	DPRINTF(" - pcb address: %p\n", &pcb);
	DPRINTF( "- prog dynamic: %p\n", prog_info.dynamic);

	rc = ldr_load_dyn_linked(&prog_info);
#else
	rc = ENOTSUP;
#endif
	async_answer_0(rid, rc);
	return 0;
}

#ifdef CONFIG_RTLD

static int ldr_load_dyn_linked(elf_info_t *p_info)
{
	runtime_env = &dload_re;

	DPRINTF("Load dynamically linked program.\n");

	/*
	 * First we need to process dynamic sections of the executable
	 * program and insert it into the module graph.
	 */

	DPRINTF("Parse program .dynamic section at %p\n", p_info->dynamic);
	dynamic_parse(p_info->dynamic, 0, &prog_mod.dyn);
	prog_mod.bias = 0;
	prog_mod.dyn.soname = "[program]";

	/* Initialize list of loaded modules */
	list_initialize(&runtime_env->modules);
	list_append(&prog_mod.modules_link, &runtime_env->modules);

	/* Pointer to program module. Used as root of the module graph. */
	runtime_env->program = &prog_mod;

	/* Work around non-existent memory space allocation. */
	runtime_env->next_bias = 0x1000000;

	/*
	 * Now we can continue with loading all other modules.
	 */

	DPRINTF("Load all program dependencies\n");
	module_load_deps(&prog_mod);

	/*
	 * Now relocate/link all modules together.
	 */

	/* Process relocations in all modules */
	DPRINTF("Relocate all modules\n");
	modules_process_relocs(&prog_mod);

	/* Pass runtime evironment pointer through PCB. */
	pcb.rtld_runtime = (void *) runtime_env;

	return 0;
}
#endif

/** Run the previously loaded program.
 *
 * @param rid
 * @param request
 * @return 0 on success, !0 on error.
 */
static void ldr_run(ipc_callid_t rid, ipc_call_t *request)
{
	const char *cp;
	
	DPRINTF("Set task name\n");

	/* Set the task name. */
	cp = str_rchr(pathname, '/');
	cp = (cp == NULL) ? pathname : (cp + 1);
	task_set_name(cp);
	
	/* Run program */
	DPRINTF("Reply OK\n");
	async_answer_0(rid, EOK);
	DPRINTF("Jump to entry point at %p\n", pcb.entry);
	entry_point_jmp(prog_info.entry, &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 ldr_connection(ipc_callid_t iid, ipc_call_t *icall, void *arg)
{
	/* Already have a connection? */
	if (connected) {
		async_answer_0(iid, ELIMIT);
		return;
	}
	
	connected = true;
	
	/* Accept the connection */
	async_answer_0(iid, EOK);
	
	/* Ignore parameters, the connection is already open */
	(void) icall;
	
	while (true) {
		int retval;
		ipc_call_t call;
		ipc_callid_t callid = async_get_call(&call);
		
		if (!IPC_GET_IMETHOD(call))
			exit(0);
		
		switch (IPC_GET_IMETHOD(call)) {
		case LOADER_GET_TASKID:
			ldr_get_taskid(callid, &call);
			continue;
		case LOADER_SET_CWD:
			ldr_set_cwd(callid, &call);
			continue;
		case LOADER_SET_PATHNAME:
			ldr_set_pathname(callid, &call);
			continue;
		case LOADER_SET_ARGS:
			ldr_set_args(callid, &call);
			continue;
		case LOADER_SET_FILES:
			ldr_set_files(callid, &call);
			continue;
		case LOADER_LOAD:
			ldr_load(callid, &call);
			continue;
		case LOADER_RUN:
			ldr_run(callid, &call);
			/* Not reached */
		default:
			retval = EINVAL;
			break;
		}
		
		async_answer_0(callid, retval);
	}
}

/** Program loader main function.
 */
int main(int argc, char *argv[])
{
	/* Set a handler of incomming connections. */
	async_set_client_connection(ldr_connection);
	
	/* Introduce this task to the NS (give it our task ID). */
	task_id_t id = task_get_id();
	int rc = ns_intro(id);
	if (rc != EOK)
		return rc;
	
	/* Register at naming service. */
	rc = service_register(SERVICE_LOAD);
	if (rc != EOK)
		return rc;
	
	async_manager();
	
	/* Never reached */
	return 0;
}

/** @}
 */