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/*
 * 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>

/** 
 * Bias used for loading the dynamic linker. This will be soon replaced
 * by automatic placement.
 */
#define RTLD_BIAS 0x80000

/** 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_write_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;

//  printf("Load program '%s'\n", pathname);

    rc = elf_load_file(pathname, 0, &prog_info);
    if (rc < 0) {
        printf("failed to load program\n");
        ipc_answer_0(rid, EINVAL);
        return 1;
    }

//  printf("Create PCB\n");
    elf_create_pcb(&prog_info, &pcb);

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

    if (prog_info.interp == NULL) {
        /* Statically linked program */
//      printf("Run statically linked program\n");
//      printf("entry point: 0x%llx\n", prog_info.entry);
        is_dyn_linked = false;
        ipc_answer_0(rid, EOK);
        return 0;
    }

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

    /*
     * Provide dynamic linker with some useful data
     */
    pcb.rtld_dynamic = interp_info.dynamic;
    pcb.rtld_bias = RTLD_BIAS;

    printf("run dynamic linker\n");
    printf("rtld_dynamic = 0x%lx\n", pcb.rtld_dynamic);
    printf("entry point: 0x%lx\n", interp_info.entry);
    printf("pcb address: 0x%lx\n", &pcb);

    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%llx\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 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;
}

/** @}
 */