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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/services.h>
#include <ipc/loader.h>
#include <loader/pcb.h>
#include <errno.h>
#include <async.h>
#include <string.h>
#include <as.h>

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

#define DPRINTF(...)

/** 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;

/** Number of preset files */
static int filc = 0;
/** Preset files vector */
static char **filv = NULL;
/** Buffer holding all preset files */
static inode_t *fil_buf = NULL;

static elf_info_t prog_info;
static elf_info_t interp_info;

static bool is_dyn_linked;

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

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 (!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 ldr_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 ldr_set_args(ipc_callid_t rid, ipc_call_t *request)
{
    ipc_callid_t callid;
    size_t buf_size, arg_size;
    char *p;
    int n;
    
    if (!ipc_data_write_receive(&callid, &buf_size)) {
        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_size + 1);
    if (!arg_buf) {
        ipc_answer_0(callid, ENOMEM);
        ipc_answer_0(rid, ENOMEM);
        return;
    }
    
    ipc_data_write_finalize(callid, arg_buf, buf_size);
    
    arg_buf[buf_size] = '\0';
    
    /*
     * Count number of arguments
     */
    p = arg_buf;
    n = 0;
    while (p < arg_buf + buf_size) {
        arg_size = str_size(p);
        p = p + arg_size + 1;
        ++n;
    }
    
    /* Allocate argv */
    argv = malloc((n + 1) * sizeof(char *));
    
    if (argv == NULL) {
        free(arg_buf);
        ipc_answer_0(rid, ENOMEM);
        return;
    }

    /*
     * Fill argv with argument pointers
     */
    p = arg_buf;
    n = 0;
    while (p < arg_buf + buf_size) {
        argv[n] = p;
        
        arg_size = str_size(p);
        p = p + arg_size + 1;
        ++n;
    }
    
    argc = n;
    argv[n] = NULL;

    ipc_answer_0(rid, EOK);
}

/** 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)
{
    ipc_callid_t callid;
    size_t buf_size;
    if (!ipc_data_write_receive(&callid, &buf_size)) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
    
    if ((buf_size % sizeof(inode_t)) != 0) {
        ipc_answer_0(callid, EINVAL);
        ipc_answer_0(rid, EINVAL);
        return;
    }
    
    if (fil_buf != NULL) {
        free(fil_buf);
        fil_buf = NULL;
    }
    
    if (filv != NULL) {
        free(filv);
        filv = NULL;
    }
    
    fil_buf = malloc(buf_size);
    if (!fil_buf) {
        ipc_answer_0(callid, ENOMEM);
        ipc_answer_0(rid, ENOMEM);
        return;
    }
    
    ipc_data_write_finalize(callid, fil_buf, buf_size);
    
    int count = buf_size / sizeof(inode_t);
    
    /* Allocate filvv */
    filv = malloc((count + 1) * sizeof(inode_t *));
    
    if (filv == NULL) {
        free(fil_buf);
        ipc_answer_0(rid, ENOMEM);
        return;
    }
    
    /*
     * Fill filv with argument pointers
     */
    int i;
    for (i = 0; i < count; i++)
        filv[i] = &fil_buf[i];
    
    filc = count;
    filv[count] = NULL;
    
    ipc_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, &prog_info);
    if (rc != EE_OK) {
        DPRINTF("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;
    
    pcb.filc = filc;
    pcb.filv = filv;
    
    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 != EE_OK) {
        DPRINTF("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 ldr_run(ipc_callid_t rid, ipc_call_t *request)
{
    const char *cp;
    
    /* Set the task name. */
    cp = str_rchr(pathname, '/');
    cp = (cp == NULL) ? pathname : (cp + 1);
    task_set_name(cp);
    
    if (is_dyn_linked == true) {
        /* Dynamically linked program */
        DPRINTF("Run ELF interpreter.\n");
        DPRINTF("Entry point: 0x%lx\n", interp_info.entry);
        
        ipc_answer_0(rid, EOK);
        elf_run(&interp_info, &pcb);
    } else {
        /* Statically linked program */
        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 ldr_connection(ipc_callid_t iid, ipc_call_t *icall)
{
    ipc_callid_t callid;
    ipc_call_t call;
    int retval;
    
    /* Already have a connection? */
    if (connected) {
        ipc_answer_0(iid, ELIMIT);
        return;
    }
    
    connected = true;
    
    /* Accept the connection */
    ipc_answer_0(iid, EOK);
    
    /* 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:
            ldr_get_taskid(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 = ENOENT;
            break;
        }
        if ((callid & IPC_CALLID_NOTIFICATION) == 0 &&
            IPC_GET_METHOD(call) != IPC_M_PHONE_HUNGUP) {
            DPRINTF("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[])
{
    ipcarg_t phonead;
    
    connected = false;
    
    /* Set a handler of incomming connections. */
    async_set_client_connection(ldr_connection);
    
    /* Register at naming service. */
    if (ipc_connect_to_me(PHONE_NS, SERVICE_LOAD, 0, 0, &phonead) != 0) 
        return -1;
    
    async_manager();
    
    /* Never reached */
    return 0;
}

/** @}
 */