/*

 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. 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.

 *

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR

 * CONTRIBUTORS 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.

 */

#include <assert.h>

#include <string.h>

#include <stdlib.h>

#include "endian.hpp"

#include "imageDecompressor.hpp"

#include "imageFile.hpp"

#include "inttypes.hpp"

#include "jni.h"

#include "osSupport.hpp"

// Map the full jimage, only with 64 bit addressing.

bool ImageFileReader::memory_map_image = sizeof(void *) == 8;

#ifdef WIN32

const char FileSeparator = '\\';

#else

const char FileSeparator = '/';

#endif

// Image files are an alternate file format for storing classes and resources. The

// goal is to supply file access which is faster and smaller than the jar format.

//

// (More detailed nodes in the header.)

//

// Compute the Perfect Hashing hash code for the supplied UTF-8 string.

s4 ImageStrings::hash_code(const char* string, s4 seed) {

    // Access bytes as unsigned.

    u1* bytes = (u1*)string;

    // Compute hash code.

    for (u1 byte = *bytes++; byte; byte = *bytes++) {

        seed = (seed * HASH_MULTIPLIER) ^ byte;

    }

    // Ensure the result is not signed.

    return seed & 0x7FFFFFFF;

}

// Match up a string in a perfect hash table.

// Returns the index where the name should be.

// Result still needs validation for precise match (false positive.)

s4 ImageStrings::find(Endian* endian, const char* name, s4* redirect, u4 length) {

    // If the table is empty, then short cut.

    if (!redirect || !length) {

        return NOT_FOUND;

    }

    // Compute the basic perfect hash for name.

    s4 hash_code = ImageStrings::hash_code(name);

    // Modulo table size.

    s4 index = hash_code % length;

    // Get redirect entry.

    //   value == 0 then not found

    //   value < 0 then -1 - value is true index

    //   value > 0 then value is seed for recomputing hash.

    s4 value = endian->get(redirect[index]);

    // if recompute is required.

    if (value > 0 ) {

        // Entry collision value, need to recompute hash.

        hash_code = ImageStrings::hash_code(name, value);

        // Modulo table size.

        return hash_code % length;

    } else if (value < 0) {

        // Compute direct index.

        return -1 - value;

    }

    // No entry found.

    return NOT_FOUND;

}

// Test to see if UTF-8 string begins with the start UTF-8 string.  If so,

// return non-NULL address of remaining portion of string.  Otherwise, return

// NULL.    Used to test sections of a path without copying from image string

// table.

const char* ImageStrings::starts_with(const char* string, const char* start) {

    char ch1, ch2;

    // Match up the strings the best we can.

    while ((ch1 = *string) && (ch2 = *start)) {

        if (ch1 != ch2) {

            // Mismatch, return NULL.

            return NULL;

        }

        // Next characters.

        string++, start++;

    }

    // Return remainder of string.

    return string;

}

// Inflates the attribute stream into individual values stored in the long

// array _attributes. This allows an attribute value to be quickly accessed by

// direct indexing.  Unspecified values default to zero (from constructor.)

void ImageLocation::set_data(u1* data) {

    // Deflate the attribute stream into an array of attributes.

    u1 byte;

    // Repeat until end header is found.

    while ((data != NULL) && (byte = *data)) {

        // Extract kind from header byte.

        u1 kind = attribute_kind(byte);

        assert(kind < ATTRIBUTE_COUNT && "invalid image location attribute");

        // Extract length of data (in bytes).

        u1 n = attribute_length(byte);

        // Read value (most significant first.)

        _attributes[kind] = attribute_value(data + 1, n);

        // Position to next attribute by skipping attribute header and data bytes.

        data += n + 1;

    }

}

// Zero all attribute values.

void ImageLocation::clear_data() {

    // Set defaults to zero.

    memset(_attributes, 0, sizeof(_attributes));

}

// ImageModuleData constructor maps out sub-tables for faster access.

ImageModuleData::ImageModuleData(const ImageFileReader* image_file) :

        _image_file(image_file),

        _endian(image_file->endian()) {

}

// Release module data resource.

ImageModuleData::~ImageModuleData() {

}

// Return the module in which a package resides.    Returns NULL if not found.

const char* ImageModuleData::package_to_module(const char* package_name) {

    // replace all '/' by '.'

    char* replaced = new char[(int) strlen(package_name) + 1];

    assert(replaced != NULL && "allocation failed");

    int i;

    for (i = 0; package_name[i] != '\0'; i++) {

      replaced[i] = package_name[i] == '/' ? '.' : package_name[i];

    }

    replaced[i] = '\0';

    // build path /packages/<package_name>

    const char* radical = "/packages/";

    char* path = new char[(int) strlen(radical) + (int) strlen(package_name) + 1];

    assert(path != NULL && "allocation failed");

    strcpy(path, radical);

    strcat(path, replaced);

    delete[] replaced;

    // retrieve package location

    ImageLocation location;

    bool found = _image_file->find_location(path, location);

    if (!found) {

        delete[] path;

        return NULL;

    }

    // retrieve offsets to module name

    int size = (int)location.get_attribute(ImageLocation::ATTRIBUTE_UNCOMPRESSED);

    u1* content = new u1[size];

    assert(content != NULL && "allocation failed");

    _image_file->get_resource(location, content);

    u1* ptr = content;

    // sequence of sizeof(8) isEmpty|offset. Use the first module that is not empty.

    u4 offset = 0;

    for (i = 0; i < size; i+=8) {

        u4 isEmpty = _endian->get(*((u4*)ptr));

        ptr += 4;

        if (!isEmpty) {

            offset = _endian->get(*((u4*)ptr));

            break;

        }

        ptr += 4;

    }

    delete[] content;

    return _image_file->get_strings().get(offset);

}

// Manage a table of open image files.  This table allows multiple access points

// to share an open image.

ImageFileReaderTable::ImageFileReaderTable() : _count(0), _max(_growth) {

    _table = new ImageFileReader*[_max];

    assert(_table != NULL && "allocation failed");

}

ImageFileReaderTable::~ImageFileReaderTable() {

    delete[] _table;

}

// Add a new image entry to the table.

void ImageFileReaderTable::add(ImageFileReader* image) {

    if (_count == _max) {

        _max += _growth;

        _table = static_cast<ImageFileReader**>(realloc(_table, _max * sizeof(ImageFileReader*)));

    }

    _table[_count++] = image;

}

// Remove an image entry from the table.

void ImageFileReaderTable::remove(ImageFileReader* image) {

    for (u4 i = 0; i < _count; i++) {

        if (_table[i] == image) {

            // Swap the last element into the found slot

            _table[i] = _table[--_count];

            break;

        }

    }

    if (_count != 0 && _count == _max - _growth) {

        _max -= _growth;

        _table = static_cast<ImageFileReader**>(realloc(_table, _max * sizeof(ImageFileReader*)));

    }

}

// Determine if image entry is in table.

bool ImageFileReaderTable::contains(ImageFileReader* image) {

    for (u4 i = 0; i < _count; i++) {

        if (_table[i] == image) {

            return true;

        }

    }

    return false;

}

// Table to manage multiple opens of an image file.

ImageFileReaderTable ImageFileReader::_reader_table;

SimpleCriticalSection _reader_table_lock;

// Locate an image if file already open.

ImageFileReader* ImageFileReader::find_image(const char* name) {

    // Lock out _reader_table.

    SimpleCriticalSectionLock cs(&_reader_table_lock);

    // Search for an exist image file.

    for (u4 i = 0; i < _reader_table.count(); i++) {

        // Retrieve table entry.

        ImageFileReader* reader = _reader_table.get(i);

        // If name matches, then reuse (bump up use count.)

        assert(reader->name() != NULL && "reader->name must not be null");

        if (strcmp(reader->name(), name) == 0) {

            reader->inc_use();

            return reader;

        }

    }

    return NULL;

}

// Open an image file, reuse structure if file already open.

ImageFileReader* ImageFileReader::open(const char* name, bool big_endian) {

    ImageFileReader* reader = find_image(name);

    if (reader != NULL) {

        return reader;

    }

    // Need a new image reader.

    reader = new ImageFileReader(name, big_endian);

    if (reader == NULL || !reader->open()) {

        // Failed to open.

        delete reader;

        return NULL;

    }

    // Lock to update

    SimpleCriticalSectionLock cs(&_reader_table_lock);

    // Search for an existing image file.

    for (u4 i = 0; i < _reader_table.count(); i++) {

        // Retrieve table entry.

        ImageFileReader* existing_reader = _reader_table.get(i);

        // If name matches, then reuse (bump up use count.)

        assert(reader->name() != NULL && "reader->name still must not be null");

        if (strcmp(existing_reader->name(), name) == 0) {

            existing_reader->inc_use();

            reader->close();

            delete reader;

            return existing_reader;

        }

    }

    // Bump use count and add to table.

    reader->inc_use();

    _reader_table.add(reader);

    return reader;

}

// Close an image file if the file is not in use elsewhere.

void ImageFileReader::close(ImageFileReader *reader) {

    // Lock out _reader_table.

    SimpleCriticalSectionLock cs(&_reader_table_lock);

    // If last use then remove from table and then close.

    if (reader->dec_use()) {

        _reader_table.remove(reader);

        delete reader;

    }

}

// Return an id for the specifed ImageFileReader.

u8 ImageFileReader::reader_to_ID(ImageFileReader *reader) {

    // ID is just the cloaked reader address.

    return (u8)reader;

}

// Validate the image id.

bool ImageFileReader::id_check(u8 id) {

    // Make sure the ID is a managed (_reader_table) reader.

    SimpleCriticalSectionLock cs(&_reader_table_lock);

    return _reader_table.contains((ImageFileReader*)id);

}

// Return an id for the specifed ImageFileReader.

ImageFileReader* ImageFileReader::id_to_reader(u8 id) {

    assert(id_check(id) && "invalid image id");

    return (ImageFileReader*)id;

}

// Constructor intializes to a closed state.

ImageFileReader::ImageFileReader(const char* name, bool big_endian) {

    // Copy the image file name.

     int len = (int) strlen(name) + 1;

    _name = new char[len];

    assert(_name != NULL  && "allocation failed");

    strncpy(_name, name, len);

    // Initialize for a closed file.

    _fd = -1;

    _endian = Endian::get_handler(big_endian);

    _index_data = NULL;

}

// Close image and free up data structures.

ImageFileReader::~ImageFileReader() {

    // Ensure file is closed.

    close();

    // Free up name.

    if (_name) {

        delete[] _name;

        _name = NULL;

    }

}

// Open image file for read access.

bool ImageFileReader::open() {

    // If file exists open for reading.

    _fd = osSupport::openReadOnly(_name);

    if (_fd == -1) {

        return false;

    }

    // Retrieve the file size.

    _file_size = osSupport::size(_name);

    // Read image file header and verify it has a valid header.

    size_t header_size = sizeof(ImageHeader);

    if (_file_size < header_size ||

        !read_at((u1*)&_header, header_size, 0) ||

        _header.magic(_endian) != IMAGE_MAGIC ||

        _header.major_version(_endian) != MAJOR_VERSION ||

        _header.minor_version(_endian) != MINOR_VERSION) {

        close();

        return false;

    }

    // Size of image index.

    _index_size = index_size();

    // Make sure file is large enough to contain the index.

    if (_file_size < _index_size) {

        return false;

    }

    // Memory map image (minimally the index.)

    _index_data = (u1*)osSupport::map_memory(_fd, _name, 0, (size_t)map_size());

    assert(_index_data && "image file not memory mapped");

    // Retrieve length of index perfect hash table.

    u4 length = table_length();

    // Compute offset of the perfect hash table redirect table.

    u4 redirect_table_offset = (u4)header_size;

    // Compute offset of index attribute offsets.

    u4 offsets_table_offset = redirect_table_offset + length * (u4)sizeof(s4);

    // Compute offset of index location attribute data.

    u4 location_bytes_offset = offsets_table_offset + length * (u4)sizeof(u4);

    // Compute offset of index string table.

    u4 string_bytes_offset = location_bytes_offset + locations_size();

    // Compute address of the perfect hash table redirect table.

    _redirect_table = (s4*)(_index_data + redirect_table_offset);

    // Compute address of index attribute offsets.

    _offsets_table = (u4*)(_index_data + offsets_table_offset);

    // Compute address of index location attribute data.

    _location_bytes = _index_data + location_bytes_offset;

    // Compute address of index string table.

    _string_bytes = _index_data + string_bytes_offset;

    // Initialize the module data

    module_data = new ImageModuleData(this);

    // Successful open (if memory allocation succeeded).

    return module_data != NULL;

}

// Close image file.

void ImageFileReader::close() {

    // Deallocate the index.

    if (_index_data) {

        osSupport::unmap_memory((char*)_index_data, _index_size);

        _index_data = NULL;

    }

    // Close file.

    if (_fd != -1) {

        osSupport::close(_fd);

        _fd = -1;

    }

}

// Read directly from the file.

bool ImageFileReader::read_at(u1* data, u8 size, u8 offset) const {

    return (u8)osSupport::read(_fd, (char*)data, size, offset) == size;

}

// Find the location attributes associated with the path.    Returns true if

// the location is found, false otherwise.

bool ImageFileReader::find_location(const char* path, ImageLocation& location) const {

    // Locate the entry in the index perfect hash table.

    s4 index = ImageStrings::find(_endian, path, _redirect_table, table_length());

    // If is found.

    if (index != ImageStrings::NOT_FOUND) {

        // Get address of first byte of location attribute stream.

        u1* data = get_location_data(index);

        // Expand location attributes.

        location.set_data(data);

        // Make sure result is not a false positive.

        return verify_location(location, path);

    }

    return false;

}

// Find the location index and size associated with the path.

// Returns the location index and size if the location is found, 0 otherwise.

u4 ImageFileReader::find_location_index(const char* path, u8 *size) const {

    // Locate the entry in the index perfect hash table.

    s4 index = ImageStrings::find(_endian, path, _redirect_table, table_length());

    // If found.

    if (index != ImageStrings::NOT_FOUND) {

        // Get address of first byte of location attribute stream.

        u4 offset = get_location_offset(index);

        u1* data = get_location_offset_data(offset);

        // Expand location attributes.

        ImageLocation location(data);

        // Make sure result is not a false positive.

        if (verify_location(location, path)) {

                *size = (jlong)location.get_attribute(ImageLocation::ATTRIBUTE_UNCOMPRESSED);

                return offset;

        }

    }

    return 0;            // not found

}

// Assemble the location path from the string fragments indicated in the location attributes.

void ImageFileReader::location_path(ImageLocation& location, char* path, size_t max) const {

    // Manage the image string table.

    ImageStrings strings(_string_bytes, _header.strings_size(_endian));

    // Position to first character of the path buffer.

    char* next = path;

    // Temp for string length.

    size_t length;

    // Get module string.

    const char* module = location.get_attribute(ImageLocation::ATTRIBUTE_MODULE, strings);

    // If module string is not empty string.

    if (*module != '\0') {

        // Get length of module name.

        length = strlen(module);

        // Make sure there is no buffer overflow.

        assert(next - path + length + 2 < max && "buffer overflow");

        // Append '/module/'.

        *next++ = '/';

        strncpy(next, module, length); next += length;

        *next++ = '/';

    }

    // Get parent (package) string.

    const char* parent = location.get_attribute(ImageLocation::ATTRIBUTE_PARENT, strings);