/*

  zip_source_zip_new.c -- prepare data structures for zip_fopen/zip_source_zip

  Copyright (C) 2012-2024 Dieter Baron and Thomas Klausner

  This file is part of libzip, a library to manipulate ZIP archives.

  The authors can be contacted at <info@libzip.org>

  Redistribution and use in source and binary forms, with or without

  modification, are permitted provided that the following conditions

  are met:

  1. Redistributions of source code must retain the above copyright

     notice, this list of conditions and the following disclaimer.

  2. 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.

  3. The names of the authors may not be used to endorse or promote

     products derived from this software without specific prior

     written permission.

  THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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 <stdlib.h>

#include "zipint.h"

static void _zip_file_attributes_from_dirent(zip_file_attributes_t *attributes, zip_dirent_t *de);

ZIP_EXTERN zip_source_t *zip_source_zip_file(zip_t *za, zip_t *srcza, zip_uint64_t srcidx, zip_flags_t flags, zip_uint64_t start, zip_int64_t len, const char *password) {

    return zip_source_zip_file_create(srcza, srcidx, flags, start, len, password, &za->error);

}

ZIP_EXTERN zip_source_t *zip_source_zip_file_create(zip_t *srcza, zip_uint64_t srcidx, zip_flags_t flags, zip_uint64_t start, zip_int64_t len, const char *password, zip_error_t *error) {

    /* TODO: We need to make sure that the returned source is invalidated when srcza is closed. */

    zip_source_t *src, *s2;

    zip_stat_t st;

    zip_file_attributes_t attributes;

    zip_dirent_t *de;

    bool partial_data, needs_crc, encrypted, needs_decrypt, compressed, needs_decompress, changed_data, have_size, have_comp_size;

    zip_flags_t stat_flags;

    zip_int64_t data_len;

    bool take_ownership = false;

    bool empty_data = false;

    if (srcza == NULL || srcidx >= srcza->nentry || len < -1) {

        zip_error_set(error, ZIP_ER_INVAL, 0);

        return NULL;

    }

    if (flags & ZIP_FL_ENCRYPTED) {

        flags |= ZIP_FL_COMPRESSED;

    }

    changed_data = false;

    if ((flags & ZIP_FL_UNCHANGED) == 0) {

        zip_entry_t *entry = srcza->entry + srcidx;

        if (ZIP_ENTRY_DATA_CHANGED(entry)) {

            if ((flags & ZIP_FL_COMPRESSED) || !zip_source_supports_reopen(entry->source)) {

                zip_error_set(error, ZIP_ER_CHANGED, 0);

                return NULL;

            }

            changed_data = true;

        }

        else if (entry->deleted) {

            zip_error_set(error, ZIP_ER_CHANGED, 0);

            return NULL;

        }

    }

    stat_flags = flags;

    if (!changed_data) {

        stat_flags |= ZIP_FL_UNCHANGED;

    }

    if (zip_stat_index(srcza, srcidx, stat_flags, &st) < 0) {

        zip_error_set(error, ZIP_ER_INTERNAL, 0);

        return NULL;

    }

    if ((start > 0 || len >= 0) && (flags & ZIP_FL_COMPRESSED)) {

        zip_error_set(error, ZIP_ER_INVAL, 0);

        return NULL;

    }

    have_size = (st.valid & ZIP_STAT_SIZE) != 0;

    /* overflow or past end of file */

    if (len >= 0 && ((start > 0 && start + len < start) || (have_size && start + len > st.size))) {

        zip_error_set(error, ZIP_ER_INVAL, 0);

        return NULL;

    }

    if (len == -1) {

        if (have_size) {

            if (st.size - start > ZIP_INT64_MAX) {

                zip_error_set(error, ZIP_ER_INVAL, 0);

                return NULL;

            }

            data_len = (zip_int64_t)(st.size - start);

        }

        else {

            data_len = -1;

        }

    }

    else {

        data_len = len;

    }

    if (have_size) {

        partial_data = (zip_uint64_t)(data_len) < st.size;

    }

    else {

        partial_data = true;

    }

    encrypted = (st.valid & ZIP_STAT_ENCRYPTION_METHOD) && (st.encryption_method != ZIP_EM_NONE);

    needs_decrypt = ((flags & ZIP_FL_ENCRYPTED) == 0) && encrypted;

    compressed = (st.valid & ZIP_STAT_COMP_METHOD) && (st.comp_method != ZIP_CM_STORE);

    needs_decompress = ((flags & ZIP_FL_COMPRESSED) == 0) && compressed;

    /* when reading the whole file, check for CRC errors */

    needs_crc = ((flags & ZIP_FL_COMPRESSED) == 0 || !compressed) && !partial_data && (st.valid & ZIP_STAT_CRC) != 0;

    if (needs_decrypt) {

        if (password == NULL) {

            password = srcza->default_password;

        }

        if (password == NULL) {

            zip_error_set(error, ZIP_ER_NOPASSWD, 0);

            return NULL;

        }

    }

    if ((de = _zip_get_dirent(srcza, srcidx, flags, error)) == NULL) {

        return NULL;

    }

    _zip_file_attributes_from_dirent(&attributes, de);

    have_comp_size = (st.valid & ZIP_STAT_COMP_SIZE) != 0;

    if (needs_decrypt || needs_decompress) {

        empty_data = (have_comp_size && st.comp_size == 0);

    }

    else {

        empty_data = (have_size && st.size == 0);

    }

    if (empty_data) {

        src = zip_source_buffer_with_attributes_create(NULL, 0, 0, &attributes, error);

    }

    else {

        src = NULL;

    }

    /* If we created source buffer above, we want the window source to take ownership of it. */

    take_ownership = src != NULL;

    /* if we created a buffer source above, then treat it as if

       reading the changed data - that way we don't need add another

       special case to the code below that wraps it in the window

       source */

    changed_data = changed_data || (src != NULL);

    if (partial_data && !needs_decrypt && !needs_decompress) {

        struct zip_stat st2;

        zip_t *source_archive;

        zip_uint64_t source_index;

        if (changed_data) {

            if (src == NULL) {

                src = srcza->entry[srcidx].source;

            }

            source_archive = NULL;

            source_index = 0;

        }

        else {

            src = srcza->src;

            source_archive = srcza;

            source_index = srcidx;

        }

        st2.comp_method = ZIP_CM_STORE;

        st2.valid = ZIP_STAT_COMP_METHOD;

        if (data_len >= 0) {

            st2.size = (zip_uint64_t)data_len;

            st2.comp_size = (zip_uint64_t)data_len;

            st2.valid |= ZIP_STAT_SIZE | ZIP_STAT_COMP_SIZE;

        }

        if (st.valid & ZIP_STAT_MTIME) {

            st2.mtime = st.mtime;

            st2.valid |= ZIP_STAT_MTIME;

        }

        s2 = _zip_source_window_new(src, start, data_len, &st2, ZIP_STAT_NAME, &attributes, &de->last_mod, source_archive, source_index, take_ownership, error);

        if (s2 == NULL) {

            if (take_ownership) {

                zip_source_free(src);

            }

            return NULL;

        }

        src = s2;

    }

    /* here we restrict src to file data, so no point in doing it for

       source that already represents only the file data */

    else if (!changed_data) {

        /* this branch is executed only for archive sources; we know

           that stat data come from the archive too, so it's safe to

           assume that st has a comp_size specified */

        if (st.comp_size > ZIP_INT64_MAX) {

            zip_error_set(error, ZIP_ER_INVAL, 0);

            return NULL;

        }

        /* despite the fact that we want the whole data file, we still

           wrap the source into a window source to add st and

           attributes and to have a source that positions the read

           offset properly before each read for multiple zip_file_t

           referring to the same underlying source */

        if ((src = _zip_source_window_new(srcza->src, 0, (zip_int64_t)st.comp_size, &st, ZIP_STAT_NAME, &attributes, &de->last_mod, srcza, srcidx, take_ownership, error)) == NULL) {

            return NULL;

        }

    }

    else {

        /* this branch gets executed when reading the whole changed

           data file or when "reading" from a zero-sized source buffer

           that we created above */

        if (src == NULL) {

            src = srcza->entry[srcidx].source;

        }

        /* despite the fact that we want the whole data file, we still

           wrap the source into a window source to add st and

           attributes and to have a source that positions the read

           offset properly before each read for multiple zip_file_t

           referring to the same underlying source */

        s2 = _zip_source_window_new(src, 0, data_len, &st, ZIP_STAT_NAME, &attributes, &de->last_mod, NULL, 0, take_ownership, error);

        if (s2 == NULL) {

            if (take_ownership) {

                zip_source_free(src);

            }

            return NULL;

        }

        src = s2;

    }

    /* In all cases, src is a window source and therefore is owned by this function. */

    if (_zip_source_set_source_archive(src, srcza) < 0) {

        zip_source_free(src);

        return NULL;

    }

    /* creating a layered source calls zip_keep() on the lower layer, so we free it */

    if (needs_decrypt) {

        zip_encryption_implementation enc_impl;

        if ((enc_impl = _zip_get_encryption_implementation(st.encryption_method, ZIP_CODEC_DECODE)) == NULL) {

            zip_source_free(src);

            zip_error_set(error, ZIP_ER_ENCRNOTSUPP, 0);

            return NULL;

        }

        s2 = enc_impl(srcza, src, st.encryption_method, 0, password);

        if (s2 == NULL) {

            zip_source_free(src);

            return NULL;

        }

        src = s2;

    }

    if (needs_decompress) {

        s2 = zip_source_decompress(srcza, src, st.comp_method);

        if (s2 == NULL) {

            zip_source_free(src);

            return NULL;

        }

        src = s2;

    }

    if (needs_crc) {

        s2 = zip_source_crc_create(src, 1, error);

        if (s2 == NULL) {

            zip_source_free(src);

            return NULL;

        }

        src = s2;

    }

    if (partial_data && (needs_decrypt || needs_decompress)) {

        zip_stat_t st2;

        zip_stat_init(&st2);

        if (data_len >= 0) {

            st2.valid = ZIP_STAT_SIZE;

            st2.size = (zip_uint64_t)data_len;

        }

        s2 = _zip_source_window_new(src, start, data_len, &st2, ZIP_STAT_NAME, NULL, NULL, NULL, 0, true, error);

        if (s2 == NULL) {

            zip_source_free(src);

            return NULL;

        }

        src = s2;

    }

    return src;

}

static void _zip_file_attributes_from_dirent(zip_file_attributes_t *attributes, zip_dirent_t *de) {

    zip_file_attributes_init(attributes);

    attributes->valid = ZIP_FILE_ATTRIBUTES_ASCII | ZIP_FILE_ATTRIBUTES_HOST_SYSTEM | ZIP_FILE_ATTRIBUTES_EXTERNAL_FILE_ATTRIBUTES | ZIP_FILE_ATTRIBUTES_GENERAL_PURPOSE_BIT_FLAGS;

    attributes->ascii = de->int_attrib & 1;

    attributes->host_system = de->version_madeby >> 8;

    attributes->external_file_attributes = de->ext_attrib;

    attributes->general_purpose_bit_flags = de->bitflags;

    attributes->general_purpose_bit_mask = ZIP_FILE_ATTRIBUTES_GENERAL_PURPOSE_BIT_FLAGS_ALLOWED_MASK;

}