source: mainline/uspace/lib/bithenge/src/blob.c

/*
 * Copyright (c) 2012 Sean Bartell
 * 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 bithenge
 * @{
 */
/**
 * @file
 * Raw binary blobs.
 */

#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include "common.h"
#include <bithenge/blob.h>
#include <bithenge/tree.h>

/** Initialize a random access blob.
 * @memberof bithenge_blob_t
 * @param[out] blob The blob to initialize.
 * @param[in] ops Operations providing random access support. This pointer must
 * be valid until the blob is destroyed.
 * @return EOK on success or an error code from errno.h.
 */
errno_t bithenge_init_random_access_blob(bithenge_blob_t *blob,
    const bithenge_random_access_blob_ops_t *ops)
{
        assert(blob);
        assert(ops);
        assert(ops->destroy);
        assert(ops->read || ops->read_bits);
        assert(ops->size);

        if (bithenge_should_fail())
                return ENOMEM;

        blob->base.type = BITHENGE_NODE_BLOB;
        blob->base.refs = 1;
        blob->base.blob_ops = ops;
        return EOK;
}

static errno_t sequential_buffer(bithenge_sequential_blob_t *blob, aoff64_t end)
{
        bool need_realloc = false;
        while (end > blob->buffer_size) {
                blob->buffer_size = max(4096, 2 * blob->buffer_size);
                need_realloc = true;
        }
        if (need_realloc) {
                char *buffer = realloc(blob->buffer, blob->buffer_size);
                if (!buffer)
                        return ENOMEM;
                blob->buffer = buffer;
        }
        aoff64_t size = end - blob->data_size;
        errno_t rc = blob->ops->read(blob, blob->buffer + blob->data_size, &size);
        if (rc != EOK)
                return rc;
        blob->data_size += size;
        return EOK;
}

static inline bithenge_sequential_blob_t *blob_as_sequential(
    bithenge_blob_t *base)
{
        return (bithenge_sequential_blob_t *)base;
}

static inline bithenge_blob_t *sequential_as_blob(
    bithenge_sequential_blob_t *blob)
{
        return &blob->base;
}

static errno_t sequential_size(bithenge_blob_t *base, aoff64_t *size)
{
        bithenge_sequential_blob_t *blob = blob_as_sequential(base);
        errno_t rc;
        if (blob->ops->size) {
                rc = blob->ops->size(blob, size);
                if (rc == EOK)
                        return EOK;
        }
        rc = sequential_buffer(blob, blob->buffer_size);
        if (rc != EOK)
                return rc;
        while (blob->data_size == blob->buffer_size) {
                rc = sequential_buffer(blob, 2 * blob->buffer_size);
                if (rc != EOK)
                        return rc;
        }
        *size = blob->data_size;
        return EOK;
}

static errno_t sequential_read(bithenge_blob_t *base, aoff64_t offset,
    char *buffer, aoff64_t *size)
{
        bithenge_sequential_blob_t *blob = blob_as_sequential(base);
        aoff64_t end = offset + *size;
        if (end > blob->data_size) {
                errno_t rc = sequential_buffer(blob, end);
                if (rc != EOK)
                        return rc;
        }
        if (offset > blob->data_size)
                return EINVAL;
        *size = min(*size, blob->data_size - end);
        memcpy(buffer, blob->buffer + offset, *size);
        return EOK;
}

static void sequential_destroy(bithenge_blob_t *base)
{
        bithenge_sequential_blob_t *blob = blob_as_sequential(base);
        free(blob->buffer);
        blob->ops->destroy(blob);
}

static const bithenge_random_access_blob_ops_t sequential_ops = {
        .size = sequential_size,
        .read = sequential_read,
        .destroy = sequential_destroy,
};

/** Initialize a sequential blob.
 * @memberof bithenge_sequential_blob_t
 * @param[out] blob The blob to initialize.
 * @param[in] ops Operations providing sequential access support. This pointer
 * must be valid until the blob is destroyed.
 * @return EOK on success or an error code from errno.h.
 */
errno_t bithenge_init_sequential_blob(bithenge_sequential_blob_t *blob,
    const bithenge_sequential_blob_ops_t *ops)
{
        assert(blob);
        assert(ops);
        assert(ops->destroy);
        assert(ops->read);
        // ops->size is optional

        errno_t rc = bithenge_init_random_access_blob(sequential_as_blob(blob),
            &sequential_ops);
        if (rc != EOK)
                return rc;
        blob->ops = ops;
        blob->buffer = NULL; // realloc(NULL, ...) works like malloc
        blob->buffer_size = 0;
        blob->data_size = 0;
        return EOK;
}

typedef struct {
        bithenge_blob_t base;
        const char *buffer;
        size_t size;
        bool needs_free;
} memory_blob_t;

static inline memory_blob_t *blob_as_memory(bithenge_blob_t *base)
{
        return (memory_blob_t *)base;
}

static inline bithenge_blob_t *memory_as_blob(memory_blob_t *blob)
{
        return &blob->base;
}

static errno_t memory_size(bithenge_blob_t *base, aoff64_t *size)
{
        memory_blob_t *blob = blob_as_memory(base);
        if (bithenge_should_fail())
                return EIO;
        *size = blob->size;
        return EOK;
}

static errno_t memory_read(bithenge_blob_t *base, aoff64_t offset, char *buffer,
    aoff64_t *size)
{
        memory_blob_t *blob = blob_as_memory(base);
        if (offset > blob->size)
                return ELIMIT;
        *size = min(*size, blob->size - offset);
        memcpy(buffer, blob->buffer + offset, *size);
        return EOK;
}

static void memory_destroy(bithenge_blob_t *base)
{
        memory_blob_t *blob = blob_as_memory(base);
        if (blob->needs_free)
                free((void *)blob->buffer);
        free(blob);
}

static const bithenge_random_access_blob_ops_t memory_ops = {
        .size = memory_size,
        .read = memory_read,
        .destroy = memory_destroy,
};

/** Create a blob node from a buffer. The buffer must exist as long as the blob
 * does. The blob must be freed with @a bithenge_node_t::bithenge_node_destroy
 * after it is used.
 * @memberof bithenge_blob_t
 * @param[out] out Stores the created blob node.
 * @param[in] buffer The buffer, which must not be changed until the blob is
 * destroyed.
 * @param len The length of the data.
 * @param needs_free If true, the buffer will be freed with free() if this
 * function fails or the blob is destroyed.
 * @return EOK on success or an error code from errno.h.
 */
errno_t bithenge_new_blob_from_buffer(bithenge_node_t **out, const void *buffer,
    size_t len, bool needs_free)
{
        errno_t rc;
        assert(buffer || !len);

        memory_blob_t *blob = malloc(sizeof(*blob));
        if (!blob) {
                rc = ENOMEM;
                goto error;
        }
        rc = bithenge_init_random_access_blob(memory_as_blob(blob),
            &memory_ops);
        if (rc != EOK)
                goto error;
        blob->buffer = buffer;
        blob->size = len;
        blob->needs_free = needs_free;
        *out = bithenge_blob_as_node(memory_as_blob(blob));
        return EOK;

error:
        if (needs_free)
                free((void *)buffer);
        free(blob);
        return rc;
}

/** Create a blob node from data. Unlike with @a
 * bithenge_blob_t::bithenge_new_blob_from_buffer, the data is copied into a
 * new buffer and the original data can be changed after this call. The blob
 * must be freed with @a bithenge_node_t::bithenge_node_destroy after it is
 * used.
 * @memberof bithenge_blob_t
 * @param[out] out Stores the created blob node.
 * @param[in] data The data.
 * @param len The length of the data.
 * @return EOK on success or an error code from errno.h.
 */
errno_t bithenge_new_blob_from_data(bithenge_node_t **out, const void *data,
    size_t len)
{
        char *buffer = malloc(len);
        if (!buffer)
                return ENOMEM;
        memcpy(buffer, data, len);

        return bithenge_new_blob_from_buffer(out, buffer, len, true);
}

typedef struct {
        bithenge_blob_t base;
        bithenge_blob_t *source;
        aoff64_t offset;
        aoff64_t size;
        bool size_matters;
} subblob_t;

static inline subblob_t *blob_as_subblob(bithenge_blob_t *base)
{
        return (subblob_t *)base;
}

static inline bithenge_blob_t *subblob_as_blob(subblob_t *blob)
{
        return &blob->base;
}

static errno_t subblob_size(bithenge_blob_t *base, aoff64_t *size)
{
        subblob_t *blob = blob_as_subblob(base);
        if (blob->size_matters) {
                *size = blob->size;
                return EOK;
        } else {
                errno_t rc = bithenge_blob_size(blob->source, size);
                *size -= blob->offset;
                return rc;
        }
}

static errno_t subblob_read(bithenge_blob_t *base, aoff64_t offset,
    char *buffer, aoff64_t *size)
{
        subblob_t *blob = blob_as_subblob(base);
        if (blob->size_matters) {
                if (offset > blob->size)
                        return EINVAL;
                *size = min(*size, blob->size - offset);
        }
        offset += blob->offset;
        return bithenge_blob_read(blob->source, offset, buffer, size);
}

static errno_t subblob_read_bits(bithenge_blob_t *base, aoff64_t offset,
    char *buffer, aoff64_t *size, bool little_endian)
{
        subblob_t *blob = blob_as_subblob(base);
        if (blob->size_matters) {
                if (offset > blob->size)
                        return EINVAL;
                *size = min(*size, blob->size - offset);
        }
        offset += blob->offset;
        return bithenge_blob_read_bits(blob->source, offset, buffer, size,
            little_endian);
}

static void subblob_destroy(bithenge_blob_t *base)
{
        subblob_t *blob = blob_as_subblob(base);
        bithenge_blob_dec_ref(blob->source);
        free(blob);
}

static const bithenge_random_access_blob_ops_t subblob_ops = {
        .size = subblob_size,
        .read = subblob_read,
        .read_bits = subblob_read_bits,
        .destroy = subblob_destroy,
};

static bool is_subblob(bithenge_blob_t *blob)
{
        return blob->base.blob_ops == &subblob_ops;
}

static errno_t new_subblob(bithenge_node_t **out, bithenge_blob_t *source,
    aoff64_t offset, aoff64_t size, bool size_matters)
{
        assert(out);
        assert(source);
        errno_t rc;
        subblob_t *blob = 0;

        if (is_subblob(source)) {
                /* We can do some optimizations this way */
                if (!size_matters)
                        size = 0;
                subblob_t *source_subblob = blob_as_subblob(source);
                if (source_subblob->size_matters &&
                    offset + size > source_subblob->size) {
                        rc = EINVAL;
                        goto error;
                }

                if (source->base.refs == 1) {
                        source_subblob->offset += offset;
                        source_subblob->size -= offset;
                        if (size_matters) {
                                source_subblob->size_matters = true;
                                source_subblob->size = size;
                        }
                        *out = bithenge_blob_as_node(source);
                        return EOK;
                }

                if (!size_matters && source_subblob->size_matters) {
                        size_matters = true;
                        size = source_subblob->size - offset;
                }
                offset += source_subblob->offset;
                source = source_subblob->source;
                bithenge_blob_inc_ref(source);
                bithenge_blob_dec_ref(subblob_as_blob(source_subblob));
        }

        blob = malloc(sizeof(*blob));
        if (!blob) {
                rc = ENOMEM;
                goto error;
        }
        rc = bithenge_init_random_access_blob(subblob_as_blob(blob),
            &subblob_ops);
        if (rc != EOK)
                goto error;
        blob->source = source;
        blob->offset = offset;
        blob->size = size;
        blob->size_matters = size_matters;
        *out = bithenge_blob_as_node(subblob_as_blob(blob));
        return EOK;

error:
        bithenge_blob_dec_ref(source);
        free(blob);
        return rc;
}

/** Create a blob from data offset within another blob. This function takes
 * ownership of a reference to @a blob.
 * @param[out] out Stores the created blob node. On error, this is unchanged.
 * @param[in] source The input blob.
 * @param offset The offset within the input blob at which the new blob will start.
 * @return EOK on success or an error code from errno.h.
 */
errno_t bithenge_new_offset_blob(bithenge_node_t **out, bithenge_blob_t *source,
    aoff64_t offset)
{
        return new_subblob(out, source, offset, 0, false);
}

/** Create a blob from part of another blob. This function takes ownership of a
 * reference to @a blob.
 * @param[out] out Stores the created blob node. On error, this is unchanged.
 * @param[in] source The input blob.
 * @param offset The offset within the input blob at which the new blob will start.
 * @param size The size of the new blob.
 * @return EOK on success or an error code from errno.h.
 */
errno_t bithenge_new_subblob(bithenge_node_t **out, bithenge_blob_t *source,
    aoff64_t offset, aoff64_t size)
{
        return new_subblob(out, source, offset, size, true);
}

/** Check whether the contents of two blobs are equal.
 * @memberof bithenge_blob_t
 * @param[out] out Holds whether the blobs are equal.
 * @param a, b Blobs to compare.
 * @return EOK on success, or an error code from errno.h.
 */
errno_t bithenge_blob_equal(bool *out, bithenge_blob_t *a, bithenge_blob_t *b)
{
        assert(a);
        assert(a->base.blob_ops);
        assert(b);
        assert(b->base.blob_ops);
        errno_t rc;
        char buffer_a[4096], buffer_b[4096];
        aoff64_t offset = 0, size_a = sizeof(buffer_a), size_b = sizeof(buffer_b);
        do {
                rc = bithenge_blob_read(a, offset, buffer_a, &size_a);
                if (rc != EOK)
                        return rc;
                rc = bithenge_blob_read(b, offset, buffer_b, &size_b);
                if (rc != EOK)
                        return rc;
                if (size_a != size_b || memcmp(buffer_a, buffer_b, size_a) != 0) {
                        *out = false;
                        return EOK;
                }
                offset += size_a;
        } while (size_a == sizeof(buffer_a));
        *out = true;
        return EOK;
}

/** @}
 */