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/*

 * Copyright © 2014 Intel Corporation

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the next

 * paragraph) shall be included in all copies or substantial portions of the

 * Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 */

#pragma once

#ifndef BLOB_H

#define BLOB_H

#ifdef __cplusplus

extern "C" {

#endif

#include 

/* The blob functions implement a simple, low-level API for serializing and

 * deserializing.

 *

 * All objects written to a blob will be serialized directly, (without any

 * additional meta-data to describe the data written). Therefore, it is the

 * caller's responsibility to ensure that any data can be read later, (either

 * by knowing exactly what data is expected, or by writing to the blob

 * sufficient meta-data to describe what has been written).

 *

 * A blob is efficient in that it dynamically grows by doubling in size, so

 * allocation costs are logarithmic.

 */

struct blob {

   /* The data actually written to the blob. */

   uint8_t *data;

   /** Number of bytes that have been allocated for \c data. */

   size_t allocated;

   /** The number of bytes that have actual data written to them. */

   size_t size;

};

/* When done reading, the caller can ensure that everything was consumed by

 * checking the following:

 *

 *   1. blob->current should be equal to blob->end, (if not, too little was

 *      read).

 *

 *   2. blob->overrun should be false, (otherwise, too much was read).

 */

struct blob_reader {

   uint8_t *data;

   uint8_t *end;

   uint8_t *current;

   bool overrun;

};

/**

 * Create a new, empty blob, belonging to \mem_ctx.

 *

 * \return The new blob, (or NULL in case of allocation failure).

 */

struct blob *

blob_create (void *mem_ctx);

/**

 * Add some unstructured, fixed-size data to a blob.

 *

 * \return True unless allocation failed.

 */

bool

blob_write_bytes (struct blob *blob, const void *bytes, size_t to_write);

/**

 * Reserve space in \blob for a number of bytes.

 *

 * Space will be allocated within the blob for these byes, but the bytes will

 * be left uninitialized. The caller is expected to use the return value to

 * write directly (and immediately) to these bytes.

 *

 * \note The return value is valid immediately upon return, but can be

 * invalidated by any other call to a blob function. So the caller should call

 * blob_reserve_byes immediately before writing through the returned pointer.

 *

 * This function is intended to be used when interfacing with an existing API

 * that is not aware of the blob API, (so that blob_write_bytes cannot be

 * called).

 *

 * \return A pointer to space allocated within \blob to which \to_write bytes

 * can be written, (or NULL in case of any allocation error).

 */

uint8_t *

blob_reserve_bytes (struct blob *blob, size_t to_write);

/**

 * Overwrite some data previously written to the blob.

 *

 * Writes data to an existing portion of the blob at an offset of \offset.

 * This data range must have previously been written to the blob by one of the

 * blob_write_* calls.

 *

 * For example usage, see blob_overwrite_uint32

 *

 * \return True unless the requested offset or offset+to_write lie outside

 * the current blob's size.

 */

bool

blob_overwrite_bytes (struct blob *blob,

                      size_t offset,

                      const void *bytes,

                      size_t to_write);

/**

 * Add a uint32_t to a blob.

 *

 * \note This function will only write to a uint32_t-aligned offset from the

 * beginning of the blob's data, so some padding bytes may be added to the

 * blob if this write follows some unaligned write (such as

 * blob_write_string).

 *

 * \return True unless allocation failed.

 */

bool

blob_write_uint32 (struct blob *blob, uint32_t value);

/**

 * Overwrite a uint32_t previously written to the blob.

 *

 * Writes a uint32_t value to an existing portion of the blob at an offset of

 * \offset.  This data range must have previously been written to the blob by

 * one of the blob_write_* calls.

 *

 *

 * The expected usage is something like the following pattern:

 *

 *	size_t offset;

 *

 *	offset = blob->size;

 *	blob_write_uint32 (blob, 0); // placeholder

 *	... various blob write calls, writing N items ...

 *	blob_overwrite_uint32 (blob, offset, N);

 *

 * \return True unless the requested position or position+to_write lie outside

 * the current blob's size.

 */

bool

blob_overwrite_uint32 (struct blob *blob,

                       size_t offset,

                       uint32_t value);

/**

 * Add a uint64_t to a blob.

 *

 * \note This function will only write to a uint64_t-aligned offset from the

 * beginning of the blob's data, so some padding bytes may be added to the

 * blob if this write follows some unaligned write (such as

 * blob_write_string).

 *

 * \return True unless allocation failed.

 */

bool

blob_write_uint64 (struct blob *blob, uint64_t value);

/**

 * Add an intptr_t to a blob.

 *

 * \note This function will only write to an intptr_t-aligned offset from the

 * beginning of the blob's data, so some padding bytes may be added to the

 * blob if this write follows some unaligned write (such as

 * blob_write_string).

 *

 * \return True unless allocation failed.

 */

bool

blob_write_intptr (struct blob *blob, intptr_t value);

/**

 * Add a NULL-terminated string to a blob, (including the NULL terminator).

 *

 * \return True unless allocation failed.

 */

bool

blob_write_string (struct blob *blob, const char *str);

/**

 * Start reading a blob, (initializing the contents of \blob for reading).

 *

 * After this call, the caller can use the various blob_read_* functions to

 * read elements from the data array.

 *

 * For all of the blob_read_* functions, if there is insufficient data

 * remaining, the functions will do nothing, (perhaps returning default values

 * such as 0). The caller can detect this by noting that the blob_reader's

 * current value is unchanged before and after the call.

 */

void

blob_reader_init (struct blob_reader *blob, uint8_t *data, size_t size);

/**

 * Read some unstructured, fixed-size data from the current location, (and

 * update the current location to just past this data).

 *

 * \note The memory returned belongs to the data underlying the blob reader. The

 * caller must copy the data in order to use it after the lifetime of the data

 * underlying the blob reader.

 *

 * \return The bytes read (see note above about memory lifetime).

 */

void *

blob_read_bytes (struct blob_reader *blob, size_t size);

/**

 * Read some unstructured, fixed-size data from the current location, copying

 * it to \dest (and update the current location to just past this data)

 */

void

blob_copy_bytes (struct blob_reader *blob, uint8_t *dest, size_t size);

/**

 * Read a uint32_t from the current location, (and update the current location

 * to just past this uint32_t).

 *

 * \note This function will only read from a uint32_t-aligned offset from the

 * beginning of the blob's data, so some padding bytes may be skipped.

 *

 * \return The uint32_t read

 */

uint32_t

blob_read_uint32 (struct blob_reader *blob);

/**

 * Read a uint64_t from the current location, (and update the current location

 * to just past this uint64_t).

 *

 * \note This function will only read from a uint64_t-aligned offset from the

 * beginning of the blob's data, so some padding bytes may be skipped.

 *

 * \return The uint64_t read

 */

uint64_t

blob_read_uint64 (struct blob_reader *blob);

/**

 * Read an intptr_t value from the current location, (and update the

 * current location to just past this intptr_t).

 *

 * \note This function will only read from an intptr_t-aligned offset from the

 * beginning of the blob's data, so some padding bytes may be skipped.

 *

 * \return The intptr_t read

 */

intptr_t

blob_read_intptr (struct blob_reader *blob);

/**

 * Read a NULL-terminated string from the current location, (and update the

 * current location to just past this string).

 *

 * \note The memory returned belongs to the data underlying the blob reader. The

 * caller must copy the string in order to use the string after the lifetime

 * of the data underlying the blob reader.

 *

 * \return The string read (see note above about memory lifetime). However, if

 * there is no NULL byte remaining within the blob, this function returns

 * NULL.

 */

char *

blob_read_string (struct blob_reader *blob);

#ifdef __cplusplus

}

#endif

#endif /* BLOB_H */