/*
* 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 <stdint.h>
/* 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 */