443 lines
13 KiB
C
443 lines
13 KiB
C
/*
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* Copyright © 2014 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#ifndef BLOB_H
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#define BLOB_H
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* The blob functions implement a simple, low-level API for serializing and
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* deserializing.
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*
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* All objects written to a blob will be serialized directly, (without any
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* additional meta-data to describe the data written). Therefore, it is the
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* caller's responsibility to ensure that any data can be read later, (either
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* by knowing exactly what data is expected, or by writing to the blob
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* sufficient meta-data to describe what has been written).
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*
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* A blob is efficient in that it dynamically grows by doubling in size, so
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* allocation costs are logarithmic.
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*/
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struct blob {
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/* The data actually written to the blob. Never read or write this directly
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* when serializing, use blob_reserve_* and blob_overwrite_* instead which
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* check for out_of_memory and handle fixed-size blobs correctly.
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*/
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uint8_t *data;
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/** Number of bytes that have been allocated for \c data. */
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size_t allocated;
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/** The number of bytes that have actual data written to them. */
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size_t size;
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/** True if \c data a fixed allocation that we cannot resize
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*
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* \see blob_init_fixed
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*/
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bool fixed_allocation;
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/**
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* True if we've ever failed to realloc or if we go pas the end of a fixed
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* allocation blob.
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*/
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bool out_of_memory;
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};
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/* When done reading, the caller can ensure that everything was consumed by
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* checking the following:
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*
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* 1. blob->current should be equal to blob->end, (if not, too little was
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* read).
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*
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* 2. blob->overrun should be false, (otherwise, too much was read).
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*/
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struct blob_reader {
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const uint8_t *data;
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const uint8_t *end;
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const uint8_t *current;
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bool overrun;
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};
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/**
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* Init a new, empty blob.
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*/
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void
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blob_init(struct blob *blob);
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/**
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* Init a new, fixed-size blob.
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*
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* A fixed-size blob has a fixed block of data that will not be freed on
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* blob_finish and will never be grown. If we hit the end, we simply start
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* returning false from the write functions.
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*
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* If a fixed-size blob has a NULL data pointer then the data is written but
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* it otherwise operates normally. This can be used to determine the size
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* that will be required to write a given data structure.
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*/
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void
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blob_init_fixed(struct blob *blob, void *data, size_t size);
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/**
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* Finish a blob and free its memory.
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*
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* If \blob was initialized with blob_init_fixed, the data pointer is
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* considered to be owned by the user and will not be freed.
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*/
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static inline void
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blob_finish(struct blob *blob)
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{
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if (!blob->fixed_allocation)
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free(blob->data);
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}
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void
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blob_finish_get_buffer(struct blob *blob, void **buffer, size_t *size);
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/**
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* Aligns the blob to the given alignment.
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*
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* \see blob_reader_align
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*
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* \return True unless allocation fails
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*/
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bool
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blob_align(struct blob *blob, size_t alignment);
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/**
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* Add some unstructured, fixed-size data to a blob.
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*
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* \return True unless allocation failed.
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*/
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bool
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blob_write_bytes(struct blob *blob, const void *bytes, size_t to_write);
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/**
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* Reserve space in \blob for a number of bytes.
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*
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* Space will be allocated within the blob for these byes, but the bytes will
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* be left uninitialized. The caller is expected to use \sa
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* blob_overwrite_bytes to write to these bytes.
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*
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* \return An offset to space allocated within \blob to which \to_write bytes
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* can be written, (or -1 in case of any allocation error).
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*/
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intptr_t
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blob_reserve_bytes(struct blob *blob, size_t to_write);
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/**
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* Similar to \sa blob_reserve_bytes, but only reserves an uint32_t worth of
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* space. Note that this must be used if later reading with \sa
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* blob_read_uint32, since it aligns the offset correctly.
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*/
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intptr_t
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blob_reserve_uint32(struct blob *blob);
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/**
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* Similar to \sa blob_reserve_bytes, but only reserves an intptr_t worth of
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* space. Note that this must be used if later reading with \sa
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* blob_read_intptr, since it aligns the offset correctly.
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*/
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intptr_t
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blob_reserve_intptr(struct blob *blob);
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/**
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* Overwrite some data previously written to the blob.
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*
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* Writes data to an existing portion of the blob at an offset of \offset.
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* This data range must have previously been written to the blob by one of the
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* blob_write_* calls.
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*
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* For example usage, see blob_overwrite_uint32
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*
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* \return True unless the requested offset or offset+to_write lie outside
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* the current blob's size.
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*/
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bool
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blob_overwrite_bytes(struct blob *blob,
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size_t offset,
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const void *bytes,
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size_t to_write);
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/**
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* Add a uint8_t to a blob.
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*
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* \return True unless allocation failed.
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*/
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bool
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blob_write_uint8(struct blob *blob, uint8_t value);
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/**
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* Overwrite a uint8_t previously written to the blob.
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*
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* Writes a uint8_t value to an existing portion of the blob at an offset of
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* \offset. This data range must have previously been written to the blob by
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* one of the blob_write_* calls.
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*
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* \return True unless the requested position or position+to_write lie outside
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* the current blob's size.
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*/
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bool
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blob_overwrite_uint8(struct blob *blob,
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size_t offset,
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uint8_t value);
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/**
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* Add a uint16_t to a blob.
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*
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* \note This function will only write to a uint16_t-aligned offset from the
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* beginning of the blob's data, so some padding bytes may be added to the
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* blob if this write follows some unaligned write (such as
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* blob_write_string).
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*
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* \return True unless allocation failed.
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*/
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bool
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blob_write_uint16(struct blob *blob, uint16_t value);
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/**
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* Add a uint32_t to a blob.
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*
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* \note This function will only write to a uint32_t-aligned offset from the
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* beginning of the blob's data, so some padding bytes may be added to the
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* blob if this write follows some unaligned write (such as
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* blob_write_string).
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*
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* \return True unless allocation failed.
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*/
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bool
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blob_write_uint32(struct blob *blob, uint32_t value);
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/**
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* Overwrite a uint32_t previously written to the blob.
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*
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* Writes a uint32_t value to an existing portion of the blob at an offset of
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* \offset. This data range must have previously been written to the blob by
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* one of the blob_write_* calls.
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*
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*
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* The expected usage is something like the following pattern:
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*
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* size_t offset;
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*
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* offset = blob_reserve_uint32(blob);
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* ... various blob write calls, writing N items ...
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* blob_overwrite_uint32 (blob, offset, N);
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*
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* \return True unless the requested position or position+to_write lie outside
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* the current blob's size.
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*/
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bool
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blob_overwrite_uint32(struct blob *blob,
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size_t offset,
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uint32_t value);
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/**
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* Add a uint64_t to a blob.
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*
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* \note This function will only write to a uint64_t-aligned offset from the
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* beginning of the blob's data, so some padding bytes may be added to the
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* blob if this write follows some unaligned write (such as
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* blob_write_string).
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*
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* \return True unless allocation failed.
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*/
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bool
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blob_write_uint64(struct blob *blob, uint64_t value);
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/**
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* Add an intptr_t to a blob.
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*
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* \note This function will only write to an intptr_t-aligned offset from the
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* beginning of the blob's data, so some padding bytes may be added to the
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* blob if this write follows some unaligned write (such as
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* blob_write_string).
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*
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* \return True unless allocation failed.
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*/
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bool
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blob_write_intptr(struct blob *blob, intptr_t value);
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/**
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* Overwrite an intptr_t previously written to the blob.
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*
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* Writes a intptr_t value to an existing portion of the blob at an offset of
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* \offset. This data range must have previously been written to the blob by
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* one of the blob_write_* calls.
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*
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* For example usage, see blob_overwrite_uint32
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*
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* \return True unless the requested position or position+to_write lie outside
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* the current blob's size.
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*/
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bool
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blob_overwrite_intptr(struct blob *blob,
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size_t offset,
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intptr_t value);
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/**
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* Add a NULL-terminated string to a blob, (including the NULL terminator).
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*
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* \return True unless allocation failed.
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*/
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bool
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blob_write_string(struct blob *blob, const char *str);
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/**
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* Start reading a blob, (initializing the contents of \blob for reading).
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*
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* After this call, the caller can use the various blob_read_* functions to
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* read elements from the data array.
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*
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* For all of the blob_read_* functions, if there is insufficient data
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* remaining, the functions will do nothing, (perhaps returning default values
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* such as 0). The caller can detect this by noting that the blob_reader's
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* current value is unchanged before and after the call.
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*/
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void
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blob_reader_init(struct blob_reader *blob, const void *data, size_t size);
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/**
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* Align the current offset of the blob reader to the given alignment.
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*
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* This may be useful if you need the result of blob_read_bytes to have a
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* particular alignment. Note that this only aligns relative to blob->data
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* and the alignment of the resulting pointer is only guaranteed if blob->data
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* is also aligned to the requested alignment.
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*/
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void
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blob_reader_align(struct blob_reader *blob, size_t alignment);
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/**
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* Read some unstructured, fixed-size data from the current location, (and
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* update the current location to just past this data).
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*
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* \note The memory returned belongs to the data underlying the blob reader. The
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* caller must copy the data in order to use it after the lifetime of the data
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* underlying the blob reader.
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*
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* \return The bytes read (see note above about memory lifetime).
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*/
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const void *
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blob_read_bytes(struct blob_reader *blob, size_t size);
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/**
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* Read some unstructured, fixed-size data from the current location, copying
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* it to \dest (and update the current location to just past this data)
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*/
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void
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blob_copy_bytes(struct blob_reader *blob, void *dest, size_t size);
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/**
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* Skip \size bytes within the blob.
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*/
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void
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blob_skip_bytes(struct blob_reader *blob, size_t size);
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/**
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* Read a uint8_t from the current location, (and update the current location
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* to just past this uint8_t).
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*
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* \return The uint8_t read
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*/
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uint8_t
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blob_read_uint8(struct blob_reader *blob);
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/**
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* Read a uint16_t from the current location, (and update the current location
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* to just past this uint16_t).
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*
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* \note This function will only read from a uint16_t-aligned offset from the
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* beginning of the blob's data, so some padding bytes may be skipped.
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*
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* \return The uint16_t read
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*/
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uint16_t
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blob_read_uint16(struct blob_reader *blob);
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/**
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* Read a uint32_t from the current location, (and update the current location
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* to just past this uint32_t).
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*
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* \note This function will only read from a uint32_t-aligned offset from the
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* beginning of the blob's data, so some padding bytes may be skipped.
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*
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* \return The uint32_t read
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*/
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uint32_t
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blob_read_uint32(struct blob_reader *blob);
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/**
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* Read a uint64_t from the current location, (and update the current location
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* to just past this uint64_t).
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*
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* \note This function will only read from a uint64_t-aligned offset from the
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* beginning of the blob's data, so some padding bytes may be skipped.
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*
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* \return The uint64_t read
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*/
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uint64_t
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blob_read_uint64(struct blob_reader *blob);
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/**
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* Read an intptr_t value from the current location, (and update the
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* current location to just past this intptr_t).
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*
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* \note This function will only read from an intptr_t-aligned offset from the
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* beginning of the blob's data, so some padding bytes may be skipped.
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*
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* \return The intptr_t read
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*/
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intptr_t
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blob_read_intptr(struct blob_reader *blob);
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/**
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* Read a NULL-terminated string from the current location, (and update the
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* current location to just past this string).
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*
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* \note The memory returned belongs to the data underlying the blob reader. The
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* caller must copy the string in order to use the string after the lifetime
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* of the data underlying the blob reader.
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*
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* \return The string read (see note above about memory lifetime). However, if
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* there is no NULL byte remaining within the blob, this function returns
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* NULL.
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*/
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char *
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blob_read_string(struct blob_reader *blob);
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#ifdef __cplusplus
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}
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#endif
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#endif /* BLOB_H */
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