/* * 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. */ #ifndef BLOB_H #define BLOB_H #include <stdbool.h> #include <stddef.h> #include <stdint.h> #include <stdlib.h> #ifdef __cplusplus extern "C" { #endif /* 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; /** True if \c data a fixed allocation that we cannot resize * * \see blob_init_fixed */ bool fixed_allocation; /** * True if we've ever failed to realloc or if we go pas the end of a fixed * allocation blob. */ bool out_of_memory; }; /* 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 { const uint8_t *data; const uint8_t *end; const uint8_t *current; bool overrun; }; /** * Init a new, empty blob. */ void blob_init(struct blob *blob); /** * Init a new, fixed-size blob. * * A fixed-size blob has a fixed block of data that will not be freed on * blob_finish and will never be grown. If we hit the end, we simply start * returning false from the write functions. * * If a fixed-size blob has a NULL data pointer then the data is written but * it otherwise operates normally. This can be used to determine the size * that will be required to write a given data structure. */ void blob_init_fixed(struct blob *blob, void *data, size_t size); /** * Finish a blob and free its memory. * * If \blob was initialized with blob_init_fixed, the data pointer is * considered to be owned by the user and will not be freed. */ static inline void blob_finish(struct blob *blob) { if (!blob->fixed_allocation) free(blob->data); } /** * 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 \sa * blob_overwrite_bytes to write to these bytes. * * \return An offset to space allocated within \blob to which \to_write bytes * can be written, (or -1 in case of any allocation error). */ intptr_t blob_reserve_bytes(struct blob *blob, size_t to_write); /** * Similar to \sa blob_reserve_bytes, but only reserves an uint32_t worth of * space. Note that this must be used if later reading with \sa * blob_read_uint32, since it aligns the offset correctly. */ intptr_t blob_reserve_uint32(struct blob *blob); /** * Similar to \sa blob_reserve_bytes, but only reserves an intptr_t worth of * space. Note that this must be used if later reading with \sa * blob_read_intptr, since it aligns the offset correctly. */ intptr_t blob_reserve_intptr(struct blob *blob); /** * 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_reserve_uint32(blob); * ... 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); /** * Overwrite an intptr_t previously written to the blob. * * Writes a intptr_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. * * For example usage, see blob_overwrite_uint32 * * \return True unless the requested position or position+to_write lie outside * the current blob's size. */ bool blob_overwrite_intptr(struct blob *blob, size_t offset, 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, const void *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). */ const 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, void *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 */