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Diffstat (limited to 'src/util/blob.h')
| -rw-r--r-- | src/util/blob.h | 358 |
1 files changed, 358 insertions, 0 deletions
diff --git a/src/util/blob.h b/src/util/blob.h new file mode 100644 index 00000000000..b56fa4b2fe0 --- /dev/null +++ b/src/util/blob.h @@ -0,0 +1,358 @@ +/* + * 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); + +/** + * Skip \size bytes within the blob. + */ +void +blob_skip_bytes(struct blob_reader *blob, 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 */ |