2 * Copyright © 2014 Intel Corporation
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5 * copy of this software and associated documentation files (the "Software"),
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36 /* The blob functions implement a simple, low-level API for serializing and
39 * All objects written to a blob will be serialized directly, (without any
40 * additional meta-data to describe the data written). Therefore, it is the
41 * caller's responsibility to ensure that any data can be read later, (either
42 * by knowing exactly what data is expected, or by writing to the blob
43 * sufficient meta-data to describe what has been written).
45 * A blob is efficient in that it dynamically grows by doubling in size, so
46 * allocation costs are logarithmic.
50 /* The data actually written to the blob. */
53 /** Number of bytes that have been allocated for \c data. */
56 /** The number of bytes that have actual data written to them. */
59 /** True if \c data a fixed allocation that we cannot resize
61 * \see blob_init_fixed
63 bool fixed_allocation
;
66 * True if we've ever failed to realloc or if we go pas the end of a fixed
72 /* When done reading, the caller can ensure that everything was consumed by
73 * checking the following:
75 * 1. blob->current should be equal to blob->end, (if not, too little was
78 * 2. blob->overrun should be false, (otherwise, too much was read).
83 const uint8_t *current
;
88 * Init a new, empty blob.
91 blob_init(struct blob
*blob
);
94 * Init a new, fixed-size blob.
96 * A fixed-size blob has a fixed block of data that will not be freed on
97 * blob_finish and will never be grown. If we hit the end, we simply start
98 * returning false from the write functions.
100 * If a fixed-size blob has a NULL data pointer then the data is written but
101 * it otherwise operates normally. This can be used to determine the size
102 * that will be required to write a given data structure.
105 blob_init_fixed(struct blob
*blob
, void *data
, size_t size
);
108 * Finish a blob and free its memory.
110 * If \blob was initialized with blob_init_fixed, the data pointer is
111 * considered to be owned by the user and will not be freed.
114 blob_finish(struct blob
*blob
)
116 if (!blob
->fixed_allocation
)
121 * Add some unstructured, fixed-size data to a blob.
123 * \return True unless allocation failed.
126 blob_write_bytes(struct blob
*blob
, const void *bytes
, size_t to_write
);
129 * Reserve space in \blob for a number of bytes.
131 * Space will be allocated within the blob for these byes, but the bytes will
132 * be left uninitialized. The caller is expected to use \sa
133 * blob_overwrite_bytes to write to these bytes.
135 * \return An offset to space allocated within \blob to which \to_write bytes
136 * can be written, (or -1 in case of any allocation error).
139 blob_reserve_bytes(struct blob
*blob
, size_t to_write
);
142 * Similar to \sa blob_reserve_bytes, but only reserves an uint32_t worth of
143 * space. Note that this must be used if later reading with \sa
144 * blob_read_uint32, since it aligns the offset correctly.
147 blob_reserve_uint32(struct blob
*blob
);
150 * Similar to \sa blob_reserve_bytes, but only reserves an intptr_t worth of
151 * space. Note that this must be used if later reading with \sa
152 * blob_read_intptr, since it aligns the offset correctly.
155 blob_reserve_intptr(struct blob
*blob
);
158 * Overwrite some data previously written to the blob.
160 * Writes data to an existing portion of the blob at an offset of \offset.
161 * This data range must have previously been written to the blob by one of the
162 * blob_write_* calls.
164 * For example usage, see blob_overwrite_uint32
166 * \return True unless the requested offset or offset+to_write lie outside
167 * the current blob's size.
170 blob_overwrite_bytes(struct blob
*blob
,
176 * Add a uint32_t to a blob.
178 * \note This function will only write to a uint32_t-aligned offset from the
179 * beginning of the blob's data, so some padding bytes may be added to the
180 * blob if this write follows some unaligned write (such as
181 * blob_write_string).
183 * \return True unless allocation failed.
186 blob_write_uint32(struct blob
*blob
, uint32_t value
);
189 * Overwrite a uint32_t previously written to the blob.
191 * Writes a uint32_t value to an existing portion of the blob at an offset of
192 * \offset. This data range must have previously been written to the blob by
193 * one of the blob_write_* calls.
196 * The expected usage is something like the following pattern:
200 * offset = blob_reserve_uint32(blob);
201 * ... various blob write calls, writing N items ...
202 * blob_overwrite_uint32 (blob, offset, N);
204 * \return True unless the requested position or position+to_write lie outside
205 * the current blob's size.
208 blob_overwrite_uint32(struct blob
*blob
,
213 * Add a uint64_t to a blob.
215 * \note This function will only write to a uint64_t-aligned offset from the
216 * beginning of the blob's data, so some padding bytes may be added to the
217 * blob if this write follows some unaligned write (such as
218 * blob_write_string).
220 * \return True unless allocation failed.
223 blob_write_uint64(struct blob
*blob
, uint64_t value
);
226 * Add an intptr_t to a blob.
228 * \note This function will only write to an intptr_t-aligned offset from the
229 * beginning of the blob's data, so some padding bytes may be added to the
230 * blob if this write follows some unaligned write (such as
231 * blob_write_string).
233 * \return True unless allocation failed.
236 blob_write_intptr(struct blob
*blob
, intptr_t value
);
239 * Overwrite an intptr_t previously written to the blob.
241 * Writes a intptr_t value to an existing portion of the blob at an offset of
242 * \offset. This data range must have previously been written to the blob by
243 * one of the blob_write_* calls.
245 * For example usage, see blob_overwrite_uint32
247 * \return True unless the requested position or position+to_write lie outside
248 * the current blob's size.
251 blob_overwrite_intptr(struct blob
*blob
,
256 * Add a NULL-terminated string to a blob, (including the NULL terminator).
258 * \return True unless allocation failed.
261 blob_write_string(struct blob
*blob
, const char *str
);
264 * Start reading a blob, (initializing the contents of \blob for reading).
266 * After this call, the caller can use the various blob_read_* functions to
267 * read elements from the data array.
269 * For all of the blob_read_* functions, if there is insufficient data
270 * remaining, the functions will do nothing, (perhaps returning default values
271 * such as 0). The caller can detect this by noting that the blob_reader's
272 * current value is unchanged before and after the call.
275 blob_reader_init(struct blob_reader
*blob
, const void *data
, size_t size
);
278 * Read some unstructured, fixed-size data from the current location, (and
279 * update the current location to just past this data).
281 * \note The memory returned belongs to the data underlying the blob reader. The
282 * caller must copy the data in order to use it after the lifetime of the data
283 * underlying the blob reader.
285 * \return The bytes read (see note above about memory lifetime).
288 blob_read_bytes(struct blob_reader
*blob
, size_t size
);
291 * Read some unstructured, fixed-size data from the current location, copying
292 * it to \dest (and update the current location to just past this data)
295 blob_copy_bytes(struct blob_reader
*blob
, void *dest
, size_t size
);
298 * Skip \size bytes within the blob.
301 blob_skip_bytes(struct blob_reader
*blob
, size_t size
);
304 * Read a uint32_t from the current location, (and update the current location
305 * to just past this uint32_t).
307 * \note This function will only read from a uint32_t-aligned offset from the
308 * beginning of the blob's data, so some padding bytes may be skipped.
310 * \return The uint32_t read
313 blob_read_uint32(struct blob_reader
*blob
);
316 * Read a uint64_t from the current location, (and update the current location
317 * to just past this uint64_t).
319 * \note This function will only read from a uint64_t-aligned offset from the
320 * beginning of the blob's data, so some padding bytes may be skipped.
322 * \return The uint64_t read
325 blob_read_uint64(struct blob_reader
*blob
);
328 * Read an intptr_t value from the current location, (and update the
329 * current location to just past this intptr_t).
331 * \note This function will only read from an intptr_t-aligned offset from the
332 * beginning of the blob's data, so some padding bytes may be skipped.
334 * \return The intptr_t read
337 blob_read_intptr(struct blob_reader
*blob
);
340 * Read a NULL-terminated string from the current location, (and update the
341 * current location to just past this string).
343 * \note The memory returned belongs to the data underlying the blob reader. The
344 * caller must copy the string in order to use the string after the lifetime
345 * of the data underlying the blob reader.
347 * \return The string read (see note above about memory lifetime). However, if
348 * there is no NULL byte remaining within the blob, this function returns
352 blob_read_string(struct blob_reader
*blob
);