2 * Copyright © 2014 Intel Corporation
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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).
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.
101 blob_init_fixed(struct blob
*blob
, void *data
, size_t size
);
104 * Finish a blob and free its memory.
106 * If \blob was initialized with blob_init_fixed, the data pointer is
107 * considered to be owned by the user and will not be freed.
110 blob_finish(struct blob
*blob
)
112 if (!blob
->fixed_allocation
)
117 * Add some unstructured, fixed-size data to a blob.
119 * \return True unless allocation failed.
122 blob_write_bytes(struct blob
*blob
, const void *bytes
, size_t to_write
);
125 * Reserve space in \blob for a number of bytes.
127 * Space will be allocated within the blob for these byes, but the bytes will
128 * be left uninitialized. The caller is expected to use the return value to
129 * write directly (and immediately) to these bytes.
131 * \note The return value is valid immediately upon return, but can be
132 * invalidated by any other call to a blob function. So the caller should call
133 * blob_reserve_byes immediately before writing through the returned pointer.
135 * This function is intended to be used when interfacing with an existing API
136 * that is not aware of the blob API, (so that blob_write_bytes cannot be
139 * \return A pointer to space allocated within \blob to which \to_write bytes
140 * can be written, (or NULL in case of any allocation error).
143 blob_reserve_bytes(struct blob
*blob
, size_t to_write
);
146 * Overwrite some data previously written to the blob.
148 * Writes data to an existing portion of the blob at an offset of \offset.
149 * This data range must have previously been written to the blob by one of the
150 * blob_write_* calls.
152 * For example usage, see blob_overwrite_uint32
154 * \return True unless the requested offset or offset+to_write lie outside
155 * the current blob's size.
158 blob_overwrite_bytes(struct blob
*blob
,
164 * Add a uint32_t to a blob.
166 * \note This function will only write to a uint32_t-aligned offset from the
167 * beginning of the blob's data, so some padding bytes may be added to the
168 * blob if this write follows some unaligned write (such as
169 * blob_write_string).
171 * \return True unless allocation failed.
174 blob_write_uint32(struct blob
*blob
, uint32_t value
);
177 * Overwrite a uint32_t previously written to the blob.
179 * Writes a uint32_t value to an existing portion of the blob at an offset of
180 * \offset. This data range must have previously been written to the blob by
181 * one of the blob_write_* calls.
184 * The expected usage is something like the following pattern:
188 * offset = blob->size;
189 * blob_write_uint32 (blob, 0); // placeholder
190 * ... various blob write calls, writing N items ...
191 * blob_overwrite_uint32 (blob, offset, N);
193 * \return True unless the requested position or position+to_write lie outside
194 * the current blob's size.
197 blob_overwrite_uint32(struct blob
*blob
,
202 * Add a uint64_t to a blob.
204 * \note This function will only write to a uint64_t-aligned offset from the
205 * beginning of the blob's data, so some padding bytes may be added to the
206 * blob if this write follows some unaligned write (such as
207 * blob_write_string).
209 * \return True unless allocation failed.
212 blob_write_uint64(struct blob
*blob
, uint64_t value
);
215 * Add an intptr_t to a blob.
217 * \note This function will only write to an intptr_t-aligned offset from the
218 * beginning of the blob's data, so some padding bytes may be added to the
219 * blob if this write follows some unaligned write (such as
220 * blob_write_string).
222 * \return True unless allocation failed.
225 blob_write_intptr(struct blob
*blob
, intptr_t value
);
228 * Add a NULL-terminated string to a blob, (including the NULL terminator).
230 * \return True unless allocation failed.
233 blob_write_string(struct blob
*blob
, const char *str
);
236 * Start reading a blob, (initializing the contents of \blob for reading).
238 * After this call, the caller can use the various blob_read_* functions to
239 * read elements from the data array.
241 * For all of the blob_read_* functions, if there is insufficient data
242 * remaining, the functions will do nothing, (perhaps returning default values
243 * such as 0). The caller can detect this by noting that the blob_reader's
244 * current value is unchanged before and after the call.
247 blob_reader_init(struct blob_reader
*blob
, uint8_t *data
, size_t size
);
250 * Read some unstructured, fixed-size data from the current location, (and
251 * update the current location to just past this data).
253 * \note The memory returned belongs to the data underlying the blob reader. The
254 * caller must copy the data in order to use it after the lifetime of the data
255 * underlying the blob reader.
257 * \return The bytes read (see note above about memory lifetime).
260 blob_read_bytes(struct blob_reader
*blob
, size_t size
);
263 * Read some unstructured, fixed-size data from the current location, copying
264 * it to \dest (and update the current location to just past this data)
267 blob_copy_bytes(struct blob_reader
*blob
, uint8_t *dest
, size_t size
);
270 * Read a uint32_t from the current location, (and update the current location
271 * to just past this uint32_t).
273 * \note This function will only read from a uint32_t-aligned offset from the
274 * beginning of the blob's data, so some padding bytes may be skipped.
276 * \return The uint32_t read
279 blob_read_uint32(struct blob_reader
*blob
);
282 * Read a uint64_t from the current location, (and update the current location
283 * to just past this uint64_t).
285 * \note This function will only read from a uint64_t-aligned offset from the
286 * beginning of the blob's data, so some padding bytes may be skipped.
288 * \return The uint64_t read
291 blob_read_uint64(struct blob_reader
*blob
);
294 * Read an intptr_t value from the current location, (and update the
295 * current location to just past this intptr_t).
297 * \note This function will only read from an intptr_t-aligned offset from the
298 * beginning of the blob's data, so some padding bytes may be skipped.
300 * \return The intptr_t read
303 blob_read_intptr(struct blob_reader
*blob
);
306 * Read a NULL-terminated string from the current location, (and update the
307 * current location to just past this string).
309 * \note The memory returned belongs to the data underlying the blob reader. The
310 * caller must copy the string in order to use the string after the lifetime
311 * of the data underlying the blob reader.
313 * \return The string read (see note above about memory lifetime). However, if
314 * there is no NULL byte remaining within the blob, this function returns
318 blob_read_string(struct blob_reader
*blob
);