2 * Copyright © 2014 Intel Corporation
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34 /* The blob functions implement a simple, low-level API for serializing and
37 * All objects written to a blob will be serialized directly, (without any
38 * additional meta-data to describe the data written). Therefore, it is the
39 * caller's responsibility to ensure that any data can be read later, (either
40 * by knowing exactly what data is expected, or by writing to the blob
41 * sufficient meta-data to describe what has been written).
43 * A blob is efficient in that it dynamically grows by doubling in size, so
44 * allocation costs are logarithmic.
48 /* The data actually written to the blob. */
51 /** Number of bytes that have been allocated for \c data. */
54 /** The number of bytes that have actual data written to them. */
58 /* When done reading, the caller can ensure that everything was consumed by
59 * checking the following:
61 * 1. blob->current should be equal to blob->end, (if not, too little was
64 * 2. blob->overrun should be false, (otherwise, too much was read).
74 * Create a new, empty blob, belonging to \mem_ctx.
76 * \return The new blob, (or NULL in case of allocation failure).
79 blob_create (void *mem_ctx
);
82 * Add some unstructured, fixed-size data to a blob.
84 * \return True unless allocation failed.
87 blob_write_bytes (struct blob
*blob
, const void *bytes
, size_t to_write
);
90 * Reserve space in \blob for a number of bytes.
92 * Space will be allocated within the blob for these byes, but the bytes will
93 * be left uninitialized. The caller is expected to use the return value to
94 * write directly (and immediately) to these bytes.
96 * \note The return value is valid immediately upon return, but can be
97 * invalidated by any other call to a blob function. So the caller should call
98 * blob_reserve_byes immediately before writing through the returned pointer.
100 * This function is intended to be used when interfacing with an existing API
101 * that is not aware of the blob API, (so that blob_write_bytes cannot be
104 * \return A pointer to space allocated within \blob to which \to_write bytes
105 * can be written, (or NULL in case of any allocation error).
108 blob_reserve_bytes (struct blob
*blob
, size_t to_write
);
111 * Overwrite some data previously written to the blob.
113 * Writes data to an existing portion of the blob at an offset of \offset.
114 * This data range must have previously been written to the blob by one of the
115 * blob_write_* calls.
117 * For example usage, see blob_overwrite_uint32
119 * \return True unless the requested offset or offset+to_write lie outside
120 * the current blob's size.
123 blob_overwrite_bytes (struct blob
*blob
,
129 * Add a uint32_t to a blob.
131 * \note This function will only write to a uint32_t-aligned offset from the
132 * beginning of the blob's data, so some padding bytes may be added to the
133 * blob if this write follows some unaligned write (such as
134 * blob_write_string).
136 * \return True unless allocation failed.
139 blob_write_uint32 (struct blob
*blob
, uint32_t value
);
142 * Overwrite a uint32_t previously written to the blob.
144 * Writes a uint32_t value to an existing portion of the blob at an offset of
145 * \offset. This data range must have previously been written to the blob by
146 * one of the blob_write_* calls.
149 * The expected usage is something like the following pattern:
153 * offset = blob->size;
154 * blob_write_uint32 (blob, 0); // placeholder
155 * ... various blob write calls, writing N items ...
156 * blob_overwrite_uint32 (blob, offset, N);
158 * \return True unless the requested position or position+to_write lie outside
159 * the current blob's size.
162 blob_overwrite_uint32 (struct blob
*blob
,
167 * Add a uint64_t to a blob.
169 * \note This function will only write to a uint64_t-aligned offset from the
170 * beginning of the blob's data, so some padding bytes may be added to the
171 * blob if this write follows some unaligned write (such as
172 * blob_write_string).
174 * \return True unless allocation failed.
177 blob_write_uint64 (struct blob
*blob
, uint64_t value
);
180 * Add an intptr_t to a blob.
182 * \note This function will only write to an intptr_t-aligned offset from the
183 * beginning of the blob's data, so some padding bytes may be added to the
184 * blob if this write follows some unaligned write (such as
185 * blob_write_string).
187 * \return True unless allocation failed.
190 blob_write_intptr (struct blob
*blob
, intptr_t value
);
193 * Add a NULL-terminated string to a blob, (including the NULL terminator).
195 * \return True unless allocation failed.
198 blob_write_string (struct blob
*blob
, const char *str
);
201 * Start reading a blob, (initializing the contents of \blob for reading).
203 * After this call, the caller can use the various blob_read_* functions to
204 * read elements from the data array.
206 * For all of the blob_read_* functions, if there is insufficient data
207 * remaining, the functions will do nothing, (perhaps returning default values
208 * such as 0). The caller can detect this by noting that the blob_reader's
209 * current value is unchanged before and after the call.
212 blob_reader_init (struct blob_reader
*blob
, uint8_t *data
, size_t size
);
215 * Read some unstructured, fixed-size data from the current location, (and
216 * update the current location to just past this data).
218 * \note The memory returned belongs to the data underlying the blob reader. The
219 * caller must copy the data in order to use it after the lifetime of the data
220 * underlying the blob reader.
222 * \return The bytes read (see note above about memory lifetime).
225 blob_read_bytes (struct blob_reader
*blob
, size_t size
);
228 * Read some unstructured, fixed-size data from the current location, copying
229 * it to \dest (and update the current location to just past this data)
232 blob_copy_bytes (struct blob_reader
*blob
, uint8_t *dest
, size_t size
);
235 * Read a uint32_t from the current location, (and update the current location
236 * to just past this uint32_t).
238 * \note This function will only read from a uint32_t-aligned offset from the
239 * beginning of the blob's data, so some padding bytes may be skipped.
241 * \return The uint32_t read
244 blob_read_uint32 (struct blob_reader
*blob
);
247 * Read a uint64_t from the current location, (and update the current location
248 * to just past this uint64_t).
250 * \note This function will only read from a uint64_t-aligned offset from the
251 * beginning of the blob's data, so some padding bytes may be skipped.
253 * \return The uint64_t read
256 blob_read_uint64 (struct blob_reader
*blob
);
259 * Read an intptr_t value from the current location, (and update the
260 * current location to just past this intptr_t).
262 * \note This function will only read from an intptr_t-aligned offset from the
263 * beginning of the blob's data, so some padding bytes may be skipped.
265 * \return The intptr_t read
268 blob_read_intptr (struct blob_reader
*blob
);
271 * Read a NULL-terminated string from the current location, (and update the
272 * current location to just past this string).
274 * \note The memory returned belongs to the data underlying the blob reader. The
275 * caller must copy the string in order to use the string after the lifetime
276 * of the data underlying the blob reader.
278 * \return The string read (see note above about memory lifetime). However, if
279 * there is no NULL byte remaining within the blob, this function returns
283 blob_read_string (struct blob_reader
*blob
);