/** 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.
* 2. blob->overrun should be false, (otherwise, too much was read).
*/
struct blob_reader {
- uint8_t *data;
- uint8_t *end;
- uint8_t *current;
+ const uint8_t *data;
+ const uint8_t *end;
+ const uint8_t *current;
bool overrun;
};
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)
{
- free(blob->data);
+ if (!blob->fixed_allocation)
+ free(blob->data);
}
/**
* 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 the return value to
- * write directly (and immediately) to these bytes.
- *
- * \note The return value is valid immediately upon return, but can be
- * invalidated by any other call to a blob function. So the caller should call
- * blob_reserve_byes immediately before writing through the returned pointer.
+ * be left uninitialized. The caller is expected to use \sa
+ * blob_overwrite_bytes to write to these bytes.
*
- * This function is intended to be used when interfacing with an existing API
- * that is not aware of the blob API, (so that blob_write_bytes cannot be
- * called).
- *
- * \return A pointer to space allocated within \blob to which \to_write bytes
- * can be written, (or NULL in case of any allocation error).
+ * \return An offset to space allocated within \blob to which \to_write bytes
+ * can be written, (or -1 in case of any allocation error).
*/
-uint8_t *
+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.
*
*
* size_t offset;
*
- * offset = blob->size;
- * blob_write_uint32 (blob, 0); // placeholder
+ * offset = blob_reserve_uint32(blob);
* ... various blob write calls, writing N items ...
* blob_overwrite_uint32 (blob, offset, N);
*
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).
*
* current value is unchanged before and after the call.
*/
void
-blob_reader_init(struct blob_reader *blob, uint8_t *data, size_t size);
+blob_reader_init(struct blob_reader *blob, const void *data, size_t size);
/**
* Read some unstructured, fixed-size data from the current location, (and
*
* \return The bytes read (see note above about memory lifetime).
*/
-void *
+const void *
blob_read_bytes(struct blob_reader *blob, size_t size);
/**
* it to \dest (and update the current location to just past this data)
*/
void
-blob_copy_bytes(struct blob_reader *blob, uint8_t *dest, size_t size);
+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
projects / mesa.git / blobdiff