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authorCarl Worth <cworth@cworth.org>2014-12-04 14:16:47 -0800
committerCarl Worth <cworth@cworth.org>2015-01-16 13:47:40 -0800
commit1c9877327ead37b7dd5a0ca3a8c7912e924328e5 (patch)
treed5af477abe55e2d575522e54a583ad371ab36d85 /src/glsl/blob.h
parent165575d0a8ca2af582a7c78776a4a76a84cc2ed8 (diff)
glsl: Add blob.c---a simple interface for serializing data
This new interface allows for writing a series of objects to a chunk of memory (a "blob").. The allocated memory is maintained within the blob itself, (and re-allocated by doubling when necessary). There are also functions for reading objects from a blob as well. If code attempts to read beyond the available memory, the read functions return 0 values (or its moral equivalent) without reading past the allocated memory. Once the caller is done with the reads, it can check blob->overrun to ensure whether any invalid values were previously returned due to attempts to read too far. Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Diffstat (limited to 'src/glsl/blob.h')
-rw-r--r--src/glsl/blob.h246
1 files changed, 246 insertions, 0 deletions
diff --git a/src/glsl/blob.h b/src/glsl/blob.h
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+/*
+ * 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.
+ */
+
+#pragma once
+#ifndef BLOB_H
+#define BLOB_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+
+/* 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;
+};
+
+/* 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 {
+ uint8_t *data;
+ uint8_t *end;
+ uint8_t *current;
+ bool overrun;
+};
+
+/**
+ * Create a new, empty blob, belonging to \mem_ctx.
+ *
+ * \return The new blob, (or NULL in case of allocation failure).
+ */
+struct blob *
+blob_create (void *mem_ctx);
+
+/**
+ * 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 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.
+ *
+ * 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).
+ */
+uint8_t *
+blob_reserve_bytes (struct blob *blob, 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);
+
+/**
+ * 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);
+
+/**
+ * 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, uint8_t *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).
+ */
+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, uint8_t *dest, 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 */