Commit 1c987732 authored by Carl Worth's avatar Carl Worth
Browse files

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: default avatarJason Ekstrand <jason.ekstrand@intel.com>
parent 165575d0
......@@ -65,6 +65,8 @@ LIBGLSL_FILES = \
$(GLSL_SRCDIR)/ast_function.cpp \
$(GLSL_SRCDIR)/ast_to_hir.cpp \
$(GLSL_SRCDIR)/ast_type.cpp \
$(GLSL_SRCDIR)/blob.c \
$(GLSL_SRCDIR)/blob.h \
$(GLSL_SRCDIR)/builtin_functions.cpp \
$(GLSL_SRCDIR)/builtin_type_macros.h \
$(GLSL_SRCDIR)/builtin_types.cpp \
......
/*
* 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.
*/
#include <string.h>
#include "main/macros.h"
#include "util/ralloc.h"
#include "blob.h"
#define BLOB_INITIAL_SIZE 4096
/* Ensure that \blob will be able to fit an additional object of size
* \additional. The growing (if any) will occur by doubling the existing
* allocation.
*/
static bool
grow_to_fit(struct blob *blob, size_t additional)
{
size_t to_allocate;
uint8_t *new_data;
if (blob->size + additional <= blob->allocated)
return true;
if (blob->allocated == 0)
to_allocate = BLOB_INITIAL_SIZE;
else
to_allocate = blob->allocated * 2;
to_allocate = MAX2(to_allocate, blob->allocated + additional);
new_data = reralloc_size(blob, blob->data, to_allocate);
if (new_data == NULL)
return false;
blob->data = new_data;
blob->allocated = to_allocate;
return true;
}
/* Align the blob->size so that reading or writing a value at (blob->data +
* blob->size) will result in an access aligned to a granularity of \alignment
* bytes.
*
* \return True unless allocation fails
*/
static bool
align_blob(struct blob *blob, size_t alignment)
{
const size_t new_size = ALIGN(blob->size, alignment);
if (! grow_to_fit (blob, new_size - blob->size))
return false;
blob->size = new_size;
return true;
}
static void
align_blob_reader(struct blob_reader *blob, size_t alignment)
{
blob->current = blob->data + ALIGN(blob->current - blob->data, alignment);
}
struct blob *
blob_create(void *mem_ctx)
{
struct blob *blob;
blob = ralloc(mem_ctx, struct blob);
if (blob == NULL)
return NULL;
blob->data = NULL;
blob->allocated = 0;
blob->size = 0;
return blob;
}
bool
blob_write_bytes(struct blob *blob, const void *bytes, size_t to_write)
{
if (! grow_to_fit(blob, to_write))
return false;
memcpy(blob->data + blob->size, bytes, to_write);
blob->size += to_write;
return true;
}
uint8_t *
blob_reserve_bytes(struct blob *blob, size_t to_write)
{
uint8_t *ret;
if (! grow_to_fit (blob, to_write))
return NULL;
ret = blob->data + blob->size;
blob->size += to_write;
return ret;
}
bool
blob_write_uint32(struct blob *blob, uint32_t value)
{
align_blob(blob, sizeof(value));
return blob_write_bytes(blob, &value, sizeof(value));
}
bool
blob_write_uint64(struct blob *blob, uint64_t value)
{
align_blob(blob, sizeof(value));
return blob_write_bytes(blob, &value, sizeof(value));
}
bool
blob_write_intptr(struct blob *blob, intptr_t value)
{
align_blob(blob, sizeof(value));
return blob_write_bytes(blob, &value, sizeof(value));
}
bool
blob_write_string(struct blob *blob, const char *str)
{
return blob_write_bytes(blob, str, strlen(str) + 1);
}
void
blob_reader_init(struct blob_reader *blob, uint8_t *data, size_t size)
{
blob->data = data;
blob->end = data + size;
blob->current = data;
blob->overrun = false;
}
/* Check that an object of size \size can be read from this blob.
*
* If not, set blob->overrun to indicate that we attempted to read too far.
*/
static bool
ensure_can_read(struct blob_reader *blob, size_t size)
{
if (blob->current < blob->end && blob->end - blob->current >= size)
return true;
blob->overrun = true;
return false;
}
void *
blob_read_bytes(struct blob_reader *blob, size_t size)
{
void *ret;
if (! ensure_can_read (blob, size))
return NULL;
ret = blob->current;
blob->current += size;
return ret;
}
void
blob_copy_bytes(struct blob_reader *blob, uint8_t *dest, size_t size)
{
uint8_t *bytes;
bytes = blob_read_bytes(blob, size);
if (bytes == NULL)
return;
memcpy(dest, bytes, size);
}
/* These next three read functions have identical form. If we add any beyond
* these first three we should probably switch to generating these with a
* preprocessor macro.
*/
uint32_t
blob_read_uint32(struct blob_reader *blob)
{
uint32_t ret;
int size = sizeof(ret);
align_blob_reader(blob, size);
if (! ensure_can_read(blob, size))
return 0;
ret = *((uint32_t*) blob->current);
blob->current += size;
return ret;
}
uint64_t
blob_read_uint64(struct blob_reader *blob)
{
uint64_t ret;
int size = sizeof(ret);
align_blob_reader(blob, size);
if (! ensure_can_read(blob, size))
return 0;
ret = *((uint64_t*) blob->current);
blob->current += size;
return ret;
}
intptr_t
blob_read_intptr(struct blob_reader *blob)
{
intptr_t ret;
int size = sizeof(ret);
align_blob_reader(blob, size);
if (! ensure_can_read(blob, size))
return 0;
ret = *((intptr_t *) blob->current);
blob->current += size;
return ret;
}
char *
blob_read_string(struct blob_reader *blob)
{
int size;
char *ret;
uint8_t *nul;
/* If we're already at the end, then this is an overrun. */
if (blob->current >= blob->end) {
blob->overrun = true;
return NULL;
}
/* Similarly, if there is no zero byte in the data remaining in this blob,
* we also consider that an overrun.
*/
nul = memchr(blob->current, 0, blob->end - blob->current);
if (nul == NULL) {
blob->overrun = true;
return NULL;
}
size = nul - blob->current + 1;
assert(ensure_can_read(blob, size));
ret = (char *) blob->current;
blob->current += size;
return ret;
}
/*
* 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 */
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment