/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @file buffer.h
*
* @brief Advanced buffer implementation.
*
* Instances of CxBuffer can be used to read from or to write to like one
* would do with a stream.
*
* Some features for convenient use of the buffer
* can be enabled. See the documentation of the macro constants for more
* information.
*
* @author Mike Becker
* @author Olaf Wintermann
* @copyright 2-Clause BSD License
*/
#ifndef UCX_BUFFER_H
#define UCX_BUFFER_H
#include "common.h"
#include "allocator.h"
#include "string.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* No buffer features enabled (all flags cleared).
*/
#define CX_BUFFER_DEFAULT 0x00
/**
* If this flag is enabled, the buffer will automatically free its contents when destroyed.
*
* Do NOT set this flag together with #CX_BUFFER_COPY_ON_WRITE. It will be automatically
* set when the copy-on-write operation is performed.
*/
#define CX_BUFFER_FREE_CONTENTS 0x01
/**
* If this flag is enabled, the buffer will automatically extend its capacity.
*/
#define CX_BUFFER_AUTO_EXTEND 0x02
/**
* If this flag is enabled, the buffer will allocate new memory when written to.
*
* The current contents of the buffer will be copied to the new memory, and the flag
* will be cleared while the #CX_BUFFER_FREE_CONTENTS flag will be set automatically.
*/
#define CX_BUFFER_COPY_ON_WRITE 0x04
/**
* If this flag is enabled, the buffer will copy its contents to a new memory area on reallocation.
*
* After performing the copy, the flag is automatically cleared.
* This flag has no effect on buffers which do not have #CX_BUFFER_AUTO_EXTEND set, which is why
* buffers automatically admit the auto-extend flag when initialized with copy-on-extend enabled.
*/
#define CX_BUFFER_COPY_ON_EXTEND 0x08
/**
* If this flag is enabled, the buffer will never free its contents regardless of #CX_BUFFER_FREE_CONTENTS.
*
* This is useful, for example, when you want to keep a pointer to the data after destroying the buffer.
*/
#define CX_BUFFER_DO_NOT_FREE 0x10
/**
* Function pointer for cxBufferWrite that is compatible with cx_write_func.
* @see cx_write_func
*/
#define cxBufferWriteFunc ((cx_write_func) cxBufferWrite)
/**
* Function pointer for cxBufferRead that is compatible with cx_read_func.
* @see cx_read_func
*/
#define cxBufferReadFunc ((cx_read_func) cxBufferRead)
/** Structure for the UCX buffer data. */
struct cx_buffer_s {
/** A pointer to the buffer contents. */
union {
/**
* Data is interpreted as text.
*/
char *space;
/**
* Data is interpreted as binary.
*/
unsigned char *bytes;
};
/** The allocator to use for automatic memory management. */
const CxAllocator *allocator;
/** Current position of the buffer. */
size_t pos;
/** Current capacity (i.e. maximum size) of the buffer. */
size_t capacity;
/** Maximum capacity that this buffer may grow to. */
size_t max_capacity;
/** Current size of the buffer content. */
size_t size;
/**
* Flag register for buffer features.
* @see #CX_BUFFER_DEFAULT
* @see #CX_BUFFER_FREE_CONTENTS
* @see #CX_BUFFER_AUTO_EXTEND
* @see #CX_BUFFER_COPY_ON_WRITE
*/
int flags;
};
/**
* UCX buffer.
*/
typedef struct cx_buffer_s CxBuffer;
/**
* Initializes a fresh buffer.
*
* You may also provide a read-only @p space, in which case
* you will need to cast the pointer, and you should set the
* #CX_BUFFER_COPY_ON_WRITE flag.
*
* You need to set the size manually after initialization if
* you provide @p space which already contains data.
*
* When you specify stack memory as @p space and decide to use
* the auto-extension feature, you @em must use the
* #CX_BUFFER_COPY_ON_EXTEND flag, instead of the
* #CX_BUFFER_AUTO_EXTEND flag.
*
* @note You may provide @c NULL as the argument for @p space.
* Then this function will allocate the space and enforce
* the #CX_BUFFER_FREE_CONTENTS flag. In that case, specifying
* copy-on-write should be avoided, because the allocated
* space will be leaking after the copy-on-write operation.
*
* @param buffer the buffer to initialize
* @param space pointer to the memory area, or @c NULL to allocate
* new memory
* @param capacity the capacity of the buffer
* @param allocator the allocator this buffer shall use for automatic
* memory management
* (if @c NULL, the cxDefaultAllocator will be used)
* @param flags buffer features (see cx_buffer_s.flags)
* @return zero on success, non-zero if a required allocation failed
*/
cx_attr_nonnull_arg(1)
CX_EXPORT int cxBufferInit(CxBuffer *buffer, void *space, size_t capacity,
const CxAllocator *allocator, int flags);
/**
* Destroys the buffer contents.
*
* Has no effect if the #CX_BUFFER_FREE_CONTENTS feature is not enabled.
* If you want to free the memory of the entire buffer, use cxBufferFree().
*
* @param buffer the buffer which contents shall be destroyed
* @see cxBufferInit()
*/
cx_attr_nonnull
CX_EXPORT void cxBufferDestroy(CxBuffer *buffer);
/**
* Deallocates the buffer.
*
* If the #CX_BUFFER_FREE_CONTENTS feature is enabled, this function also destroys
* the contents. If you @em only want to destroy the contents, use cxBufferDestroy().
*
* @param buffer the buffer to deallocate
* @see cxBufferCreate()
*/
CX_EXPORT void cxBufferFree(CxBuffer *buffer);
/**
* Allocates and initializes a fresh buffer.
*
* You may also provide a read-only @p space, in which case
* you will need to cast the pointer, and you should set the
* #CX_BUFFER_COPY_ON_WRITE flag.
* When you specify stack memory as @p space and decide to use
* the auto-extension feature, you @em must use the
* #CX_BUFFER_COPY_ON_EXTEND flag, instead of the
* #CX_BUFFER_AUTO_EXTEND flag.
*
* @note You may provide @c NULL as the argument for @p space.
* Then this function will allocate the space and enforce
* the #CX_BUFFER_FREE_CONTENTS flag.
*
* @param space pointer to the memory area, or @c NULL to allocate
* new memory
* @param capacity the capacity of the buffer
* @param allocator the allocator to use for allocating the structure and the automatic
* memory management within the buffer
* (if @c NULL, the cxDefaultAllocator will be used)
* @param flags buffer features (see cx_buffer_s.flags)
* @return a pointer to the buffer on success, @c NULL if a required allocation failed
*/
cx_attr_malloc cx_attr_dealloc(cxBufferFree, 1) cx_attr_nodiscard
CX_EXPORT CxBuffer *cxBufferCreate(void *space, size_t capacity,
const CxAllocator *allocator, int flags);
/**
* Shifts the contents of the buffer by the given offset.
*
* If the offset is positive, the contents are shifted to the right.
* If auto extension is enabled, the buffer grows, if necessary.
* In case the auto extension fails, this function returns a non-zero value and
* no contents are changed.
* When the auto extension is disabled, the contents that do not fit into the
* buffer are discarded.
*
* If the offset is negative, the contents are shifted to the left where the
* first @p shift bytes are discarded.
* The new size of the buffer is the old size minus the absolute shift value.
* If this value is larger than the buffer size, the buffer is emptied (but
* not cleared, see the security note below).
*
* The buffer position gets shifted alongside the content but is kept
* within the boundaries of the buffer.
*
* @note For situations where @c off_t is not large enough, there are specialized cxBufferShiftLeft() and
* cxBufferShiftRight() functions using a @c size_t as the parameter type.
*
* @attention
* Security Note: The shifting operation does @em not erase the previously occupied memory cells.
* But you can do that manually by calling
* <code>memset(buffer->bytes, 0, shift)</code> for a right shift or
* <code>memset(buffer->bytes + buffer->size, 0, buffer->capacity - buffer->size)</code>
* for a left shift.
*
* @param buffer the buffer
* @param shift the shift offset (negative means left shift)
* @retval zero success
* @retval non-zero if a required auto-extension or copy-on-write fails
* @see cxBufferShiftLeft()
* @see cxBufferShiftRight()
*/
cx_attr_nonnull
CX_EXPORT int cxBufferShift(CxBuffer *buffer, off_t shift);
/**
* Shifts the buffer to the right.
* See cxBufferShift() for details.
*
* @param buffer the buffer
* @param shift the shift offset
* @retval zero success
* @retval non-zero if a required auto-extension or copy-on-write fails
* @see cxBufferShift()
*/
cx_attr_nonnull
CX_EXPORT int cxBufferShiftRight(CxBuffer *buffer, size_t shift);
/**
* Shifts the buffer to the left.
* See cxBufferShift() for details.
*
* @param buffer the buffer
* @param shift the positive shift offset
* @retval zero success
* @retval non-zero if the buffer uses copy-on-write and the allocation fails
* @see cxBufferShift()
*/
cx_attr_nonnull
CX_EXPORT int cxBufferShiftLeft(CxBuffer *buffer, size_t shift);
/**
* Moves the position of the buffer.
*
* The new position is relative to the @p whence argument.
*
* @li @c SEEK_SET marks the start of the buffer.
* @li @c SEEK_CUR marks the current position.
* @li @c SEEK_END marks the end of the buffer.
*
* With an offset of zero, this function sets the buffer position to zero
* (@c SEEK_SET), the buffer size (@c SEEK_END) or leaves the buffer position
* unchanged (@c SEEK_CUR).
*
* @param buffer the buffer
* @param offset position offset relative to @p whence
* @param whence one of @c SEEK_SET, @c SEEK_CUR or @c SEEK_END
* @retval zero success
* @retval non-zero if the position is invalid
*
*/
cx_attr_nonnull
CX_EXPORT int cxBufferSeek(CxBuffer *buffer, off_t offset, int whence);
/**
* Discards items from the end of the buffer.
*
* When the current position points to a byte that gets discarded,
* the position is set to the buffer size.
*
* @param buffer the buffer
* @param size the size of one item
* @param nitems the number of items to discard
* @return the actual number of discarded items
*/
cx_attr_nonnull
CX_EXPORT size_t cxBufferPop(CxBuffer *buffer, size_t size, size_t nitems);
/**
* Clears the buffer by resetting the position and deleting the data.
*
* The data is deleted by zeroing it with a call to memset().
* If you do not need that, you can use the faster cxBufferReset().
*
* @note If the #CX_BUFFER_COPY_ON_WRITE flag is set, this function
* will not erase the data and behave exactly as cxBufferReset().
*
* @param buffer the buffer to be cleared
* @see cxBufferReset()
*/
cx_attr_nonnull
CX_EXPORT void cxBufferClear(CxBuffer *buffer);
/**
* Resets the buffer by resetting the position and size to zero.
*
* The data in the buffer is not deleted. If you need a safe
* reset of the buffer, use cxBufferClear().
*
* @param buffer the buffer to be cleared
* @see cxBufferClear()
*/
cx_attr_nonnull
CX_EXPORT void cxBufferReset(CxBuffer *buffer);
/**
* Tests, if the buffer position has exceeded the buffer size.
*
* @param buffer the buffer to test
* @retval true if the current buffer position has exceeded the last
* byte of the buffer's contents
* @retval false otherwise
*/
cx_attr_nonnull cx_attr_nodiscard
CX_EXPORT bool cxBufferEof(const CxBuffer *buffer);
/**
* Ensures that the buffer has the required capacity.
*
* If the current capacity is not sufficient, the buffer will be extended.
* If the current capacity is larger, the buffer is shrunk and superfluous
* content is discarded.
*
* This function will reserve no more bytes than requested, in contrast to
* cxBufferMinimumCapacity(), which may reserve more bytes to improve the
* number of future necessary reallocations.
*
* @param buffer the buffer
* @param capacity the required capacity for this buffer
* @retval zero on success
* @retval non-zero on allocation failure
* @see cxBufferShrink()
* @see cxBufferMinimumCapacity()
*/
cx_attr_nonnull
CX_EXPORT int cxBufferReserve(CxBuffer *buffer, size_t capacity);
/**
* Limits the buffer's capacity.
*
* If the current capacity is already larger, this function fails and returns
* non-zero.
*
* The capacity limit will affect auto-extension features, as well as future
* calls to cxBufferMinimumCapacity() and cxBufferReserve().
*
* @param buffer the buffer
* @param capacity the maximum allowed capacity for this buffer
* @retval zero the limit is applied
* @retval non-zero the new limit is smaller than the current capacity
* @see cxBufferReserve()
* @see cxBufferMinimumCapacity()
*/
cx_attr_nonnull
CX_EXPORT int cxBufferMaximumCapacity(CxBuffer *buffer, size_t capacity);
/**
* Ensures that the buffer has a minimum capacity.
*
* If the current capacity is not sufficient, the buffer will be generously
* extended.
*
* The new capacity will be a power of two until the system's page size is reached.
* Then, the new capacity will be a multiple of the page size.
*
* @param buffer the buffer
* @param capacity the minimum required capacity for this buffer
* @retval zero the capacity was already sufficient or successfully increased
* @retval non-zero on allocation failure
* @see cxBufferMaximumCapacity()
* @see cxBufferReserve()
* @see cxBufferShrink()
*/
cx_attr_nonnull
CX_EXPORT int cxBufferMinimumCapacity(CxBuffer *buffer, size_t capacity);
/**
* Shrinks the capacity of the buffer to fit its current size.
*
* If @p reserve is larger than zero, the buffer is shrunk to its size plus
* the number of reserved bytes.
*
* If the current capacity is not larger than the size plus the reserved bytes,
* nothing happens.
*
* If the #CX_BUFFER_COPY_ON_WRITE or #CX_BUFFER_COPY_ON_EXTEND flag is set,
* this function does nothing.
*
* @param buffer the buffer
* @param reserve the number of bytes that shall remain reserved
* @see cxBufferReserve()
* @see cxBufferMinimumCapacity()
*/
cx_attr_nonnull
CX_EXPORT void cxBufferShrink(CxBuffer *buffer, size_t reserve);
/**
* Writes data to a CxBuffer.
*
* If auto-extension is enabled, the buffer's capacity is automatically
* increased when it is not large enough to hold all data.
* By default, the capacity grows indefinitely, unless limited with
* cxBufferMaximumCapacity().
* When auto-extension fails, this function writes no data and returns zero.
*
* The position of the buffer is moved alongside the written data.
*
* @note The signature is compatible with the fwrite() family of functions.
*
* @param ptr a pointer to the memory area containing the bytes to be written
* @param size the length of one element
* @param nitems the element count
* @param buffer the CxBuffer to write to
* @return the total count of elements written
* @see cxBufferAppend()
* @see cxBufferRead()
*/
cx_attr_nonnull
CX_EXPORT size_t cxBufferWrite(const void *ptr, size_t size,
size_t nitems, CxBuffer *buffer);
/**
* Appends data to a CxBuffer.
*
* The data is always appended to current data within the buffer,
* regardless of the current position.
* This is especially useful when the buffer is primarily meant for reading
* while additional data is added to the buffer occasionally.
* Consequently, the position of the buffer is unchanged after this operation.
*
* @note The signature is compatible with the fwrite() family of functions.
*
* @param ptr a pointer to the memory area containing the bytes to be written
* @param size the length of one element
* @param nitems the element count
* @param buffer the CxBuffer to write to
* @return the total count of elements written
* @see cxBufferWrite()
* @see cxBufferRead()
*/
cx_attr_nonnull
CX_EXPORT size_t cxBufferAppend(const void *ptr, size_t size,
size_t nitems, CxBuffer *buffer);
/**
* Reads data from a CxBuffer.
*
* The position of the buffer is increased by the number of bytes read.
*
* @note The signature is compatible with the fread() family of functions.
*
* @param ptr a pointer to the memory area where to store the read data
* @param size the length of one element
* @param nitems the element count
* @param buffer the CxBuffer to read from
* @return the total number of elements read
* @see cxBufferWrite()
* @see cxBufferAppend()
*/
cx_attr_nonnull
CX_EXPORT size_t cxBufferRead(void *ptr, size_t size,
size_t nitems, CxBuffer *buffer);
/**
* Writes a character to a buffer.
*
* The least significant byte of the argument is written to the buffer. If the
* end of the buffer is reached and #CX_BUFFER_AUTO_EXTEND feature is enabled,
* the buffer capacity is extended, unless a limit set by
* cxBufferMaximumCapacity() is reached.
* If the feature is disabled or the buffer extension fails, @c EOF is returned.
*
* On successful writing, the position of the buffer is increased.
*
* If you just want to write a null-terminator at the current position, you
* should use cxBufferTerminate() instead.
*
* @param buffer the buffer to write to
* @param c the character to write
* @return the byte that has been written or @c EOF when the end of the
* stream is reached, and automatic extension is not enabled or not possible
* @see cxBufferTerminate()
*/
cx_attr_nonnull
CX_EXPORT int cxBufferPut(CxBuffer *buffer, int c);
/**
* Writes a terminating zero to a buffer at the current position.
*
* If successful, also sets the size to the current position and shrinks the buffer.
*
* The purpose of this function is to have the written data ready to be used as
* a C string with the buffer's size being the length of that string.
*
* @param buffer the buffer to write to
* @return zero, if the terminator could be written, non-zero otherwise
* @see cxBufferShrink()
*/
cx_attr_nonnull
CX_EXPORT int cxBufferTerminate(CxBuffer *buffer);
/**
* Internal function - do not use.
*
* @param buffer the buffer
* @param str the string
* @return the number of bytes written
* @see cxBufferPutString()
*/
cx_attr_nonnull
CX_EXPORT size_t cx_buffer_put_string(CxBuffer *buffer, cxstring str);
/**
* Writes a string to a buffer with cxBufferWrite().
*
* @param buffer (@c CxBuffer*) the buffer
* @param str (any string) the zero-terminated string
* @return (@c size_t) the number of bytes written
* @see cxBufferWrite()
* @see cx_strcast()
*/
#define cxBufferPutString(buffer, str) cx_buffer_put_string(buffer, cx_strcast(str))
/**
* Internal function - do not use.
*
* @param buffer the buffer
* @param str the string
* @return the number of bytes written
* @see cxBufferPutString()
*/
cx_attr_nonnull
CX_EXPORT size_t cx_buffer_append_string(CxBuffer *buffer, cxstring str);
/**
* Appends a string to a buffer with cxBufferAppend().
*
* @param buffer (@c CxBuffer*) the buffer
* @param str (any string) the zero-terminated string
* @return (@c size_t) the number of bytes written
* @see cxBufferAppend()
* @see cx_strcast()
*/
#define cxBufferAppendString(buffer, str) cx_buffer_append_string(buffer, cx_strcast(str))
/**
* Gets a character from a buffer.
*
* The current position of the buffer is increased after a successful read.
*
* @param buffer the buffer to read from
* @return the character or @c EOF, if the end of the buffer is reached
*/
cx_attr_nonnull
CX_EXPORT int cxBufferGet(CxBuffer *buffer);
#ifdef __cplusplus
}
#endif
#endif // UCX_BUFFER_H