ucx: src/cx/buffer.h@1e2be40f0cb5 (annotated)

src/cx/buffer.h@1e2be40f0cb5 (annotated)

src/cx/buffer.h

Sun, 20 Nov 2022 21:08:36 +0100

author: Mike Becker <universe@uap-core.de>
date: Sun, 20 Nov 2022 21:08:36 +0100
changeset 628: 1e2be40f0cb5
parent 567: f90a7cfe2480
child 673: 60fb6aec157d
permissions: -rw-r--r--

use //-style single line comments everywhere

 /*
  * 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
  * \version 3.0
  * \copyright 2-Clause BSD License
  */
 #ifndef UCX_BUFFER_H
 #define UCX_BUFFER_H
 #include "common.h"
 #include "allocator.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.
  */
 #define CX_BUFFER_FREE_CONTENTS 0x01
 /**
  * If this flag is enabled, the buffer will automatically extends its capacity.
  */
 #define CX_BUFFER_AUTO_EXTEND 0x02
 /** Structure for the UCX buffer data. */
 typedef struct {
     /** 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. */
     CxAllocator const *allocator;
     /** Current position of the buffer. */
     size_t pos;
     /** Current capacity (i.e. maximum size) of the buffer. */
     size_t capacity;
     /** Current size of the buffer content. */
     size_t size;
     /**
      * The buffer may not extend beyond this threshold before starting to flush.
      * Default is \c SIZE_MAX (flushing disabled when auto extension is enabled).
      */
     size_t flush_threshold;
     /**
      * The block size for the elements to flush.
      * Default is 4096 bytes.
      */
     size_t flush_blksize;
     /**
      * The maximum number of blocks to flush in one cycle.
      * Zero disables flushing entirely (this is the default).
      * Set this to \c SIZE_MAX to flush the entire buffer.
      *
      * @attention if the maximum number of blocks multiplied with the block size
      * is smaller than the expected contents written to this buffer within one write
      * operation, multiple flush cycles are performed after that write.
      * That means the total number of blocks flushed after one write to this buffer may
      * be larger than \c flush_blkmax.
      */
     size_t flush_blkmax;
     /**
      * The write function used for flushing.
      * If NULL, the flushed content gets discarded.
      */
     cx_write_func flush_func;
     /**
      * The target for \c flush_func.
      */
     void *flush_target;
     /**
      * Flag register for buffer features.
      * @see #CX_BUFFER_DEFAULT
      * @see #CX_BUFFER_FREE_CONTENTS
      * @see #CX_BUFFER_AUTO_EXTEND
      */
     int flags;
 } cx_buffer_s;
 /**
  * UCX buffer.
  */
 typedef cx_buffer_s CxBuffer;
 /**
  * Initializes a fresh buffer.
  *
  * \note You may provide \c NULL as argument for \p space.
  * Then this function will allocate the space and enforce
  * the #CX_BUFFER_FREE_CONTENTS flag.
  *
  * @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
  * @param flags buffer features (see cx_buffer_s.flags)
  * @return zero on success, non-zero if a required allocation failed
  */
 __attribute__((__nonnull__(1, 4)))
 int cxBufferInit(
         CxBuffer *buffer,
         void *space,
         size_t capacity,
         CxAllocator const *allocator,
         int flags
 );
 /**
  * Destroys the buffer contents.
  *
  * Has no effect if the #CX_BUFFER_FREE_CONTENTS feature is not enabled.
  *
  * @param buffer the buffer which contents shall be destroyed
  */
 __attribute__((__nonnull__))
 void cxBufferDestroy(CxBuffer *buffer);
 /**
  * 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.
  * If 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 with 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 parameter type.
  *
  * \attention
  * Security Note: The shifting operation does \em not erase the previously occupied memory cells.
  * But you can easily do that manually, e.g. 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)
  * @return 0 on success, non-zero if a required auto-extension fails
  */
 __attribute__((__nonnull__))
 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
  * @return 0 on success, non-zero if a required auto-extension fails
  * @see cxBufferShift()
  */
 __attribute__((__nonnull__))
 int cxBufferShiftRight(
         CxBuffer *buffer,
         size_t shift
 );
 /**
  * Shifts the buffer to the left.
  * See cxBufferShift() for details.
  *
  * \note Since a left shift cannot fail due to memory allocation problems, this
  * function always returns zero.
  *
  * @param buffer the buffer
  * @param shift the positive shift offset
  * @return always zero
  * @see cxBufferShift()
  */
 __attribute__((__nonnull__))
 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
  * @return 0 on success, non-zero if the position is invalid
  *
  */
 __attribute__((__nonnull__))
 int cxBufferSeek(
         CxBuffer *buffer,
         off_t offset,
         int whence
 );
 /**
  * Clears the buffer by resetting the position and deleting the data.
  *
  * The data is deleted by zeroing it with a call to memset().
  *
  * @param buffer the buffer to be cleared
  */
 __attribute__((__nonnull__))
 void cxBufferClear(CxBuffer *buffer);
 /**
  * Tests, if the buffer position has exceeded the buffer capacity.
  *
  * @param buffer the buffer to test
  * @return non-zero, if the current buffer position has exceeded the last
  * available byte of the buffer.
  */
 __attribute__((__nonnull__))
 int cxBufferEof(CxBuffer const *buffer);
 /**
  * Ensures that the buffer has a minimum capacity.
  *
  * If the current capacity is not sufficient, the buffer will be extended.
  *
  * @param buffer the buffer
  * @param capacity the minimum required capacity for this buffer
  * @return 0 on success or a non-zero value on failure
  */
 __attribute__((__nonnull__))
 int cxBufferMinimumCapacity(
         CxBuffer *buffer,
         size_t capacity
 );
 /**
  * Writes data to a CxBuffer.
  *
  * If flushing is enabled and the buffer needs to flush, the data is flushed to
  * the target until the target signals that it cannot take more data by
  * returning zero via the respective write function. In that case, the remaining
  * data in this buffer is shifted to the beginning of this buffer so that the
  * newly available space can be used to append as much data as possible. This
  * function only stops writing more elements, when the flush target and this
  * buffer are both incapable of taking more data or all data has been written.
  * The number returned by this function is the total number of elements that
  * could be written during the process. It does not necessarily mean that those
  * elements are still in this buffer, because some of them could have also be
  * flushed already.
  *
  * If automatic flushing is not enabled, the position of the buffer is increased
  * by the number of bytes written.
  *
  * \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
  */
 __attribute__((__nonnull__))
 size_t cxBufferWrite(
         void const *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
  */
 __attribute__((__nonnull__))
 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 by cxBufferMinimumCapacity(). If the feature is
  * disabled or buffer extension fails, \c EOF is returned.
  *
  * On successful write, the position of the buffer is increased.
  *
  * @param buffer the buffer to write to
  * @param c the character to write
  * @return the byte that has bean written or \c EOF when the end of the stream is
  * reached and automatic extension is not enabled or not possible
  */
 __attribute__((__nonnull__))
 int cxBufferPut(
         CxBuffer *buffer,
         int c
 );
 /**
  * Writes a string to a buffer.
  *
  * @param buffer the buffer
  * @param str the zero-terminated string
  * @return the number of bytes written
  */
 __attribute__((__nonnull__))
 size_t cxBufferPutString(
         CxBuffer *buffer,
         const char *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
  */
 __attribute__((__nonnull__))
 int cxBufferGet(CxBuffer *buffer);
 #ifdef __cplusplus
 }
 #endif
 #endif // UCX_BUFFER_H

Mercurial > hg > ucx / annotate

src/cx/buffer.h@1e2be40f0cb5 (annotated)

src/cx/buffer.h