/*
* 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.
*/
#include "cx/buffer.h"
#include "cx/utils.h"
#include <stdio.h>
#include <string.h>
int cxBufferInit(
CxBuffer *buffer,
void *space,
size_t capacity,
CxAllocator const *allocator,
int flags
) {
if (allocator == NULL) allocator = cxDefaultAllocator;
buffer->allocator = allocator;
buffer->flags = flags;
if (!space) {
buffer->bytes = cxMalloc(allocator, capacity);
if (buffer->bytes == NULL) {
return 1;
}
buffer->flags |= CX_BUFFER_FREE_CONTENTS;
} else {
buffer->bytes = space;
}
buffer->capacity = capacity;
buffer->size = 0;
buffer->pos = 0;
buffer->flush_func = NULL;
buffer->flush_target = NULL;
buffer->flush_blkmax = 0;
buffer->flush_blksize = 4096;
buffer->flush_threshold = SIZE_MAX;
return 0;
}
void cxBufferDestroy(CxBuffer *buffer) {
if ((buffer->flags & CX_BUFFER_FREE_CONTENTS) == CX_BUFFER_FREE_CONTENTS) {
cxFree(buffer->allocator, buffer->bytes);
}
}
CxBuffer *cxBufferCreate(
void *space,
size_t capacity,
CxAllocator const *allocator,
int flags
) {
CxBuffer *buf = cxMalloc(allocator, sizeof(CxBuffer));
if (buf == NULL) return NULL;
if (0 == cxBufferInit(buf, space, capacity, allocator, flags)) {
return buf;
} else {
cxFree(allocator, buf);
return NULL;
}
}
void cxBufferFree(CxBuffer *buffer) {
if ((buffer->flags & CX_BUFFER_FREE_CONTENTS) == CX_BUFFER_FREE_CONTENTS) {
cxFree(buffer->allocator, buffer->bytes);
}
cxFree(buffer->allocator, buffer);
}
int cxBufferSeek(
CxBuffer *buffer,
off_t offset,
int whence
) {
size_t npos;
switch (whence) {
case SEEK_CUR:
npos = buffer->pos;
break;
case SEEK_END:
npos = buffer->size;
break;
case SEEK_SET:
npos = 0;
break;
default:
return -1;
}
size_t opos = npos;
npos += offset;
if ((offset > 0 && npos < opos) || (offset < 0 && npos > opos)) {
return -1;
}
if (npos >= buffer->size) {
return -1;
} else {
buffer->pos = npos;
return 0;
}
}
void cxBufferClear(CxBuffer *buffer) {
memset(buffer->bytes, 0, buffer->size);
buffer->size = 0;
buffer->pos = 0;
}
int cxBufferEof(CxBuffer const *buffer) {
return buffer->pos >= buffer->size;
}
int cxBufferMinimumCapacity(
CxBuffer *buffer,
size_t newcap
) {
if (newcap <= buffer->capacity) {
return 0;
}
if (cxReallocate(buffer->allocator,
(void **) &buffer->bytes, newcap) == 0) {
buffer->capacity = newcap;
return 0;
} else {
return -1;
}
}
/**
* Helps flushing data to the flush target of a buffer.
*
* @param buffer the buffer containing the config
* @param space the data to flush
* @param size the element size
* @param nitems the number of items
* @return the number of items flushed
*/
static size_t cx_buffer_write_flush_helper(
CxBuffer *buffer,
unsigned char const *space,
size_t size,
size_t nitems
) {
size_t pos = 0;
size_t remaining = nitems;
size_t max_items = buffer->flush_blksize / size;
while (remaining > 0) {
size_t items = remaining > max_items ? max_items : remaining;
size_t flushed = buffer->flush_func(
space + pos,
size, items,
buffer->flush_target);
if (flushed > 0) {
pos += (flushed * size);
remaining -= flushed;
} else {
// if no bytes can be flushed out anymore, we give up
break;
}
}
return nitems - remaining;
}
size_t cxBufferWrite(
void const *ptr,
size_t size,
size_t nitems,
CxBuffer *buffer
) {
// optimize for easy case
if (size == 1 && (buffer->capacity - buffer->pos) >= nitems) {
memcpy(buffer->bytes + buffer->pos, ptr, nitems);
buffer->pos += nitems;
if (buffer->pos > buffer->size) {
buffer->size = buffer->pos;
}
return nitems;
}
size_t len;
size_t nitems_out = nitems;
if (cx_szmul(size, nitems, &len)) {
return 0;
}
size_t required = buffer->pos + len;
if (buffer->pos > required) {
return 0;
}
bool perform_flush = false;
if (required > buffer->capacity) {
if ((buffer->flags & CX_BUFFER_AUTO_EXTEND) == CX_BUFFER_AUTO_EXTEND && required) {
if (buffer->flush_blkmax > 0 && required > buffer->flush_threshold) {
perform_flush = true;
} else {
if (cxBufferMinimumCapacity(buffer, required)) {
return 0;
}
}
} else {
if (buffer->flush_blkmax > 0) {
perform_flush = true;
} else {
// truncate data to be written, if we can neither extend nor flush
len = buffer->capacity - buffer->pos;
if (size > 1) {
len -= len % size;
}
nitems_out = len / size;
}
}
}
if (len == 0) {
return len;
}
if (perform_flush) {
size_t flush_max;
if (cx_szmul(buffer->flush_blkmax, buffer->flush_blksize, &flush_max)) {
return 0;
}
size_t flush_pos = buffer->flush_func == NULL || buffer->flush_target == NULL
? buffer->pos
: cx_buffer_write_flush_helper(buffer, buffer->bytes, 1, buffer->pos);
if (flush_pos == buffer->pos) {
// entire buffer has been flushed, we can reset
buffer->size = buffer->pos = 0;
size_t items_flush; // how many items can also be directly flushed
size_t items_keep; // how many items have to be written to the buffer
items_flush = flush_max >= required ? nitems : (flush_max - flush_pos) / size;
if (items_flush > 0) {
items_flush = cx_buffer_write_flush_helper(buffer, ptr, size, items_flush / size);
// in case we could not flush everything, keep the rest
}
items_keep = nitems - items_flush;
if (items_keep > 0) {
// try again with the remaining stuff
unsigned char const *new_ptr = ptr;
new_ptr += items_flush * size;
// report the directly flushed items as written plus the remaining stuff
return items_flush + cxBufferWrite(new_ptr, size, items_keep, buffer);
} else {
// all items have been flushed - report them as written
return nitems;
}
} else if (flush_pos == 0) {
// nothing could be flushed at all, we immediately give up without writing any data
return 0;
} else {
// we were partially successful, we shift left and try again
cxBufferShiftLeft(buffer, flush_pos);
return cxBufferWrite(ptr, size, nitems, buffer);
}
} else {
memcpy(buffer->bytes + buffer->pos, ptr, len);
buffer->pos += len;
if (buffer->pos > buffer->size) {
buffer->size = buffer->pos;
}
return nitems_out;
}
}
int cxBufferPut(
CxBuffer *buffer,
int c
) {
c &= 0xFF;
unsigned char const ch = c;
if (cxBufferWrite(&ch, 1, 1, buffer) == 1) {
return c;
} else {
return EOF;
}
}
size_t cxBufferPutString(
CxBuffer *buffer,
const char *str
) {
return cxBufferWrite(str, 1, strlen(str), buffer);
}
size_t cxBufferRead(
void *ptr,
size_t size,
size_t nitems,
CxBuffer *buffer
) {
size_t len;
if (cx_szmul(size, nitems, &len)) {
return 0;
}
if (buffer->pos + len > buffer->size) {
len = buffer->size - buffer->pos;
if (size > 1) len -= len % size;
}
if (len <= 0) {
return len;
}
memcpy(ptr, buffer->bytes + buffer->pos, len);
buffer->pos += len;
return len / size;
}
int cxBufferGet(CxBuffer *buffer) {
if (cxBufferEof(buffer)) {
return EOF;
} else {
int c = buffer->bytes[buffer->pos];
buffer->pos++;
return c;
}
}
int cxBufferShiftLeft(
CxBuffer *buffer,
size_t shift
) {
if (shift >= buffer->size) {
buffer->pos = buffer->size = 0;
} else {
memmove(buffer->bytes, buffer->bytes + shift, buffer->size - shift);
buffer->size -= shift;
if (buffer->pos >= shift) {
buffer->pos -= shift;
} else {
buffer->pos = 0;
}
}
return 0;
}
int cxBufferShiftRight(
CxBuffer *buffer,
size_t shift
) {
size_t req_capacity = buffer->size + shift;
size_t movebytes;
// auto extend buffer, if required and enabled
if (buffer->capacity < req_capacity) {
if ((buffer->flags & CX_BUFFER_AUTO_EXTEND) == CX_BUFFER_AUTO_EXTEND) {
if (cxBufferMinimumCapacity(buffer, req_capacity)) {
return 1;
}
movebytes = buffer->size;
} else {
movebytes = buffer->capacity - shift;
}
} else {
movebytes = buffer->size;
}
memmove(buffer->bytes + shift, buffer->bytes, movebytes);
buffer->size = shift + movebytes;
buffer->pos += shift;
if (buffer->pos > buffer->size) {
buffer->pos = buffer->size;
}
return 0;
}
int cxBufferShift(
CxBuffer *buffer,
off_t shift
) {
if (shift < 0) {
return cxBufferShiftLeft(buffer, (size_t) (-shift));
} else if (shift > 0) {
return cxBufferShiftRight(buffer, (size_t) shift);
} else {
return 0;
}
}