152 lines
4.0 KiB
C++
152 lines
4.0 KiB
C++
/*
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Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __BUFFER_HPP_INCLUDED__
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#define __BUFFER_HPP_INCLUDED__
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#include <ndb_global.h>
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/* This class represents a buffer of binary data, where you can append
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* data at the end, and later read the entire bunch.
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* It will take care of the hairy details of realloc()ing the space
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* for you.
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*/
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class UtilBuffer {
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public:
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UtilBuffer() : data(nullptr), len(0), alloc_size(0) { }
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~UtilBuffer() { free(data); }
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/* Grow buffer to specified length.
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On success, returns 0. On failure, returns -1 and sets errno.
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*/
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int grow(size_t l) {
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if(l > alloc_size)
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return reallocate(l);
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return 0;
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}
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/* Append to current data.
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On success, returns 0. On failure, returns -1 and sets errno.
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*/
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int append(const void *d, size_t l) {
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if (likely(l > 0))
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{
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if (unlikely(d == nullptr))
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{
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errno = EINVAL;
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return -1;
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}
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void * pos = append(l);
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if(pos == nullptr)
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{
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return -1;
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}
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memcpy(pos, d, l);
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}
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return 0;
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}
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/* Append to current data.
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Returns pointer where data of length l can be written.
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On failure, returns nullptr and sets errno.
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*/
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void * append(size_t l){
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if(grow(len+l) != 0)
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return nullptr;
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void * ret = (char*)data+len;
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len += l;
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return ret;
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}
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/* Free the current buffer memory, and assign new content.
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On success, returns 0. On failure, returns -1 and sets errno.
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*/
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int assign(const void * d, size_t l) {
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/* Free the old data only after copying, in case d==data. */
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void *old_data= data;
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data = nullptr;
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len = 0;
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alloc_size = 0;
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int ret= append(d, l);
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if (old_data)
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free(old_data);
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return ret;
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}
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/* Truncate contents to 0 length without freeing buffer memory. */
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void clear() {
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len = 0;
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}
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int length() const { assert(Uint64(len) == Uint32(len)); return (int)len; }
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void *get_data() const { return data; }
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bool empty () const { return len == 0; }
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bool equal(const UtilBuffer &cmp) const {
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if(len==0 && cmp.len==0)
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return true;
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else if(len!=cmp.len)
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return false;
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else
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return (memcmp(get_data(), cmp.get_data(), len) == 0);
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}
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int assign(const UtilBuffer& buf) {
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int ret = 0;
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if(this != &buf) {
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ret = assign(buf.get_data(), buf.length());
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}
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return ret;
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}
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private:
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int reallocate(size_t newsize) {
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if(newsize < len) {
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errno = EINVAL;
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return -1;
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}
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void *newdata;
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if((newdata = realloc(data, newsize)) == NULL) {
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errno = ENOMEM;
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return -1;
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}
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alloc_size = newsize;
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data = newdata;
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return 0;
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}
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void *data; /* Pointer to data storage */
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size_t len; /* Size of the stored data */
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size_t alloc_size; /* Size of the allocated space,
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* i.e. len can grow to this size */
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};
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#endif /* !__BUFFER_HPP_INCLUDED__ */
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