Mercurial > libjeffpc
view buffer_static.c @ 712:8295148e8f44
buffer: rename internal 'used' member to a more obvious name
It really keeps track of the number of readable bytes in the buffer. In
other words, it keeps track of the size - hence the new name.
Signed-off-by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
author | Josef 'Jeff' Sipek <jeffpc@josefsipek.net> |
---|---|
date | Tue, 19 Mar 2019 14:43:26 -0400 |
parents | 0fa2f6606c5e |
children | 1c4d7ff0a682 |
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/* * Copyright (c) 2017-2019 Josef 'Jeff' Sipek <jeffpc@josefsipek.net> * * 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 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 "buffer_impl.h" /* * Static buffers * * Since we have a borrowed buffer we must never allow: * * - resizing of the buffer * - freeing of the buffer * * Conveniently, if we leave the realloc op NULL, the generic code returns * -ENOTSUP for us. Leaving the free op NULL turns it into a no-op. * * There is a slight difference between the read-only and read-write * variants. Namely, the read-only variant does not support *any* writes or * changes to the (apparent) buffer size. In both cases, -EROFS is * returned. The read-write variant allows changes to the amount of used * space, truncation, etc. as long as the result fits within the borrowed * buffer. */ static int static_buffer_check_append_ro(struct buffer *buffer, const void *data, size_t size) { return -EROFS; } static int static_buffer_check_append_rw(struct buffer *buffer, const void *data, size_t size) { if ((buffer->size + size) <= buffer->allocsize) return 0; return -ENOSPC; } static int static_buffer_check_truncate_ro(struct buffer *buffer, size_t size) { return -EROFS; } static int static_buffer_check_truncate_rw(struct buffer *buffer, size_t size) { if (size <= buffer->allocsize) return 0; return -ENOSPC; } static int static_buffer_check_write_ro(struct buffer *buffer, const void *buf, size_t len, size_t off) { return -EROFS; } static int static_buffer_check_write_rw(struct buffer *buffer, const void *buf, size_t len, size_t off) { if ((off + len) <= buffer->allocsize) return 0; return -ENOSPC; } /* a read-only static buffer */ const struct buffer_ops static_buffer_ro = { .check_append = static_buffer_check_append_ro, .check_truncate = static_buffer_check_truncate_ro, .check_write = static_buffer_check_write_ro, .clear = generic_buffer_clear_panic, .copyin = generic_buffer_copyin_panic, .copyout = generic_buffer_copyout_memcpy, }; /* a read-write static buffer */ const struct buffer_ops static_buffer_rw = { .check_append = static_buffer_check_append_rw, .check_truncate = static_buffer_check_truncate_rw, .check_write = static_buffer_check_write_rw, .clear = generic_buffer_clear_memset, .copyin = generic_buffer_copyin_memcpy, .copyout = generic_buffer_copyout_memcpy, };