/*-
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* Copyright (C) 2013 Pietro Cerutti <gahr@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "local.h"
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// See http://pubs.opengroup.org/onlinepubs/9699919799/functions/fmemopen.html
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// and http://man7.org/linux/man-pages/man3/fmemopen.3.html for documentation.
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struct fmemopen_cookie {
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char* buf;
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char* allocation;
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size_t capacity;
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size_t size;
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size_t offset;
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bool append;
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};
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static int fmemopen_read(void* cookie, char* buf, int n) {
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fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(cookie);
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if (static_cast<size_t>(n) > ck->size - ck->offset) n = ck->size - ck->offset;
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if (n > 0) {
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memmove(buf, ck->buf + ck->offset, n);
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ck->offset += n;
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}
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return n;
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}
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static int fmemopen_write(void* cookie, const char* buf, int n) {
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fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(cookie);
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// We don't need to add the trailing NUL if there's already a trailing NUL
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// in the data we're writing.
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size_t space_for_null = (n > 0 && buf[n - 1] != '\0') ? 1 : 0;
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// Undo any seeking/reading on an append-only stream.
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if (ck->append) ck->offset = ck->size;
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// How much can we actually fit?
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if (static_cast<size_t>(n) + space_for_null > ck->capacity - ck->offset) {
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n = ck->capacity - ck->offset - space_for_null;
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// Give up if we don't even have room for one byte of userdata.
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if (n <= 0) {
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errno = ENOSPC;
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return -1;
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}
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}
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if (n > 0) {
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memmove(ck->buf + ck->offset, buf, n);
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ck->offset += n;
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// Is this the furthest we've ever been?
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if (ck->offset >= ck->size) {
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if (buf[n - 1] != '\0') ck->buf[ck->offset] = '\0';
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ck->size = ck->offset;
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}
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}
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return n;
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}
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static fpos_t fmemopen_seek(void* cookie, fpos_t offset, int whence) {
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fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(cookie);
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if (whence == SEEK_SET && (offset >= 0 && static_cast<size_t>(offset) <= ck->capacity)) {
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return (ck->offset = offset);
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} else if (whence == SEEK_CUR && (ck->offset + offset <= ck->capacity)) {
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return (ck->offset += offset);
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} else if (whence == SEEK_END && (offset <= 0 && static_cast<size_t>(-offset) <= ck->size)) {
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return (ck->offset = ck->size + offset);
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}
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errno = EINVAL;
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return -1;
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}
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static int fmemopen_close(void* cookie) {
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fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(cookie);
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free(ck->allocation);
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free(ck);
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return 0;
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}
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FILE* fmemopen(void* buf, size_t capacity, const char* mode) {
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int flags;
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if (__sflags(mode, &flags) == 0) {
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errno = EINVAL;
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return nullptr;
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}
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fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(calloc(sizeof(fmemopen_cookie), 1));
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if (ck == nullptr) return nullptr;
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ck->buf = static_cast<char*>(buf);
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ck->capacity = capacity;
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if (ck->buf == nullptr) ck->buf = ck->allocation = static_cast<char*>(calloc(capacity, 1));
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if (ck->buf == nullptr) {
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free(ck);
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return nullptr;
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}
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FILE* fp = funopen(ck,
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(flags & O_WRONLY) ? nullptr : fmemopen_read,
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(flags & O_RDONLY) ? nullptr : fmemopen_write,
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fmemopen_seek,
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fmemopen_close);
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if (fp == nullptr) {
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fmemopen_close(ck);
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return nullptr;
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}
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if (mode[0] == 'a') {
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ck->size = strnlen(ck->buf, ck->capacity);
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ck->offset = ck->size;
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ck->append = true;
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} else if (mode[0] == 'r') {
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ck->size = capacity;
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ck->offset = 0;
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} else if (mode[0] == 'w') {
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ck->size = 0;
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ck->offset = 0;
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if (capacity > 0) {
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ck->buf[0] = '\0';
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}
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}
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return fp;
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}
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