/* * Copyright (c) 2018 Apple Computer, Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this * file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_LICENSE_HEADER_END@ */ #include "stuff/write64.h" ssize_t write64(int fildes, const void *buf, size_t nbyte) { unsigned char* uchars = (unsigned char*)buf; ssize_t total = 0; while (nbyte) { /* * If we were writing socket- or stream-safe code we'd chuck the * entire buf to write(2) and then gracefully re-request bytes that * didn't get written. But write(2) will return EINVAL if you ask it to * write more than 2^31-1 bytes. So instead we actually need to throttle * the input to write. * * Historically code using write(2) to write to disk will assert that * that all of the requested bytes were written. It seems harmless to * re-request bytes as one does when writing to streams, with the * compromise that we will return immediately when write(2) returns 0 * bytes written. */ size_t limit = 0x7FFFFFFF; size_t towrite = nbyte < limit ? nbyte : limit; ssize_t wrote = write(fildes, uchars, towrite); if (-1 == wrote) { return -1; } else if (0 == wrote) { break; } else { nbyte -= wrote; uchars += wrote; total += wrote; } } return total; }