27dca4d857
首先，POSIX规范规定文件描述符需要支持close-on-exec属性，修改前的vfs不支持close-on-exec，当exec系列函数执行时，进程所有的文件将会被关闭（0，1，2也重新被打开）。但是，系统有些时候是不能在exec时关闭全部文件的，例如在执行exec之前，就需要重定向进程的某些文件描述符时（使用dup2），就希望该文件不被关闭，继续保持重定向属性，shell执行进程并重定向其标准输出到文件，这是我们经常做的事情。 BREAKING CHANGE: 执行exec类函数后，进程拥有的文件描述符情况发生变化：修改前，默认关闭所有的进程文件描述符，0，1，2重新打开；修改后，除非文件描述符拥有FD_CLOEXEC标记，否则该描述符不会被关闭。 re #I3U81W Change-Id: I54e841ac88e9835ec23e97de0cbc906c4e11f5a4 Signed-off-by: Guangyao Ma <guangyao.ma@outlook.com>
140 lines
4.2 KiB
C
140 lines
4.2 KiB
C
/*
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* Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved.
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* Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this list of
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* conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice, this list
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* of conditions and the following disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its contributors may be used
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* to endorse or promote products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "sys/types.h"
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#include "sys/uio.h"
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#include "unistd.h"
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#include "string.h"
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#include "stdlib.h"
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#include "fs/file.h"
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#include "user_copy.h"
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#include "limits.h"
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static int iov_trans_to_buf(char *buf, ssize_t totallen, const struct iovec *iov, int iovcnt)
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{
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int i;
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size_t ret, writepart;
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size_t bytestowrite;
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char *writebuf = NULL;
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char *curbuf = buf;
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for (i = 0; i < iovcnt; ++i) {
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writebuf = (char *)iov[i].iov_base;
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bytestowrite = iov[i].iov_len;
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if (bytestowrite == 0) {
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continue;
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}
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if (totallen == 0) {
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break;
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}
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bytestowrite = (totallen < bytestowrite) ? totallen : bytestowrite;
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ret = LOS_CopyToKernel(curbuf, bytestowrite, writebuf, bytestowrite);
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if (ret != 0) {
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if (ret == bytestowrite) {
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set_errno(EFAULT);
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return VFS_ERROR;
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} else {
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writepart = bytestowrite - ret;
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curbuf += writepart;
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totallen -= writepart;
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break;
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}
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}
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curbuf += bytestowrite;
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totallen -= bytestowrite;
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}
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return (int)((intptr_t)curbuf - (intptr_t)buf);
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}
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ssize_t vfs_writev(int fd, const struct iovec *iov, int iovcnt, off_t *offset)
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{
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int i, ret;
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char *buf = NULL;
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size_t buflen = 0;
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size_t bytestowrite;
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ssize_t totalbyteswritten;
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size_t totallen;
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if ((iov == NULL) || (iovcnt > IOV_MAX)) {
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return VFS_ERROR;
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}
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for (i = 0; i < iovcnt; ++i) {
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if (SSIZE_MAX - buflen < iov[i].iov_len) {
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set_errno(EINVAL);
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return VFS_ERROR;
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}
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buflen += iov[i].iov_len;
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}
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if (buflen == 0) {
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return 0;
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}
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totallen = buflen * sizeof(char);
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#ifdef LOSCFG_KERNEL_VM
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buf = (char *)LOS_VMalloc(totallen);
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#else
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buf = (char *)malloc(totallen);
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#endif
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if (buf == NULL) {
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return VFS_ERROR;
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}
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ret = iov_trans_to_buf(buf, totallen, iov, iovcnt);
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if (ret <= 0) {
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#ifdef LOSCFG_KERNEL_VM
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LOS_VFree(buf);
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#else
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free(buf);
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#endif
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return VFS_ERROR;
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}
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bytestowrite = (ssize_t)ret;
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totalbyteswritten = (offset == NULL) ? write(fd, buf, bytestowrite)
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: pwrite(fd, buf, bytestowrite, *offset);
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#ifdef LOSCFG_KERNEL_VM
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LOS_VFree(buf);
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#else
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free(buf);
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#endif
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return totalbyteswritten;
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}
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ssize_t writev(int fd, const struct iovec *iov, int iovcnt)
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{
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return vfs_writev(fd, iov, iovcnt, NULL);
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}
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