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218 lines
5.1 KiB
C++
218 lines
5.1 KiB
C++
/**
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* Copyright (c) 2023, Timothy Stack
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*
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* All rights reserved.
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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 are met:
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*
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* * Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* * Neither the name of Timothy Stack nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* @file auto_fd.cc
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*/
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#include "auto_fd.hh"
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#include <fcntl.h>
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#include <unistd.h>
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#include "lnav_log.hh"
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int
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auto_fd::pipe(auto_fd* af)
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{
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int retval, fd[2];
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require(af != nullptr);
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if ((retval = ::pipe(fd)) == 0) {
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af[0] = fd[0];
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af[1] = fd[1];
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}
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return retval;
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}
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auto_fd
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auto_fd::dup_of(int fd)
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{
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if (fd == -1) {
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return auto_fd{};
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}
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auto new_fd = ::dup(fd);
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if (new_fd == -1) {
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throw std::bad_alloc();
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}
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return auto_fd(new_fd);
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}
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auto_fd::auto_fd(int fd) : af_fd(fd)
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{
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require(fd >= -1);
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}
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auto_fd::auto_fd(auto_fd&& af) noexcept : af_fd(af.release()) {}
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auto_fd
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auto_fd::dup() const
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{
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int new_fd;
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if (this->af_fd == -1 || (new_fd = ::dup(this->af_fd)) == -1) {
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throw std::bad_alloc();
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}
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return auto_fd{new_fd};
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}
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auto_fd::~auto_fd()
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{
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this->reset();
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}
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void
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auto_fd::reset(int fd)
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{
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require(fd >= -1);
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if (this->af_fd != fd) {
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if (this->af_fd != -1) {
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switch (this->af_fd) {
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case STDIN_FILENO:
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case STDOUT_FILENO:
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case STDERR_FILENO:
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break;
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default:
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close(this->af_fd);
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break;
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}
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}
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this->af_fd = fd;
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}
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}
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void
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auto_fd::close_on_exec() const
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{
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if (this->af_fd == -1) {
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return;
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}
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log_perror(fcntl(this->af_fd, F_SETFD, FD_CLOEXEC));
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}
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void
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auto_fd::non_blocking() const
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{
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auto fl = fcntl(this->af_fd, F_GETFL, 0);
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if (fl < 0) {
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return;
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}
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log_perror(fcntl(this->af_fd, F_SETFL, fl | O_NONBLOCK));
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}
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auto_fd&
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auto_fd::operator=(int fd)
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{
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require(fd >= -1);
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this->reset(fd);
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return *this;
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}
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Result<auto_pipe, std::string>
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auto_pipe::for_child_fd(int child_fd)
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{
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auto_pipe retval(child_fd);
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if (retval.open() == -1) {
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return Err(std::string(strerror(errno)));
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}
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return Ok(std::move(retval));
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}
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auto_pipe::auto_pipe(int child_fd, int child_flags)
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: ap_child_flags(child_flags), ap_child_fd(child_fd)
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{
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switch (child_fd) {
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case STDIN_FILENO:
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this->ap_child_flags = O_RDONLY;
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break;
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case STDOUT_FILENO:
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case STDERR_FILENO:
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this->ap_child_flags = O_WRONLY;
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break;
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}
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}
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void
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auto_pipe::after_fork(pid_t child_pid)
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{
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int new_fd;
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switch (child_pid) {
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case -1:
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this->close();
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break;
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case 0:
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if (this->ap_child_flags == O_RDONLY) {
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this->write_end().reset();
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if (this->read_end().get() == -1) {
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this->read_end() = ::open("/dev/null", O_RDONLY);
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}
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new_fd = this->read_end().get();
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} else {
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this->read_end().reset();
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if (this->write_end().get() == -1) {
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this->write_end() = ::open("/dev/null", O_WRONLY);
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}
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new_fd = this->write_end().get();
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}
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if (this->ap_child_fd != -1) {
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if (new_fd != this->ap_child_fd) {
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dup2(new_fd, this->ap_child_fd);
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this->close();
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}
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}
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break;
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default:
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if (this->ap_child_flags == O_RDONLY) {
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this->read_end().reset();
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} else {
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this->write_end().reset();
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}
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break;
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}
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}
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int
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auto_pipe::open()
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{
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int retval = auto_fd::pipe(this->ap_fd);
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this->ap_fd[0].close_on_exec();
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this->ap_fd[1].close_on_exec();
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return retval;
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}
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