144 lines
4.6 KiB
C++
144 lines
4.6 KiB
C++
/*
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* Copyright (c) 2003-2013, John Wiegley. 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
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* met:
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*
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* - 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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*
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* - 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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* - Neither the name of New Artisans LLC nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written 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
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* 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
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <system.hh>
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#include "stream.h"
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namespace ledger {
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namespace {
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/**
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* @brief Forks a child process so that Ledger may handle running a
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* pager
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*
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* In order for the pager option to work, Ledger has to run the pager
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* itself, which requires Ledger to fork a new process in order to run
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* the pager. This function does the necessary fork. After the fork,
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* two processes exist. One of them is exec'd to create the pager;
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* the other is still Ledger.
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*
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* This function returns only for the process that is still Ledger.
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*
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* @param pager_path Path to the pager command.
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*
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* @return The file descriptor of the pipe to the pager. The caller
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* is responsible for cleaning this up.
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*
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* @exception std::logic_error Some problem was encountered, such as
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* failure to create a pipe or failure to fork a child process.
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*/
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int do_fork(std::ostream ** os, const path& pager_path)
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{
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#ifndef WIN32
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int pfd[2];
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int status = pipe(pfd);
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if (status == -1)
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throw std::logic_error(_("Failed to create pipe"));
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status = fork();
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if (status < 0) {
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throw std::logic_error(_("Failed to fork child process"));
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}
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else if (status == 0) { // child
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// Duplicate pipe's reading end into stdin
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status = dup2(pfd[0], STDIN_FILENO);
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if (status == -1)
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perror("dup2");
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// Close unuseful file descriptors: the pipe's writing and reading
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// ends (the latter is not needed anymore, after the duplication).
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close(pfd[1]);
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close(pfd[0]);
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// Find command name: its the substring starting right of the
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// rightmost '/' character in the pager pathname. See manpage for
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// strrchr.
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#if BOOST_VERSION >= 103700
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path basename(pager_path.filename());
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#else
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path basename(pager_path.leaf());
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#endif
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execlp(pager_path.string().c_str(), basename.string().c_str(), NULL);
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// We should never, ever reach here
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perror((std::string("execlp: ") + pager_path.string()).c_str());
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exit(1);
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}
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else { // parent
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close(pfd[0]);
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typedef iostreams::stream<iostreams::file_descriptor_sink> fdstream;
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#if BOOST_VERSION >= 104400
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*os = new fdstream(pfd[1], iostreams::never_close_handle);
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#else // BOOST_VERSION >= 104400
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*os = new fdstream(pfd[1]);
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#endif // BOOST_VERSION >= 104400
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}
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return pfd[1];
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#else
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return 0;
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#endif
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}
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}
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void output_stream_t::initialize(const optional<path>& output_file,
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const optional<path>& pager_path)
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{
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if (output_file && *output_file != "-")
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os = new ofstream(*output_file);
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else if (pager_path)
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pipe_to_pager_fd = do_fork(&os, *pager_path);
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else
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os = &std::cout;
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}
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void output_stream_t::close()
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{
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#ifndef WIN32
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if (os != &std::cout) {
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checked_delete(os);
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os = &std::cout;
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}
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if (pipe_to_pager_fd != -1) {
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::close(pipe_to_pager_fd);
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pipe_to_pager_fd = -1;
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int status;
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wait(&status);
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if (! WIFEXITED(status) || WEXITSTATUS(status) != 0)
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throw std::logic_error(_("Error in the pager"));
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}
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#endif
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}
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} // namespace ledger
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