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/*
* Copyright (c) 2003-2023, John Wiegley. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of New Artisans LLC nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <system.hh>
#include "stream.h"
namespace ledger {
namespace {
/**
* @brief Forks a child process so that Ledger may handle running a
* pager
*
* In order for the pager option to work, Ledger has to run the pager
* itself, which requires Ledger to fork a new process in order to run
* the pager. This function does the necessary fork. After the fork,
* two processes exist. One of them is exec'd to create the pager;
* the other is still Ledger.
*
* This function returns only for the process that is still Ledger.
*
* @param pager_path Path to the pager command.
*
* @return The file descriptor of the pipe to the pager. The caller
* is responsible for cleaning this up.
*
* @exception std::logic_error Some problem was encountered, such as
* failure to create a pipe or failure to fork a child process.
*/
int do_fork(std::ostream ** os, const path& pager_path)
{
#if !defined(_WIN32) && !defined(__CYGWIN__)
int pfd[2];
int status = pipe(pfd);
if (status == -1)
throw std::logic_error(_("Failed to create pipe"));
status = fork();
if (status < 0) {
throw std::logic_error(_("Failed to fork child process"));
}
else if (status == 0) { // child
// Duplicate pipe's reading end into stdin
status = dup2(pfd[0], STDIN_FILENO);
if (status == -1)
perror("dup2");
// Close unused file descriptors: the pipe's writing and reading
// ends (the latter is not needed anymore, after the duplication).
close(pfd[1]);
close(pfd[0]);
execlp("/bin/sh", "/bin/sh", "-c", pager_path.string().c_str(), NULL);
// We should never, ever reach here
perror("execlp: /bin/sh");
exit(1);
}
else { // parent
close(pfd[0]);
typedef iostreams::stream<iostreams::file_descriptor_sink> fdstream;
*os = new fdstream(pfd[1], iostreams::never_close_handle);
}
return pfd[1];
#else
return 0;
#endif
}
}
void output_stream_t::initialize(const optional<path>& output_file,
const optional<path>& pager_path)
{
if (output_file && *output_file != "-")
os = new ofstream(*output_file);
else if (pager_path)
pipe_to_pager_fd = do_fork(&os, *pager_path);
else
os = &std::cout;
}
void output_stream_t::close()
{
#if !defined(_WIN32) && !defined(__CYGWIN__)
if (os != &std::cout) {
checked_delete(os);
os = &std::cout;
}
if (pipe_to_pager_fd != -1) {
::close(pipe_to_pager_fd);
pipe_to_pager_fd = -1;
int status;
wait(&status);
if (! WIFEXITED(status) || WEXITSTATUS(status) != 0)
throw std::logic_error(_("Error in the pager"));
}
#endif
}
} // namespace ledger
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