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111 lines (91 loc) · 4.15 KB
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// system headers
#include <algorithm>
#include <iostream>
#include <memory>
#include <stdexcept>
#include <utility>
#include <unistd.h>
#include <thread>
// local headers
#include "linuxdeploy/subprocess/subprocess.h"
#include "linuxdeploy/subprocess/process.h"
#include "linuxdeploy/subprocess/pipe_reader.h"
#include "linuxdeploy/util/assert.h"
namespace linuxdeploy {
namespace subprocess {
subprocess::subprocess(std::initializer_list<std::string> args)
: subprocess(std::vector<std::string>(args), get_environment()) {}
subprocess::subprocess(std::initializer_list<std::string> args, subprocess_env_map_t env)
: subprocess(std::vector<std::string>(args), std::move(env)) {}
subprocess::subprocess(std::vector<std::string> args)
: args_(std::move(args)), env_(get_environment()) {}
subprocess::subprocess(std::vector<std::string> args, subprocess_env_map_t env)
: args_(std::move(args)), env_(std::move(env)) {
// preconditions
util::assert::assert_not_empty(args_);
}
subprocess_result subprocess::run() const {
process proc{args_, env_};
class PipeState {
public:
pipe_reader reader;
subprocess_result_buffer_t buffer;
bool eof = false;
explicit PipeState(int fd) : reader(fd) {}
};
// create pipe readers and empty buffers for both stdout and stderr
// we manage them in this (admittedly, kind of complex-looking) array so we can later easily perform the
// operations in a loop
std::array<PipeState, 2> buffers = {
PipeState(proc.stdout_fd()),
PipeState(proc.stderr_fd())
};
for (;;) {
for (auto& pipe_state : buffers) {
// read some bytes into smaller intermediate buffer to prevent either of the pipes to overflow
// the results are immediately appended to the main buffer
subprocess_result_buffer_t intermediate_buffer(4096);
// (try to) read all available data from pipe
for (; !pipe_state.eof; ) {
switch (pipe_state.reader.read(intermediate_buffer)) {
case pipe_reader::result::SUCCESS: {
// append to main buffer
pipe_state.buffer.reserve(pipe_state.buffer.size() + intermediate_buffer.size());
std::copy(intermediate_buffer.begin(), intermediate_buffer.end(), std::back_inserter(pipe_state.buffer));
break;
}
case pipe_reader::result::END_OF_FILE: {
pipe_state.eof = true;
break;
}
default:
break;
}
}
}
if (proc.is_running()) {
// reduce load on CPU until EOF
std::this_thread::sleep_for(std::chrono::milliseconds(50));
}
// once all buffers are EOF, we can stop reading
if (std::all_of(buffers.begin(), buffers.end(), [](const PipeState& pipe_state) {
return pipe_state.eof;
})) {
break;
}
}
// make sure contents are null-terminated
buffers[0].buffer.emplace_back('\0');
buffers[1].buffer.emplace_back('\0');
auto exit_code = proc.close();
return subprocess_result{exit_code, buffers[0].buffer, buffers[1].buffer};
}
std::string subprocess::check_output() const {
const auto result = run();
if (result.exit_code() != 0) {
throw std::logic_error{"subprocess failed (exit code " + std::to_string(result.exit_code()) + ")"};
}
return result.stdout_string();
}
}
}