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// -*- c++ -*-
// Distributed under the BSD 2-Clause License.
// See accompanying file LICENSE for details.
#include "execute.h"
#include <unistd.h>
#include <cstring>
#include <sys/types.h>
#include <sys/wait.h>
#include <spawn.h>
#include <iostream>
/*
https://blog.famzah.net/2009/11/20/a-much-faster-popen-and-system-implementation-for-linux/
https://github.com/famzah/popen-noshell/commit/1f9eaf4eeef348d1efe0f3c7fe8ab670653cfbb1
https://blog.famzah.net/2018/12/19/posix_spawn-performance-benchmarks-and-usage-examples/
https://stackoverflow.com/questions/4259629/what-is-the-difference-between-fork-and-vfork/5207945#5207945
*/
namespace
{
class Env
: public std::vector<char*>
{
public:
Env(const std::vector<std::string>& args)
{
for(const auto& arg : args)
{
push_back(strdup(arg.data()));
}
push_back(nullptr);
}
~Env()
{
for(auto ptr : *this)
{
free(ptr);
}
}
};
int parent_waitpid(pid_t pid)
{
int status;
if(waitpid(pid, &status, 0) != pid)
{
return 1;
}
return WEXITSTATUS(status);
}
} // namespace ::
extern char **environ; // see 'man environ'
int execute(const std::string& command,
const std::vector<std::string>& args,
const std::map<std::string, std::string>& env,
bool verbose)
{
std::vector<const char*> argv;
argv.push_back(command.data());
for(const auto& arg : args)
{
argv.push_back(arg.data());
}
argv.push_back(nullptr);
std::string cmd;
for(const auto& arg : argv)
{
if(arg == nullptr)
{
break;
}
if(!cmd.empty())
{
cmd += " ";
}
cmd += arg;
}
if(verbose)
{
std::cout << cmd << std::endl;
}
#if 1
auto pid = vfork();
if(pid == 0)
{
std::vector<std::string> venv;
for(const auto& [key, value] : env)
{
venv.push_back(key + "=" + value);
}
for(auto current = environ; *current; ++current)
{
venv.push_back(*current);
}
Env penv(venv);
execve(command.data(), (char**)argv.data(), penv.data());
std::cout << "Could not execute " << command << ": " <<
strerror(errno) << "\n";
_exit(1); // execve only returns if an error occurred
}
return parent_waitpid(pid);
#elif 0
pid_t pid;
std::vector<std::string> venv;
for(const auto& [key, value] : env)
{
venv.push_back(key + "=" + value);
}
Env penv(venv);
if(posix_spawn(&pid, command.data(), nullptr, nullptr,
(char**)argv.data(), penv.data()))
{
return 1;
}
return parent_waitpid(pid);
#else
(void)parent_waitpid;
return system(cmd.data());
#endif
return 1;
}
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