system_exec.cc

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/*
    Copyright (C) 2010 Paul Davis
    Copyright (C) 2010-2014 Robin Gareus <robin@gareus.org>
    Copyright (C) 2005-2008 Lennart Poettering

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <algorithm>

#include <assert.h>

#ifndef COMPILER_MSVC
#include <dirent.h>
#endif

#ifdef PLATFORM_WINDOWS
#include <windows.h>
#else
#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/resource.h>
#endif

#include <glibmm/miscutils.h>

#define USE_VFORK

#include "pbd/file_utils.h"
#include "pbd/search_path.h"
#include "pbd/system_exec.h"

using namespace std;
using namespace PBD;

static void * interposer_thread (void *arg);

#ifndef PLATFORM_WINDOWS /* POSIX Process only */
static void close_fd (int& fd) { if (fd >= 0) ::close (fd); fd = -1; }
#endif

#if (!defined PLATFORM_WINDOWS && defined NO_VFORK)
/*
 * This function was part of libasyncns.
 * LGPL v2.1
 * Copyright 2005-2008 Lennart Poettering
 */
static int close_allv(const int except_fds[]) {
        struct rlimit rl;
        int fd;

#ifdef __linux__

        DIR *d;

        assert(except_fds);

        if ((d = opendir("/proc/self/fd"))) {
                struct dirent *de;

                while ((de = readdir(d))) {
                        int found;
                        long l;
                        char *e = NULL;
                        int i;

                        if (de->d_name[0] == '.')
                                        continue;

                        errno = 0;
                        l = strtol(de->d_name, &e, 10);
                        if (errno != 0 || !e || *e) {
                                closedir(d);
                                errno = EINVAL;
                                return -1;
                        }

                        fd = (int) l;

                        if ((long) fd != l) {
                                closedir(d);
                                errno = EINVAL;
                                return -1;
                        }

                        if (fd < 3)
                                continue;

                        if (fd == dirfd(d))
                                continue;

                        found = 0;
                        for (i = 0; except_fds[i] >= 0; i++)
                                if (except_fds[i] == fd) {
                                                found = 1;
                                                break;
                                }

                        if (found) continue;

                        if (close(fd) < 0) {
                                int saved_errno;

                                saved_errno = errno;
                                closedir(d);
                                errno = saved_errno;

                                return -1;
                        }
                }

                closedir(d);
                return 0;
        }

#endif

        if (getrlimit(RLIMIT_NOFILE, &rl) < 0)
                return -1;

        for (fd = 0; fd < (int) rl.rlim_max; fd++) {
                int i;

                if (fd <= 3)
                                continue;

                for (i = 0; except_fds[i] >= 0; i++)
                        if (except_fds[i] == fd)
                                continue;

                if (close(fd) < 0 && errno != EBADF)
                        return -1;
        }

        return 0;
}
#endif /* not on windows, nor vfork */

void
SystemExec::init ()
{
        pthread_mutex_init(&write_lock, NULL);
        thread_active=false;
        pid = 0;
        pin[1] = -1;
        nicelevel = 0;
        envp = NULL;
#ifdef PLATFORM_WINDOWS
        stdinP[0] = stdinP[1] = INVALID_HANDLE_VALUE;
        stdoutP[0] = stdoutP[1] = INVALID_HANDLE_VALUE;
        stderrP[0] = stderrP[1] = INVALID_HANDLE_VALUE;
#endif
}

SystemExec::SystemExec (std::string c, std::string a)
        : cmd(c)
{
        init ();

        argp = NULL;
        make_envp();
        make_argp(a);
}

SystemExec::SystemExec (std::string c, char **a)
        : cmd(c) , argp(a)
{
        init ();

#ifdef PLATFORM_WINDOWS
        make_wargs(a);
#endif
        make_envp();
}

SystemExec::SystemExec (std::string command, const std::map<char, std::string> subs)
{
        init ();
        make_argp_escaped(command, subs);

        if (find_file (Searchpath (Glib::getenv ("PATH")), argp[0], cmd)) {
                // argp[0] exists in $PATH` - set it to the actual path where it was found
                free (argp[0]);
                argp[0] = strdup(cmd.c_str ());
        }
        // else argp[0] not found in path - leave it as-is, it might be an absolute path

        // Glib::find_program_in_path () is only available in Glib >= 2.28
        // cmd = Glib::find_program_in_path (argp[0]);

        make_envp();
}

void
SystemExec::make_argp_escaped(std::string command, const std::map<char, std::string> subs)
{

        int inquotes = 0;
        int n = 0;
        size_t i = 0;
        std::string arg = "";

        argp = (char **) malloc(sizeof(char *));

        for (i = 0; i <= command.length(); i++) { // include terminating '\0'
                char c = command.c_str()[i];
                if (inquotes) {
                        if (c == '"') {
                                inquotes = 0;
                        } else {
                                // still in quotes - just copy
                                arg += c;
                        }
                } else switch (c) {
                        case '%' :
                                c = command.c_str()[++i];
                                if (c == '%' || c == '\0') {
                                        // "%%", "%" at end-of-string => "%"
                                        arg += '%';
                                } else {
                                        // search subs for string to substitute for char
                                        std::map<char, std::string>::const_iterator s = subs.find(c);
                                        if (s != subs.end()) {
                                                // found substitution
                                                arg += s->second;
                                        } else {
                                                // not a valid substitution, just copy
                                                arg += '%';
                                                arg += c;
                                        }
                                }
                                break;
                        case '\\':
                                c = command.c_str()[++i];
                                switch (c) {
                                        case ' ' :
                                        case '"' : arg += c; break; // "\\", "\" at end-of-string => "\"
                                        case '\0': 
                                        case '\\': arg += '\\'; break;
                                        default  : arg += '\\'; arg += c; break;
                                }
                                break;
                        case '"' :
                                inquotes = 1;
                                break;
                        case ' ' :
                        case '\t':
                        case '\0':
                                if (arg.length() > 0) {
                                        // if there wasn't already a space or tab, start a new parameter
                                        argp = (char **) realloc(argp, (n + 2) * sizeof(char *));
                                        argp[n++] = strdup (arg.c_str());
                                        arg = "";
                                }
                                break;
                        default :
                                arg += c;
                                break;
                }
        }
        argp[n] = NULL;
}

SystemExec::~SystemExec ()
{
        terminate ();
        if (envp) {
                for (int i=0;envp[i];++i) {
                        free(envp[i]);
                }
                free (envp);
        }
        if (argp) {
                for (int i=0;argp[i];++i) {
                        free(argp[i]);
                }
                free (argp);
        }
#ifdef PLATFORM_WINDOWS
        if (w_args) free(w_args);
#endif
        pthread_mutex_destroy(&write_lock);
}

static void *
interposer_thread (void *arg) {
        SystemExec *sex = static_cast<SystemExec *>(arg);
        sex->output_interposer();
        pthread_exit(0);
        return 0;
}

#ifdef PLATFORM_WINDOWS /* Windows Process */

/* HELPER FUNCTIONS */

static void create_pipe (HANDLE *pipe, bool in) {
        SECURITY_ATTRIBUTES secAtt = { sizeof( SECURITY_ATTRIBUTES ), NULL, TRUE };
        HANDLE tmpHandle;
        if (in) {
                if (!CreatePipe(&pipe[0], &tmpHandle, &secAtt, 1024 * 1024)) return;
                if (!DuplicateHandle(GetCurrentProcess(), tmpHandle, GetCurrentProcess(), &pipe[1], 0, FALSE, DUPLICATE_SAME_ACCESS)) return;
        } else {
                if (!CreatePipe(&tmpHandle, &pipe[1], &secAtt, 1024 * 1024)) return;
                if (!DuplicateHandle(GetCurrentProcess(), tmpHandle, GetCurrentProcess(), &pipe[0], 0, FALSE, DUPLICATE_SAME_ACCESS)) return;
        }
        CloseHandle(tmpHandle);
}

static void destroy_pipe (HANDLE pipe[2]) {
        if (pipe[0] != INVALID_HANDLE_VALUE) {
                CloseHandle(pipe[0]);
                pipe[0] = INVALID_HANDLE_VALUE;
        }
        if (pipe[1] != INVALID_HANDLE_VALUE) {
                CloseHandle(pipe[1]);
                pipe[1] = INVALID_HANDLE_VALUE;
        }
}

static BOOL CALLBACK my_terminateApp(HWND hwnd, LPARAM procId)
{
        DWORD currentProcId = 0;
        GetWindowThreadProcessId(hwnd, &currentProcId);
        if (currentProcId == (DWORD)procId)
                PostMessage(hwnd, WM_CLOSE, 0, 0);
        return TRUE;
}

/* PROCESS API */

void
SystemExec::make_envp() {
        ;/* environemt is copied over with CreateProcess(...,env=0 ,..) */
}

void
SystemExec::make_wargs(char **a) {
        std::string wa = cmd;
        if (cmd[0] != '"' && cmd[cmd.size()] != '"' && strchr(cmd.c_str(), ' ')) { wa = "\"" + cmd + "\""; }
        std::replace(cmd.begin(), cmd.end(), '/', '\\' );
        char **tmp = ++a;
        while (tmp && *tmp) {
                wa.append(" \"");
                std::string arg(*tmp);
                size_t start_pos = 0;
                while((start_pos = arg.find("\\", start_pos)) != std::string::npos) {
                        arg.replace(start_pos, 1, "\\\\");
                        start_pos += 2;
                }
                wa.append(arg);
                wa.append("\"");
                tmp++;
        }
        w_args = strdup(wa.c_str());
}

void
SystemExec::make_argp(std::string args) {
        std::string wa = cmd;
        if (cmd[0] != '"' && cmd[cmd.size()] != '"' && strchr(cmd.c_str(), ' ')) { wa = "\"" + cmd + "\""; }
        std::replace(cmd.begin(), cmd.end(), '/', '\\' );
        wa.append(" ");
        wa.append(args);
        w_args = strdup(wa.c_str());
}

void
SystemExec::terminate ()
{
        ::pthread_mutex_lock(&write_lock);

        close_stdin();

        if (pid) {
                /* terminate */
                EnumWindows(my_terminateApp, (LPARAM)pid->dwProcessId);
                PostThreadMessage(pid->dwThreadId, WM_CLOSE, 0, 0);

                /* kill ! */
                TerminateProcess(pid->hProcess, 0xf291);

                CloseHandle(pid->hThread);
                CloseHandle(pid->hProcess);
                destroy_pipe(stdinP);
                destroy_pipe(stdoutP);
                destroy_pipe(stderrP);
                delete pid;
                pid=0;
        }
        ::pthread_mutex_unlock(&write_lock);
}

int
SystemExec::wait (int options)
{
        while (is_running()) {
                WaitForSingleObject(pid->hProcess, 40);
        }
        return 0;
}

bool
SystemExec::is_running ()
{
        if (!pid) return false;
        DWORD exit_code;
        if (GetExitCodeProcess(pid->hProcess, &exit_code)) {
                if (exit_code == STILL_ACTIVE) return true;
        }
        return false;
}

int
SystemExec::start (int stderr_mode, const char * /*vfork_exec_wrapper*/)
{
        char* working_dir = 0;

        if (pid) { return 0; }

        pid = new PROCESS_INFORMATION;
        memset(pid, 0, sizeof(PROCESS_INFORMATION));

        create_pipe(stdinP, true);
        create_pipe(stdoutP, false);

        if (stderr_mode == 2) {
        /* merge stout & stderr */
                DuplicateHandle(GetCurrentProcess(), stdoutP[1], GetCurrentProcess(), &stderrP[1], 0, TRUE, DUPLICATE_SAME_ACCESS);
        } else if (stderr_mode == 1) {
                //TODO read/flush this pipe or close it...
                create_pipe(stderrP, false);
        } else {
                //TODO: keep stderr of this process mode.
        }

        bool success = false;
        STARTUPINFOA startupInfo = { sizeof( STARTUPINFO ), 0, 0, 0,
                (unsigned long)CW_USEDEFAULT, (unsigned long)CW_USEDEFAULT,
                (unsigned long)CW_USEDEFAULT, (unsigned long)CW_USEDEFAULT,
                0, 0, 0,
                STARTF_USESTDHANDLES,
                0, 0, 0,
                stdinP[0], stdoutP[1], stderrP[1]
        };

        success = CreateProcess(0, w_args,
                0, 0, /* bInheritHandles = */ TRUE,
                (CREATE_NO_WINDOW&0) | CREATE_UNICODE_ENVIRONMENT | (0&CREATE_NEW_CONSOLE),
                /*env = */ 0,
                working_dir,
                &startupInfo, pid);

        if (stdinP[0] != INVALID_HANDLE_VALUE) {
                CloseHandle(stdinP[0]);
                stdinP[0] = INVALID_HANDLE_VALUE;
        }
        if (stdoutP[1] != INVALID_HANDLE_VALUE) {
                CloseHandle(stdoutP[1]);
                stdoutP[1] = INVALID_HANDLE_VALUE;
        }
        if (stderrP[1] != INVALID_HANDLE_VALUE) {
                CloseHandle(stderrP[1]);
                stderrP[1] = INVALID_HANDLE_VALUE;
        }

        if (!success) {
                CloseHandle(pid->hThread);
                CloseHandle(pid->hProcess);
                destroy_pipe(stdinP);
                destroy_pipe(stdoutP);
                destroy_pipe(stderrP);
                delete pid;
                pid=0;
                return -1;
        }

        int rv = pthread_create(&thread_id_tt, NULL, interposer_thread, this);
        thread_active=true;
        if (rv) {
                thread_active=false;
                terminate();
                return -2;
        }
        Sleep(20);
        return 0;
}

void
SystemExec::output_interposer()
{
        DWORD bytesRead = 0;
        char data[BUFSIZ];
#if 0 // untested code to set up nonblocking
        unsigned long l = 1;
        ioctlsocket(stdoutP[0], FIONBIO, &l);
#endif
        while(1) {
#if 0 // for non-blocking pipes..
                DWORD bytesAvail = 0;
                PeekNamedPipe(stdoutP[0], 0, 0, 0, &bytesAvail, 0);
                if (bytesAvail < 1) {Sleep(500); printf("N/A\n"); continue;}
#endif
                if (stdoutP[0] == INVALID_HANDLE_VALUE) break;
                if (!ReadFile(stdoutP[0], data, BUFSIZ, &bytesRead, 0)) {
                        DWORD err =  GetLastError();
                        if (err == ERROR_IO_PENDING) continue;
                        break;
                }
                if (bytesRead < 1) continue; /* actually not needed; but this is safe. */
                data[bytesRead] = 0;
                ReadStdout(data, bytesRead);/* EMIT SIGNAL */
        }
        Terminated();/* EMIT SIGNAL */
}

void
SystemExec::close_stdin()
{
        if (stdinP[0]!= INVALID_HANDLE_VALUE)  FlushFileBuffers(stdinP[0]);
        if (stdinP[1]!= INVALID_HANDLE_VALUE)  FlushFileBuffers(stdinP[1]);
        Sleep(200);
        destroy_pipe(stdinP);
}

int
SystemExec::write_to_stdin(std::string d, size_t len)
{
        const char *data;
        DWORD r,c;

        ::pthread_mutex_lock(&write_lock);

        data=d.c_str();
        if (len == 0) {
                len=(d.length());
        }
        c=0;
        while (c < len) {
                if (!WriteFile(stdinP[1], data+c, len-c, &r, NULL)) {
                        if (GetLastError() == 0xE8 /*NT_STATUS_INVALID_USER_BUFFER*/) {
                                Sleep(100);
                                continue;
                        } else {
                                fprintf(stderr, "SYSTEM-EXEC: stdin write error.\n");
                                break;
                        }
                }
                c += r;
        }
        ::pthread_mutex_unlock(&write_lock);
        return c;
}


/* end windows process */
#else
/* UNIX/POSIX process */

extern char **environ;
void
SystemExec::make_envp() {
        int i=0;
        envp = (char **) calloc(1, sizeof(char*));
        /* copy current environment */
        for (i=0;environ[i];++i) {
          envp[i] = strdup(environ[i]);
          envp = (char **) realloc(envp, (i+2) * sizeof(char*));
        }
        envp[i] = 0;
}

void
SystemExec::make_argp(std::string args) {
        int argn = 1;
        char *cp1;
        char *cp2;

        char *carg = strdup(args.c_str());

        argp = (char **) malloc((argn + 1) * sizeof(char *));
        if (argp == (char **) 0) {
                free(carg);
                return; // FATAL
        }

        argp[0] = strdup(cmd.c_str());

        /* TODO: quotations and escapes
         * http://stackoverflow.com/questions/1511797/convert-string-to-argv-in-c
         *
         * It's actually not needed. All relevant invocations specify 'argp' directly.
         * Only 'xjadeo -L -R' uses this function and that uses neither quotations
         * nor arguments with white-space.
         */
        for (cp1 = cp2 = carg; *cp2 != '\0'; ++cp2) {
                if (*cp2 == ' ') {
                        *cp2 = '\0';
                        argp[argn++] = strdup(cp1);
                        cp1 = cp2 + 1;
                        argp = (char **) realloc(argp, (argn + 1) * sizeof(char *));
                }
        }
        if (cp2 != cp1) {
                argp[argn++] = strdup(cp1);
                argp = (char **) realloc(argp, (argn + 1) * sizeof(char *));
        }
        argp[argn] = (char *) 0;
        free(carg);
}



void
SystemExec::terminate ()
{
        ::pthread_mutex_lock(&write_lock);

        /* close stdin in an attempt to get the child to exit cleanly.
         */

        close_stdin();

        if (pid) {
                ::usleep(200000);
                sched_yield();
                wait(WNOHANG);
        }

        /* if pid is non-zero, the child task is still executing (i.e. it did
         * not exit in response to stdin being closed). try to kill it.
         */
        
        if (pid) {
                ::kill(pid, SIGTERM);
                ::usleep(250000);
                sched_yield();
                wait(WNOHANG);
        }

        /* if pid is non-zero, the child task is STILL executing after being
         * sent SIGTERM. Act tough ... send SIGKILL
         */

        if (pid) {
                ::fprintf(stderr, "Process is still running! trying SIGKILL\n");
                ::kill(pid, SIGKILL);
        }

        wait();
        if (thread_active) pthread_join(thread_id_tt, NULL);
        thread_active = false;
        assert(pid == 0);
        ::pthread_mutex_unlock(&write_lock);
}

int
SystemExec::wait (int options)
{
        int status=0;
        int ret;

        if (pid==0) return -1;

        ret = waitpid (pid, &status, options);

        if (ret == pid) {
                if (WEXITSTATUS(status) || WIFSIGNALED(status)) {
                        pid=0;
                }
        } else {
                if (ret != 0) {
                        if (errno == ECHILD) {
                                /* no currently running children, reset pid */
                                pid=0;
                        }
                } /* else the process is still running */
        }
        return status;
}

bool
SystemExec::is_running ()
{
        int status=0;
        if (pid==0) return false;
        if (::waitpid(pid, &status, WNOHANG)==0) return true;
        return false;
}

int
SystemExec::start (int stderr_mode, const char *vfork_exec_wrapper)
{
        if (is_running()) {
                return 0; // mmh what to return here?
        }
        int r;

        if (::pipe(pin) < 0 || ::pipe(pout) < 0 || ::pipe(pok) < 0) {
                /* Something unexpected went wrong creating a pipe. */
                return -1;
        }

#ifndef NO_VFORK
        r = ::vfork();
#else
        r = ::fork();
#endif
        if (r < 0) {
                /* failed to fork */
                return -2;
        }

        if (r > 0) {
                /* main */
                pid=r;

                /* check if execve was successful. */
                close_fd(pok[1]);
                char buf;
                for ( ;; ) {
                        ssize_t n = ::read(pok[0], &buf, 1 );
                        if ( n==1 ) {
                                /* child process returned from execve */
                                pid=0;
                                close_fd(pok[0]);
                                close_fd(pok[1]);
                                close_fd(pin[1]);
                                close_fd(pin[0]);
                                close_fd(pout[1]);
                                close_fd(pout[0]);
                                return -3;
                        } else if ( n==-1 ) {
                                 if ( errno==EAGAIN || errno==EINTR )
                                         continue;
                        }
                        break;
                }
                close_fd(pok[0]);
                /* child started successfully */

                close_fd(pout[1]);
                close_fd(pin[0]);
                int rv = pthread_create(&thread_id_tt, NULL, interposer_thread, this);

                thread_active=true;
                if (rv) {
                        thread_active=false;
                        terminate();
                        return -2;
                }
                return 0; /* all systems go - return to main */
        }

#ifdef NO_VFORK
        /* child process - exec external process */
        close_fd(pok[0]);
        ::fcntl(pok[1], F_SETFD, FD_CLOEXEC);

        close_fd(pin[1]);
        if (pin[0] != STDIN_FILENO) {
          ::dup2(pin[0], STDIN_FILENO);
        }
        close_fd(pin[0]);
        close_fd(pout[0]);
        if (pout[1] != STDOUT_FILENO) {
                ::dup2(pout[1], STDOUT_FILENO);
        }

        if (stderr_mode == 2) {
                /* merge STDERR into output */
                if (pout[1] != STDERR_FILENO) {
                        ::dup2(pout[1], STDERR_FILENO);
                }
        } else if (stderr_mode == 1) {
                /* ignore STDERR */
                ::close(STDERR_FILENO);
        } else {
                /* keep STDERR */
        }

        if (pout[1] != STDOUT_FILENO && pout[1] != STDERR_FILENO) {
                close_fd(pout[1]);
        }

        if (nicelevel !=0) {
                ::nice(nicelevel);
        }

#ifdef HAVE_SIGSET
        sigset(SIGPIPE, SIG_DFL);
#else
        signal(SIGPIPE, SIG_DFL);
#endif
        if (!vfork_exec_wrapper) {
                error << _("Cannot start external process, no vfork wrapper") << endmsg;
                return -1;
        }

        int good_fds[2] = { pok[1],  -1 };
        close_allv(good_fds);

        ::execve(argp[0], argp, envp);
        /* if we reach here something went wrong.. */
        char buf = 0;
        (void) ::write(pok[1], &buf, 1 );
        close_fd(pok[1]);
        exit(-1);
        return -1;
#else

        /* XXX this should be done before vfork()
         * calling malloc here only increases the time vfork() blocks
         */
        int argn = 0;
        for (int i=0;argp[i];++i) { argn++; }
        char **argx = (char **) malloc((argn + 10) * sizeof(char *));
        argx[0] = strdup(vfork_exec_wrapper); // XXX

#define FDARG(NUM, FDN) \
        argx[NUM] = (char*) calloc(6, sizeof(char)); snprintf(argx[NUM], 6, "%d", FDN);

        FDARG(1, pok[0])
        FDARG(2, pok[1])
        FDARG(3, pin[0])
        FDARG(4, pin[1])
        FDARG(5, pout[0])
        FDARG(6, pout[1])
        FDARG(7, stderr_mode)
        FDARG(8, nicelevel)

        for (int i=0;argp[i];++i) {
                argx[9+i] = argp[i];
        }
        argx[argn+9] = NULL;

        ::execve(argx[0], argx, envp);

        /* if we reach here something went wrong.. */
        char buf = 0;
        (void) ::write(pok[1], &buf, 1 );
        close_fd(pok[1]);
        exit(-1);
        return -1;
#endif
}

void
SystemExec::output_interposer()
{
        int rfd=pout[0];
        char buf[BUFSIZ];
        ssize_t r;
        unsigned long l = 1;

        ioctl(rfd, FIONBIO, &l); // set non-blocking I/O

        for (;fcntl(rfd, F_GETFL)!=-1;) {
                r = read(rfd, buf, sizeof(buf));
                if (r < 0 && (errno == EINTR || errno == EAGAIN)) {
                        fd_set rfds;
                        struct timeval tv;
                        FD_ZERO(&rfds);
                        FD_SET(rfd, &rfds);
                        tv.tv_sec = 0;
                        tv.tv_usec = 10000;
                        int rv = select(1, &rfds, NULL, NULL, &tv);
                        if (rv == -1) {
                                break;
                        }
                        continue;
                }
                if (r <= 0) {
                        break;
                }
                buf[r]=0;
                std::string rv = std::string(buf,r); // TODO: check allocation strategy
                ReadStdout(rv, r);/* EMIT SIGNAL */
        }
        Terminated();/* EMIT SIGNAL */
}

void
SystemExec::close_stdin()
{
        if (pin[1]<0) return;
        close_fd(pin[0]);
        close_fd(pin[1]);
        close_fd(pout[0]);
        close_fd(pout[1]);
}

int
SystemExec::write_to_stdin(std::string d, size_t len)
{
        const char *data;
        ssize_t r;
        size_t c;
        ::pthread_mutex_lock(&write_lock);

        data=d.c_str();
        if (len == 0) {
                len=(d.length());
        }
        c=0;
        while (c < len) {
                for (;;) {
                        r=::write(pin[1], data+c, len-c);
                        if (r < 0 && (errno == EINTR || errno == EAGAIN)) {
                                sleep(1);
                                continue;
                        }
                        if ((size_t) r != (len-c)) {
                                ::pthread_mutex_unlock(&write_lock);
                                return c;
                        }
                        break;
                }
                c += r;
        }
        fsync(pin[1]);
        ::pthread_mutex_unlock(&write_lock);
        return c;
}

#endif // end UNIX process