ExternalProgram.cc

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/*---------------------------------------------------------------------\
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|                           / / \ V /|  _/  _/                         |
|                          / /__ | | | | | |                           |
|                         /_____||_| |_| |_|                           |
|                                                                      |
\---------------------------------------------------------------------*/
#define _GNU_SOURCE 1 // for ::getline

#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <pty.h> // openpty
#include <stdlib.h> // setenv

#include <cstring> // strsignal
#include <iostream>
#include <sstream>

#include "zypp/base/Logger.h"
#include "zypp/base/String.h"
#include "zypp/base/Gettext.h"
#include "zypp/ExternalProgram.h"

using namespace std;

namespace zypp {

    ExternalProgram::ExternalProgram()
      : use_pty (false)
      , pid( -1 )
    {}


    ExternalProgram::ExternalProgram( std::string commandline,
                                      Stderr_Disposition stderr_disp,
                                      bool use_pty,
                                      int stderr_fd,
                                      bool default_locale,
                                      const Pathname & root )
      : use_pty (use_pty)
      , pid( -1 )
    {
      const char *argv[4];
      argv[0] = "/bin/sh";
      argv[1] = "-c";
      argv[2] = commandline.c_str();
      argv[3] = 0;

      start_program( argv, Environment(), stderr_disp, stderr_fd, default_locale, root.c_str() );
    }


    ExternalProgram::ExternalProgram( const Arguments & argv,
                                      Stderr_Disposition stderr_disp,
                                      bool use_pty,
                                      int stderr_fd,
                                      bool default_locale,
                                      const Pathname & root )
      : use_pty (use_pty)
      , pid( -1 )
    {
      const char * argvp[argv.size() + 1];
      unsigned c = 0;
      for_( i, argv.begin(), argv.end() )
      {
        argvp[c] = i->c_str();
        ++c;
      }
      argvp[c] = 0;

      start_program( argvp, Environment(), stderr_disp, stderr_fd, default_locale, root.c_str() );
    }


    ExternalProgram::ExternalProgram( const Arguments & argv,
                                      const Environment & environment,
                                      Stderr_Disposition stderr_disp,
                                      bool use_pty,
                                      int stderr_fd,
                                      bool default_locale,
                                      const Pathname & root )
      : use_pty (use_pty)
      , pid( -1 )
    {
      const char * argvp[argv.size() + 1];
      unsigned c = 0;
      for_( i, argv.begin(), argv.end() )
      {
        argvp[c] = i->c_str();
        ++c;
      }
      argvp[c] = 0;

      start_program( argvp, environment, stderr_disp, stderr_fd, default_locale, root.c_str() );
    }



    ExternalProgram::ExternalProgram( const char *const *argv,
                                      Stderr_Disposition stderr_disp,
                                      bool use_pty,
                                      int stderr_fd,
                                      bool default_locale,
                                      const Pathname & root )
      : use_pty (use_pty)
      , pid( -1 )
    {
      start_program( argv, Environment(), stderr_disp, stderr_fd, default_locale, root.c_str() );
    }


    ExternalProgram::ExternalProgram( const char *const * argv,
                                      const Environment & environment,
                                      Stderr_Disposition stderr_disp,
                                      bool use_pty,
                                      int stderr_fd,
                                      bool default_locale,
                                      const Pathname & root )
      : use_pty (use_pty)
      , pid( -1 )
    {
      start_program( argv, environment, stderr_disp, stderr_fd, default_locale, root.c_str() );
    }


    ExternalProgram::ExternalProgram( const char *binpath,
                                      const char *const *argv_1,
                                      bool use_pty )
      : use_pty (use_pty)
      , pid( -1 )
    {
      int i = 0;
      while (argv_1[i++])
        ;
      const char *argv[i + 1];
      argv[0] = binpath;
      memcpy( &argv[1], argv_1, (i - 1) * sizeof (char *) );
      start_program( argv, Environment() );
    }


    ExternalProgram::ExternalProgram( const char *binpath,
                                      const char *const *argv_1,
                                      const Environment & environment,
                                      bool use_pty )
      : use_pty (use_pty)
      , pid( -1 )
    {
      int i = 0;
      while (argv_1[i++])
        ;
      const char *argv[i + 1];
      argv[0] = binpath;
      memcpy( &argv[1], argv_1, (i - 1) * sizeof (char *) );
      start_program( argv, environment );
    }


    ExternalProgram::~ExternalProgram()
    {}



    void ExternalProgram::start_program( const char *const *argv,
                                         const Environment & environment,
                                         Stderr_Disposition stderr_disp,
                                         int stderr_fd,
                                         bool default_locale,
                                         const char * root )
    {
      pid = -1;
      _exitStatus = 0;
      int to_external[2], from_external[2];     // fds for pair of pipes
      int master_tty,   slave_tty;              // fds for pair of ttys

      // retrieve options at beginning of arglist
      const char * redirectStdin = nullptr;     // <[file]
      const char * chdirTo = nullptr;           // #/[path]

      if ( root )
      {
        if ( root[0] == '\0' )
        {
          root = nullptr;       // ignore empty root
        }
        else if ( root[0] == '/' && root[1] == '\0' )
        {
          // If root is '/' do not chroot, but chdir to '/'
          // unless arglist defines another dir.
          chdirTo = "/";
          root = nullptr;
        }
      }

      for ( bool strip = false; argv[0]; ++argv )
      {
        strip = false;
        switch ( argv[0][0] )
        {
          case '<':
            strip = true;
            redirectStdin = argv[0]+1;
            if ( *redirectStdin == '\0' )
              redirectStdin = "/dev/null";
            break;

          case '#':
            strip = true;
            if ( argv[0][1] == '/' )    // #/[path]
              chdirTo = argv[0]+1;
            break;
        }
        if ( ! strip )
          break;
      }

      // do not remove the single quotes around every argument, copy&paste of
      // command to shell will not work otherwise!
      {
        stringstream cmdstr;
        for (int i = 0; argv[i]; i++)
        {
          if (i>0) cmdstr << ' ';
          cmdstr << '\'';
          cmdstr << argv[i];
          cmdstr << '\'';
        }
        if ( redirectStdin )
          cmdstr << " < '" << redirectStdin << "'";
        _command = cmdstr.str();
      }
      DBG << "Executing " << _command << endl;


      if (use_pty)
      {
        // Create pair of ttys
        DBG << "Using ttys for communication with " << argv[0] << endl;
        if (openpty (&master_tty, &slave_tty, 0, 0, 0) != 0)
        {
          _execError = str::form( _("Can't open pty (%s)."), strerror(errno) );
          _exitStatus = 126;
          ERR << _execError << endl;
          return;
        }
      }
      else
      {
        // Create pair of pipes
        if (pipe (to_external) != 0 || pipe (from_external) != 0)
        {
          _execError = str::form( _("Can't open pipe (%s)."), strerror(errno) );
          _exitStatus = 126;
          ERR << _execError << endl;
          return;
        }
      }

      // Create module process
      if ((pid = fork()) == 0)
      {
        // Don't write to the logfile after fork!
        if (use_pty)
        {
            setsid();
            if(slave_tty != 1)
                dup2 (slave_tty, 1);      // set new stdout
            renumber_fd (slave_tty, 0);   // set new stdin
            ::close(master_tty);          // Belongs to father process

            // We currently have no controlling terminal (due to setsid).
            // The first open call will also set the new ctty (due to historical
            // unix guru knowledge ;-) )

            char name[512];
            ttyname_r(slave_tty, name, sizeof(name));
            ::close(open(name, O_RDONLY));
        }
        else
        {
            renumber_fd (to_external[0], 0); // set new stdin
            ::close(from_external[0]);    // Belongs to father process

            renumber_fd (from_external[1], 1); // set new stdout
            ::close(to_external  [1]);    // Belongs to father process
        }

        if ( redirectStdin )
        {
          ::close( 0 );
          int inp_fd = open( redirectStdin, O_RDONLY );
          dup2( inp_fd, 0 );
        }

        // Handle stderr
        if (stderr_disp == Discard_Stderr)
        {
            int null_fd = open("/dev/null", O_WRONLY);
            dup2(null_fd, 2);
            ::close(null_fd);
        }
        else if (stderr_disp == Stderr_To_Stdout)
        {
            dup2(1, 2);
        }
        else if (stderr_disp == Stderr_To_FileDesc)
        {
            // Note: We don't have to close anything regarding stderr_fd.
            // Our caller is responsible for that.
            dup2 (stderr_fd, 2);
        }

        for ( Environment::const_iterator it = environment.begin(); it != environment.end(); ++it ) {
          setenv( it->first.c_str(), it->second.c_str(), 1 );
        }

        if(default_locale)
                setenv("LC_ALL","C",1);

        if(root)
        {
            if(chroot(root) == -1)
            {
                _execError = str::form( _("Can't chroot to '%s' (%s)."), root, strerror(errno) );
                std::cerr << _execError << endl;// After fork log on stderr too
                _exit (128);                    // No sense in returning! I am forked away!!
            }
            if ( ! chdirTo )
              chdirTo = "/";
        }

        if ( chdirTo && chdir( chdirTo ) == -1 )
        {
          _execError = root ? str::form( _("Can't chdir to '%s' inside chroot '%s' (%s)."), chdirTo, root, strerror(errno) )
                            : str::form( _("Can't chdir to '%s' (%s)."), chdirTo, strerror(errno) );
          std::cerr << _execError << endl;// After fork log on stderr too
          _exit (128);                  // No sense in returning! I am forked away!!
        }

        // close all filedesctiptors above stderr
        for ( int i = ::getdtablesize() - 1; i > 2; --i ) {
          ::close( i );
        }

        execvp(argv[0], const_cast<char *const *>(argv));
        // don't want to get here
        _execError = str::form( _("Can't exec '%s' (%s)."), argv[0], strerror(errno) );
        std::cerr << _execError << endl;// After fork log on stderr too
        _exit (129);                    // No sense in returning! I am forked away!!
      }

      else if (pid == -1)        // Fork failed, close everything.
      {
        _execError = str::form( _("Can't fork (%s)."), strerror(errno) );
        _exitStatus = 127;
        ERR << _execError << endl;

        if (use_pty) {
            ::close(master_tty);
            ::close(slave_tty);
        }
        else {
            ::close(to_external[0]);
            ::close(to_external[1]);
            ::close(from_external[0]);
            ::close(from_external[1]);
        }
      }

      else {
        if (use_pty)
        {
            ::close(slave_tty);        // belongs to child process
            inputfile  = fdopen(master_tty, "r");
            outputfile = fdopen(master_tty, "w");
        }
        else
        {
            ::close(to_external[0]);   // belongs to child process
            ::close(from_external[1]); // belongs to child process
            inputfile = fdopen(from_external[0], "r");
            outputfile = fdopen(to_external[1], "w");
        }

        DBG << "pid " << pid << " launched" << endl;

        if (!inputfile || !outputfile)
        {
            ERR << "Cannot create streams to external program " << argv[0] << endl;
            close();
        }
      }
    }


    int
    ExternalProgram::close()
    {
      if (pid > 0)
      {
        if ( inputFile() )
        {
          // Discard any output instead of closing the pipe,
          // but watch out for the command exiting while some
          // subprocess keeps the filedescriptor open.
          setBlocking( false );
          FILE * inputfile = inputFile();
          int    inputfileFd = ::fileno( inputfile );
          long   delay = 0;
          do
          {
            /* Watch inputFile to see when it has input. */
            fd_set rfds;
            FD_ZERO( &rfds );
            FD_SET( inputfileFd, &rfds );

            /* Wait up to 1 seconds. */
            struct timeval tv;
            tv.tv_sec  = (delay < 0 ? 1 : 0);
            tv.tv_usec = (delay < 0 ? 0 : delay*100000);
            if ( delay >= 0 && ++delay > 9 )
              delay = -1;
            int retval = select( inputfileFd+1, &rfds, NULL, NULL, &tv );

            if ( retval == -1 )
            {
              ERR << "select error: " << strerror(errno) << endl;
              if ( errno != EINTR )
                break;
            }
            else if ( retval )
            {
              // Data is available now.
              static size_t linebuffer_size = 0;      // static because getline allocs
              static char * linebuffer = 0;           // and reallocs if buffer is too small
              getline( &linebuffer, &linebuffer_size, inputfile );
              // ::feof check is important as select returns
              // positive if the file was closed.
              if ( ::feof( inputfile ) )
                break;
              clearerr( inputfile );
            }
            else
            {
              // No data within time.
              if ( ! running() )
                break;
            }
          } while ( true );
        }

        // Wait for child to exit
        int ret;
        int status = 0;
        do
        {
          ret = waitpid(pid, &status, 0);
        }
        while (ret == -1 && errno == EINTR);

        if (ret != -1)
        {
         _exitStatus = checkStatus( status );
        }
        pid = -1;
      }

      return _exitStatus;
    }


    int ExternalProgram::checkStatus( int status )
    {
      if (WIFEXITED (status))
      {
        status = WEXITSTATUS (status);
        if(status)
        {
            DBG << "Pid " << pid << " exited with status " << status << endl;
            _execError = str::form( _("Command exited with status %d."), status );
        }
        else
        {
            // if 'launch' is logged, completion should be logged,
            // even if successfull.
            DBG << "Pid " << pid << " successfully completed" << endl;
            _execError.clear(); // empty if running or successfully completed
        }
      }
      else if (WIFSIGNALED (status))
      {
        status = WTERMSIG (status);
        WAR << "Pid " << pid << " was killed by signal " << status
                << " (" << strsignal(status);
        if (WCOREDUMP (status))
        {
            WAR << ", core dumped";
        }
        WAR << ")" << endl;
        _execError = str::form( _("Command was killed by signal %d (%s)."), status, strsignal(status) );
        status+=128;
      }
      else {
        ERR << "Pid " << pid << " exited with unknown error" << endl;
        _execError = _("Command exited with unknown error.");
      }

      return status;
    }

    bool
    ExternalProgram::kill()
    {
      if (pid > 0)
      {
        ::kill(pid, SIGKILL);
        close();
      }
      return true;
    }


    bool
    ExternalProgram::running()
    {
      if ( pid < 0 ) return false;

      int status = 0;
      int p = waitpid( pid, &status, WNOHANG );
      switch ( p )
        {
        case -1:
          ERR << "waitpid( " << pid << ") returned error '" << strerror(errno) << "'" << endl;
          return false;
          break;
        case 0:
          return true; // still running
          break;
        }

      // Here: completed...
      _exitStatus = checkStatus( status );
      pid = -1;
      return false;
    }

    // origfd will be accessible as newfd and closed (unless they were equal)
    void ExternalProgram::renumber_fd (int origfd, int newfd)
    {
      // It may happen that origfd is already the one we want
      // (Although in our circumstances, that would mean somebody has closed
      // our stdin or stdout... weird but has appened to Cray, #49797)
      if (origfd != newfd)
      {
        dup2 (origfd, newfd);
        ::close (origfd);
      }
    }

    std::ostream & ExternalProgram::operator>>( std::ostream & out_r )
    {
      setBlocking( true );
      for ( std::string line = receiveLine(); line.length(); line = receiveLine() )
        out_r << line;
      return out_r;
    }

    //
    // class ExternalProgramWithStderr
    //

    namespace _ExternalProgram
    {
      EarlyPipe::EarlyPipe()
      {
        _fds[R] = _fds[W] = -1;
#ifdef HAVE_PIPE2
        ::pipe2( _fds, O_NONBLOCK );
#else
        ::pipe( _fds );
        ::fcntl(_fds[R], F_SETFD, O_NONBLOCK );
        ::fcntl(_fds[W], F_SETFD, O_NONBLOCK );
#endif
        _stderr = ::fdopen( _fds[R], "r" );
      }

      EarlyPipe::~EarlyPipe()
      {
        closeW();
        if ( _stderr )
          ::fclose( _stderr );
      }
    }

    bool ExternalProgramWithStderr::stderrGetUpTo( std::string & retval_r, const char delim_r, bool returnDelim_r )
    {
      if ( ! _stderr )
        return false;
      if ( delim_r && ! _buffer.empty() )
      {
        // check for delim already in buffer
        std::string::size_type pos( _buffer.find( delim_r ) );
        if ( pos != std::string::npos )
        {
          retval_r = _buffer.substr( 0, returnDelim_r ? pos+1 : pos );
          _buffer.erase( 0, pos+1 );
          return true;
        }
      }
      ::clearerr( _stderr );
      do {
        int ch = fgetc( _stderr );
        if ( ch != EOF )
        {
          if ( ch != delim_r || ! delim_r )
            _buffer.push_back( ch );
          else
          {
            if ( returnDelim_r )
              _buffer.push_back( delim_r );
            break;
          }
        }
        else if ( ::feof( _stderr ) )
        {
          if ( _buffer.empty() )
            return false;
          break;
        }
        else if ( errno != EINTR )
          return false;
      } while ( true );
      // HERE: we left after readig at least one char (\n)
      retval_r.swap( _buffer );
      _buffer.clear();
      return true;
    }


} // namespace zypp