ExternalProgram.cc

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\---------------------------------------------------------------------*/
#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/ExternalProgram.h"

using namespace std;

namespace zypp {

    ExternalProgram::ExternalProgram()
    : use_pty (false)
    {
    }

    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)
    {
      const char *argv[4];
      argv[0] = "/bin/sh";
      argv[1] = "-c";
      argv[2] = commandline.c_str();
      argv[3] = 0;

      const char* rootdir = NULL;
      if(!root.empty() && root != "/")
      {
        rootdir = root.asString().c_str();
      }
      Environment environment;
      start_program (argv, environment, stderr_disp, stderr_fd, default_locale, rootdir);
    }


    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)
    {
      const char* rootdir = NULL;
      if(!root.empty() && root != "/")
      {
        rootdir = root.asString().c_str();
      }
      Environment environment;
      start_program (argv, environment, stderr_disp, stderr_fd, default_locale, rootdir);
    }


    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)
    {
      const char* rootdir = NULL;
      if(!root.empty() && root != "/")
      {
        rootdir = root.asString().c_str();
      }
      start_program (argv, environment, stderr_disp, stderr_fd, default_locale, rootdir);
    }


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


    ExternalProgram::ExternalProgram (const char *binpath, const char *const *argv_1, const Environment & environment,
                                  bool use_pty)
      : use_pty (use_pty)
    {
      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

      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)
        {
            ERR << "openpty failed" << endl;
            return;
        }
      }
      else
      {
        // Create pair of pipes
        if (pipe (to_external) != 0 || pipe (from_external) != 0)
        {
            ERR << "pipe failed" << endl;
            return;
        }
      }

      // do not remove the single quotes around every argument, copy&paste of
      // command to shell will not work otherwise!

      stringstream cmdstr;

      cmdstr << "Executing ";
      for (int i = 0; argv[i]; i++)
      {
        if (i>0) cmdstr << ' ';
        cmdstr << '\'';
        cmdstr << argv[i];
        cmdstr << '\'';
      }
      DBG << cmdstr.str() << endl;

      // Create module process
      if ((pid = fork()) == 0)
      {
        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
        }

        // 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)
            {
                ERR << "chroot to " << root << " failed: " << strerror(errno) << endl;
                _exit (3);                      // No sense in returning! I am forked away!!
            }
            if(chdir("/") == -1)
            {
                ERR << "chdir to / inside chroot failed: " << strerror(errno) << endl;
                _exit (4);                      // 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));
        ERR << "Cannot execute external program "
                 << argv[0] << ":" << strerror(errno) << endl;
        _exit (5);                      // No sense in returning! I am forked away!!
      }

      else if (pid == -1)        // Fork failed, close everything.
      {
        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]);
        }
        ERR << "Cannot fork " << strerror(errno) << endl;
        _exitStatus = -127;
      }

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

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


    int ExternalProgram::checkStatus( int status )
    {
      if (WIFEXITED (status))
      {
        status = WEXITSTATUS (status);
        if(status)
        {
            DBG << "pid " << pid << " exited with status " << status << endl;
        }
        else
        {
            // if 'launch' is logged, completion should be logged,
            // even if successfull.
            DBG << "pid " << pid << " successfully completed" << endl;
        }
      }
      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;
        status+=128;
      }
      else {
        ERR << "pid " << pid << " exited with unknown error" << endl;
      }

      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);
      }
    }

} // namespace zypp

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