/* *  server.c  Set up and handle communications with a server process. * *  Server Handling copyright 1992-1999, 2004 The Free Software Foundation * *  Server Handling is free software. *  You may 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, or (at your option) any later version. * *  Server Handling 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 Server Handling.  See the file "COPYING".  If not, *  write to:  The Free Software Foundation, Inc., *             51 Franklin Street, Fifth Floor, *             Boston,  MA  02110-1301, USA. * * As a special exception, The Free Software Foundation gives * permission for additional uses of the text contained in his release * of ServerHandler. * * The exception is that, if you link the ServerHandler library with other * files to produce an executable, this does not by itself cause the * resulting executable to be covered by the GNU General Public License. * Your use of that executable is in no way restricted on account of * linking the ServerHandler library code into it. * * This exception does not however invalidate any other reasons why * the executable file might be covered by the GNU General Public License. * * This exception applies only to the code released by The Free * Software Foundation under the name ServerHandler.  If you copy code * from other sources under the General Public License into a copy of * ServerHandler, as the General Public License permits, the exception * does not apply to the code that you add in this way.  To avoid * misleading anyone as to the status of such modified files, you must * delete this exception notice from them. * * If you write modifications of your own for ServerHandler, it is your * choice whether to permit this exception to apply to your modifications. * If you do not wish that, delete this exception notice. */ #include "fixlib.h"#include "server.h" STATIC const char* def_args[] ={ (char *) NULL, (char *) NULL }; /* *  chain_open * *  Given an FD for an inferior process to use as stdin, *  start that process and return a NEW FD that that process *  will use for its stdout.  Requires the argument vector *  for the new process and, optionally, a pointer to a place *  to store the child's process id. */intchain_open (int stdin_fd, tCC** pp_args, pid_t* p_child){  t_fd_pair stdout_pair;  pid_t ch_id;  tCC *pz_cmd;   stdout_pair.read_fd = stdout_pair.write_fd = -1;   /*   *  Create a pipe it will be the child process' stdout,   *  and the parent will read from it.   */  if (pipe ((int *) &stdout_pair) < 0)    {      if (p_child != (pid_t *) NULL)        *p_child = NOPROCESS;      return -1;    }   /*   *  If we did not get an arg list, use the default   */  if (pp_args == (tCC **) NULL)    pp_args = def_args;   /*   *  If the arg list does not have a program,   *  assume the "SHELL" from the environment, or, failing   *  that, then sh.  Set argv[0] to whatever we decided on.   */  if (pz_cmd = *pp_args,      (pz_cmd == (char *) NULL) || (*pz_cmd == '\0'))    {       pz_cmd = getenv ("SHELL");      if (pz_cmd == (char *) NULL)        pz_cmd = "sh";    } #ifdef DEBUG_PRINT  printf ("START:  %s\n", pz_cmd);  {    int idx = 0;        while (pp_args[++idx] != (char *) NULL)      printf ("  ARG %2d:  %s\n", idx, pp_args[idx]);  }#endif   /*   *  Call fork() and see which process we become   */  ch_id = fork ();  switch (ch_id)    {    case NOPROCESS:             /* parent - error in call */      close (stdout_pair.read_fd);      close (stdout_pair.write_fd);      if (p_child != (pid_t *) NULL)        *p_child = NOPROCESS;      return -1;     default:                    /* parent - return opposite FD's */      if (p_child != (pid_t *) NULL)        *p_child = ch_id;#ifdef DEBUG_PRINT      printf ("for pid %d:  stdin from %d, stdout to %d\n"              "for parent:  read from %d\n",              ch_id, stdin_fd, stdout_pair.write_fd, stdout_pair.read_fd);#endif      close (stdin_fd);      close (stdout_pair.write_fd);      return stdout_pair.read_fd;     case NULLPROCESS:           /* child - continue processing */      break;    }   /*   *  Close the pipe end handed back to the parent process   */  close (stdout_pair.read_fd);   /*   *  Close our current stdin and stdout   */  close (STDIN_FILENO);  close (STDOUT_FILENO);   /*   *  Make the fd passed in the stdin, and the write end of   *  the new pipe become the stdout.   */  dup2 (stdout_pair.write_fd, STDOUT_FILENO);  dup2 (stdin_fd, STDIN_FILENO);   if (*pp_args == (char *) NULL)    *pp_args = pz_cmd;   execvp (pz_cmd, (char**)pp_args);  fprintf (stderr, "Error %d:  Could not execvp( '%s', ... ):  %s\n",           errno, pz_cmd, xstrerror (errno));  exit (EXIT_PANIC);}  /* *  proc2_open * *  Given a pointer to an argument vector, start a process and *  place its stdin and stdout file descriptors into an fd pair *  structure.  The "write_fd" connects to the inferior process *  stdin, and the "read_fd" connects to its stdout.  The calling *  process should write to "write_fd" and read from "read_fd". *  The return value is the process id of the created process. */pid_tproc2_open (t_fd_pair* p_pair, tCC** pp_args){  pid_t ch_id;   /*  Create a bi-directional pipe.  Writes on 0 arrive on 1 and vice     versa, so the parent and child processes will read and write to     opposite FD's.  */  if (pipe ((int *) p_pair) < 0)    return NOPROCESS;   p_pair->read_fd = chain_open (p_pair->read_fd, pp_args, &ch_id);  if (ch_id == NOPROCESS)    close (p_pair->write_fd);   return ch_id;}  /* *  proc2_fopen * *  Identical to "proc2_open()", except that the "fd"'s are *  "fdopen(3)"-ed into file pointers instead. */pid_tproc2_fopen (t_pf_pair* pf_pair, tCC** pp_args){  t_fd_pair fd_pair;  pid_t ch_id = proc2_open (&fd_pair, pp_args);   if (ch_id == NOPROCESS)    return ch_id;   pf_pair->pf_read = fdopen (fd_pair.read_fd, "r");  pf_pair->pf_write = fdopen (fd_pair.write_fd, "w");  return ch_id;}