/* *  server.c  Set up and handle communications with a server process. * *  Server Handling copyright 1992-1999 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., *             59 Temple Place - Suite 330, *             Boston,  MA  02111-1307, 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 "auto-host.h"#include "gansidecl.h"#include "system.h"#include <signal.h>#include "server.h"/* If this particular system's header files define the macro `MAXPATHLEN',   we happily take advantage of it; otherwise we use a value which ought   to be large enough.  */#ifndef MAXPATHLEN# define MAXPATHLEN     4096#endif#ifndef STDIN_FILENO# define STDIN_FILENO	0#endif#ifndef STDOUT_FILENO# define STDOUT_FILENO	1#endif#ifdef DEBUG#define STATIC#else#define STATIC static#endif#ifndef tSCC#define tSCC static const char#endif#ifndef NUL#define NUL '\0'#endif#if !defined(volatile) && !defined(HAVE_VOLATILE)# define volatile#endifSTATIC volatile bool read_pipe_timeout;static t_pchar def_args[] ={ (char *) NULL, (char *) NULL };STATIC t_pf_pair server_pair ={ (FILE *) NULL, (FILE *) NULL };STATIC pid_t server_id = NULLPROCESS;/* *  Arbitrary text that should not be found in the shell output. *  It must be a single line and appear verbatim at the start of *  the terminating output line. */tSCC z_done[] = "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd";STATIC t_pchar p_cur_dir = (char *) NULL;/* *  load_data * *  Read data from a file pointer (a pipe to a process in this context) *  until we either get EOF or we get a marker line back. *  The read data are stored in a malloc-ed string that is truncated *  to size at the end.  Input is assumed to be an ASCII string. */static char *load_data (fp)     FILE *fp;{  char *pz_text;  size_t text_size;  char *pz_scan;  char z_line[1024];  text_size = sizeof (z_line) * 2;  pz_scan = pz_text = malloc (text_size);  if (pz_text == (char *) NULL)    return (char *) NULL;  for (;;)    {      size_t used_ct;      alarm (10);      read_pipe_timeout = BOOL_FALSE;      if (fgets (z_line, sizeof (z_line), fp) == (char *) NULL)        break;      if (strncmp (z_line, z_done, sizeof (z_done) - 1) == 0)        break;      strcpy (pz_scan, z_line);      pz_scan += strlen (z_line);      used_ct = (size_t) (pz_scan - pz_text);      if (text_size - used_ct < sizeof (z_line))        {          size_t off = (size_t) (pz_scan - pz_text);          void *p;	            text_size += 4096;          p = realloc ((void *) pz_text, text_size);          if (p == (void *) NULL)            {              fprintf (stderr, "Failed to get 0x%08lX bytes\n",                      (long) text_size);              free ((void *) pz_text);              return (char *) NULL;            }          pz_text = (char *) p;          pz_scan = pz_text + off;        }    }  alarm (0);  if (read_pipe_timeout)    {      free ((void *) pz_text);      return (char *) NULL;    }  while ((pz_scan > pz_text) && isspace (pz_scan[-1]))    pz_scan--;  *pz_scan = NUL;  return realloc ((void *) pz_text, strlen (pz_text) + 1);}/* *  close_server * *  Make certain the server process is dead, close the  *  pipes to it and from it, finally NULL out the file pointers */voidclose_server (){  if (server_id != NULLPROCESS)    {      kill ((pid_t) server_id, SIGKILL);      server_id = NULLPROCESS;      fclose (server_pair.pf_read);      fclose (server_pair.pf_write);      server_pair.pf_read = server_pair.pf_write = (FILE *) NULL;    }}/* *  sig_handler really only handles the timeout and pipe signals. *  This ensures that we do not wait forever on a request *  to our server, and also that if the server dies, we do not *  die from a sigpipe problem. */static voidsig_handler (signo)     int signo;{#ifdef DEBUG  /* FIXME: this is illegal to do in a signal handler.  */  fprintf (stderr,          "fixincl ERROR:  sig_handler: killed pid %ld due to %s\n",          (long) server_id, signo == SIGPIPE ? "SIGPIPE" : "SIGALRM");#endif  close_server ();  read_pipe_timeout = BOOL_TRUE;}/* *  server_setup  Establish the signal handler for PIPE and ALARM. *  Also establishes the current directory to give to the *  server process at the start of every server command. */static voidserver_setup (){  static int atexit_done = 0;    if (atexit_done++ == 0)    atexit (&close_server);  signal (SIGPIPE, sig_handler);  signal (SIGALRM, sig_handler);  fputs ("trap : 1\n", server_pair.pf_write);  fflush (server_pair.pf_write);  p_cur_dir = getcwd ((char *) NULL, MAXPATHLEN + 1);}/* *  run_shell * *  Run a shell command on the server.  The command string *  passed in is wrapped inside the sequence: * *     cd <original directory> *     <command string> *     echo *     echo <end-of-command-marker> * *  This ensures that all commands start at a known place in *  the directory structure, that any incomplete output lines *  are completed and that our special marker sequence appears on *  a line by itself.  We have chosen a marker that is *  excessively unlikely to be reproduced in normal output: * *     "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd" */char *run_shell (pz_cmd)     const char *pz_cmd;{  /*  IF the shell server process is not running yet,      THEN try to start it.  */  if (server_id == NULLPROCESS)    {      server_id = proc2_fopen (&server_pair, def_args);      if (server_id > 0)        server_setup ();    }  /*  IF it is still not running, THEN return the nil string.  */  if (server_id <= 0)    {      char *pz = (char *) malloc (1);            if (pz != (char *) NULL)        *pz = '\0';      return pz;    }  /*  Make sure the process will pay attention to us, send the     supplied command, and then have it output a special marker that     we can find.  */  fprintf (server_pair.pf_write, "cd %s\n%s\n\necho\necho %s\n",           p_cur_dir, pz_cmd, z_done);  fflush (server_pair.pf_write);  /*  IF the server died and we received a SIGPIPE,      THEN return an empty string.  */  if (server_id == NULLPROCESS)    {      char *pz = (char *) malloc (1);            if (pz != (char *) NULL)        *pz = '\0';      return pz;    }  /*  Now try to read back all the data.  If we fail due to either a     sigpipe or sigalrm (timeout), we will return the nil string.  */  {    char *pz = load_data (server_pair.pf_read);        if (pz == (char *) NULL)      {        fprintf (stderr, "CLOSING SHELL SERVER - command failure:\n\t%s\n",                 pz_cmd);        close_server ();        pz = (char *) malloc (1);        if (pz != (char *) NULL)          *pz = '\0';      }    return pz;  }}