/* *  server.c  Set up and handle communications with a server process. * *  Server Handling copyright 1992-1999, 2001 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 volatile enum t_bool read_pipe_timeout;STATIC pid_t server_master_pid = NOPROCESS; tSCC* 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";tSCC* 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 (FILE* fp){  char *pz_text;  size_t text_size;  char *pz_scan;  char z_line[1024];  t_bool got_done = BOOL_FALSE;   text_size = sizeof (z_line) * 2;  pz_scan = pz_text = XNEWVEC (char, text_size);   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)	{	  got_done = BOOL_TRUE;	  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);	            text_size += 4096;          pz_text = XRESIZEVEC (char, pz_text, text_size);          pz_scan = pz_text + off;        }    }   alarm (0);  if (read_pipe_timeout || ! got_done)    {      free ((void *) pz_text);      return (char *) NULL;    }   while ((pz_scan > pz_text) && ISSPACE (pz_scan[-1]))    pz_scan--;  *pz_scan = NUL;  return XRESIZEVEC (char, 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 (void){  if (  (server_id != NULLPROCESS)     && (server_master_pid == getpid ()))    {      kill ((pid_t) server_id, SIGKILL);      server_id = NULLPROCESS;      server_master_pid = NOPROCESS;      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 (int signo ATTRIBUTE_UNUSED){#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 (void){  static int atexit_done = 0;  char buff [MAXPATHLEN + 1];    if (atexit_done++ == 0)    atexit (close_server);  else    fputs ("NOTE: server restarted\n", stderr);   server_master_pid = getpid ();   signal (SIGPIPE, sig_handler);  signal (SIGALRM, sig_handler);   fputs ("trap : 1\n", server_pair.pf_write);  fflush (server_pair.pf_write);  if (getcwd (buff, MAXPATHLEN + 1) == NULL)    buff[0] = 0;  p_cur_dir = xstrdup (buff);} /* *  find_shell * *  Locate a shell suitable for use.  For various reasons *  (like the use of "trap" in server_setup(), it must be a *  Bourne-like shell. * *  Most of the time, /bin/sh is preferred, but sometimes *  it's quite broken (like on Ultrix).  autoconf lets you *  override with $CONFIG_SHELL, so we do the same. */ static const char *find_shell (void){  char * shell = getenv ("CONFIG_SHELL");  if (shell)    return shell;   return "/bin/sh";}  /* *  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 (const char* pz_cmd){  tSCC zNoServer[] = "Server not running, cannot run:\n%s\n\n";  t_bool retry = BOOL_TRUE;  do_retry:  /*  IF the shell server process is not running yet,      THEN try to start it.  */  if (server_id == NULLPROCESS)    {      def_args[0] = find_shell ();       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)    {      fprintf (stderr, zNoServer, pz_cmd);      return XCNEW (char);    }   /*  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)    {      fprintf (stderr, zNoServer, pz_cmd);      return XCNEW (char);    }   /*  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)      {	close_server (); 	if (retry)	  {	    retry = BOOL_FALSE;	    goto do_retry;	  }         fprintf (stderr, "CLOSING SHELL SERVER - command failure:\n\t%s\n",                 pz_cmd);        pz = XCNEW (char);      }#ifdef DEBUG    fprintf( stderr, "run_shell command success:  %s\n", pz );#endif    return pz;  }}