gcc/fixinc/server.c

   1
   2 /*
   3  *  server.c  Set up and handle communications with a server process.
   4  *
   5  *  Server Handling copyright 1992-1999, 2001 The Free Software Foundation
   6  *
   7  *  Server Handling is free software.
   8  *  You may redistribute it and/or modify it under the terms of the
   9  *  GNU General Public License, as published by the Free Software
  10  *  Foundation; either version 2, or (at your option) any later version.
  11  *
  12  *  Server Handling is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with Server Handling.  See the file "COPYING".  If not,
  19  *  write to:  The Free Software Foundation, Inc.,
  20  *             59 Temple Place - Suite 330,
  21  *             Boston,  MA  02111-1307, USA.
  22  *
  23  * As a special exception, The Free Software Foundation gives
  24  * permission for additional uses of the text contained in his release
  25  * of ServerHandler.
  26  *
  27  * The exception is that, if you link the ServerHandler library with other
  28  * files to produce an executable, this does not by itself cause the
  29  * resulting executable to be covered by the GNU General Public License.
  30  * Your use of that executable is in no way restricted on account of
  31  * linking the ServerHandler library code into it.
  32  *
  33  * This exception does not however invalidate any other reasons why
  34  * the executable file might be covered by the GNU General Public License.
  35  *
  36  * This exception applies only to the code released by The Free
  37  * Software Foundation under the name ServerHandler.  If you copy code
  38  * from other sources under the General Public License into a copy of
  39  * ServerHandler, as the General Public License permits, the exception
  40  * does not apply to the code that you add in this way.  To avoid
  41  * misleading anyone as to the status of such modified files, you must
  42  * delete this exception notice from them.
  43  *
  44  * If you write modifications of your own for ServerHandler, it is your
  45  * choice whether to permit this exception to apply to your modifications.
  46  * If you do not wish that, delete this exception notice.
  47  */
  48
  49 #include "fixlib.h"
  50 #include "server.h"
  51
  52 STATIC volatile enum t_bool read_pipe_timeout;
  53 STATIC pid_t server_master_pid = NOPROCESS;
  54
  55 tSCC* def_args[] =
  56 { (char *) NULL, (char *) NULL };
  57 STATIC t_pf_pair server_pair =
  58 { (FILE *) NULL, (FILE *) NULL };
  59 STATIC pid_t server_id = NULLPROCESS;
  60 /*
  61  *  Arbitrary text that should not be found in the shell output.
  62  *  It must be a single line and appear verbatim at the start of
  63  *  the terminating output line.
  64  */
  65 tSCC z_done[] = "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd";
  66 tSCC* p_cur_dir = (char *) NULL;
  67
  68 /*
  69  *  load_data
  70  *
  71  *  Read data from a file pointer (a pipe to a process in this context)
  72  *  until we either get EOF or we get a marker line back.
  73  *  The read data are stored in a malloc-ed string that is truncated
  74  *  to size at the end.  Input is assumed to be an ASCII string.
  75  */
  76 static char *load_data PARAMS ((FILE *));
  77 static char *
  78 load_data (fp)
  79      FILE *fp;
  80 {
  81   char *pz_text;
  82   size_t text_size;
  83   char *pz_scan;
  84   char z_line[1024];
  85   t_bool got_done = BOOL_FALSE;
  86
  87   text_size = sizeof (z_line) * 2;
  88   pz_scan = pz_text = xmalloc (text_size);
  89
  90   for (;;)
  91     {
  92       size_t used_ct;
  93
  94       alarm (10);
  95       read_pipe_timeout = BOOL_FALSE;
  96       if (fgets (z_line, sizeof (z_line), fp) == (char *) NULL)
  97         break;
  98
  99       if (strncmp (z_line, z_done, sizeof (z_done) - 1) == 0)
 100         {
 101           got_done = BOOL_TRUE;
 102           break;
 103         }
 104
 105       strcpy (pz_scan, z_line);
 106       pz_scan += strlen (z_line);
 107       used_ct = (size_t) (pz_scan - pz_text);
 108
 109       if (text_size - used_ct < sizeof (z_line))
 110         {
 111           size_t off = (size_t) (pz_scan - pz_text);
 112
 113           text_size += 4096;
 114           pz_text = xrealloc ((void *) pz_text, text_size);
 115           pz_scan = pz_text + off;
 116         }
 117     }
 118
 119   alarm (0);
 120   if (read_pipe_timeout || ! got_done)
 121     {
 122       free ((void *) pz_text);
 123       return (char *) NULL;
 124     }
 125
 126   while ((pz_scan > pz_text) && ISSPACE (pz_scan[-1]))
 127     pz_scan--;
 128   *pz_scan = NUL;
 129   return xrealloc ((void *) pz_text, strlen (pz_text) + 1);
 130 }
 131
 132
 133 /*
 134  *  close_server
 135  *
 136  *  Make certain the server process is dead, close the
 137  *  pipes to it and from it, finally NULL out the file pointers
 138  */
 139 void
 140 close_server ()
 141 {
 142   if (  (server_id != NULLPROCESS)
 143      && (server_master_pid == getpid ()))
 144     {
 145       kill ((pid_t) server_id, SIGKILL);
 146       server_id = NULLPROCESS;
 147       server_master_pid = NOPROCESS;
 148       fclose (server_pair.pf_read);
 149       fclose (server_pair.pf_write);
 150       server_pair.pf_read = server_pair.pf_write = (FILE *) NULL;
 151     }
 152 }
 153
 154 /*
 155  *  sig_handler really only handles the timeout and pipe signals.
 156  *  This ensures that we do not wait forever on a request
 157  *  to our server, and also that if the server dies, we do not
 158  *  die from a sigpipe problem.
 159  */
 160 static void sig_handler PARAMS ((int));
 161 static void
 162 sig_handler (signo)
 163      int signo ATTRIBUTE_UNUSED;
 164 {
 165 #ifdef DEBUG
 166   /* FIXME: this is illegal to do in a signal handler.  */
 167   fprintf (stderr,
 168           "fixincl ERROR:  sig_handler: killed pid %ld due to %s\n",
 169           (long) server_id, signo == SIGPIPE ? "SIGPIPE" : "SIGALRM");
 170 #endif
 171   close_server ();
 172   read_pipe_timeout = BOOL_TRUE;
 173 }
 174
 175
 176 /*
 177  *  server_setup  Establish the signal handler for PIPE and ALARM.
 178  *  Also establishes the current directory to give to the
 179  *  server process at the start of every server command.
 180  */
 181 static void server_setup PARAMS ((void));
 182 static void
 183 server_setup ()
 184 {
 185   static int atexit_done = 0;
 186
 187   if (atexit_done++ == 0)
 188     atexit (close_server);
 189   else
 190     fputs ("NOTE: server restarted\n", stderr);
 191
 192   server_master_pid = getpid ();
 193
 194   signal (SIGPIPE, sig_handler);
 195   signal (SIGALRM, sig_handler);
 196
 197   fputs ("trap : 1\n", server_pair.pf_write);
 198   fflush (server_pair.pf_write);
 199   p_cur_dir = getcwd ((char *) NULL, MAXPATHLEN + 1);
 200 }
 201
 202 /*
 203  *  find_shell
 204  *
 205  *  Locate a shell suitable for use.  For various reasons
 206  *  (like the use of "trap" in server_setup(), it must be a
 207  *  Bourne-like shell.
 208  *
 209  *  Most of the time, /bin/sh is preferred, but sometimes
 210  *  it's quite broken (like on Ultrix).  autoconf lets you
 211  *  override with $CONFIG_SHELL, so we do the same.
 212  */
 213
 214 static const char *find_shell PARAMS ((void));
 215 static const char *
 216 find_shell ()
 217 {
 218   char * shell = getenv ("CONFIG_SHELL");
 219   if (shell)
 220     return shell;
 221
 222   return "/bin/sh";
 223 }
 224
 225
 226 /*
 227  *  run_shell
 228  *
 229  *  Run a shell command on the server.  The command string
 230  *  passed in is wrapped inside the sequence:
 231  *
 232  *     cd <original directory>
 233  *     <command string>
 234  *     echo
 235  *     echo <end-of-command-marker>
 236  *
 237  *  This ensures that all commands start at a known place in
 238  *  the directory structure, that any incomplete output lines
 239  *  are completed and that our special marker sequence appears on
 240  *  a line by itself.  We have chosen a marker that is
 241  *  excessively unlikely to be reproduced in normal output:
 242  *
 243  *     "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd"
 244  */
 245 char *
 246 run_shell (pz_cmd)
 247      const char *pz_cmd;
 248 {
 249   tSCC zNoServer[] = "Server not running, cannot run:\n%s\n\n";
 250   t_bool retry = BOOL_TRUE;
 251
 252  do_retry:
 253   /*  IF the shell server process is not running yet,
 254       THEN try to start it.  */
 255   if (server_id == NULLPROCESS)
 256     {
 257       def_args[0] = find_shell ();
 258
 259       server_id = proc2_fopen (&server_pair, def_args);
 260       if (server_id > 0)
 261         server_setup ();
 262     }
 263
 264   /*  IF it is still not running, THEN return the nil string.  */
 265   if (server_id <= 0)
 266     {
 267       fprintf (stderr, zNoServer, pz_cmd);
 268       return xcalloc (1, 1);
 269     }
 270
 271   /*  Make sure the process will pay attention to us, send the
 272      supplied command, and then have it output a special marker that
 273      we can find.  */
 274   fprintf (server_pair.pf_write, "cd %s\n%s\n\necho\necho %s\n",
 275            p_cur_dir, pz_cmd, z_done);
 276   fflush (server_pair.pf_write);
 277
 278   /*  IF the server died and we received a SIGPIPE,
 279       THEN return an empty string.  */
 280   if (server_id == NULLPROCESS)
 281     {
 282       fprintf (stderr, zNoServer, pz_cmd);
 283       return xcalloc (1, 1);
 284     }
 285
 286   /*  Now try to read back all the data.  If we fail due to either a
 287      sigpipe or sigalrm (timeout), we will return the nil string.  */
 288   {
 289     char *pz = load_data (server_pair.pf_read);
 290
 291     if (pz == (char *) NULL)
 292       {
 293         close_server ();
 294
 295         if (retry)
 296           {
 297             retry = BOOL_FALSE;
 298             goto do_retry;
 299           }
 300
 301         fprintf (stderr, "CLOSING SHELL SERVER - command failure:\n\t%s\n",
 302                  pz_cmd);
 303         pz = xcalloc (1, 1);
 304       }
 305 #ifdef DEBUG
 306     fprintf( stderr, "run_shell command success:  %s\n", pz );
 307 #endif
 308     return pz;
 309   }
 310 }