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 #include "auto-host.h"
  49
  50 #include "ansidecl.h"
  51 #include "system.h"
  52 #include <signal.h>
  53
  54 #include "server.h"
  55
  56 #if !defined(volatile) && !defined(HAVE_VOLATILE)
  57 # define volatile
  58 #endif
  59
  60 STATIC volatile enum t_bool read_pipe_timeout;
  61 STATIC pid_t server_master_pid = NOPROCESS;
  62
  63 tSCC* def_args[] =
  64 { (char *) NULL, (char *) NULL };
  65 STATIC t_pf_pair server_pair =
  66 { (FILE *) NULL, (FILE *) NULL };
  67 STATIC pid_t server_id = NULLPROCESS;
  68 /*
  69  *  Arbitrary text that should not be found in the shell output.
  70  *  It must be a single line and appear verbatim at the start of
  71  *  the terminating output line.
  72  */
  73 tSCC z_done[] = "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd";
  74 tSCC* p_cur_dir = (char *) NULL;
  75
  76 /*
  77  *  load_data
  78  *
  79  *  Read data from a file pointer (a pipe to a process in this context)
  80  *  until we either get EOF or we get a marker line back.
  81  *  The read data are stored in a malloc-ed string that is truncated
  82  *  to size at the end.  Input is assumed to be an ASCII string.
  83  */
  84 static char *load_data PARAMS ((FILE *));
  85 static char *
  86 load_data (fp)
  87      FILE *fp;
  88 {
  89   char *pz_text;
  90   size_t text_size;
  91   char *pz_scan;
  92   char z_line[1024];
  93   t_bool got_done = BOOL_FALSE;
  94
  95   text_size = sizeof (z_line) * 2;
  96   pz_scan = pz_text = xmalloc (text_size);
  97
  98   for (;;)
  99     {
 100       size_t used_ct;
 101
 102       alarm (10);
 103       read_pipe_timeout = BOOL_FALSE;
 104       if (fgets (z_line, sizeof (z_line), fp) == (char *) NULL)
 105         break;
 106
 107       if (strncmp (z_line, z_done, sizeof (z_done) - 1) == 0)
 108         {
 109           got_done = BOOL_TRUE;
 110           break;
 111         }
 112
 113       strcpy (pz_scan, z_line);
 114       pz_scan += strlen (z_line);
 115       used_ct = (size_t) (pz_scan - pz_text);
 116
 117       if (text_size - used_ct < sizeof (z_line))
 118         {
 119           size_t off = (size_t) (pz_scan - pz_text);
 120
 121           text_size += 4096;
 122           pz_text = xrealloc ((void *) pz_text, text_size);
 123           pz_scan = pz_text + off;
 124         }
 125     }
 126
 127   alarm (0);
 128   if (read_pipe_timeout || ! got_done)
 129     {
 130       free ((void *) pz_text);
 131       return (char *) NULL;
 132     }
 133
 134   while ((pz_scan > pz_text) && ISSPACE (pz_scan[-1]))
 135     pz_scan--;
 136   *pz_scan = NUL;
 137   return xrealloc ((void *) pz_text, strlen (pz_text) + 1);
 138 }
 139
 140
 141 /*
 142  *  close_server
 143  *
 144  *  Make certain the server process is dead, close the
 145  *  pipes to it and from it, finally NULL out the file pointers
 146  */
 147 void
 148 close_server ()
 149 {
 150   if (  (server_id != NULLPROCESS)
 151      && (server_master_pid == getpid ()))
 152     {
 153       kill ((pid_t) server_id, SIGKILL);
 154       server_id = NULLPROCESS;
 155       server_master_pid = NOPROCESS;
 156       fclose (server_pair.pf_read);
 157       fclose (server_pair.pf_write);
 158       server_pair.pf_read = server_pair.pf_write = (FILE *) NULL;
 159     }
 160 }
 161
 162 /*
 163  *  sig_handler really only handles the timeout and pipe signals.
 164  *  This ensures that we do not wait forever on a request
 165  *  to our server, and also that if the server dies, we do not
 166  *  die from a sigpipe problem.
 167  */
 168 static void sig_handler PARAMS ((int));
 169 static void
 170 sig_handler (signo)
 171      int signo ATTRIBUTE_UNUSED;
 172 {
 173 #ifdef DEBUG
 174   /* FIXME: this is illegal to do in a signal handler.  */
 175   fprintf (stderr,
 176           "fixincl ERROR:  sig_handler: killed pid %ld due to %s\n",
 177           (long) server_id, signo == SIGPIPE ? "SIGPIPE" : "SIGALRM");
 178 #endif
 179   close_server ();
 180   read_pipe_timeout = BOOL_TRUE;
 181 }
 182
 183
 184 /*
 185  *  server_setup  Establish the signal handler for PIPE and ALARM.
 186  *  Also establishes the current directory to give to the
 187  *  server process at the start of every server command.
 188  */
 189 static void server_setup PARAMS ((void));
 190 static void
 191 server_setup ()
 192 {
 193   static int atexit_done = 0;
 194
 195   if (atexit_done++ == 0)
 196     atexit (close_server);
 197   else
 198     fputs ("NOTE: server restarted\n", stderr);
 199
 200   server_master_pid = getpid ();
 201
 202   signal (SIGPIPE, sig_handler);
 203   signal (SIGALRM, sig_handler);
 204
 205   fputs ("trap : 1\n", server_pair.pf_write);
 206   fflush (server_pair.pf_write);
 207   p_cur_dir = getcwd ((char *) NULL, MAXPATHLEN + 1);
 208 }
 209
 210 /*
 211  *  find_shell
 212  *
 213  *  Locate a shell suitable for use.  For various reasons
 214  *  (like the use of "trap" in server_setup(), it must be a
 215  *  Bourne-like shell.
 216  *
 217  *  Most of the time, /bin/sh is preferred, but sometimes
 218  *  it's quite broken (like on Ultrix).  autoconf lets you
 219  *  override with $CONFIG_SHELL, so we do the same.
 220  */
 221
 222 static const char *find_shell PARAMS ((void));
 223 static const char *
 224 find_shell ()
 225 {
 226   char * shell = getenv ("CONFIG_SHELL");
 227   if (shell)
 228     return shell;
 229
 230   return "/bin/sh";
 231 }
 232
 233
 234 /*
 235  *  run_shell
 236  *
 237  *  Run a shell command on the server.  The command string
 238  *  passed in is wrapped inside the sequence:
 239  *
 240  *     cd <original directory>
 241  *     <command string>
 242  *     echo
 243  *     echo <end-of-command-marker>
 244  *
 245  *  This ensures that all commands start at a known place in
 246  *  the directory structure, that any incomplete output lines
 247  *  are completed and that our special marker sequence appears on
 248  *  a line by itself.  We have chosen a marker that is
 249  *  excessively unlikely to be reproduced in normal output:
 250  *
 251  *     "ShElL-OuTpUt-HaS-bEeN-cOmPlEtEd"
 252  */
 253 char *
 254 run_shell (pz_cmd)
 255      const char *pz_cmd;
 256 {
 257   tSCC zNoServer[] = "Server not running, cannot run:\n%s\n\n";
 258   t_bool retry = BOOL_TRUE;
 259
 260  do_retry:
 261   /*  IF the shell server process is not running yet,
 262       THEN try to start it.  */
 263   if (server_id == NULLPROCESS)
 264     {
 265       def_args[0] = find_shell ();
 266
 267       server_id = proc2_fopen (&server_pair, def_args);
 268       if (server_id > 0)
 269         server_setup ();
 270     }
 271
 272   /*  IF it is still not running, THEN return the nil string.  */
 273   if (server_id <= 0)
 274     {
 275       fprintf (stderr, zNoServer, pz_cmd);
 276       return xcalloc (1, 1);
 277     }
 278
 279   /*  Make sure the process will pay attention to us, send the
 280      supplied command, and then have it output a special marker that
 281      we can find.  */
 282   fprintf (server_pair.pf_write, "cd %s\n%s\n\necho\necho %s\n",
 283            p_cur_dir, pz_cmd, z_done);
 284   fflush (server_pair.pf_write);
 285
 286   /*  IF the server died and we received a SIGPIPE,
 287       THEN return an empty string.  */
 288   if (server_id == NULLPROCESS)
 289     {
 290       fprintf (stderr, zNoServer, pz_cmd);
 291       return xcalloc (1, 1);
 292     }
 293
 294   /*  Now try to read back all the data.  If we fail due to either a
 295      sigpipe or sigalrm (timeout), we will return the nil string.  */
 296   {
 297     char *pz = load_data (server_pair.pf_read);
 298
 299     if (pz == (char *) NULL)
 300       {
 301         close_server ();
 302
 303         if (retry)
 304           {
 305             retry = BOOL_FALSE;
 306             goto do_retry;
 307           }
 308
 309         fprintf (stderr, "CLOSING SHELL SERVER - command failure:\n\t%s\n",
 310                  pz_cmd);
 311         pz = xcalloc (1, 1);
 312       }
 313 #ifdef DEBUG
 314     fprintf( stderr, "run_shell command success:  %s\n", pz );
 315 #endif
 316     return pz;
 317   }
 318 }