gcc/fixinc/procopen.c

   1
   2 /*
   3  *  server.c  Set up and handle communications with a server process.
   4  *
   5  *  Server Handling copyright 1992-1999 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 #include "ansidecl.h"
  50 #include "system.h"
  51
  52 #include "server.h"
  53 #include "fixlib.h"
  54
  55 STATIC const char* def_args[] =
  56 { (char *) NULL, (char *) NULL };
  57
  58 /*
  59  *  chain_open
  60  *
  61  *  Given an FD for an inferior process to use as stdin,
  62  *  start that process and return a NEW FD that that process
  63  *  will use for its stdout.  Requires the argument vector
  64  *  for the new process and, optionally, a pointer to a place
  65  *  to store the child's process id.
  66  */
  67 int
  68 chain_open (stdin_fd, pp_args, p_child)
  69      int stdin_fd;
  70      tCC **pp_args;
  71      pid_t *p_child;
  72 {
  73   t_fd_pair stdout_pair;
  74   pid_t ch_id;
  75   tCC *pz_cmd;
  76
  77   stdout_pair.read_fd = stdout_pair.write_fd = -1;
  78
  79   /*
  80    *  Create a pipe it will be the child process' stdout,
  81    *  and the parent will read from it.
  82    */
  83   if (pipe ((int *) &stdout_pair) < 0)
  84     {
  85       if (p_child != (pid_t *) NULL)
  86         *p_child = NOPROCESS;
  87       return -1;
  88     }
  89
  90   /*
  91    *  If we did not get an arg list, use the default
  92    */
  93   if (pp_args == (tCC **) NULL)
  94     pp_args = def_args;
  95
  96   /*
  97    *  If the arg list does not have a program,
  98    *  assume the "SHELL" from the environment, or, failing
  99    *  that, then sh.  Set argv[0] to whatever we decided on.
 100    */
 101   if (pz_cmd = *pp_args,
 102       (pz_cmd == (char *) NULL) || (*pz_cmd == '\0'))
 103     {
 104
 105       pz_cmd = getenv ("SHELL");
 106       if (pz_cmd == (char *) NULL)
 107         pz_cmd = "sh";
 108     }
 109
 110 #ifdef DEBUG_PRINT
 111   printf ("START:  %s\n", pz_cmd);
 112   {
 113     int idx = 0;
 114
 115     while (pp_args[++idx] != (char *) NULL)
 116       printf ("  ARG %2d:  %s\n", idx, pp_args[idx]);
 117   }
 118 #endif
 119
 120   /*
 121    *  Call fork() and see which process we become
 122    */
 123   ch_id = fork ();
 124   switch (ch_id)
 125     {
 126     case NOPROCESS:             /* parent - error in call */
 127       close (stdout_pair.read_fd);
 128       close (stdout_pair.write_fd);
 129       if (p_child != (pid_t *) NULL)
 130         *p_child = NOPROCESS;
 131       return -1;
 132
 133     default:                    /* parent - return opposite FD's */
 134       if (p_child != (pid_t *) NULL)
 135         *p_child = ch_id;
 136 #ifdef DEBUG_PRINT
 137       printf ("for pid %d:  stdin from %d, stdout to %d\n"
 138               "for parent:  read from %d\n",
 139               ch_id, stdin_fd, stdout_pair.write_fd, stdout_pair.read_fd);
 140 #endif
 141       close (stdin_fd);
 142       close (stdout_pair.write_fd);
 143       return stdout_pair.read_fd;
 144
 145     case NULLPROCESS:           /* child - continue processing */
 146       break;
 147     }
 148
 149   /*
 150    *  Close the pipe end handed back to the parent process
 151    */
 152   close (stdout_pair.read_fd);
 153
 154   /*
 155    *  Close our current stdin and stdout
 156    */
 157   close (STDIN_FILENO);
 158   close (STDOUT_FILENO);
 159
 160   /*
 161    *  Make the fd passed in the stdin, and the write end of
 162    *  the new pipe become the stdout.
 163    */
 164   fcntl (stdout_pair.write_fd, F_DUPFD, STDOUT_FILENO);
 165   fcntl (stdin_fd, F_DUPFD, STDIN_FILENO);
 166
 167   if (*pp_args == (char *) NULL)
 168     *pp_args = pz_cmd;
 169
 170   execvp (pz_cmd, (char**)pp_args);
 171   fprintf (stderr, "Error %d:  Could not execvp( '%s', ... ):  %s\n",
 172            errno, pz_cmd, xstrerror (errno));
 173   exit (EXIT_PANIC);
 174 }
 175
 176
 177 /*
 178  *  proc2_open
 179  *
 180  *  Given a pointer to an argument vector, start a process and
 181  *  place its stdin and stdout file descriptors into an fd pair
 182  *  structure.  The "write_fd" connects to the inferior process
 183  *  stdin, and the "read_fd" connects to its stdout.  The calling
 184  *  process should write to "write_fd" and read from "read_fd".
 185  *  The return value is the process id of the created process.
 186  */
 187 pid_t
 188 proc2_open (p_pair, pp_args)
 189      t_fd_pair *p_pair;
 190      tCC **pp_args;
 191 {
 192   pid_t ch_id;
 193
 194   /*  Create a bi-directional pipe.  Writes on 0 arrive on 1 and vice
 195      versa, so the parent and child processes will read and write to
 196      opposite FD's.  */
 197   if (pipe ((int *) p_pair) < 0)
 198     return NOPROCESS;
 199
 200   p_pair->read_fd = chain_open (p_pair->read_fd, pp_args, &ch_id);
 201   if (ch_id == NOPROCESS)
 202     close (p_pair->write_fd);
 203
 204   return ch_id;
 205 }
 206
 207
 208 /*
 209  *  proc2_fopen
 210  *
 211  *  Identical to "proc2_open()", except that the "fd"'s are
 212  *  "fdopen(3)"-ed into file pointers instead.
 213  */
 214 pid_t
 215 proc2_fopen (pf_pair, pp_args)
 216      t_pf_pair *pf_pair;
 217      tCC **pp_args;
 218 {
 219   t_fd_pair fd_pair;
 220   pid_t ch_id = proc2_open (&fd_pair, pp_args);
 221
 222   if (ch_id == NOPROCESS)
 223     return ch_id;
 224
 225   pf_pair->pf_read = fdopen (fd_pair.read_fd, "r");
 226   pf_pair->pf_write = fdopen (fd_pair.write_fd, "w");
 227   return ch_id;
 228 }