eval.c

   1 /* eval.c -- reading and evaluating commands. */
   2
   3 /* Copyright (C) 1996 Free Software Foundation, Inc.
   4
   5    This file is part of GNU Bash, the Bourne Again SHell.
   6
   7    Bash is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    Bash is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with Bash; see the file COPYING.  If not, write to the Free
  19    Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */
  20
  21 #include "config.h"
  22
  23 #if defined (HAVE_UNISTD_H)
  24 #  ifdef _MINIX
  25 #    include <sys/types.h>
  26 #  endif
  27 #  include <unistd.h>
  28 #endif
  29
  30 #include "bashansi.h"
  31 #include <stdio.h>
  32
  33 #include "shell.h"
  34 #include "flags.h"
  35 #include "trap.h"
  36
  37 #include "builtins/common.h"
  38
  39 #include "input.h"
  40 #include "execute_cmd.h"
  41
  42 #if defined (HISTORY)
  43 #  include "bashhist.h"
  44 #endif
  45
  46 extern int yyparse ();
  47
  48 extern int EOF_reached;
  49 extern int indirection_level, interactive, interactive_shell;
  50 extern int posixly_correct;
  51 extern int subshell_environment, running_under_emacs;
  52 extern int last_command_exit_value, stdin_redir;
  53 extern int need_here_doc;
  54 extern int current_command_number, current_command_line_count, line_number;
  55 extern int expand_aliases;
  56
  57 /* Read and execute commands until EOF is reached.  This assumes that
  58    the input source has already been initialized. */
  59 int
  60 reader_loop ()
  61 {
  62   int our_indirection_level;
  63   COMMAND *current_command = (COMMAND *)NULL;
  64
  65   our_indirection_level = ++indirection_level;
  66
  67   while (EOF_Reached == 0)
  68     {
  69       int code;
  70
  71       code = setjmp (top_level);
  72
  73 #if defined (PROCESS_SUBSTITUTION)
  74       unlink_fifo_list ();
  75 #endif /* PROCESS_SUBSTITUTION */
  76
  77       if (interactive_shell && signal_is_ignored (SIGINT) == 0)
  78         set_signal_handler (SIGINT, sigint_sighandler);
  79
  80       if (code != NOT_JUMPED)
  81         {
  82           indirection_level = our_indirection_level;
  83
  84           switch (code)
  85             {
  86               /* Some kind of throw to top_level has occured. */
  87             case FORCE_EOF:
  88             case EXITPROG:
  89               current_command = (COMMAND *)NULL;
  90               if (exit_immediately_on_error)
  91                 variable_context = 0;   /* not in a function */
  92               EOF_Reached = EOF;
  93               goto exec_done;
  94
  95             case DISCARD:
  96               last_command_exit_value = 1;
  97               if (subshell_environment)
  98                 {
  99                   current_command = (COMMAND *)NULL;
 100                   EOF_Reached = EOF;
 101                   goto exec_done;
 102                 }
 103               /* Obstack free command elements, etc. */
 104               if (current_command)
 105                 {
 106                   dispose_command (current_command);
 107                   current_command = (COMMAND *)NULL;
 108                 }
 109               break;
 110
 111             default:
 112               command_error ("reader_loop", CMDERR_BADJUMP, code, 0);
 113             }
 114         }
 115
 116       executing = 0;
 117       dispose_used_env_vars ();
 118
 119 #if (defined (ultrix) && defined (mips)) || defined (C_ALLOCA)
 120       /* Attempt to reclaim memory allocated with alloca (). */
 121       (void) alloca (0);
 122 #endif
 123
 124       if (read_command () == 0)
 125         {
 126           if (interactive_shell == 0 && read_but_dont_execute)
 127             {
 128               last_command_exit_value = EXECUTION_SUCCESS;
 129               dispose_command (global_command);
 130               global_command = (COMMAND *)NULL;
 131             }
 132           else if (current_command = global_command)
 133             {
 134               global_command = (COMMAND *)NULL;
 135               current_command_number++;
 136
 137               executing = 1;
 138               stdin_redir = 0;
 139               execute_command (current_command);
 140
 141             exec_done:
 142               if (current_command)
 143                 {
 144                   dispose_command (current_command);
 145                   current_command = (COMMAND *)NULL;
 146                 }
 147
 148               QUIT;
 149             }
 150         }
 151       else
 152         {
 153           /* Parse error, maybe discard rest of stream if not interactive. */
 154           if (interactive == 0)
 155             EOF_Reached = EOF;
 156         }
 157       if (just_one_command)
 158         EOF_Reached = EOF;
 159     }
 160   indirection_level--;
 161   return (last_command_exit_value);
 162 }
 163
 164 static sighandler
 165 alrm_catcher(i)
 166      int i;
 167 {
 168   printf ("\007timed out waiting for input: auto-logout\n");
 169   jump_to_top_level (EXITPROG);
 170   SIGRETURN (0);
 171 }
 172
 173 /* Send an escape sequence to emacs term mode to tell it the
 174    current working directory. */
 175 static void
 176 send_pwd_to_eterm ()
 177 {
 178   char *pwd;
 179
 180   pwd = get_string_value ("PWD");
 181   if (pwd == 0)
 182     pwd = get_working_directory ("eterm");
 183   fprintf (stderr, "\032/%s\n", pwd);
 184 }
 185
 186 /* Call the YACC-generated parser and return the status of the parse.
 187    Input is read from the current input stream (bash_input).  yyparse
 188    leaves the parsed command in the global variable GLOBAL_COMMAND.
 189    This is where PROMPT_COMMAND is executed. */
 190 int
 191 parse_command ()
 192 {
 193   int r;
 194   char *command_to_execute;
 195
 196   need_here_doc = 0;
 197   run_pending_traps ();
 198
 199   /* Allow the execution of a random command just before the printing
 200      of each primary prompt.  If the shell variable PROMPT_COMMAND
 201      is set then the value of it is the command to execute. */
 202   if (interactive && bash_input.type != st_string)
 203     {
 204       command_to_execute = get_string_value ("PROMPT_COMMAND");
 205       if (command_to_execute)
 206         execute_prompt_command (command_to_execute);
 207
 208       if (running_under_emacs == 2)
 209         send_pwd_to_eterm ();   /* Yuck */
 210     }
 211
 212   current_command_line_count = 0;
 213   r = yyparse ();
 214
 215   if (need_here_doc)
 216     gather_here_documents ();
 217
 218   return (r);
 219 }
 220
 221 /* Read and parse a command, returning the status of the parse.  The command
 222    is left in the globval variable GLOBAL_COMMAND for use by reader_loop.
 223    This is where the shell timeout code is executed. */
 224 int
 225 read_command ()
 226 {
 227   SHELL_VAR *tmout_var;
 228   int tmout_len, result;
 229   SigHandler *old_alrm;
 230
 231   set_current_prompt_level (1);
 232   global_command = (COMMAND *)NULL;
 233
 234   /* Only do timeouts if interactive. */
 235   tmout_var = (SHELL_VAR *)NULL;
 236   tmout_len = 0;
 237
 238   if (interactive)
 239     {
 240       tmout_var = find_variable ("TMOUT");
 241       old_alrm = (SigHandler *)NULL;
 242
 243       if (tmout_var && tmout_var->value)
 244         {
 245           tmout_len = atoi (tmout_var->value);
 246           if (tmout_len > 0)
 247             {
 248               old_alrm = set_signal_handler (SIGALRM, alrm_catcher);
 249               alarm (tmout_len);
 250             }
 251         }
 252     }
 253
 254   QUIT;
 255
 256   current_command_line_count = 0;
 257   result = parse_command ();
 258
 259   if (interactive && tmout_var && (tmout_len > 0))
 260     {
 261       alarm(0);
 262       set_signal_handler (SIGALRM, old_alrm);
 263     }
 264
 265   return (result);
 266 }