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1 | /* eval.c -- reading and evaluating commands. */ | |
2 | ||
3 | /* Copyright (C) 1996-2011 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 | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation, either version 3 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>. | |
19 | */ | |
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 <signal.h> | |
34 | ||
35 | #include "bashintl.h" | |
36 | ||
37 | #include "shell.h" | |
38 | #include "flags.h" | |
39 | #include "trap.h" | |
40 | ||
41 | #include "builtins/common.h" | |
42 | ||
43 | #include "input.h" | |
44 | #include "execute_cmd.h" | |
45 | ||
46 | #if defined (HISTORY) | |
47 | # include "bashhist.h" | |
48 | #endif | |
49 | ||
50 | extern int EOF_reached; | |
51 | extern int indirection_level; | |
52 | extern int posixly_correct; | |
53 | extern int subshell_environment, running_under_emacs; | |
54 | extern int last_command_exit_value, stdin_redir; | |
55 | extern int need_here_doc; | |
56 | extern int current_command_number, current_command_line_count, line_number; | |
57 | extern int expand_aliases; | |
58 | extern char *ps0_prompt; | |
59 | ||
60 | #if defined (HAVE_POSIX_SIGNALS) | |
61 | extern sigset_t top_level_mask; | |
62 | #endif | |
63 | ||
64 | static void send_pwd_to_eterm __P((void)); | |
65 | static sighandler alrm_catcher __P((int)); | |
66 | ||
67 | /* Read and execute commands until EOF is reached. This assumes that | |
68 | the input source has already been initialized. */ | |
69 | int | |
70 | reader_loop () | |
71 | { | |
72 | int our_indirection_level; | |
73 | COMMAND * volatile current_command; | |
74 | ||
75 | USE_VAR(current_command); | |
76 | ||
77 | current_command = (COMMAND *)NULL; | |
78 | ||
79 | our_indirection_level = ++indirection_level; | |
80 | ||
81 | while (EOF_Reached == 0) | |
82 | { | |
83 | int code; | |
84 | ||
85 | code = setjmp_nosigs (top_level); | |
86 | ||
87 | #if defined (PROCESS_SUBSTITUTION) | |
88 | unlink_fifo_list (); | |
89 | #endif /* PROCESS_SUBSTITUTION */ | |
90 | ||
91 | /* XXX - why do we set this every time through the loop? And why do | |
92 | it if SIGINT is trapped in an interactive shell? */ | |
93 | if (interactive_shell && signal_is_ignored (SIGINT) == 0) | |
94 | set_signal_handler (SIGINT, sigint_sighandler); | |
95 | ||
96 | if (code != NOT_JUMPED) | |
97 | { | |
98 | indirection_level = our_indirection_level; | |
99 | ||
100 | switch (code) | |
101 | { | |
102 | /* Some kind of throw to top_level has occurred. */ | |
103 | case FORCE_EOF: | |
104 | case ERREXIT: | |
105 | case EXITPROG: | |
106 | current_command = (COMMAND *)NULL; | |
107 | if (exit_immediately_on_error) | |
108 | variable_context = 0; /* not in a function */ | |
109 | EOF_Reached = EOF; | |
110 | goto exec_done; | |
111 | ||
112 | case DISCARD: | |
113 | /* Make sure the exit status is reset to a non-zero value, but | |
114 | leave existing non-zero values (e.g., > 128 on signal) | |
115 | alone. */ | |
116 | if (last_command_exit_value == 0) | |
117 | last_command_exit_value = EXECUTION_FAILURE; | |
118 | if (subshell_environment) | |
119 | { | |
120 | current_command = (COMMAND *)NULL; | |
121 | EOF_Reached = EOF; | |
122 | goto exec_done; | |
123 | } | |
124 | /* Obstack free command elements, etc. */ | |
125 | if (current_command) | |
126 | { | |
127 | dispose_command (current_command); | |
128 | current_command = (COMMAND *)NULL; | |
129 | } | |
130 | #if defined (HAVE_POSIX_SIGNALS) | |
131 | sigprocmask (SIG_SETMASK, &top_level_mask, (sigset_t *)NULL); | |
132 | #endif | |
133 | break; | |
134 | ||
135 | default: | |
136 | command_error ("reader_loop", CMDERR_BADJUMP, code, 0); | |
137 | } | |
138 | } | |
139 | ||
140 | executing = 0; | |
141 | if (temporary_env) | |
142 | dispose_used_env_vars (); | |
143 | ||
144 | #if (defined (ultrix) && defined (mips)) || defined (C_ALLOCA) | |
145 | /* Attempt to reclaim memory allocated with alloca (). */ | |
146 | (void) alloca (0); | |
147 | #endif | |
148 | ||
149 | if (read_command () == 0) | |
150 | { | |
151 | if (interactive_shell == 0 && read_but_dont_execute) | |
152 | { | |
153 | last_command_exit_value = EXECUTION_SUCCESS; | |
154 | dispose_command (global_command); | |
155 | global_command = (COMMAND *)NULL; | |
156 | } | |
157 | else if (current_command = global_command) | |
158 | { | |
159 | global_command = (COMMAND *)NULL; | |
160 | current_command_number++; | |
161 | ||
162 | executing = 1; | |
163 | stdin_redir = 0; | |
164 | ||
165 | /* If the shell is interactive, expand and display $PS0 after reading a | |
166 | command (possibly a list or pipeline) and before executing it. */ | |
167 | if (interactive && ps0_prompt) | |
168 | { | |
169 | char *ps0_string; | |
170 | ||
171 | ps0_string = decode_prompt_string (ps0_prompt); | |
172 | if (ps0_string && *ps0_string) | |
173 | { | |
174 | fprintf (stderr, "%s", ps0_string); | |
175 | fflush (stderr); | |
176 | } | |
177 | free (ps0_string); | |
178 | } | |
179 | ||
180 | execute_command (current_command); | |
181 | ||
182 | exec_done: | |
183 | QUIT; | |
184 | ||
185 | if (current_command) | |
186 | { | |
187 | dispose_command (current_command); | |
188 | current_command = (COMMAND *)NULL; | |
189 | } | |
190 | } | |
191 | } | |
192 | else | |
193 | { | |
194 | /* Parse error, maybe discard rest of stream if not interactive. */ | |
195 | if (interactive == 0) | |
196 | EOF_Reached = EOF; | |
197 | } | |
198 | if (just_one_command) | |
199 | EOF_Reached = EOF; | |
200 | } | |
201 | indirection_level--; | |
202 | return (last_command_exit_value); | |
203 | } | |
204 | ||
205 | static sighandler | |
206 | alrm_catcher(i) | |
207 | int i; | |
208 | { | |
209 | printf (_("\007timed out waiting for input: auto-logout\n")); | |
210 | fflush (stdout); | |
211 | bash_logout (); /* run ~/.bash_logout if this is a login shell */ | |
212 | jump_to_top_level (EXITPROG); | |
213 | SIGRETURN (0); | |
214 | } | |
215 | ||
216 | /* Send an escape sequence to emacs term mode to tell it the | |
217 | current working directory. */ | |
218 | static void | |
219 | send_pwd_to_eterm () | |
220 | { | |
221 | char *pwd, *f; | |
222 | ||
223 | f = 0; | |
224 | pwd = get_string_value ("PWD"); | |
225 | if (pwd == 0) | |
226 | f = pwd = get_working_directory ("eterm"); | |
227 | fprintf (stderr, "\032/%s\n", pwd); | |
228 | free (f); | |
229 | } | |
230 | ||
231 | /* Call the YACC-generated parser and return the status of the parse. | |
232 | Input is read from the current input stream (bash_input). yyparse | |
233 | leaves the parsed command in the global variable GLOBAL_COMMAND. | |
234 | This is where PROMPT_COMMAND is executed. */ | |
235 | int | |
236 | parse_command () | |
237 | { | |
238 | int r; | |
239 | char *command_to_execute; | |
240 | ||
241 | need_here_doc = 0; | |
242 | run_pending_traps (); | |
243 | ||
244 | /* Allow the execution of a random command just before the printing | |
245 | of each primary prompt. If the shell variable PROMPT_COMMAND | |
246 | is set then the value of it is the command to execute. */ | |
247 | /* The tests are a combination of SHOULD_PROMPT() and prompt_again() | |
248 | from parse.y, which are the conditions under which the prompt is | |
249 | actually printed. */ | |
250 | if (interactive && bash_input.type != st_string && parser_expanding_alias() == 0) | |
251 | { | |
252 | command_to_execute = get_string_value ("PROMPT_COMMAND"); | |
253 | if (command_to_execute) | |
254 | execute_variable_command (command_to_execute, "PROMPT_COMMAND"); | |
255 | ||
256 | if (running_under_emacs == 2) | |
257 | send_pwd_to_eterm (); /* Yuck */ | |
258 | } | |
259 | ||
260 | current_command_line_count = 0; | |
261 | r = yyparse (); | |
262 | ||
263 | if (need_here_doc) | |
264 | gather_here_documents (); | |
265 | ||
266 | return (r); | |
267 | } | |
268 | ||
269 | /* Read and parse a command, returning the status of the parse. The command | |
270 | is left in the globval variable GLOBAL_COMMAND for use by reader_loop. | |
271 | This is where the shell timeout code is executed. */ | |
272 | int | |
273 | read_command () | |
274 | { | |
275 | SHELL_VAR *tmout_var; | |
276 | int tmout_len, result; | |
277 | SigHandler *old_alrm; | |
278 | ||
279 | set_current_prompt_level (1); | |
280 | global_command = (COMMAND *)NULL; | |
281 | ||
282 | /* Only do timeouts if interactive. */ | |
283 | tmout_var = (SHELL_VAR *)NULL; | |
284 | tmout_len = 0; | |
285 | old_alrm = (SigHandler *)NULL; | |
286 | ||
287 | if (interactive) | |
288 | { | |
289 | tmout_var = find_variable ("TMOUT"); | |
290 | ||
291 | if (tmout_var && var_isset (tmout_var)) | |
292 | { | |
293 | tmout_len = atoi (value_cell (tmout_var)); | |
294 | if (tmout_len > 0) | |
295 | { | |
296 | old_alrm = set_signal_handler (SIGALRM, alrm_catcher); | |
297 | alarm (tmout_len); | |
298 | } | |
299 | } | |
300 | } | |
301 | ||
302 | QUIT; | |
303 | ||
304 | current_command_line_count = 0; | |
305 | result = parse_command (); | |
306 | ||
307 | if (interactive && tmout_var && (tmout_len > 0)) | |
308 | { | |
309 | alarm(0); | |
310 | set_signal_handler (SIGALRM, old_alrm); | |
311 | } | |
312 | ||
313 | return (result); | |
314 | } |