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eval.c
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eval.c
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/* eval.c -- reading and evaluating commands. */
/* Copyright (C) 1996-2022 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Bash is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#if defined (HAVE_UNISTD_H)
# ifdef _MINIX
# include <sys/types.h>
# endif
# include <unistd.h>
#endif
#include "bashansi.h"
#include <stdio.h>
#include <signal.h>
#include "bashintl.h"
#include "shell.h"
#include "parser.h"
#include "flags.h"
#include "trap.h"
#include "builtins/common.h"
#include "input.h"
#include "execute_cmd.h"
#if defined (HISTORY)
# include "bashhist.h"
#endif
static void send_pwd_to_eterm PARAMS((void));
static sighandler alrm_catcher PARAMS((int));
/* Read and execute commands until EOF is reached. This assumes that
the input source has already been initialized. */
int
reader_loop ()
{
int our_indirection_level;
COMMAND * volatile current_command;
USE_VAR(current_command);
current_command = (COMMAND *)NULL;
our_indirection_level = ++indirection_level;
if (just_one_command)
reset_readahead_token ();
while (EOF_Reached == 0)
{
int code;
code = setjmp_nosigs (top_level);
#if defined (PROCESS_SUBSTITUTION)
unlink_fifo_list ();
#endif /* PROCESS_SUBSTITUTION */
/* XXX - why do we set this every time through the loop? And why do
it if SIGINT is trapped in an interactive shell? */
if (interactive_shell && signal_is_ignored (SIGINT) == 0 && signal_is_trapped (SIGINT) == 0)
set_signal_handler (SIGINT, sigint_sighandler);
if (code != NOT_JUMPED)
{
indirection_level = our_indirection_level;
switch (code)
{
/* Some kind of throw to top_level has occurred. */
case ERREXIT:
if (exit_immediately_on_error)
reset_local_contexts (); /* not in a function */
case FORCE_EOF:
case EXITPROG:
case EXITBLTIN:
current_command = (COMMAND *)NULL;
EOF_Reached = EOF;
goto exec_done;
case DISCARD:
/* Make sure the exit status is reset to a non-zero value, but
leave existing non-zero values (e.g., > 128 on signal)
alone. */
if (last_command_exit_value == 0)
set_exit_status (EXECUTION_FAILURE);
if (subshell_environment)
{
current_command = (COMMAND *)NULL;
EOF_Reached = EOF;
goto exec_done;
}
/* Obstack free command elements, etc. */
if (current_command)
{
dispose_command (current_command);
current_command = (COMMAND *)NULL;
}
restore_sigmask ();
break;
default:
command_error ("reader_loop", CMDERR_BADJUMP, code, 0);
}
}
executing = 0;
if (temporary_env)
dispose_used_env_vars ();
#if (defined (ultrix) && defined (mips)) || defined (C_ALLOCA)
/* Attempt to reclaim memory allocated with alloca (). */
(void) alloca (0);
#endif
if (read_command () == 0)
{
if (interactive_shell == 0 && read_but_dont_execute)
{
set_exit_status (last_command_exit_value);
dispose_command (global_command);
global_command = (COMMAND *)NULL;
}
else if (current_command = global_command)
{
global_command = (COMMAND *)NULL;
/* If the shell is interactive, expand and display $PS0 after reading a
command (possibly a list or pipeline) and before executing it. */
if (interactive && ps0_prompt)
{
char *ps0_string;
ps0_string = decode_prompt_string (ps0_prompt);
if (ps0_string && *ps0_string)
{
fprintf (stderr, "%s", ps0_string);
fflush (stderr);
}
free (ps0_string);
}
current_command_number++;
executing = 1;
stdin_redir = 0;
execute_command (current_command);
exec_done:
QUIT;
if (current_command)
{
dispose_command (current_command);
current_command = (COMMAND *)NULL;
}
}
}
else
{
/* Parse error, maybe discard rest of stream if not interactive. */
if (interactive == 0)
EOF_Reached = EOF;
}
if (just_one_command)
EOF_Reached = EOF;
}
indirection_level--;
return (last_command_exit_value);
}
/* Pretty print shell scripts */
int
pretty_print_loop ()
{
COMMAND *current_command;
char *command_to_print;
int code;
int global_posix_mode, last_was_newline;
global_posix_mode = posixly_correct;
last_was_newline = 0;
while (EOF_Reached == 0)
{
code = setjmp_nosigs (top_level);
if (code)
return (EXECUTION_FAILURE);
if (read_command() == 0)
{
current_command = global_command;
global_command = 0;
posixly_correct = 1; /* print posix-conformant */
if (current_command && (command_to_print = make_command_string (current_command)))
{
printf ("%s\n", command_to_print); /* for now */
last_was_newline = 0;
}
else if (last_was_newline == 0)
{
printf ("\n");
last_was_newline = 1;
}
posixly_correct = global_posix_mode;
dispose_command (current_command);
}
else
return (EXECUTION_FAILURE);
}
return (EXECUTION_SUCCESS);
}
static sighandler
alrm_catcher(i)
int i;
{
char *msg;
msg = _("\007timed out waiting for input: auto-logout\n");
write (1, msg, strlen (msg));
bash_logout (); /* run ~/.bash_logout if this is a login shell */
jump_to_top_level (EXITPROG);
SIGRETURN (0);
}
/* Send an escape sequence to emacs term mode to tell it the
current working directory. */
static void
send_pwd_to_eterm ()
{
char *pwd, *f;
f = 0;
pwd = get_string_value ("PWD");
if (pwd == 0)
f = pwd = get_working_directory ("eterm");
fprintf (stderr, "\032/%s\n", pwd);
free (f);
}
#if defined (ARRAY_VARS)
/* Caller ensures that A has a non-zero number of elements */
int
execute_array_command (a, v)
ARRAY *a;
void *v;
{
char *tag;
char **argv;
int argc, i;
tag = (char *)v;
argc = 0;
argv = array_to_argv (a, &argc);
for (i = 0; i < argc; i++)
{
if (argv[i] && argv[i][0])
execute_variable_command (argv[i], tag);
}
strvec_dispose (argv);
return 0;
}
#endif
static void
execute_prompt_command ()
{
char *command_to_execute;
SHELL_VAR *pcv;
#if defined (ARRAY_VARS)
ARRAY *pcmds;
#endif
pcv = find_variable ("PROMPT_COMMAND");
if (pcv == 0 || var_isset (pcv) == 0 || invisible_p (pcv))
return;
#if defined (ARRAY_VARS)
if (array_p (pcv))
{
if ((pcmds = array_cell (pcv)) && array_num_elements (pcmds) > 0)
execute_array_command (pcmds, "PROMPT_COMMAND");
return;
}
else if (assoc_p (pcv))
return; /* currently don't allow associative arrays here */
#endif
command_to_execute = value_cell (pcv);
if (command_to_execute && *command_to_execute)
execute_variable_command (command_to_execute, "PROMPT_COMMAND");
}
/* Call the YACC-generated parser and return the status of the parse.
Input is read from the current input stream (bash_input). yyparse
leaves the parsed command in the global variable GLOBAL_COMMAND.
This is where PROMPT_COMMAND is executed. */
int
parse_command ()
{
int r;
need_here_doc = 0;
run_pending_traps ();
/* Allow the execution of a random command just before the printing
of each primary prompt. If the shell variable PROMPT_COMMAND
is set then its value (array or string) is the command(s) to execute. */
/* The tests are a combination of SHOULD_PROMPT() and prompt_again()
from parse.y, which are the conditions under which the prompt is
actually printed. */
if (interactive && bash_input.type != st_string && parser_expanding_alias() == 0)
{
#if defined (READLINE)
if (no_line_editing || (bash_input.type == st_stdin && parser_will_prompt ()))
#endif
execute_prompt_command ();
if (running_under_emacs == 2)
send_pwd_to_eterm (); /* Yuck */
}
current_command_line_count = 0;
r = yyparse ();
if (need_here_doc)
gather_here_documents ();
return (r);
}
/* Read and parse a command, returning the status of the parse. The command
is left in the globval variable GLOBAL_COMMAND for use by reader_loop.
This is where the shell timeout code is executed. */
int
read_command ()
{
SHELL_VAR *tmout_var;
int tmout_len, result;
SigHandler *old_alrm;
set_current_prompt_level (1);
global_command = (COMMAND *)NULL;
/* Only do timeouts if interactive. */
tmout_var = (SHELL_VAR *)NULL;
tmout_len = 0;
old_alrm = (SigHandler *)NULL;
if (interactive)
{
tmout_var = find_variable ("TMOUT");
if (tmout_var && var_isset (tmout_var))
{
tmout_len = atoi (value_cell (tmout_var));
if (tmout_len > 0)
{
old_alrm = set_signal_handler (SIGALRM, alrm_catcher);
alarm (tmout_len);
}
}
}
QUIT;
current_command_line_count = 0;
result = parse_command ();
if (interactive && tmout_var && (tmout_len > 0))
{
alarm(0);
set_signal_handler (SIGALRM, old_alrm);
}
return (result);
}
// libbash - equivalent to read_command, but calls setjmp to catch errors
int read_command_safe()
{
COMMAND *last_command = global_command;
if (last_command)
dispose_command(last_command);
global_command = (COMMAND *)NULL;
int code = setjmp_nosigs(top_level);
if (code)
return (EXECUTION_FAILURE);
return read_command();
}