flags.c

   1 /* flags.c -- Everything about flags except the `set' command.  That
   2    is in builtins.c */
   3
   4 /* Copyright (C) 1987-2021 Free Software Foundation, Inc.
   5
   6    This file is part of GNU Bash, the Bourne Again SHell.
   7
   8    Bash is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    Bash is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "config.h"
  23 #if defined (HAVE_UNISTD_H)
  24 #  include <unistd.h>
  25 #endif
  26
  27 #include "shell.h"
  28 #include "execute_cmd.h"
  29 #include "flags.h"
  30
  31 #if defined (BANG_HISTORY)
  32 #  include "bashhist.h"
  33 #endif
  34
  35 #if defined (JOB_CONTROL)
  36 extern int set_job_control PARAMS((int));
  37 #endif
  38
  39 /* **************************************************************** */
  40 /*                                                                  */
  41 /*                      The Standard sh Flags.                      */
  42 /*                                                                  */
  43 /* **************************************************************** */
  44
  45 /* Non-zero means automatically mark variables which are modified or created
  46    as auto export variables. */
  47 int mark_modified_vars = 0;
  48
  49 /* Non-zero causes asynchronous job notification.  Otherwise, job state
  50    notification only takes place just before a primary prompt is printed. */
  51 int asynchronous_notification = 0;
  52
  53 /* Non-zero means exit immediately if a command exits with a non-zero
  54    exit status.  The first is what controls set -e; the second is what
  55    bash uses internally. */
  56 int errexit_flag = 0;
  57 int exit_immediately_on_error = 0;
  58
  59 /* Non-zero means disable filename globbing. */
  60 int disallow_filename_globbing = 0;
  61
  62 /* Non-zero means that all keyword arguments are placed into the environment
  63    for a command, not just those that appear on the line before the command
  64    name. */
  65 int place_keywords_in_env = 0;
  66
  67 /* Non-zero means read commands, but don't execute them.  This is useful
  68    for debugging shell scripts that should do something hairy and possibly
  69    destructive. */
  70 int read_but_dont_execute = 0;
  71
  72 /* Non-zero means end of file is after one command. */
  73 int just_one_command = 0;
  74
  75 /* Non-zero means don't overwrite existing files while doing redirections. */
  76 int noclobber = 0;
  77
  78 /* Non-zero means trying to get the value of $i where $i is undefined
  79    causes an error, instead of a null substitution. */
  80 int unbound_vars_is_error = 0;
  81
  82 /* Non-zero means type out input lines after you read them. */
  83 int echo_input_at_read = 0;
  84 int verbose_flag = 0;
  85
  86 /* Non-zero means type out the command definition after reading, but
  87    before executing. */
  88 int echo_command_at_execute = 0;
  89
  90 /* Non-zero means turn on the job control features. */
  91 int jobs_m_flag = 0;
  92
  93 /* Non-zero means this shell is interactive, even if running under a
  94    pipe. */
  95 int forced_interactive = 0;
  96
  97 /* By default, follow the symbolic links as if they were real directories
  98    while hacking the `cd' command.  This means that `cd ..' moves up in
  99    the string of symbolic links that make up the current directory, instead
 100    of the absolute directory.  The shell variable `nolinks' also controls
 101    this flag. */
 102 int no_symbolic_links = 0;
 103
 104 /* **************************************************************** */
 105 /*                                                                  */
 106 /*                   Non-Standard Flags Follow Here.                */
 107 /*                                                                  */
 108 /* **************************************************************** */
 109
 110 #if 0
 111 /* Non-zero means do lexical scoping in the body of a FOR command. */
 112 int lexical_scoping = 0;
 113 #endif
 114
 115 /* Non-zero means look up and remember command names in a hash table, */
 116 int hashing_enabled = 1;
 117
 118 #if defined (BANG_HISTORY)
 119 /* Non-zero means that we are doing history expansion.  The default.
 120    This means !22 gets the 22nd line of history. */
 121 int history_expansion = HISTEXPAND_DEFAULT;
 122 int histexp_flag = 0;
 123 #endif /* BANG_HISTORY */
 124
 125 /* Non-zero means that we allow comments to appear in interactive commands. */
 126 int interactive_comments = 1;
 127
 128 #if defined (RESTRICTED_SHELL)
 129 /* Non-zero means that this shell is `restricted'.  A restricted shell
 130    disallows: changing directories, command or path names containing `/',
 131    unsetting or resetting the values of $PATH and $SHELL, and any type of
 132    output redirection. */
 133 int restricted = 0;             /* currently restricted */
 134 int restricted_shell = 0;       /* shell was started in restricted mode. */
 135 #endif /* RESTRICTED_SHELL */
 136
 137 /* Non-zero means that this shell is running in `privileged' mode.  This
 138    is required if the shell is to run setuid.  If the `-p' option is
 139    not supplied at startup, and the real and effective uids or gids
 140    differ, disable_priv_mode is called to relinquish setuid status. */
 141 int privileged_mode = 0;
 142
 143 #if defined (BRACE_EXPANSION)
 144 /* Zero means to disable brace expansion: foo{a,b} -> fooa foob */
 145 int brace_expansion = 1;
 146 #endif
 147
 148 /* Non-zero means that shell functions inherit the DEBUG trap. */
 149 int function_trace_mode = 0;
 150
 151 /* Non-zero means that shell functions inherit the ERR trap. */
 152 int error_trace_mode = 0;
 153
 154 /* Non-zero means that the rightmost non-zero exit status in a pipeline
 155    is the exit status of the entire pipeline.  If each processes exits
 156    with a 0 status, the status of the pipeline is 0. */
 157 int pipefail_opt = 0;
 158
 159 /* **************************************************************** */
 160 /*                                                                  */
 161 /*                      The Flags ALIST.                            */
 162 /*                                                                  */
 163 /* **************************************************************** */
 164
 165 const struct flags_alist shell_flags[] = {
 166   /* Standard sh flags. */
 167   { 'a', &mark_modified_vars },
 168 #if defined (JOB_CONTROL)
 169   { 'b', &asynchronous_notification },
 170 #endif /* JOB_CONTROL */
 171   { 'e', &errexit_flag },
 172   { 'f', &disallow_filename_globbing },
 173   { 'h', &hashing_enabled },
 174   { 'i', &forced_interactive },
 175   { 'k', &place_keywords_in_env },
 176 #if defined (JOB_CONTROL)
 177   { 'm', &jobs_m_flag },
 178 #endif /* JOB_CONTROL */
 179   { 'n', &read_but_dont_execute },
 180   { 'p', &privileged_mode },
 181 #if defined (RESTRICTED_SHELL)
 182   { 'r', &restricted },
 183 #endif /* RESTRICTED_SHELL */
 184   { 't', &just_one_command },
 185   { 'u', &unbound_vars_is_error },
 186   { 'v', &verbose_flag },
 187   { 'x', &echo_command_at_execute },
 188
 189   /* New flags that control non-standard things. */
 190 #if 0
 191   { 'l', &lexical_scoping },
 192 #endif
 193 #if defined (BRACE_EXPANSION)
 194   { 'B', &brace_expansion },
 195 #endif
 196   { 'C', &noclobber },
 197   { 'E', &error_trace_mode },
 198 #if defined (BANG_HISTORY)
 199   { 'H', &histexp_flag },
 200 #endif /* BANG_HISTORY */
 201   { 'P', &no_symbolic_links },
 202   { 'T', &function_trace_mode },
 203   {0, (int *)NULL}
 204 };
 205
 206 #define NUM_SHELL_FLAGS (sizeof (shell_flags) / sizeof (struct flags_alist))
 207
 208 char optflags[NUM_SHELL_FLAGS+4] = { '+' };
 209
 210 int *
 211 find_flag (name)
 212      int name;
 213 {
 214   int i;
 215   for (i = 0; shell_flags[i].name; i++)
 216     {
 217       if (shell_flags[i].name == name)
 218         return (shell_flags[i].value);
 219     }
 220   return (FLAG_UNKNOWN);
 221 }
 222
 223 /* Change the state of a flag, and return it's original value, or return
 224    FLAG_ERROR if there is no flag FLAG.  ON_OR_OFF must be either
 225    FLAG_ON or FLAG_OFF. */
 226 int
 227 change_flag (flag, on_or_off)
 228   int flag;
 229   int on_or_off;
 230 {
 231   int *value, old_value;
 232
 233 #if defined (RESTRICTED_SHELL)
 234   /* Don't allow "set +r" in a shell which is `restricted'. */
 235   if (restricted && flag == 'r' && on_or_off == FLAG_OFF)
 236     return (FLAG_ERROR);
 237 #endif /* RESTRICTED_SHELL */
 238
 239   value = find_flag (flag);
 240
 241   if ((value == (int *)FLAG_UNKNOWN) || (on_or_off != FLAG_ON && on_or_off != FLAG_OFF))
 242     return (FLAG_ERROR);
 243
 244   old_value = *value;
 245   *value = (on_or_off == FLAG_ON) ? 1 : 0;
 246
 247   /* Special cases for a few flags. */
 248   switch (flag)
 249     {
 250 #if defined (BANG_HISTORY)
 251     case 'H':
 252       history_expansion = histexp_flag;
 253       if (on_or_off == FLAG_ON)
 254         bash_initialize_history ();
 255       break;
 256 #endif
 257
 258 #if defined (JOB_CONTROL)
 259     case 'm':
 260       set_job_control (on_or_off == FLAG_ON);
 261       break;
 262 #endif /* JOB_CONTROL */
 263
 264     case 'e':
 265       if (builtin_ignoring_errexit == 0)
 266         exit_immediately_on_error = errexit_flag;
 267       break;
 268
 269     case 'n':
 270       if (interactive_shell)
 271         read_but_dont_execute = 0;
 272       break;
 273
 274     case 'p':
 275       if (on_or_off == FLAG_OFF)
 276         disable_priv_mode ();
 277       break;
 278
 279 #if defined (RESTRICTED_SHELL)
 280     case 'r':
 281       if (on_or_off == FLAG_ON && shell_initialized)
 282         maybe_make_restricted (shell_name);
 283       break;
 284 #endif
 285
 286     case 'v':
 287       echo_input_at_read = verbose_flag;
 288       break;
 289     }
 290
 291   return (old_value);
 292 }
 293
 294 /* Return a string which is the names of all the currently
 295    set shell flags. */
 296 char *
 297 which_set_flags ()
 298 {
 299   char *temp;
 300   int i, string_index;
 301
 302   temp = (char *)xmalloc (1 + NUM_SHELL_FLAGS + read_from_stdin + want_pending_command);
 303   for (i = string_index = 0; shell_flags[i].name; i++)
 304     if (*(shell_flags[i].value))
 305       temp[string_index++] = shell_flags[i].name;
 306
 307   if (want_pending_command)
 308     temp[string_index++] = 'c';
 309   if (read_from_stdin)
 310     temp[string_index++] = 's';
 311
 312   temp[string_index] = '\0';
 313   return (temp);
 314 }
 315
 316 char *
 317 get_current_flags ()
 318 {
 319   char *temp;
 320   int i;
 321
 322   temp = (char *)xmalloc (1 + NUM_SHELL_FLAGS);
 323   for (i = 0; shell_flags[i].name; i++)
 324     temp[i] = *(shell_flags[i].value);
 325   temp[i] = '\0';
 326   return (temp);
 327 }
 328
 329 void
 330 set_current_flags (bitmap)
 331      const char *bitmap;
 332 {
 333   int i;
 334
 335   if (bitmap == 0)
 336     return;
 337   for (i = 0; shell_flags[i].name; i++)
 338     *(shell_flags[i].value) = bitmap[i];
 339 }
 340
 341 void
 342 reset_shell_flags ()
 343 {
 344   mark_modified_vars = disallow_filename_globbing = 0;
 345   place_keywords_in_env = read_but_dont_execute = just_one_command = 0;
 346   noclobber = unbound_vars_is_error = 0;
 347   echo_command_at_execute = jobs_m_flag = forced_interactive = 0;
 348   no_symbolic_links = 0;
 349   privileged_mode = pipefail_opt = 0;
 350
 351   error_trace_mode = function_trace_mode = 0;
 352
 353   exit_immediately_on_error = errexit_flag = 0;
 354   echo_input_at_read = verbose_flag = 0;
 355
 356   hashing_enabled = interactive_comments = 1;
 357
 358 #if defined (JOB_CONTROL)
 359   asynchronous_notification = 0;
 360 #endif
 361
 362 #if defined (BANG_HISTORY)
 363   histexp_flag = 0;
 364 #endif
 365
 366 #if defined (BRACE_EXPANSION)
 367   brace_expansion = 1;
 368 #endif
 369
 370 #if defined (RESTRICTED_SHELL)
 371   restricted = 0;
 372 #endif
 373 }
 374
 375 void
 376 initialize_flags ()
 377 {
 378   register int i;
 379
 380   for (i = 0; shell_flags[i].name; i++)
 381     optflags[i+1] = shell_flags[i].name;
 382   optflags[++i] = 'o';
 383   optflags[++i] = ';';
 384   optflags[i+1] = '\0';
 385 }