flags.c

   1 /* flags.c -- Everything about flags except the `set' command.  That
   2    is in builtins.c */
   3
   4 /* Copyright (C) 1987-2009 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 "flags.h"
  29
  30 #if defined (BANG_HISTORY)
  31 #  include "bashhist.h"
  32 #endif
  33
  34 #if defined (JOB_CONTROL)
  35 extern int set_job_control __P((int));
  36 #endif
  37
  38 #if defined (RESTRICTED_SHELL)
  39 extern char *shell_name;
  40 #endif
  41
  42 extern int shell_initialized;
  43 extern int builtin_ignoring_errexit;
  44
  45 /* -c, -s invocation options -- not really flags, but they show up in $- */
  46 extern int want_pending_command, read_from_stdin;
  47
  48 /* **************************************************************** */
  49 /*                                                                  */
  50 /*                      The Standard sh Flags.                      */
  51 /*                                                                  */
  52 /* **************************************************************** */
  53
  54 /* Non-zero means automatically mark variables which are modified or created
  55    as auto export variables. */
  56 int mark_modified_vars = 0;
  57
  58 /* Non-zero causes asynchronous job notification.  Otherwise, job state
  59    notification only takes place just before a primary prompt is printed. */
  60 int asynchronous_notification = 0;
  61
  62 /* Non-zero means exit immediately if a command exits with a non-zero
  63    exit status.  The first is what controls set -e; the second is what
  64    bash uses internally. */
  65 int errexit_flag = 0;
  66 int exit_immediately_on_error = 0;
  67
  68 /* Non-zero means disable filename globbing. */
  69 int disallow_filename_globbing = 0;
  70
  71 /* Non-zero means that all keyword arguments are placed into the environment
  72    for a command, not just those that appear on the line before the command
  73    name. */
  74 int place_keywords_in_env = 0;
  75
  76 /* Non-zero means read commands, but don't execute them.  This is useful
  77    for debugging shell scripts that should do something hairy and possibly
  78    destructive. */
  79 int read_but_dont_execute = 0;
  80
  81 /* Non-zero means end of file is after one command. */
  82 int just_one_command = 0;
  83
  84 /* Non-zero means don't overwrite existing files while doing redirections. */
  85 int noclobber = 0;
  86
  87 /* Non-zero means trying to get the value of $i where $i is undefined
  88    causes an error, instead of a null substitution. */
  89 int unbound_vars_is_error = 0;
  90
  91 /* Non-zero means type out input lines after you read them. */
  92 int echo_input_at_read = 0;
  93
  94 /* Non-zero means type out the command definition after reading, but
  95    before executing. */
  96 int echo_command_at_execute = 0;
  97
  98 /* Non-zero means turn on the job control features. */
  99 int jobs_m_flag = 0;
 100
 101 /* Non-zero means this shell is interactive, even if running under a
 102    pipe. */
 103 int forced_interactive = 0;
 104
 105 /* By default, follow the symbolic links as if they were real directories
 106    while hacking the `cd' command.  This means that `cd ..' moves up in
 107    the string of symbolic links that make up the current directory, instead
 108    of the absolute directory.  The shell variable `nolinks' also controls
 109    this flag. */
 110 int no_symbolic_links = 0;
 111
 112 /* **************************************************************** */
 113 /*                                                                  */
 114 /*                   Non-Standard Flags Follow Here.                */
 115 /*                                                                  */
 116 /* **************************************************************** */
 117
 118 #if 0
 119 /* Non-zero means do lexical scoping in the body of a FOR command. */
 120 int lexical_scoping = 0;
 121 #endif
 122
 123 /* Non-zero means no such thing as invisible variables. */
 124 int no_invisible_vars = 0;
 125
 126 /* Non-zero means look up and remember command names in a hash table, */
 127 int hashing_enabled = 1;
 128
 129 #if defined (BANG_HISTORY)
 130 /* Non-zero means that we are doing history expansion.  The default.
 131    This means !22 gets the 22nd line of history. */
 132 #  if defined (STRICT_POSIX)
 133 int history_expansion = 0;
 134 #  else
 135 int history_expansion = 1;
 136 #  endif
 137 #endif /* BANG_HISTORY */
 138
 139 /* Non-zero means that we allow comments to appear in interactive commands. */
 140 int interactive_comments = 1;
 141
 142 #if defined (RESTRICTED_SHELL)
 143 /* Non-zero means that this shell is `restricted'.  A restricted shell
 144    disallows: changing directories, command or path names containing `/',
 145    unsetting or resetting the values of $PATH and $SHELL, and any type of
 146    output redirection. */
 147 int restricted = 0;             /* currently restricted */
 148 int restricted_shell = 0;       /* shell was started in restricted mode. */
 149 #endif /* RESTRICTED_SHELL */
 150
 151 /* Non-zero means that this shell is running in `privileged' mode.  This
 152    is required if the shell is to run setuid.  If the `-p' option is
 153    not supplied at startup, and the real and effective uids or gids
 154    differ, disable_priv_mode is called to relinquish setuid status. */
 155 int privileged_mode = 0;
 156
 157 #if defined (BRACE_EXPANSION)
 158 /* Zero means to disable brace expansion: foo{a,b} -> fooa foob */
 159 int brace_expansion = 1;
 160 #endif
 161
 162 /* Non-zero means that shell functions inherit the DEBUG trap. */
 163 int function_trace_mode = 0;
 164
 165 /* Non-zero means that shell functions inherit the ERR trap. */
 166 int error_trace_mode = 0;
 167
 168 /* Non-zero means that the rightmost non-zero exit status in a pipeline
 169    is the exit status of the entire pipeline.  If each processes exits
 170    with a 0 status, the status of the pipeline is 0. */
 171 int pipefail_opt = 0;
 172
 173 /* **************************************************************** */
 174 /*                                                                  */
 175 /*                      The Flags ALIST.                            */
 176 /*                                                                  */
 177 /* **************************************************************** */
 178
 179 const struct flags_alist shell_flags[] = {
 180   /* Standard sh flags. */
 181   { 'a', &mark_modified_vars },
 182 #if defined (JOB_CONTROL)
 183   { 'b', &asynchronous_notification },
 184 #endif /* JOB_CONTROL */
 185   { 'e', &errexit_flag },
 186   { 'f', &disallow_filename_globbing },
 187   { 'h', &hashing_enabled },
 188   { 'i', &forced_interactive },
 189   { 'k', &place_keywords_in_env },
 190 #if defined (JOB_CONTROL)
 191   { 'm', &jobs_m_flag },
 192 #endif /* JOB_CONTROL */
 193   { 'n', &read_but_dont_execute },
 194   { 'p', &privileged_mode },
 195 #if defined (RESTRICTED_SHELL)
 196   { 'r', &restricted },
 197 #endif /* RESTRICTED_SHELL */
 198   { 't', &just_one_command },
 199   { 'u', &unbound_vars_is_error },
 200   { 'v', &echo_input_at_read },
 201   { 'x', &echo_command_at_execute },
 202
 203   /* New flags that control non-standard things. */
 204 #if 0
 205   { 'l', &lexical_scoping },
 206 #endif
 207 #if defined (BRACE_EXPANSION)
 208   { 'B', &brace_expansion },
 209 #endif
 210   { 'C', &noclobber },
 211   { 'E', &error_trace_mode },
 212 #if defined (BANG_HISTORY)
 213   { 'H', &history_expansion },
 214 #endif /* BANG_HISTORY */
 215   { 'I', &no_invisible_vars },
 216   { 'P', &no_symbolic_links },
 217   { 'T', &function_trace_mode },
 218   {0, (int *)NULL}
 219 };
 220
 221 #define NUM_SHELL_FLAGS (sizeof (shell_flags) / sizeof (struct flags_alist))
 222
 223 char optflags[NUM_SHELL_FLAGS+4] = { '+' };
 224
 225 int *
 226 find_flag (name)
 227      int name;
 228 {
 229   int i;
 230   for (i = 0; shell_flags[i].name; i++)
 231     {
 232       if (shell_flags[i].name == name)
 233         return (shell_flags[i].value);
 234     }
 235   return (FLAG_UNKNOWN);
 236 }
 237
 238 /* Change the state of a flag, and return it's original value, or return
 239    FLAG_ERROR if there is no flag FLAG.  ON_OR_OFF must be either
 240    FLAG_ON or FLAG_OFF. */
 241 int
 242 change_flag (flag, on_or_off)
 243   int flag;
 244   int on_or_off;
 245 {
 246   int *value, old_value;
 247
 248 #if defined (RESTRICTED_SHELL)
 249   /* Don't allow "set +r" in a shell which is `restricted'. */
 250   if (restricted && flag == 'r' && on_or_off == FLAG_OFF)
 251     return (FLAG_ERROR);
 252 #endif /* RESTRICTED_SHELL */
 253
 254   value = find_flag (flag);
 255
 256   if ((value == (int *)FLAG_UNKNOWN) || (on_or_off != FLAG_ON && on_or_off != FLAG_OFF))
 257     return (FLAG_ERROR);
 258
 259   old_value = *value;
 260   *value = (on_or_off == FLAG_ON) ? 1 : 0;
 261
 262   /* Special cases for a few flags. */
 263   switch (flag)
 264     {
 265 #if defined (BANG_HISTORY)
 266     case 'H':
 267       if (on_or_off == FLAG_ON)
 268         bash_initialize_history ();
 269       break;
 270 #endif
 271
 272 #if defined (JOB_CONTROL)
 273     case 'm':
 274       set_job_control (on_or_off == FLAG_ON);
 275       break;
 276 #endif /* JOB_CONTROL */
 277
 278     case 'e':
 279       if (builtin_ignoring_errexit == 0)
 280         exit_immediately_on_error = errexit_flag;
 281       break;
 282
 283     case 'n':
 284       if (interactive_shell)
 285         read_but_dont_execute = 0;
 286       break;
 287
 288     case 'p':
 289       if (on_or_off == FLAG_OFF)
 290         disable_priv_mode ();
 291       break;
 292
 293 #if defined (RESTRICTED_SHELL)
 294     case 'r':
 295       if (on_or_off == FLAG_ON && shell_initialized)
 296         maybe_make_restricted (shell_name);
 297       break;
 298 #endif
 299
 300     }
 301
 302   return (old_value);
 303 }
 304
 305 /* Return a string which is the names of all the currently
 306    set shell flags. */
 307 char *
 308 which_set_flags ()
 309 {
 310   char *temp;
 311   int i, string_index;
 312
 313   temp = (char *)xmalloc (1 + NUM_SHELL_FLAGS + read_from_stdin + want_pending_command);
 314   for (i = string_index = 0; shell_flags[i].name; i++)
 315     if (*(shell_flags[i].value))
 316       temp[string_index++] = shell_flags[i].name;
 317
 318   if (want_pending_command)
 319     temp[string_index++] = 'c';
 320   if (read_from_stdin)
 321     temp[string_index++] = 's';
 322
 323   temp[string_index] = '\0';
 324   return (temp);
 325 }
 326
 327 void
 328 reset_shell_flags ()
 329 {
 330   mark_modified_vars = exit_immediately_on_error = disallow_filename_globbing = 0;
 331   place_keywords_in_env = read_but_dont_execute = just_one_command = 0;
 332   noclobber = unbound_vars_is_error = echo_input_at_read = 0;
 333   echo_command_at_execute = jobs_m_flag = forced_interactive = 0;
 334   no_symbolic_links = no_invisible_vars = privileged_mode = pipefail_opt = 0;
 335
 336   hashing_enabled = interactive_comments = 1;
 337
 338 #if defined (JOB_CONTROL)
 339   asynchronous_notification = 0;
 340 #endif
 341
 342 #if defined (BANG_HISTORY)
 343   history_expansion = 1;
 344 #endif
 345
 346 #if defined (BRACE_EXPANSION)
 347   brace_expansion = 1;
 348 #endif
 349
 350 #if defined (RESTRICTED_SHELL)
 351   restricted = 0;
 352 #endif
 353 }
 354
 355 void
 356 initialize_flags ()
 357 {
 358   register int i;
 359
 360   for (i = 0; shell_flags[i].name; i++)
 361     optflags[i+1] = shell_flags[i].name;
 362   optflags[++i] = 'o';
 363   optflags[++i] = ';';
 364   optflags[i+1] = '\0';
 365 }