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