builtins/fg_bg.def

   1 This file is fg_bg.def, from which is created fg_bg.c.
   2 It implements the builtins "bg" and "fg" in Bash.
   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 $PRODUCES fg_bg.c
  22
  23 $BUILTIN fg
  24 $FUNCTION fg_builtin
  25 $DEPENDS_ON JOB_CONTROL
  26 $SHORT_DOC fg [job_spec]
  27 Move job to the foreground.
  28
  29 Place the job identified by JOB_SPEC in the foreground, making it the
  30 current job.  If JOB_SPEC is not present, the shell's notion of the
  31 current job is used.
  32
  33 Exit Status:
  34 Status of command placed in foreground, or failure if an error occurs.
  35 $END
  36
  37 #include <config.h>
  38
  39 #include "../bashtypes.h"
  40 #include <signal.h>
  41
  42 #if defined (HAVE_UNISTD_H)
  43 #  include <unistd.h>
  44 #endif
  45
  46 #include "../bashintl.h"
  47
  48 #include "../shell.h"
  49 #include "../jobs.h"
  50 #include "common.h"
  51 #include "bashgetopt.h"
  52
  53 #if defined (JOB_CONTROL)
  54 extern char *this_command_name;
  55
  56 static int fg_bg __P((WORD_LIST *, int));
  57
  58 /* How to bring a job into the foreground. */
  59 int
  60 fg_builtin (list)
  61      WORD_LIST *list;
  62 {
  63   int fg_bit;
  64   register WORD_LIST *t;
  65
  66   if (job_control == 0)
  67     {
  68       sh_nojobs ((char *)NULL);
  69       return (EXECUTION_FAILURE);
  70     }
  71
  72   if (no_options (list))
  73     return (EX_USAGE);
  74   list = loptend;
  75
  76   /* If the last arg on the line is '&', then start this job in the
  77      background.  Else, fg the job. */
  78   for (t = list; t && t->next; t = t->next)
  79     ;
  80   fg_bit = (t && t->word->word[0] == '&' && t->word->word[1] == '\0') == 0;
  81
  82   return (fg_bg (list, fg_bit));
  83 }
  84 #endif /* JOB_CONTROL */
  85
  86 $BUILTIN bg
  87 $FUNCTION bg_builtin
  88 $DEPENDS_ON JOB_CONTROL
  89 $SHORT_DOC bg [job_spec ...]
  90 Move jobs to the background.
  91
  92 Place the jobs identified by each JOB_SPEC in the background, as if they
  93 had been started with `&'.  If JOB_SPEC is not present, the shell's notion
  94 of the current job is used.
  95
  96 Exit Status:
  97 Returns success unless job control is not enabled or an error occurs.
  98 $END
  99
 100 #if defined (JOB_CONTROL)
 101 /* How to put a job into the background. */
 102 int
 103 bg_builtin (list)
 104      WORD_LIST *list;
 105 {
 106   int r;
 107
 108   if (job_control == 0)
 109     {
 110       sh_nojobs ((char *)NULL);
 111       return (EXECUTION_FAILURE);
 112     }
 113
 114   if (no_options (list))
 115     return (EX_USAGE);
 116   list = loptend;
 117
 118   /* This relies on the fact that fg_bg() takes a WORD_LIST *, but only acts
 119      on the first member (if any) of that list. */
 120   r = EXECUTION_SUCCESS;
 121   do
 122     {
 123       if (fg_bg (list, 0) == EXECUTION_FAILURE)
 124         r = EXECUTION_FAILURE;
 125       if (list)
 126         list = list->next;
 127     }
 128   while (list);
 129
 130   return r;
 131 }
 132
 133 /* How to put a job into the foreground/background. */
 134 static int
 135 fg_bg (list, foreground)
 136      WORD_LIST *list;
 137      int foreground;
 138 {
 139   sigset_t set, oset;
 140   int job, status, old_async_pid;
 141   JOB *j;
 142
 143   BLOCK_CHILD (set, oset);
 144   job = get_job_spec (list);
 145
 146   if (INVALID_JOB (job))
 147     {
 148       if (job != DUP_JOB)
 149         sh_badjob (list ? list->word->word : _("current"));
 150
 151       goto failure;
 152     }
 153
 154   j = get_job_by_jid (job);
 155   /* Or if j->pgrp == shell_pgrp. */
 156   if (IS_JOBCONTROL (job) == 0)
 157     {
 158       builtin_error (_("job %d started without job control"), job + 1);
 159       goto failure;
 160     }
 161
 162   if (foreground == 0)
 163     {
 164       old_async_pid = last_asynchronous_pid;
 165       last_asynchronous_pid = j->pgrp;  /* As per Posix.2 5.4.2 */
 166     }
 167
 168   status = start_job (job, foreground);
 169
 170   if (status >= 0)
 171     {
 172     /* win: */
 173       UNBLOCK_CHILD (oset);
 174       return (foreground ? status : EXECUTION_SUCCESS);
 175     }
 176   else
 177     {
 178       if (foreground == 0)
 179         last_asynchronous_pid = old_async_pid;
 180
 181     failure:
 182       UNBLOCK_CHILD (oset);
 183       return (EXECUTION_FAILURE);
 184     }
 185 }
 186 #endif /* JOB_CONTROL */