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 Bush.
   3
   4 Copyright (C) 1987-2020 Free Software Foundation, Inc.
   5
   6 This file is part of GNU Bush, the Bourne Again SHell.
   7
   8 Bush 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 Bush 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 Bush.  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 "../src/bushtypes.h"
  40 #include <signal.h>
  41
  42 #if defined (HAVE_UNISTD_H)
  43 #  include <unistd.h>
  44 #endif
  45
  46 #include "../src/bushintl.h"
  47
  48 #include "../src/shell.h"
  49 #include "../src/runner/execute_cmd.h"
  50 #include "../src/jobs.h"
  51 #include "common.h"
  52 #include "bushgetopt.h"
  53
  54 #if defined (JOB_CONTROL)
  55 static int fg_bg PARAMS((WORD_LIST *, int));
  56
  57 /* How to bring a job into the foreground. */
  58 int
  59 fg_builtin (list)
  60      WORD_LIST *list;
  61 {
  62   int fg_bit;
  63   register WORD_LIST *t;
  64
  65   CHECK_HELPOPT (list);
  66
  67   if (job_control == 0)
  68     {
  69       sh_nojobs ((char *)NULL);
  70       return (EXECUTION_FAILURE);
  71     }
  72
  73   if (no_options (list))
  74     return (EX_USAGE);
  75   list = loptend;
  76
  77   /* If the last arg on the line is '&', then start this job in the
  78      background.  Else, fg the job. */
  79   for (t = list; t && t->next; t = t->next)
  80     ;
  81   fg_bit = (t && t->word->word[0] == '&' && t->word->word[1] == '\0') == 0;
  82
  83   return (fg_bg (list, fg_bit));
  84 }
  85 #endif /* JOB_CONTROL */
  86
  87 $BUILTIN bg
  88 $FUNCTION bg_builtin
  89 $DEPENDS_ON JOB_CONTROL
  90 $SHORT_DOC bg [job_spec ...]
  91 Move jobs to the background.
  92
  93 Place the jobs identified by each JOB_SPEC in the background, as if they
  94 had been started with `&'.  If JOB_SPEC is not present, the shell's notion
  95 of the current job is used.
  96
  97 Exit Status:
  98 Returns success unless job control is not enabled or an error occurs.
  99 $END
 100
 101 #if defined (JOB_CONTROL)
 102 /* How to put a job into the background. */
 103 int
 104 bg_builtin (list)
 105      WORD_LIST *list;
 106 {
 107   int r;
 108
 109   CHECK_HELPOPT (list);
 110
 111   if (job_control == 0)
 112     {
 113       sh_nojobs ((char *)NULL);
 114       return (EXECUTION_FAILURE);
 115     }
 116
 117   if (no_options (list))
 118     return (EX_USAGE);
 119   list = loptend;
 120
 121   /* This relies on the fact that fg_bg() takes a WORD_LIST *, but only acts
 122      on the first member (if any) of that list. */
 123   r = EXECUTION_SUCCESS;
 124   do
 125     {
 126       if (fg_bg (list, 0) == EXECUTION_FAILURE)
 127         r = EXECUTION_FAILURE;
 128       if (list)
 129         list = list->next;
 130     }
 131   while (list);
 132
 133   return r;
 134 }
 135
 136 /* How to put a job into the foreground/background. */
 137 static int
 138 fg_bg (list, foreground)
 139      WORD_LIST *list;
 140      int foreground;
 141 {
 142   sigset_t set, oset;
 143   int job, status, old_async_pid;
 144   JOB *j;
 145
 146   BLOCK_CHILD (set, oset);
 147   job = get_job_spec (list);
 148
 149   if (INVALID_JOB (job))
 150     {
 151       if (job != DUP_JOB)
 152         sh_badjob (list ? list->word->word : _("current"));
 153
 154       goto failure;
 155     }
 156
 157   j = get_job_by_jid (job);
 158   /* Or if j->pgrp == shell_pgrp. */
 159   if (IS_JOBCONTROL (job) == 0)
 160     {
 161       builtin_error (_("job %d started without job control"), job + 1);
 162       goto failure;
 163     }
 164
 165   if (foreground == 0)
 166     {
 167       old_async_pid = last_asynchronous_pid;
 168       last_asynchronous_pid = j->pgrp;  /* As per Posix.2 5.4.2 */
 169     }
 170
 171   status = start_job (job, foreground);
 172
 173   if (status >= 0)
 174     {
 175     /* win: */
 176       UNBLOCK_CHILD (oset);
 177       return (foreground ? status : EXECUTION_SUCCESS);
 178     }
 179   else
 180     {
 181       if (foreground == 0)
 182         last_asynchronous_pid = old_async_pid;
 183
 184     failure:
 185       UNBLOCK_CHILD (oset);
 186       return (EXECUTION_FAILURE);
 187     }
 188 }
 189 #endif /* JOB_CONTROL */
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