1 files changed, 189 insertions, 0 deletions
diff --git a/builtins/fg_bg.def b/builtins/fg_bg.def
new file mode 100644
index 0000000..0fb5322
--- /dev/null
+++ b/builtins/fg_bg.def
@@ -0,0 +1,189 @@
+This file is fg_bg.def, from which is created fg_bg.c.
+It implements the builtins "bg" and "fg" in Bash.
+
+Copyright (C) 1987-2020 Free Software Foundation, Inc.
+
+This file is part of GNU Bash, the Bourne Again SHell.
+
+Bash is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Bash is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Bash.  If not, see <http://www.gnu.org/licenses/>.
+
+$PRODUCES fg_bg.c
+
+$BUILTIN fg
+$FUNCTION fg_builtin
+$DEPENDS_ON JOB_CONTROL
+$SHORT_DOC fg [job_spec]
+Move job to the foreground.
+
+Place the job identified by JOB_SPEC in the foreground, making it the
+current job.  If JOB_SPEC is not present, the shell's notion of the
+current job is used.
+
+Exit Status:
+Status of command placed in foreground, or failure if an error occurs.
+$END
+
+#include <config.h>
+
+#include "../bashtypes.h"
+#include <signal.h>
+
+#if defined (HAVE_UNISTD_H)
+#  include <unistd.h>
+#endif
+
+#include "../bashintl.h"
+
+#include "../shell.h"
+#include "../execute_cmd.h"
+#include "../jobs.h"
+#include "common.h"
+#include "bashgetopt.h"
+
+#if defined (JOB_CONTROL)
+static int fg_bg PARAMS((WORD_LIST *, int));
+
+/* How to bring a job into the foreground. */
+int
+fg_builtin (list)
+     WORD_LIST *list;
+{
+  int fg_bit;
+  register WORD_LIST *t;
+
+  CHECK_HELPOPT (list);
+
+  if (job_control == 0)
+    {
+      sh_nojobs ((char *)NULL);
+      return (EXECUTION_FAILURE);
+    }
+
+  if (no_options (list))
+    return (EX_USAGE);
+  list = loptend;
+
+  /* If the last arg on the line is '&', then start this job in the
+     background.  Else, fg the job. */
+  for (t = list; t && t->next; t = t->next)
+    ;
+  fg_bit = (t && t->word->word[0] == '&' && t->word->word[1] == '\0') == 0;
+
+  return (fg_bg (list, fg_bit));
+}
+#endif /* JOB_CONTROL */
+
+$BUILTIN bg
+$FUNCTION bg_builtin
+$DEPENDS_ON JOB_CONTROL
+$SHORT_DOC bg [job_spec ...]
+Move jobs to the background.
+
+Place the jobs identified by each JOB_SPEC in the background, as if they
+had been started with `&'.  If JOB_SPEC is not present, the shell's notion
+of the current job is used.
+
+Exit Status:
+Returns success unless job control is not enabled or an error occurs.
+$END
+
+#if defined (JOB_CONTROL)
+/* How to put a job into the background. */
+int
+bg_builtin (list)
+     WORD_LIST *list;
+{
+  int r;
+
+  CHECK_HELPOPT (list);
+
+  if (job_control == 0)
+    {
+      sh_nojobs ((char *)NULL);
+      return (EXECUTION_FAILURE);
+    }
+
+  if (no_options (list))
+    return (EX_USAGE);
+  list = loptend;
+
+  /* This relies on the fact that fg_bg() takes a WORD_LIST *, but only acts
+     on the first member (if any) of that list. */
+  r = EXECUTION_SUCCESS;
+  do
+    {
+      if (fg_bg (list, 0) == EXECUTION_FAILURE)
+	r = EXECUTION_FAILURE;
+      if (list)
+	list = list->next;
+    }
+  while (list);
+
+  return r;
+}
+
+/* How to put a job into the foreground/background. */
+static int
+fg_bg (list, foreground)
+     WORD_LIST *list;
+     int foreground;
+{
+  sigset_t set, oset;
+  int job, status, old_async_pid;
+  JOB *j;
+
+  BLOCK_CHILD (set, oset);
+  job = get_job_spec (list);
+
+  if (INVALID_JOB (job))
+    {
+      if (job != DUP_JOB)
+	sh_badjob (list ? list->word->word : _("current"));
+
+      goto failure;
+    }
+
+  j = get_job_by_jid (job);
+  /* Or if j->pgrp == shell_pgrp. */
+  if (IS_JOBCONTROL (job) == 0)
+    {
+      builtin_error (_("job %d started without job control"), job + 1);
+      goto failure;
+    }
+
+  if (foreground == 0)
+    {
+      old_async_pid = last_asynchronous_pid;
+      last_asynchronous_pid = j->pgrp;	/* As per Posix.2 5.4.2 */
+    }
+
+  status = start_job (job, foreground);
+
+  if (status >= 0)
+    {
+    /* win: */
+      UNBLOCK_CHILD (oset);
+      return (foreground ? status : EXECUTION_SUCCESS);
+    }
+  else
+    {
+      if (foreground == 0)
+	last_asynchronous_pid = old_async_pid;
+
+    failure:
+      UNBLOCK_CHILD (oset);
+      return (EXECUTION_FAILURE);
+    }
+}
+#endif /* JOB_CONTROL */