114 lines
2.7 KiB
C
114 lines
2.7 KiB
C
/* -*-comment-start: "//";comment-end:""-*-
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* GNU Mes --- Maxwell Equations of Software
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* Copyright © 2022 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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*
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* This file is part of GNU Mes.
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*
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* GNU Mes is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or (at
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* your option) any later version.
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*
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* GNU Mes is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <mes/lib.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#ifndef SHELL_FILE_NAME
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#define SHELL_FILE_NAME "/bin/sh"
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#endif
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#ifndef SHELL_COMMAND_NAME
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#define SHELL_COMMAND_NAME "sh"
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#endif
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FILE *
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popen (char const *command, char const *mode)
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{
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if (!command || !mode || (*mode != 'r' && *mode != 'w'))
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{
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errno = EINVAL;
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return 0;
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}
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int pipedes[2];
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if (pipe (pipedes) < 0)
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return NULL;
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pid_t pid = fork ();
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if (pid == -1)
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{
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close (pipedes[0]);
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close (pipedes[1]);
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return 0;
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}
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else if (pid == 0)
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{
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// child
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int dup = (*mode == 'w'
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? dup2 (pipedes[STDIN], STDIN)
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: dup2 (pipedes[STDOUT], STDOUT));
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if (dup < 0)
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_exit (127);
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close (pipedes[STDIN]);
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close (pipedes[STDOUT]);
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char const *argv[4];
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argv[0] = SHELL_COMMAND_NAME;
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argv[1] = "-c";
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argv[2] = command;
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argv[3] = 0;
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execve (SHELL_FILE_NAME, (char *const *) argv, environ);
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_exit (127);
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}
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FILE *stream;
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// parent
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if (*mode == 'r')
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{
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close (pipedes[STDOUT]);
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fcntl (pipedes[STDIN], F_SETFD, FD_CLOEXEC);
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stream = fdopen (pipedes[STDIN], mode);
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}
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else
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{
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close (pipedes[STDIN]);
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fcntl (pipedes[STDOUT], F_SETFD, FD_CLOEXEC);
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stream = fdopen (pipedes[STDOUT], mode);
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}
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if (!stream)
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{
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int save_errno = errno;
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kill (pid, SIGKILL);
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if (!stream)
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close (pipedes[*mode == 'r' ? STDOUT : STDIN]);
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else
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fclose (stream);
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waitpid (pid, (int *)0, 0);
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errno = save_errno;
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return 0;
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}
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int filedes = fileno (stream);
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// XXX misuse ungetc buffer for PID
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// XXX TODO: make proper FILE struct
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__ungetc_init ();
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__ungetc_set (filedes, pid);
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return stream;
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}
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