| /* $NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $ */ |
| |
| /* |
| * Copyright (c) 1988, 1993, 2006 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * This code is derived from software written by Ken Arnold and |
| * published in UNIX Review, Vol. 6, No. 8. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 4. Neither the name of the University nor the names of its contributors |
| * may be used to endorse or promote products derived from this software |
| * without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| /* |
| FUNCTION |
| <<popen>>, <<pclose>>---tie a stream to a command string |
| |
| INDEX |
| popen |
| INDEX |
| pclose |
| |
| ANSI_SYNOPSIS |
| #include <stdio.h> |
| FILE *popen(const char *<[s]>, const char *<[mode]>); |
| |
| int pclose(FILE *<[f]>); |
| |
| DESCRIPTION |
| Use <<popen>> to create a stream to a child process executing a |
| command string <<*<[s]>>> as processed by <</bin/sh>> on your system. |
| The argument <[mode]> must start with either `<<r>>', where the stream |
| reads from the child's <<stdout>>, or `<<w>>', where the stream writes |
| to the child's <<stdin>>. As an extension, <[mode]> may also contain |
| `<<e>>' to set the close-on-exec bit of the parent's file descriptor. |
| The stream created by <<popen>> must be closed by <<pclose>> to avoid |
| resource leaks. |
| |
| Streams created by prior calls to <<popen>> are not visible in |
| subsequent <<popen>> children, regardless of the close-on-exec bit. |
| |
| Use ``<<system(NULL)>>'' to test whether your system has <</bin/sh>> |
| available. |
| |
| RETURNS |
| <<popen>> returns a file stream opened with the specified <[mode]>, |
| or <<NULL>> if a child process could not be created. <<pclose>> |
| returns -1 if the stream was not created by <<popen>> or if the |
| application used <<wait>> or similar to steal the status; otherwise |
| it returns the exit status of the child which can be interpreted |
| in the same manner as a status obtained by <<waitpid>>. |
| |
| PORTABILITY |
| POSIX.2 requires <<popen>> and <<pclose>>, but only specifies a mode |
| of just <<r>> or <<w>>. Where <<sh>> is found is left unspecified. |
| |
| Supporting OS subroutines required: <<_exit>>, <<_execve>>, <<_fork_r>>, |
| <<_wait_r>>, <<pipe>>, <<fcntl>>, <<sbrk>>. |
| */ |
| |
| #ifndef _NO_POPEN |
| |
| #if defined(LIBC_SCCS) && !defined(lint) |
| #if 0 |
| static char sccsid[] = "@(#)popen.c 8.1 (Berkeley) 6/4/93"; |
| #else |
| static char rcsid[] = "$NetBSD: popen.c,v 1.11 1995/06/16 07:05:33 jtc Exp $"; |
| #endif |
| #endif /* LIBC_SCCS and not lint */ |
| |
| #include <sys/param.h> |
| #include <sys/types.h> |
| #include <sys/wait.h> |
| |
| #include <signal.h> |
| #include <errno.h> |
| #include <unistd.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <paths.h> |
| #include <fcntl.h> |
| |
| static struct pid { |
| struct pid *next; |
| FILE *fp; |
| pid_t pid; |
| } *pidlist; |
| |
| FILE * |
| _DEFUN(popen, (program, type), |
| const char *program _AND |
| const char *type) |
| { |
| struct pid *cur, *last; |
| FILE *iop; |
| int pdes[2], pid; |
| |
| if ((*type != 'r' && *type != 'w') |
| || (type[1] |
| #ifdef HAVE_FCNTL |
| && (type[2] || (type[1] != 'e')) |
| #endif |
| )) { |
| errno = EINVAL; |
| return (NULL); |
| } |
| |
| if ((cur = malloc(sizeof(struct pid))) == NULL) |
| return (NULL); |
| |
| if (pipe(pdes) < 0) { |
| free(cur); |
| return (NULL); |
| } |
| |
| switch (pid = vfork()) { |
| case -1: /* Error. */ |
| (void)close(pdes[0]); |
| (void)close(pdes[1]); |
| free(cur); |
| return (NULL); |
| /* NOTREACHED */ |
| case 0: /* Child. */ |
| if (*type == 'r') { |
| if (pdes[1] != STDOUT_FILENO) { |
| (void)dup2(pdes[1], STDOUT_FILENO); |
| (void)close(pdes[1]); |
| } |
| if (pdes[0] != STDOUT_FILENO) { |
| (void) close(pdes[0]); |
| } |
| } else { |
| if (pdes[0] != STDIN_FILENO) { |
| (void)dup2(pdes[0], STDIN_FILENO); |
| (void)close(pdes[0]); |
| } |
| (void)close(pdes[1]); |
| } |
| /* Close all fd's created by prior popen. */ |
| for (last = NULL, cur = pidlist; cur; |
| last = cur, cur = cur->next) |
| (void)close (fileno (cur->fp)); |
| execl(_PATH_BSHELL, "sh", "-c", program, NULL); |
| _exit(127); |
| /* NOTREACHED */ |
| } |
| |
| /* Parent; assume fdopen can't fail. */ |
| if (*type == 'r') { |
| iop = fdopen(pdes[0], type); |
| (void)close(pdes[1]); |
| } else { |
| iop = fdopen(pdes[1], type); |
| (void)close(pdes[0]); |
| } |
| |
| #ifdef HAVE_FCNTL |
| /* Mark pipe cloexec if requested. */ |
| if (type[1] == 'e') |
| fcntl (fileno (iop), F_SETFD, |
| fcntl (fileno (iop), F_GETFD, 0) | FD_CLOEXEC); |
| #endif /* HAVE_FCNTL */ |
| |
| /* Link into list of file descriptors. */ |
| cur->fp = iop; |
| cur->pid = pid; |
| cur->next = pidlist; |
| pidlist = cur; |
| |
| return (iop); |
| } |
| |
| /* |
| * pclose -- |
| * Pclose returns -1 if stream is not associated with a `popened' command, |
| * if already `pclosed', or waitpid returns an error. |
| */ |
| int |
| _DEFUN(pclose, (iop), |
| FILE *iop) |
| { |
| register struct pid *cur, *last; |
| int pstat; |
| pid_t pid; |
| |
| (void)fclose(iop); |
| |
| /* Find the appropriate file pointer. */ |
| for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) |
| if (cur->fp == iop) |
| break; |
| if (cur == NULL) |
| return (-1); |
| |
| do { |
| pid = waitpid(cur->pid, &pstat, 0); |
| } while (pid == -1 && errno == EINTR); |
| |
| /* Remove the entry from the linked list. */ |
| if (last == NULL) |
| pidlist = cur->next; |
| else |
| last->next = cur->next; |
| free(cur); |
| |
| return (pid == -1 ? -1 : pstat); |
| } |
| |
| #endif /* !_NO_POPEN */ |