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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [posix/] [popen.c] - Rev 207
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/* $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 */