/* $NetBSD: popen.c,v 1.38 2022/04/19 20:32:15 rillig Exp $ */ /* * Copyright (c) 1988, 1993 * 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. * 3. 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. */ #include #if defined(LIBC_SCCS) && !defined(lint) #if 0 static char sccsid[] = "@(#)popen.c 8.3 (Berkeley) 5/3/95"; #else __RCSID("$NetBSD: popen.c,v 1.38 2022/04/19 20:32:15 rillig Exp $"); #endif #endif /* LIBC_SCCS and not lint */ #include "namespace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include "env.h" #ifdef __weak_alias __weak_alias(popen,_popen) __weak_alias(pclose,_pclose) #endif static struct pid { struct pid *next; FILE *fp; #ifdef _REENTRANT int fd; #endif pid_t pid; } *pidlist; #ifdef _REENTRANT static mutex_t pidlist_mutex = MUTEX_INITIALIZER; # define MUTEX_LOCK() \ do { \ if (__isthreaded) \ mutex_lock(&pidlist_mutex); \ } while (0) # define MUTEX_UNLOCK() \ do { \ if (__isthreaded) \ mutex_unlock(&pidlist_mutex); \ } while (0) #else # define MUTEX_LOCK() __nothing # define MUTEX_UNLOCK() __nothing #endif static struct pid * pdes_get(int *pdes, const char **type) { struct pid *cur; int flags = strchr(*type, 'e') ? O_CLOEXEC : 0; int serrno; if (strchr(*type, '+')) { int stype = flags ? (SOCK_STREAM | SOCK_CLOEXEC) : SOCK_STREAM; *type = "r+"; if (socketpair(AF_LOCAL, stype, 0, pdes) < 0) return NULL; } else { *type = strrchr(*type, 'r') ? "r" : "w"; if (pipe2(pdes, flags) == -1) return NULL; } if ((cur = malloc(sizeof(*cur))) != NULL) return cur; serrno = errno; (void)close(pdes[0]); (void)close(pdes[1]); errno = serrno; return NULL; } static void pdes_child(int *pdes, const char *type) { struct pid *old; /* POSIX.2 B.3.2.2 "popen() shall ensure that any streams from previous popen() calls that remain open in the parent process are closed in the new child process. */ for (old = pidlist; old; old = old->next) #ifdef _REENTRANT (void)close(old->fd); /* don't allow a flush */ #else (void)close(fileno(old->fp)); /* don't allow a flush */ #endif if (type[0] == 'r') { (void)close(pdes[0]); if (pdes[1] != STDOUT_FILENO) { (void)dup2(pdes[1], STDOUT_FILENO); (void)close(pdes[1]); } if (type[1] == '+') (void)dup2(STDOUT_FILENO, STDIN_FILENO); } else { (void)close(pdes[1]); if (pdes[0] != STDIN_FILENO) { (void)dup2(pdes[0], STDIN_FILENO); (void)close(pdes[0]); } } } static void pdes_parent(int *pdes, struct pid *cur, pid_t pid, const char *type) { FILE *iop; /* Parent; assume fdopen can't fail. */ if (*type == 'r') { iop = fdopen(pdes[0], type); #ifdef _REENTRANT cur->fd = pdes[0]; #endif (void)close(pdes[1]); } else { iop = fdopen(pdes[1], type); #ifdef _REENTRANT cur->fd = pdes[1]; #endif (void)close(pdes[0]); } /* Link into list of file descriptors. */ cur->fp = iop; cur->pid = pid; cur->next = pidlist; pidlist = cur; } static void pdes_error(int *pdes, struct pid *cur) { free(cur); (void)close(pdes[0]); (void)close(pdes[1]); } FILE * popen(const char *cmd, const char *type) { struct pid *cur; int pdes[2], serrno; pid_t pid; _DIAGASSERT(cmd != NULL); _DIAGASSERT(type != NULL); if ((cur = pdes_get(pdes, &type)) == NULL) return NULL; MUTEX_LOCK(); (void)__readlockenv(); switch (pid = vfork()) { case -1: /* Error. */ serrno = errno; (void)__unlockenv(); MUTEX_UNLOCK(); pdes_error(pdes, cur); errno = serrno; return NULL; /* NOTREACHED */ case 0: /* Child. */ pdes_child(pdes, type); execl(_PATH_BSHELL, "sh", "-c", "--", cmd, NULL); _exit(127); /* NOTREACHED */ } (void)__unlockenv(); pdes_parent(pdes, cur, pid, type); MUTEX_UNLOCK(); return cur->fp; } FILE * popenve(const char *cmd, char *const *argv, char *const *envp, const char *type) { struct pid *cur; int pdes[2], serrno; pid_t pid; _DIAGASSERT(cmd != NULL); _DIAGASSERT(type != NULL); if ((cur = pdes_get(pdes, &type)) == NULL) return NULL; MUTEX_LOCK(); switch (pid = vfork()) { case -1: /* Error. */ serrno = errno; MUTEX_UNLOCK(); pdes_error(pdes, cur); errno = serrno; return NULL; /* NOTREACHED */ case 0: /* Child. */ pdes_child(pdes, type); execve(cmd, argv, envp); _exit(127); /* NOTREACHED */ } pdes_parent(pdes, cur, pid, type); MUTEX_UNLOCK(); return cur->fp; } /* * pclose -- * Pclose returns -1 if stream is not associated with a `popened' command, * if already `pclosed', or waitpid returns an error. */ int pclose(FILE *iop) { struct pid *cur, *last; int pstat; pid_t pid; _DIAGASSERT(iop != NULL); MUTEX_LOCK(); /* Find the appropriate file pointer. */ for (last = NULL, cur = pidlist; cur; last = cur, cur = cur->next) if (cur->fp == iop) break; if (cur == NULL) { MUTEX_UNLOCK(); errno = ESRCH; return -1; } (void)fclose(iop); /* Remove the entry from the linked list. */ if (last == NULL) pidlist = cur->next; else last->next = cur->next; MUTEX_UNLOCK(); do { pid = waitpid(cur->pid, &pstat, 0); } while (pid == -1 && errno == EINTR); free(cur); return pid == -1 ? -1 : pstat; }