--- /dev/null
+The file system.c included herein is taken directly from Apple's Darwin
+open-source CVS archives, and is redistributed under the BSD copyright
+notice it bears. (According to Apple's CVS logs, their version is
+identical to the FreeBSD original.) It provides our own implementation of
+the system(3) function, which ought by all rights to be identical to the
+one provided in libc on Darwin machines. Nonetheless, this version works,
+whereas the one that actually ships with Mac OS X 10.1 doesn't. The
+shipped version appears to disconnect the calling process from any shared
+memory segments it is attached to. (The symptom seen in PostgreSQL is
+that a backend attempting to execute CREATE DATABASE core-dumps.) I would
+love to know why there is a discrepancy between the published source and
+the actual behavior --- tgl 7-Nov-2001.
+
+Appropriate bug reports have been filed with Apple --- see
+Radar Bug#s 2767956, 2683531, 2805147. One hopes we can retire this
+kluge in the not too distant future.
+
+
+As of PostgreSQL 7.2 and Mac OS X 10.1, one should expect warnings
+like these while linking the backend:
+
+/usr/bin/ld: warning unused multiple definitions of symbol _system
+port/SUBSYS.o definition of _system in section (__TEXT,__text)
+/usr/lib/libm.dylib(system.o) unused definition of _system
+/usr/bin/ld: warning unused multiple definitions of symbol _semctl
+port/SUBSYS.o definition of _semctl in section (__TEXT,__text)
+/usr/lib/libm.dylib(semctl.o) unused definition of _semctl
+/usr/bin/ld: warning unused multiple definitions of symbol _semget
+port/SUBSYS.o definition of _semget in section (__TEXT,__text)
+/usr/lib/libm.dylib(semget.o) unused definition of _semget
+/usr/bin/ld: warning unused multiple definitions of symbol _semop
+port/SUBSYS.o definition of _semop in section (__TEXT,__text)
+/usr/lib/libm.dylib(semop.o) unused definition of _semop
+
+The first of these shows us overriding system() per the above-described
+hack. The rest show sem.c overriding the nonfunctional semaphore stubs
+in libc. (Perhaps sem.c can also be retired someday, but semget support
+is reportedly not high on Apple's to-do list.)
--- /dev/null
+/*
+ * Copyright (c) 1988, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * 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. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 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.
+ *
+ * $FreeBSD: src/lib/libc/stdlib/system.c,v 1.6 2000/03/16 02:14:41 jasone Exp $
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)system.c 8.1 (Berkeley) 6/4/93";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <unistd.h>
+#include <paths.h>
+#include <errno.h>
+
+int system(const char *command);
+
+int
+system(const char *command)
+{
+ pid_t pid;
+ int pstat;
+ struct sigaction ign, intact, quitact;
+ sigset_t newsigblock, oldsigblock;
+
+ if (!command) /* just checking... */
+ return(1);
+
+ /*
+ * Ignore SIGINT and SIGQUIT, block SIGCHLD. Remember to save
+ * existing signal dispositions.
+ */
+ ign.sa_handler = SIG_IGN;
+ (void)sigemptyset(&ign.sa_mask);
+ ign.sa_flags = 0;
+ (void)sigaction(SIGINT, &ign, &intact);
+ (void)sigaction(SIGQUIT, &ign, &quitact);
+ (void)sigemptyset(&newsigblock);
+ (void)sigaddset(&newsigblock, SIGCHLD);
+ (void)sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock);
+ switch(pid = fork()) {
+ case -1: /* error */
+ break;
+ case 0: /* child */
+ /*
+ * Restore original signal dispositions and exec the command.
+ */
+ (void)sigaction(SIGINT, &intact, NULL);
+ (void)sigaction(SIGQUIT, &quitact, NULL);
+ (void)sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
+ execl(_PATH_BSHELL, "sh", "-c", command, (char *)NULL);
+ _exit(127);
+ default: /* parent */
+ do {
+ pid = wait4(pid, &pstat, 0, (struct rusage *)0);
+ } while (pid == -1 && errno == EINTR);
+ break;
+ }
+ (void)sigaction(SIGINT, &intact, NULL);
+ (void)sigaction(SIGQUIT, &quitact, NULL);
+ (void)sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
+ return(pid == -1 ? -1 : pstat);
+}
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