68540557c3
getmntinfo(3) is designed around a relatively static or slow growing set of current mounts. It tried to detect a race with somewhat concurrent mount and re-call getfsstat(2) in that case, looping indefinitely. It also allocated space for a single extra mount as slop. In the case where the user has a large number of mounts and is adding them at a rapid pace, it fell over. This patch makes two functional changes: 1. Allocate even more slop. Double whatever the last getfsstat(2) returned. 2. Abort and return some known results after looping a few times (arbitrarily, 3). If the list is constantly changing, we can't guarantee we return a full result to the user at any point anyways. While here, add very basic functional tests for getmntinfo(3) to the libc suite. PR: 221743 Submitted by: Peter Eriksson <peter AT ifm.liu.se> (earlier version) Sponsored by: Dell EMC Isilon
71 lines
2.6 KiB
C
71 lines
2.6 KiB
C
/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)getmntinfo.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/ucred.h>
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#include <sys/mount.h>
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#include <stdlib.h>
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#define MAX_TRIES 3
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#define SCALING_FACTOR 2
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/*
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* Return information about mounted filesystems.
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*/
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int
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getmntinfo(struct statfs **mntbufp, int mode)
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{
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static struct statfs *mntbuf;
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static int mntsize;
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static long bufsize;
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unsigned tries = 0;
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if (mntsize <= 0 && (mntsize = getfsstat(0, 0, MNT_NOWAIT)) < 0)
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return (0);
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if (bufsize > 0 && (mntsize = getfsstat(mntbuf, bufsize, mode)) < 0)
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return (0);
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while (tries++ < MAX_TRIES && bufsize <= mntsize * sizeof(*mntbuf)) {
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bufsize = (mntsize * SCALING_FACTOR) * sizeof(*mntbuf);
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if ((mntbuf = reallocf(mntbuf, bufsize)) == NULL)
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return (0);
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if ((mntsize = getfsstat(mntbuf, bufsize, mode)) < 0)
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return (0);
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}
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*mntbufp = mntbuf;
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if (mntsize > (bufsize / sizeof(*mntbuf)))
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return (bufsize / sizeof(*mntbuf));
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return (mntsize);
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}
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