linux32_dirent.c revision 1.18 
1/*	$NetBSD: linux32_dirent.c,v 1.18 2017/07/28 15:34:06 riastradh Exp $ */
2
3/*-
4 * Copyright (c) 2006 Emmanuel Dreyfus, all rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 *    must display the following acknowledgement:
16 *	This product includes software developed by Emmanuel Dreyfus
17 * 4. The name of the author may not be used to endorse or promote
18 *    products derived from this software without specific prior written
19 *    permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS''
22 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
23 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 * POSSIBILITY OF SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35
36__KERNEL_RCSID(0, "$NetBSD: linux32_dirent.c,v 1.18 2017/07/28 15:34:06 riastradh Exp $");
37
38#include <sys/types.h>
39#include <sys/param.h>
40#include <sys/fstypes.h>
41#include <sys/signal.h>
42#include <sys/dirent.h>
43#include <sys/kernel.h>
44#include <sys/fcntl.h>
45#include <sys/file.h>
46#include <sys/filedesc.h>
47#include <sys/malloc.h>
48#include <sys/select.h>
49#include <sys/proc.h>
50#include <sys/ucred.h>
51#include <sys/vnode.h>
52#include <sys/swap.h>
53
54#include <machine/types.h>
55
56#include <sys/syscallargs.h>
57
58#include <compat/netbsd32/netbsd32.h>
59#include <compat/netbsd32/netbsd32_conv.h>
60#include <compat/netbsd32/netbsd32_syscallargs.h>
61
62#include <compat/linux/common/linux_types.h>
63#include <compat/linux/common/linux_signal.h>
64#include <compat/linux/common/linux_machdep.h>
65#include <compat/linux/common/linux_misc.h>
66#include <compat/linux/common/linux_oldolduname.h>
67#include <compat/linux/common/linux_dirent.h>
68#include <compat/linux/common/linux_ipc.h>
69#include <compat/linux/common/linux_sem.h>
70#include <compat/linux/linux_syscallargs.h>
71
72#include <compat/linux32/common/linux32_types.h>
73#include <compat/linux32/common/linux32_signal.h>
74#include <compat/linux32/common/linux32_machdep.h>
75#include <compat/linux32/common/linux32_sysctl.h>
76#include <compat/linux32/common/linux32_socketcall.h>
77#include <compat/linux32/linux32_syscallargs.h>
78
79/*
80 * Linux 'readdir' call. This code is mostly taken from the
81 * SunOS getdents call (see compat/sunos/sunos_misc.c), though
82 * an attempt has been made to keep it a little cleaner (failing
83 * miserably, because of the cruft needed if count 1 is passed).
84 *
85 * The d_off field should contain the offset of the next valid entry,
86 * but in Linux it has the offset of the entry itself. We emulate
87 * that bug here.
88 *
89 * Read in BSD-style entries, convert them, and copy them out.
90 *
91 * Note that this doesn't handle union-mounted filesystems.
92 */
93
94int
95linux32_sys_getdents(struct lwp *l, const struct linux32_sys_getdents_args *uap, register_t *retval)
96{
97	/* {
98		syscallarg(int) fd;
99		syscallarg(linux32_direntp_t) dent;
100		syscallarg(unsigned int) count;
101	} */
102	struct dirent *bdp;
103	struct vnode *vp;
104	char *inp, *tbuf;		/* BSD-format */
105	int len, reclen;		/* BSD-format */
106	char *outp;			/* Linux-format */
107	int resid, linux32_reclen = 0;	/* Linux-format */
108	struct file *fp;
109	struct uio auio;
110	struct iovec aiov;
111	struct linux32_dirent idb;
112	off_t off;		/* true file offset */
113	int buflen, error, eofflag, nbytes, oldcall;
114	struct vattr va;
115	off_t *cookiebuf = NULL, *cookie;
116	int ncookies;
117
118	/* fd_getvnode() will use the descriptor for us */
119	if ((error = fd_getvnode(SCARG(uap, fd), &fp)) != 0)
120		return (error);
121
122	if ((fp->f_flag & FREAD) == 0) {
123		error = EBADF;
124		goto out1;
125	}
126
127	vp = (struct vnode *)fp->f_data;
128	if (vp->v_type != VDIR) {
129		error = ENOTDIR;
130		goto out1;
131	}
132
133	vn_lock(vp, LK_SHARED | LK_RETRY);
134	error = VOP_GETATTR(vp, &va, l->l_cred);
135	VOP_UNLOCK(vp);
136	if (error)
137		goto out1;
138
139	nbytes = SCARG(uap, count);
140	if (nbytes == 1) {	/* emulating old, broken behaviour */
141		nbytes = sizeof (idb);
142		buflen = max(va.va_blocksize, nbytes);
143		oldcall = 1;
144	} else {
145		buflen = min(MAXBSIZE, nbytes);
146		if (buflen < va.va_blocksize)
147			buflen = va.va_blocksize;
148		oldcall = 0;
149	}
150	tbuf = malloc(buflen, M_TEMP, M_WAITOK);
151
152	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
153	off = fp->f_offset;
154again:
155	aiov.iov_base = tbuf;
156	aiov.iov_len = buflen;
157	auio.uio_iov = &aiov;
158	auio.uio_iovcnt = 1;
159	auio.uio_rw = UIO_READ;
160	auio.uio_resid = buflen;
161	auio.uio_offset = off;
162	UIO_SETUP_SYSSPACE(&auio);
163	/*
164         * First we read into the malloc'ed buffer, then
165         * we massage it into user space, one record at a time.
166         */
167	error = VOP_READDIR(vp, &auio, fp->f_cred, &eofflag, &cookiebuf,
168	    &ncookies);
169	if (error)
170		goto out;
171
172	inp = tbuf;
173	outp = (void *)SCARG_P32(uap, dent);
174	resid = nbytes;
175	if ((len = buflen - auio.uio_resid) == 0)
176		goto eof;
177
178	for (cookie = cookiebuf; len > 0; len -= reclen) {
179		bdp = (struct dirent *)inp;
180		reclen = bdp->d_reclen;
181		if (reclen & 3) {
182			error = EIO;
183			goto out;
184		}
185		if (bdp->d_fileno == 0) {
186			inp += reclen;	/* it is a hole; squish it out */
187			if (cookie)
188				off = *cookie++;
189			else
190				off += reclen;
191			continue;
192		}
193		linux32_reclen = LINUX_RECLEN(&idb, bdp->d_namlen);
194		if (reclen > len || resid < linux32_reclen) {
195			/* entry too big for buffer, so just stop */
196			outp++;
197			break;
198		}
199		/*
200		 * Massage in place to make a Linux-shaped dirent (otherwise
201		 * we have to worry about touching user memory outside of
202		 * the copyout() call).
203		 */
204		idb.d_ino = bdp->d_fileno;
205		/*
206		 * The old readdir() call misuses the offset and reclen fields.
207		 */
208		if (oldcall) {
209			idb.d_off = (linux32_off_t)linux32_reclen;
210			idb.d_reclen = (u_short)bdp->d_namlen;
211		} else {
212			if (sizeof (idb.d_off) <= 4 && (off >> 32) != 0) {
213				compat_offseterr(vp, "linux32_getdents");
214				error = EINVAL;
215				goto out;
216			}
217			idb.d_off = (linux32_off_t)off;
218			idb.d_reclen = (u_short)linux32_reclen;
219		}
220		size_t dirl = MIN(sizeof(idb.d_name) - 1, bdp->d_namlen + 1);
221		memcpy(idb.d_name, bdp->d_name, dirl);
222		idb.d_name[dirl + 1] = bdp->d_type;
223		if ((error = copyout((void *)&idb, outp, linux32_reclen)))
224			goto out;
225		/* advance past this real entry */
226		inp += reclen;
227		if (cookie)
228			off = *cookie++; /* each entry points to itself */
229		else
230			off += reclen;
231		/* advance output past Linux-shaped entry */
232		outp += linux32_reclen;
233		resid -= linux32_reclen;
234		if (oldcall)
235			break;
236	}
237
238	/* if we squished out the whole block, try again */
239	if (outp == (void *)SCARG_P32(uap, dent)) {
240		if (cookiebuf)
241			free(cookiebuf, M_TEMP);
242		cookiebuf = NULL;
243		goto again;
244	}
245	fp->f_offset = off;	/* update the vnode offset */
246
247	if (oldcall)
248		nbytes = resid + linux32_reclen;
249
250eof:
251	*retval = nbytes - resid;
252out:
253	VOP_UNLOCK(vp);
254	if (cookiebuf)
255		free(cookiebuf, M_TEMP);
256	free(tbuf, M_TEMP);
257out1:
258	fd_putfile(SCARG(uap, fd));
259	return error;
260}
261
262int
263linux32_sys_getdents64(struct lwp *l, const struct linux32_sys_getdents64_args *uap, register_t *retval)
264{
265	/* {
266		syscallarg(int) fd;
267		syscallarg(linux32_dirent64p_t) dent;
268		syscallarg(unsigned int) count;
269	} */
270	struct linux_sys_getdents64_args ua;
271
272	NETBSD32TO64_UAP(fd);
273	NETBSD32TOP_UAP(dent, struct linux_dirent64);
274	NETBSD32TO64_UAP(count);
275
276	return linux_sys_getdents64(l, &ua, retval);
277}
278
279int
280linux32_sys_readdir(struct lwp *l, const struct linux32_sys_readdir_args *uap, register_t *retval)
281{
282	/* {
283		syscallarg(int) fd;
284		syscallarg(struct linux32_direntp_t) dent;
285		syscallarg(unsigned int) count;
286	} */
287	int error;
288	struct linux32_sys_getdents_args da;
289
290	SCARG(&da, fd) = SCARG(uap, fd);
291	SCARG(&da, dent) = SCARG(uap, dent);
292	SCARG(&da, count) = 1;
293
294	error = linux32_sys_getdents(l, &da, retval);
295	if (error == 0 && *retval > 1)
296		*retval = 1;
297
298	return error;
299}
300