ext2fs: Don't assume that on-disk format of a directory is the same
as in <sys/dirent.h> ext2_readdir() has always been very fs specific and different with respect to its ufs_ counterpart. Recent changes from UFS have made it possible to share more closely the implementation. MFUFS r252438: Always start parsing at DIRBLKSIZ aligned offset, skip first entries if uio_offset is not DIRBLKSIZ aligned. Return EINVAL if buffer is too small for single entry. Preallocate buffer for cookies. Skip entries with zero inode number. Reviewed by: gleb, Zheng Liu MFC after: 1 month
This commit is contained in:
Pedro F. Giffuni
parent
338b821b0f
commit
78d912bbc3
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=253651
@ -128,33 +128,40 @@ ext2_is_dot_entry(struct componentname *cnp)
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/*
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* Vnode op for reading directories.
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*
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* This function has to convert directory entries from the on-disk
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* format to the format defined by <sys/dirent.h>. Unfortunately, the
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* conversion will blow up some entries by four bytes, so it can't be
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* done in place. Instead, the conversion is done entry by entry and
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* the converted entry is sent via uiomove.
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*
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* XXX allocate a buffer, convert as many entries as possible, then send
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* the whole buffer to uiomove
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*/
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int
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ext2_readdir(struct vop_readdir_args *ap)
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{
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struct vnode *vp = ap->a_vp;
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struct uio *uio = ap->a_uio;
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int count, error;
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struct ext2fs_direct_2 *edp, *dp;
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int ncookies;
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struct buf *bp;
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struct inode *ip;
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struct ext2fs_direct_2 *dp, *edp;
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u_long *cookies;
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struct dirent dstdp;
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struct uio auio;
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struct iovec aiov;
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caddr_t dirbuf;
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off_t offset, startoffset;
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size_t readcnt, skipcnt;
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ssize_t startresid;
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int ncookies;
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int DIRBLKSIZ = VTOI(ap->a_vp)->i_e2fs->e2fs_bsize;
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int readcnt;
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off_t startoffset = uio->uio_offset;
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int error;
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count = uio->uio_resid;
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ip = VTOI(vp);
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if (ap->a_ncookies != NULL) {
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ncookies = uio->uio_resid;
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if (uio->uio_offset >= ip->i_size)
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ncookies = 0;
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else if (ip->i_size - uio->uio_offset < ncookies)
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ncookies = ip->i_size - uio->uio_offset;
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ncookies = ncookies / (offsetof(struct ext2fs_direct_2,
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e2d_namlen) + 4) + 1;
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cookies = malloc(ncookies * sizeof(*cookies), M_TEMP, M_WAITOK);
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*ap->a_ncookies = ncookies;
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*ap->a_cookies = cookies;
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} else {
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ncookies = 0;
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cookies = NULL;
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}
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/*
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* Avoid complications for partial directory entries by adjusting
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* the i/o to end at a block boundary. Don't give up (like ufs
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@ -163,25 +170,33 @@ ext2_readdir(struct vop_readdir_args *ap)
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* size is a little larger than DIRBLKSIZ to allow for expansion
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* of directory entries, but some callers just use 512.
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*/
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count -= (uio->uio_offset + count) & (DIRBLKSIZ -1);
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if (count <= 0)
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count += DIRBLKSIZ;
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auio = *uio;
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auio.uio_iov = &aiov;
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auio.uio_iovcnt = 1;
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auio.uio_resid = count;
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auio.uio_segflg = UIO_SYSSPACE;
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aiov.iov_len = count;
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dirbuf = malloc(count, M_TEMP, M_WAITOK);
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aiov.iov_base = dirbuf;
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error = VOP_READ(ap->a_vp, &auio, 0, ap->a_cred);
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if (error == 0) {
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readcnt = count - auio.uio_resid;
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edp = (struct ext2fs_direct_2 *)&dirbuf[readcnt];
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ncookies = 0;
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bzero(&dstdp, offsetof(struct dirent, d_name));
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for (dp = (struct ext2fs_direct_2 *)dirbuf;
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!error && uio->uio_resid > 0 && dp < edp; ) {
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if (uio->uio_offset < 0)
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offset = startoffset = uio->uio_offset + DIRBLKSIZ;
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else
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offset = startoffset = uio->uio_offset;
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startresid = uio->uio_resid;
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error = 0;
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while (error == 0 && uio->uio_resid > 0 &&
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uio->uio_offset < ip->i_size) {
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error = ext2_blkatoff(vp, uio->uio_offset, NULL, &bp);
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if (error)
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break;
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if (bp->b_offset + bp->b_bcount > ip->i_size)
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readcnt = ip->i_size - bp->b_offset;
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else
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readcnt = bp->b_bcount;
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skipcnt = (size_t)(uio->uio_offset - bp->b_offset) &
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~(size_t)(DIRBLKSIZ - 1);
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offset = bp->b_offset + skipcnt;
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dp = (struct ext2fs_direct_2 *)&bp->b_data[skipcnt];
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edp = (struct ext2fs_direct_2 *)&bp->b_data[readcnt];
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while (error == 0 && uio->uio_resid > 0 && dp < edp) {
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if (dp->e2d_reclen <= offsetof(struct ext2fs_direct_2,
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e2d_namlen) || (caddr_t)dp + dp->e2d_reclen >
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(caddr_t)edp) {
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error = EIO;
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break;
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}
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/*-
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* "New" ext2fs directory entries differ in 3 ways
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* from ufs on-disk ones:
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@ -198,57 +213,60 @@ ext2_readdir(struct vop_readdir_args *ap)
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* because ext2fs uses a machine-independent disk
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* layout.
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*/
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dstdp.d_fileno = dp->e2d_ino;
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dstdp.d_type = FTTODT(dp->e2d_type);
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dstdp.d_namlen = dp->e2d_namlen;
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dstdp.d_reclen = GENERIC_DIRSIZ(&dstdp);
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bcopy(dp->e2d_name, dstdp.d_name, dstdp.d_namlen);
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bzero(dstdp.d_name + dstdp.d_namlen,
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dstdp.d_reclen - offsetof(struct dirent, d_name) -
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dstdp.d_namlen);
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if (dp->e2d_reclen > 0) {
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if(dstdp.d_reclen <= uio->uio_resid) {
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/* advance dp */
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dp = (struct ext2fs_direct_2 *)
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((char *)dp + dp->e2d_reclen);
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error =
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uiomove(&dstdp, dstdp.d_reclen, uio);
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if (!error)
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ncookies++;
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} else
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break;
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} else {
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dstdp.d_type = FTTODT(dp->e2d_type);
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if (offsetof(struct ext2fs_direct_2, e2d_namlen) +
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dstdp.d_namlen > dp->e2d_reclen) {
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error = EIO;
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break;
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}
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}
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/* we need to correct uio_offset */
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uio->uio_offset = startoffset + (caddr_t)dp - dirbuf;
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if (!error && ap->a_ncookies != NULL) {
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u_long *cookiep, *cookies, *ecookies;
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off_t off;
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if (uio->uio_segflg != UIO_SYSSPACE || uio->uio_iovcnt != 1)
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panic("ext2_readdir: unexpected uio from NFS server");
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cookies = malloc(ncookies * sizeof(u_long), M_TEMP,
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M_WAITOK);
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off = startoffset;
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for (dp = (struct ext2fs_direct_2 *)dirbuf,
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cookiep = cookies, ecookies = cookies + ncookies;
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cookiep < ecookies;
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dp = (struct ext2fs_direct_2 *)((caddr_t) dp + dp->e2d_reclen)) {
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off += dp->e2d_reclen;
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*cookiep++ = (u_long) off;
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if (offset < startoffset || dp->e2d_ino == 0)
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goto nextentry;
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dstdp.d_fileno = dp->e2d_ino;
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dstdp.d_reclen = GENERIC_DIRSIZ(&dstdp);
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bcopy(dp->e2d_name, dstdp.d_name, dstdp.d_namlen);
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dstdp.d_name[dstdp.d_namlen] = '\0';
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if (dstdp.d_reclen > uio->uio_resid) {
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if (uio->uio_resid == startresid)
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error = EINVAL;
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else
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error = EJUSTRETURN;
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break;
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}
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*ap->a_ncookies = ncookies;
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*ap->a_cookies = cookies;
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/* Advance dp. */
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error = uiomove((caddr_t)&dstdp, dstdp.d_reclen, uio);
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if (error)
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break;
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if (cookies != NULL) {
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KASSERT(ncookies > 0,
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("ext2_readdir: cookies buffer too small"));
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*cookies = offset + dp->e2d_reclen;
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cookies++;
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ncookies--;
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}
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nextentry:
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offset += dp->e2d_reclen;
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dp = (struct ext2fs_direct_2 *)((caddr_t)dp +
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dp->e2d_reclen);
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}
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bqrelse(bp);
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uio->uio_offset = offset;
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}
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/* We need to correct uio_offset. */
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uio->uio_offset = offset;
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if (error == EJUSTRETURN)
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error = 0;
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if (ap->a_ncookies != NULL) {
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if (error == 0) {
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ap->a_ncookies -= ncookies;
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} else {
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free(*ap->a_cookies, M_TEMP);
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*ap->a_ncookies = 0;
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*ap->a_cookies = NULL;
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}
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}
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free(dirbuf, M_TEMP);
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if (ap->a_eofflag)
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*ap->a_eofflag = VTOI(ap->a_vp)->i_size <= uio->uio_offset;
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if (error == 0 && ap->a_eofflag)
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*ap->a_eofflag = ip->i_size <= uio->uio_offset;
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return (error);
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}
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