Date: Wed, 29 Jul 2015 06:31:45 +0000 (UTC) From: Ed Schouten <ed@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r285998 - head/sys/compat/cloudabi Message-ID: <201507290631.t6T6Vj9x077945@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: ed Date: Wed Jul 29 06:31:44 2015 New Revision: 285998 URL: https://svnweb.freebsd.org/changeset/base/285998 Log: Implement CloudABI's readdir(). Summary: CloudABI's readdir() system call could be thought of as a mixture between FreeBSD's getdents(2) and pread(). Instead of using the file descriptor offset, userspace provides a 64-bit cloudabi_dircookie_t continue reading at a given point. CLOUDABI_DIRCOOKIE_START, having value 0, can be used to return entries at the start of the directory. The file descriptor offset is not used to store the cookie for the reason that in a file descriptor centric environment, it would make sense to allow concurrent use of a single file descriptor. The remaining space returned by the system call should be filled with a partially truncated copy of the next entry. The advantage of doing this is that it gracefully deals with long filenames. If the C library provides a buffer that is too small to hold a single entry, it can still extract the directory entry header, meaning that it can retry the read with a larger buffer or skip it using the cookie. Test Plan: This implementation passes the cloudlibc unit tests at: https://github.com/NuxiNL/cloudlibc/tree/master/src/libc/dirent Reviewers: marcel, kib Reviewed By: kib Subscribers: imp Differential Revision: https://reviews.freebsd.org/D3226 Modified: head/sys/compat/cloudabi/cloudabi_file.c Modified: head/sys/compat/cloudabi/cloudabi_file.c ============================================================================== --- head/sys/compat/cloudabi/cloudabi_file.c Wed Jul 29 06:23:06 2015 (r285997) +++ head/sys/compat/cloudabi/cloudabi_file.c Wed Jul 29 06:31:44 2015 (r285998) @@ -28,6 +28,7 @@ __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/capsicum.h> +#include <sys/dirent.h> #include <sys/fcntl.h> #include <sys/kernel.h> #include <sys/malloc.h> @@ -35,11 +36,15 @@ __FBSDID("$FreeBSD$"); #include <sys/proc.h> #include <sys/stat.h> #include <sys/syscallsubr.h> +#include <sys/uio.h> +#include <sys/vnode.h> #include <compat/cloudabi/cloudabi_proto.h> #include <compat/cloudabi/cloudabi_syscalldefs.h> #include <compat/cloudabi/cloudabi_util.h> +#include <security/mac/mac_framework.h> + static MALLOC_DEFINE(M_CLOUDABI_PATH, "cloudabipath", "CloudABI pathnames"); /* @@ -197,13 +202,180 @@ cloudabi_sys_file_open(struct thread *td return (ENOSYS); } +/* Converts a FreeBSD directory entry structure and writes it to userspace. */ +static int +write_dirent(struct dirent *bde, cloudabi_dircookie_t cookie, struct uio *uio) +{ + cloudabi_dirent_t cde = { + .d_next = cookie, + .d_ino = bde->d_fileno, + .d_namlen = bde->d_namlen, + }; + size_t len; + int error; + + /* Convert file type. */ + switch (bde->d_type) { + case DT_BLK: + cde.d_type = CLOUDABI_FILETYPE_BLOCK_DEVICE; + break; + case DT_CHR: + cde.d_type = CLOUDABI_FILETYPE_CHARACTER_DEVICE; + break; + case DT_DIR: + cde.d_type = CLOUDABI_FILETYPE_DIRECTORY; + break; + case DT_FIFO: + cde.d_type = CLOUDABI_FILETYPE_FIFO; + break; + case DT_LNK: + cde.d_type = CLOUDABI_FILETYPE_SYMBOLIC_LINK; + break; + case DT_REG: + cde.d_type = CLOUDABI_FILETYPE_REGULAR_FILE; + break; + case DT_SOCK: + /* The exact socket type cannot be derived. */ + cde.d_type = CLOUDABI_FILETYPE_SOCKET_STREAM; + break; + default: + cde.d_type = CLOUDABI_FILETYPE_UNKNOWN; + break; + } + + /* Write directory entry structure. */ + len = sizeof(cde) < uio->uio_resid ? sizeof(cde) : uio->uio_resid; + error = uiomove(&cde, len, uio); + if (error != 0) + return (error); + + /* Write filename. */ + len = bde->d_namlen < uio->uio_resid ? bde->d_namlen : uio->uio_resid; + return (uiomove(bde->d_name, len, uio)); +} + int cloudabi_sys_file_readdir(struct thread *td, struct cloudabi_sys_file_readdir_args *uap) { + struct iovec iov = { + .iov_base = uap->buf, + .iov_len = uap->nbyte + }; + struct uio uio = { + .uio_iov = &iov, + .uio_iovcnt = 1, + .uio_resid = iov.iov_len, + .uio_segflg = UIO_USERSPACE, + .uio_rw = UIO_READ, + .uio_td = td + }; + struct file *fp; + struct vnode *vp; + void *readbuf; + cap_rights_t rights; + cloudabi_dircookie_t offset; + int error; - /* Not implemented. */ - return (ENOSYS); + /* Obtain directory vnode. */ + error = getvnode(td, uap->fd, cap_rights_init(&rights, CAP_READ), &fp); + if (error != 0) { + if (error == EINVAL) + return (ENOTDIR); + return (error); + } + if ((fp->f_flag & FREAD) == 0) { + fdrop(fp, td); + return (EBADF); + } + + /* + * Call VOP_READDIR() and convert resulting data until the user + * provided buffer is filled. + */ + readbuf = malloc(MAXBSIZE, M_TEMP, M_WAITOK); + offset = uap->cookie; + vp = fp->f_vnode; + while (uio.uio_resid > 0) { + struct iovec readiov = { + .iov_base = readbuf, + .iov_len = MAXBSIZE + }; + struct uio readuio = { + .uio_iov = &readiov, + .uio_iovcnt = 1, + .uio_rw = UIO_READ, + .uio_segflg = UIO_SYSSPACE, + .uio_td = td, + .uio_resid = MAXBSIZE, + .uio_offset = offset + }; + struct dirent *bde; + unsigned long *cookies, *cookie; + size_t readbuflen; + int eof, ncookies; + + /* Validate file type. */ + vn_lock(vp, LK_SHARED | LK_RETRY); + if (vp->v_type != VDIR) { + VOP_UNLOCK(vp, 0); + error = ENOTDIR; + goto done; + } +#ifdef MAC + error = mac_vnode_check_readdir(td->td_ucred, vp); + if (error != 0) { + VOP_UNLOCK(vp, 0); + goto done; + } +#endif /* MAC */ + + /* Read new directory entries. */ + cookies = NULL; + ncookies = 0; + error = VOP_READDIR(vp, &readuio, fp->f_cred, &eof, + &ncookies, &cookies); + VOP_UNLOCK(vp, 0); + if (error != 0) + goto done; + + /* Convert entries to CloudABI's format. */ + readbuflen = MAXBSIZE - readuio.uio_resid; + bde = readbuf; + cookie = cookies; + while (readbuflen >= offsetof(struct dirent, d_name) && + uio.uio_resid > 0 && ncookies > 0) { + /* Ensure that the returned offset always increases. */ + if (readbuflen >= bde->d_reclen && bde->d_fileno != 0 && + *cookie > offset) { + error = write_dirent(bde, *cookie, &uio); + if (error != 0) { + free(cookies, M_TEMP); + goto done; + } + } + + if (offset < *cookie) + offset = *cookie; + ++cookie; + --ncookies; + readbuflen -= bde->d_reclen; + bde = (struct dirent *)((char *)bde + bde->d_reclen); + } + free(cookies, M_TEMP); + if (eof) + break; + } + +done: + fdrop(fp, td); + free(readbuf, M_TEMP); + if (error != 0) + return (error); + + /* Return number of bytes copied to userspace. */ + td->td_retval[0] = uap->nbyte - uio.uio_resid; + return (0); } int
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201507290631.t6T6Vj9x077945>