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Date:      Thu, 23 Apr 2015 08:41:51 +0000 (UTC)
From:      Edward Tomasz Napierala <trasz@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r281882 - head/sys/compat/linux
Message-ID:  <201504230841.t3N8fpYo007582@svn.freebsd.org>

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Author: trasz
Date: Thu Apr 23 08:41:50 2015
New Revision: 281882
URL: https://svnweb.freebsd.org/changeset/base/281882

Log:
  Simplify linux_getcwd(), removing code that was longer used.
  
  Differential Revision:	https://reviews.freebsd.org/D2326
  Reviewed by:	dchagin@, kib@
  MFC after:	1 month
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sys/compat/linux/linux_getcwd.c

Modified: head/sys/compat/linux/linux_getcwd.c
==============================================================================
--- head/sys/compat/linux/linux_getcwd.c	Thu Apr 23 07:41:58 2015	(r281881)
+++ head/sys/compat/linux/linux_getcwd.c	Thu Apr 23 08:41:50 2015	(r281882)
@@ -2,11 +2,15 @@
 /* $NetBSD: vfs_getcwd.c,v 1.3.2.3 1999/07/11 10:24:09 sommerfeld Exp $ */
 /*-
  * Copyright (c) 1999 The NetBSD Foundation, Inc.
+ * Copyright (c) 2015 The FreeBSD Foundation
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Bill Sommerfeld.
  *
+ * Portions of this software were developed by Edward Tomasz Napierala
+ * under sponsorship from the FreeBSD Foundation.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ -36,19 +40,9 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/systm.h>
-#include <sys/namei.h>
-#include <sys/filedesc.h>
-#include <sys/kernel.h>
-#include <sys/file.h>
-#include <sys/stat.h>
 #include <sys/syscallsubr.h>
-#include <sys/vnode.h>
-#include <sys/mount.h>
 #include <sys/proc.h>
-#include <sys/uio.h>
 #include <sys/malloc.h>
-#include <sys/dirent.h>
-#include <ufs/ufs/dir.h>	/* XXX only for DIRBLKSIZ */
 
 #ifdef COMPAT_LINUX32
 #include <machine/../linux32/linux.h>
@@ -60,408 +54,37 @@ __FBSDID("$FreeBSD$");
 #include <compat/linux/linux_misc.h>
 #include <compat/linux/linux_util.h>
 
-#include <security/mac/mac_framework.h>
-
-static int
-linux_getcwd_scandir(struct vnode **, struct vnode **,
-    char **, char *, struct thread *);
-static int
-linux_getcwd_common(struct vnode *, struct vnode *,
-		   char **, char *, int, int, struct thread *);
-
-#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)
-
-/*
- * Vnode variable naming conventions in this file:
- *
- * rvp: the current root we're aiming towards.
- * lvp, *lvpp: the "lower" vnode
- * uvp, *uvpp: the "upper" vnode.
- *
- * Since all the vnodes we're dealing with are directories, and the
- * lookups are going *up* in the filesystem rather than *down*, the
- * usual "pvp" (parent) or "dvp" (directory) naming conventions are
- * too confusing.
- */
-
-/*
- * XXX Will infinite loop in certain cases if a directory read reliably
- *	returns EINVAL on last block.
- * XXX is EINVAL the right thing to return if a directory is malformed?
- */
-
-/*
- * XXX Untested vs. mount -o union; probably does the wrong thing.
- */
-
-/*
- * Find parent vnode of *lvpp, return in *uvpp
- *
- * If we care about the name, scan it looking for name of directory
- * entry pointing at lvp.
- *
- * Place the name in the buffer which starts at bufp, immediately
- * before *bpp, and move bpp backwards to point at the start of it.
- *
- * On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed
- * On exit, *uvpp is either NULL or is a locked vnode reference.
- */
-static int
-linux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td)
-	struct vnode **lvpp;
-	struct vnode **uvpp;
-	char **bpp;
-	char *bufp;
-	struct thread *td;
-{
-	int     error = 0;
-	int     eofflag;
-	off_t   off;
-	int     tries;
-	struct uio uio;
-	struct iovec iov;
-	char   *dirbuf = NULL;
-	int	dirbuflen;
-	ino_t   fileno;
-	struct vattr va;
-	struct vnode *uvp = NULL;
-	struct vnode *lvp = *lvpp;	
-	struct componentname cn;
-	int len, reclen;
-	tries = 0;
-
-	/*
-	 * If we want the filename, get some info we need while the
-	 * current directory is still locked.
-	 */
-	if (bufp != NULL) {
-		error = VOP_GETATTR(lvp, &va, td->td_ucred);
-		if (error) {
-			vput(lvp);
-			*lvpp = NULL;
-			*uvpp = NULL;
-			return error;
-		}
-	}
-
-	/*
-	 * Ok, we have to do it the hard way..
-	 * Next, get parent vnode using lookup of ..
-	 */
-	cn.cn_nameiop = LOOKUP;
-	cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY;
-	cn.cn_thread = td;
-	cn.cn_cred = td->td_ucred;
-	cn.cn_pnbuf = NULL;
-	cn.cn_nameptr = "..";
-	cn.cn_namelen = 2;
-	cn.cn_consume = 0;
-	cn.cn_lkflags = LK_SHARED;
-	
-	/*
-	 * At this point, lvp is locked and will be unlocked by the lookup.
-	 * On successful return, *uvpp will be locked
-	 */
-#ifdef MAC
-	error = mac_vnode_check_lookup(td->td_ucred, lvp, &cn);
-	if (error == 0)
-#endif
-		error = VOP_LOOKUP(lvp, uvpp, &cn);
-	if (error) {
-		vput(lvp);
-		*lvpp = NULL;
-		*uvpp = NULL;
-		return error;
-	}
-	uvp = *uvpp;
-
-	/* If we don't care about the pathname, we're done */
-	if (bufp == NULL) {
-		vput(lvp);
-		*lvpp = NULL;
-		return 0;
-	}
-	
-	fileno = va.va_fileid;
-
-	dirbuflen = DIRBLKSIZ;
-	if (dirbuflen < va.va_blocksize)
-		dirbuflen = va.va_blocksize;
-	dirbuf = malloc(dirbuflen, M_TEMP, M_WAITOK);
-
-#if 0
-unionread:
-#endif
-	off = 0;
-	do {
-		/* call VOP_READDIR of parent */
-		iov.iov_base = dirbuf;
-		iov.iov_len = dirbuflen;
-
-		uio.uio_iov = &iov;
-		uio.uio_iovcnt = 1;
-		uio.uio_offset = off;
-		uio.uio_resid = dirbuflen;
-		uio.uio_segflg = UIO_SYSSPACE;
-		uio.uio_rw = UIO_READ;
-		uio.uio_td = td;
-
-		eofflag = 0;
-
-#ifdef MAC
-		error = mac_vnode_check_readdir(td->td_ucred, uvp);
-		if (error == 0)
-#endif /* MAC */
-			error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag,
-			    0, 0);
-
-		off = uio.uio_offset;
-
-		/*
-		 * Try again if NFS tosses its cookies.
-		 * XXX this can still loop forever if the directory is busted
-		 * such that the second or subsequent page of it always
-		 * returns EINVAL
-		 */
-		if ((error == EINVAL) && (tries < 3)) {
-			off = 0;
-			tries++;
-			continue;	/* once more, with feeling */
-		}
-
-		if (!error) {
-			char   *cpos;
-			struct dirent *dp;
-			
-			cpos = dirbuf;
-			tries = 0;
-				
-			/* scan directory page looking for matching vnode */ 
-			for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) {
-				dp = (struct dirent *) cpos;
-				reclen = dp->d_reclen;
-
-				/* check for malformed directory.. */
-				if (reclen < DIRENT_MINSIZE) {
-					error = EINVAL;
-					goto out;
-				}
-				/*
-				 * XXX should perhaps do VOP_LOOKUP to
-				 * check that we got back to the right place,
-				 * but getting the locking games for that
-				 * right would be heinous.
-				 */
-				if ((dp->d_type != DT_WHT) &&
-				    (dp->d_fileno == fileno)) {
-					char *bp = *bpp;
-					bp -= dp->d_namlen;
-					
-					if (bp <= bufp) {
-						error = ERANGE;
-						goto out;
-					}
-					bcopy(dp->d_name, bp, dp->d_namlen);
-					error = 0;
-					*bpp = bp;
-					goto out;
-				}
-				cpos += reclen;
-			}
-		}
-	} while (!eofflag);
-	error = ENOENT;
-		
-out:
-	vput(lvp);
-	*lvpp = NULL;
-	free(dirbuf, M_TEMP);
-	return error;
-}
-
-
-/*
- * common routine shared by sys___getcwd() and linux_vn_isunder()
- */
-
-#define GETCWD_CHECK_ACCESS 0x0001
-
-static int
-linux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td)
-	struct vnode *lvp;
-	struct vnode *rvp;
-	char **bpp;
-	char *bufp;
-	int limit;
-	int flags;
-	struct thread *td;
-{
-	struct filedesc *fdp = td->td_proc->p_fd;
-	struct vnode *uvp = NULL;
-	char *bp = NULL;
-	int error;
-	accmode_t accmode = VEXEC;
-
-	if (rvp == NULL) {
-		rvp = fdp->fd_rdir;
-		if (rvp == NULL)
-			rvp = rootvnode;
-	}
-	
-	VREF(rvp);
-	VREF(lvp);
-
-	/*
-	 * Error handling invariant:
-	 * Before a `goto out':
-	 *	lvp is either NULL, or locked and held.
-	 *	uvp is either NULL, or locked and held.
-	 */
-
-	error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY);
-	if (error != 0)
-		panic("vn_lock LK_RETRY returned error %d", error);
-	if (bufp)
-		bp = *bpp;
-	/*
-	 * this loop will terminate when one of the following happens:
-	 *	- we hit the root
-	 *	- getdirentries or lookup fails
-	 *	- we run out of space in the buffer.
-	 */
-	if (lvp == rvp) {
-		if (bp)
-			*(--bp) = '/';
-		goto out;
-	}
-	do {
-		if (lvp->v_type != VDIR) {
-			error = ENOTDIR;
-			goto out;
-		}
-		
-		/*
-		 * access check here is optional, depending on
-		 * whether or not caller cares.
-		 */
-		if (flags & GETCWD_CHECK_ACCESS) {
-			error = VOP_ACCESS(lvp, accmode, td->td_ucred, td);
-			if (error)
-				goto out;
-			accmode = VEXEC|VREAD;
-		}
-		
-		/*
-		 * step up if we're a covered vnode..
-		 */
-		while (lvp->v_vflag & VV_ROOT) {
-			struct vnode *tvp;
-
-			if (lvp == rvp)
-				goto out;
-			
-			tvp = lvp;
-			lvp = lvp->v_mount->mnt_vnodecovered;
-			vput(tvp);
-			/*
-			 * hodie natus est radici frater
-			 */
-			if (lvp == NULL) {
-				error = ENOENT;
-				goto out;
-			}
-			VREF(lvp);
-			error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY);
-			if (error != 0)
-				panic("vn_lock LK_RETRY returned %d", error);
-		}
-		error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td);
-		if (error)
-			goto out;
-#ifdef DIAGNOSTIC		
-		if (lvp != NULL)
-			panic("getcwd: oops, forgot to null lvp");
-		if (bufp && (bp <= bufp)) {
-			panic("getcwd: oops, went back too far");
-		}
-#endif		
-		if (bp) 
-			*(--bp) = '/';
-		lvp = uvp;
-		uvp = NULL;
-		limit--;
-	} while ((lvp != rvp) && (limit > 0)); 
-
-out:
-	if (bpp)
-		*bpp = bp;
-	if (uvp)
-		vput(uvp);
-	if (lvp)
-		vput(lvp);
-	vrele(rvp);
-	return error;
-}
-
-
 /*
  * Find pathname of process's current directory.
- *
- * Use vfs vnode-to-name reverse cache; if that fails, fall back
- * to reading directory contents.
  */
-
 int
 linux_getcwd(struct thread *td, struct linux_getcwd_args *args)
 {
-	char *bp, *bend, *path;
-	int error, len, lenused;
+	char *path;
+	int error, lenused;
 
 #ifdef DEBUG
 	if (ldebug(getcwd))
 		printf(ARGS(getcwd, "%p, %ld"), args->buf, (long)args->bufsize);
 #endif
 
-	len = args->bufsize;
-
-	if (len > LINUX_PATH_MAX)
-		len = LINUX_PATH_MAX;
-	else if (len < 2)
-		return ERANGE;
+	/*
+	 * Linux returns ERANGE instead of EINVAL.
+	 */
+	if (args->bufsize < 2)
+		return (ERANGE);
 
-	path = malloc(len, M_TEMP, M_WAITOK);
+	path = malloc(LINUX_PATH_MAX, M_TEMP, M_WAITOK);
 
-	error = kern___getcwd(td, path, UIO_SYSSPACE, len, LINUX_PATH_MAX);
-	if (!error) {
+	error = kern___getcwd(td, path, UIO_SYSSPACE, args->bufsize,
+	    LINUX_PATH_MAX);
+	if (error == 0) {
 		lenused = strlen(path) + 1;
-		if (lenused <= args->bufsize) {
+		error = copyout(path, args->buf, lenused);
+		if (error == 0)
 			td->td_retval[0] = lenused;
-			error = copyout(path, args->buf, lenused);
-		}
-		else
-			error = ERANGE;
-	} else {
-		bp = &path[len];
-		bend = bp;
-		*(--bp) = '\0';
-
-		/*
-		 * 5th argument here is "max number of vnodes to traverse".
-		 * Since each entry takes up at least 2 bytes in the output buffer,
-		 * limit it to N/2 vnodes for an N byte buffer.
-		 */
-
-		error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL,
-		    &bp, path, len/2, GETCWD_CHECK_ACCESS, td);
-		if (error)
-			goto out;
-		lenused = bend - bp;
-		td->td_retval[0] = lenused;
-		/* put the result into user buffer */
-		error = copyout(bp, args->buf, lenused);
 	}
-out:
+
 	free(path, M_TEMP);
 	return (error);
 }
-



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