svn commit: r268531 - in head: include lib/libc/gen
John Baldwin
jhb at FreeBSD.org
Fri Jul 11 16:16:28 UTC 2014
Author: jhb
Date: Fri Jul 11 16:16:26 2014
New Revision: 268531
URL: http://svnweb.freebsd.org/changeset/base/268531
Log:
Fix some edge cases with rewinddir():
- In the unionfs case, opendir() and fdopendir() read the directory's full
contents and cache it. This cache is not refreshed when rewinddir() is
called, so rewinddir() will not notice updates to a directory. Fix this
by splitting the code to fetch a directory's contents out of
__opendir_common() into a new _filldir() function and call this from
rewinddir() when operating on a unionfs directory.
- If rewinddir() is called on a directory opened with fdopendir() before
any directory entries are fetched, rewinddir() will not adjust the seek
location of the backing file descriptor. If the file descriptor passed
to fdopendir() had a non-zero offset, the rewinddir() will not rewind to
the beginning. Fix this by always seeking back to 0 in rewinddir().
This means the dd_rewind hack can also be removed.
While here, add missing locking to rewinddir().
CR: https://phabric.freebsd.org/D312
Reviewed by: jilles
MFC after: 1 week
Modified:
head/include/dirent.h
head/lib/libc/gen/gen-private.h
head/lib/libc/gen/opendir.c
head/lib/libc/gen/readdir.c
head/lib/libc/gen/rewinddir.c
head/lib/libc/gen/telldir.h
Modified: head/include/dirent.h
==============================================================================
--- head/include/dirent.h Fri Jul 11 14:34:29 2014 (r268530)
+++ head/include/dirent.h Fri Jul 11 16:16:26 2014 (r268531)
@@ -63,6 +63,7 @@ typedef struct _dirdesc DIR;
#define DTF_NODUP 0x0002 /* don't return duplicate names */
#define DTF_REWIND 0x0004 /* rewind after reading union stack */
#define __DTF_READALL 0x0008 /* everything has been read */
+#define __DTF_SKIPREAD 0x0010 /* assume internal buffer is populated */
#else /* !__BSD_VISIBLE */
Modified: head/lib/libc/gen/gen-private.h
==============================================================================
--- head/lib/libc/gen/gen-private.h Fri Jul 11 14:34:29 2014 (r268530)
+++ head/lib/libc/gen/gen-private.h Fri Jul 11 16:16:26 2014 (r268531)
@@ -48,7 +48,6 @@ struct _dirdesc {
char *dd_buf; /* data buffer */
int dd_len; /* size of data buffer */
long dd_seek; /* magic cookie returned by getdirentries */
- long dd_rewind; /* magic cookie for rewinding */
int dd_flags; /* flags for readdir */
struct pthread_mutex *dd_lock; /* lock */
struct _telldir *dd_td; /* telldir position recording */
Modified: head/lib/libc/gen/opendir.c
==============================================================================
--- head/lib/libc/gen/opendir.c Fri Jul 11 14:34:29 2014 (r268530)
+++ head/lib/libc/gen/opendir.c Fri Jul 11 16:16:26 2014 (r268531)
@@ -49,7 +49,7 @@ __FBSDID("$FreeBSD$");
#include "gen-private.h"
#include "telldir.h"
-static DIR * __opendir_common(int, int);
+static DIR * __opendir_common(int, int, bool);
/*
* Open a directory.
@@ -67,18 +67,10 @@ opendir(const char *name)
DIR *
fdopendir(int fd)
{
- struct stat statb;
- /* Check that fd is associated with a directory. */
- if (_fstat(fd, &statb) != 0)
- return (NULL);
- if (!S_ISDIR(statb.st_mode)) {
- errno = ENOTDIR;
- return (NULL);
- }
if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
return (NULL);
- return (__opendir_common(fd, DTF_HIDEW|DTF_NODUP));
+ return (__opendir_common(fd, DTF_HIDEW|DTF_NODUP, true));
}
DIR *
@@ -88,11 +80,13 @@ __opendir2(const char *name, int flags)
DIR *dir;
int saved_errno;
+ if ((flags & (__DTF_READALL | __DTF_SKIPREAD)) != 0)
+ return (NULL);
if ((fd = _open(name,
O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC)) == -1)
return (NULL);
- dir = __opendir_common(fd, flags);
+ dir = __opendir_common(fd, flags, false);
if (dir == NULL) {
saved_errno = errno;
_close(fd);
@@ -110,22 +104,195 @@ opendir_compar(const void *p1, const voi
}
/*
+ * For a directory at the top of a unionfs stack, the entire directory's
+ * contents are read and cached locally until the next call to rewinddir().
+ * For the fdopendir() case, the initial seek position must be preserved.
+ * For rewinddir(), the full directory should always be re-read from the
+ * beginning.
+ *
+ * If an error occurs, the existing buffer and state of 'dirp' is left
+ * unchanged.
+ */
+bool
+_filldir(DIR *dirp, bool use_current_pos)
+{
+ struct dirent **dpv;
+ char *buf, *ddptr, *ddeptr;
+ off_t pos;
+ int fd2, incr, len, n, saved_errno, space;
+
+ len = 0;
+ space = 0;
+ buf = NULL;
+ ddptr = NULL;
+
+ /*
+ * Use the system page size if that is a multiple of DIRBLKSIZ.
+ * Hopefully this can be a big win someday by allowing page
+ * trades to user space to be done by _getdirentries().
+ */
+ incr = getpagesize();
+ if ((incr % DIRBLKSIZ) != 0)
+ incr = DIRBLKSIZ;
+
+ /*
+ * The strategy here is to read all the directory
+ * entries into a buffer, sort the buffer, and
+ * remove duplicate entries by setting the inode
+ * number to zero.
+ *
+ * We reopen the directory because _getdirentries()
+ * on a MNT_UNION mount modifies the open directory,
+ * making it refer to the lower directory after the
+ * upper directory's entries are exhausted.
+ * This would otherwise break software that uses
+ * the directory descriptor for fchdir or *at
+ * functions, such as fts.c.
+ */
+ if ((fd2 = _openat(dirp->dd_fd, ".", O_RDONLY | O_CLOEXEC)) == -1)
+ return (false);
+
+ if (use_current_pos) {
+ pos = lseek(dirp->dd_fd, 0, SEEK_CUR);
+ if (pos == -1 || lseek(fd2, pos, SEEK_SET) == -1) {
+ saved_errno = errno;
+ _close(fd2);
+ errno = saved_errno;
+ return (false);
+ }
+ }
+
+ do {
+ /*
+ * Always make at least DIRBLKSIZ bytes
+ * available to _getdirentries
+ */
+ if (space < DIRBLKSIZ) {
+ space += incr;
+ len += incr;
+ buf = reallocf(buf, len);
+ if (buf == NULL) {
+ saved_errno = errno;
+ _close(fd2);
+ errno = saved_errno;
+ return (false);
+ }
+ ddptr = buf + (len - space);
+ }
+
+ n = _getdirentries(fd2, ddptr, space, &dirp->dd_seek);
+ if (n > 0) {
+ ddptr += n;
+ space -= n;
+ }
+ if (n < 0) {
+ saved_errno = errno;
+ _close(fd2);
+ errno = saved_errno;
+ return (false);
+ }
+ } while (n > 0);
+ _close(fd2);
+
+ ddeptr = ddptr;
+
+ /*
+ * There is now a buffer full of (possibly) duplicate
+ * names.
+ */
+ dirp->dd_buf = buf;
+
+ /*
+ * Go round this loop twice...
+ *
+ * Scan through the buffer, counting entries.
+ * On the second pass, save pointers to each one.
+ * Then sort the pointers and remove duplicate names.
+ */
+ for (dpv = 0;;) {
+ n = 0;
+ ddptr = buf;
+ while (ddptr < ddeptr) {
+ struct dirent *dp;
+
+ dp = (struct dirent *) ddptr;
+ if ((long)dp & 03L)
+ break;
+ if ((dp->d_reclen <= 0) ||
+ (dp->d_reclen > (ddeptr + 1 - ddptr)))
+ break;
+ ddptr += dp->d_reclen;
+ if (dp->d_fileno) {
+ if (dpv)
+ dpv[n] = dp;
+ n++;
+ }
+ }
+
+ if (dpv) {
+ struct dirent *xp;
+
+ /*
+ * This sort must be stable.
+ */
+ mergesort(dpv, n, sizeof(*dpv), opendir_compar);
+
+ dpv[n] = NULL;
+ xp = NULL;
+
+ /*
+ * Scan through the buffer in sort order,
+ * zapping the inode number of any
+ * duplicate names.
+ */
+ for (n = 0; dpv[n]; n++) {
+ struct dirent *dp = dpv[n];
+
+ if ((xp == NULL) ||
+ strcmp(dp->d_name, xp->d_name)) {
+ xp = dp;
+ } else {
+ dp->d_fileno = 0;
+ }
+ if (dp->d_type == DT_WHT &&
+ (dirp->dd_flags & DTF_HIDEW))
+ dp->d_fileno = 0;
+ }
+
+ free(dpv);
+ break;
+ } else {
+ dpv = malloc((n+1) * sizeof(struct dirent *));
+ if (dpv == NULL)
+ break;
+ }
+ }
+
+ dirp->dd_len = len;
+ dirp->dd_size = ddptr - dirp->dd_buf;
+ return (true);
+}
+
+
+/*
* Common routine for opendir(3), __opendir2(3) and fdopendir(3).
*/
static DIR *
-__opendir_common(int fd, int flags)
+__opendir_common(int fd, int flags, bool use_current_pos)
{
DIR *dirp;
int incr;
int saved_errno;
int unionstack;
- int fd2;
-
- fd2 = -1;
if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
return (NULL);
+ dirp->dd_buf = NULL;
+ dirp->dd_fd = fd;
+ dirp->dd_flags = flags;
+ dirp->dd_loc = 0;
+ dirp->dd_lock = NULL;
dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
LIST_INIT(&dirp->dd_td->td_locq);
dirp->dd_td->td_loccnt = 0;
@@ -154,163 +321,39 @@ __opendir_common(int fd, int flags)
}
if (unionstack) {
- int len = 0;
- int space = 0;
- char *buf = 0;
- char *ddptr = 0;
- char *ddeptr;
- int n;
- struct dirent **dpv;
-
- /*
- * The strategy here is to read all the directory
- * entries into a buffer, sort the buffer, and
- * remove duplicate entries by setting the inode
- * number to zero.
- *
- * We reopen the directory because _getdirentries()
- * on a MNT_UNION mount modifies the open directory,
- * making it refer to the lower directory after the
- * upper directory's entries are exhausted.
- * This would otherwise break software that uses
- * the directory descriptor for fchdir or *at
- * functions, such as fts.c.
- */
- if ((fd2 = _openat(fd, ".", O_RDONLY | O_CLOEXEC)) == -1) {
- saved_errno = errno;
- free(buf);
- free(dirp);
- errno = saved_errno;
- return (NULL);
- }
-
- do {
- /*
- * Always make at least DIRBLKSIZ bytes
- * available to _getdirentries
- */
- if (space < DIRBLKSIZ) {
- space += incr;
- len += incr;
- buf = reallocf(buf, len);
- if (buf == NULL)
- goto fail;
- ddptr = buf + (len - space);
- }
-
- n = _getdirentries(fd2, ddptr, space, &dirp->dd_seek);
- if (n > 0) {
- ddptr += n;
- space -= n;
- }
- } while (n > 0);
-
- ddeptr = ddptr;
- flags |= __DTF_READALL;
-
- _close(fd2);
- fd2 = -1;
-
- /*
- * There is now a buffer full of (possibly) duplicate
- * names.
- */
- dirp->dd_buf = buf;
-
- /*
- * Go round this loop twice...
- *
- * Scan through the buffer, counting entries.
- * On the second pass, save pointers to each one.
- * Then sort the pointers and remove duplicate names.
- */
- for (dpv = 0;;) {
- n = 0;
- ddptr = buf;
- while (ddptr < ddeptr) {
- struct dirent *dp;
-
- dp = (struct dirent *) ddptr;
- if ((long)dp & 03L)
- break;
- if ((dp->d_reclen <= 0) ||
- (dp->d_reclen > (ddeptr + 1 - ddptr)))
- break;
- ddptr += dp->d_reclen;
- if (dp->d_fileno) {
- if (dpv)
- dpv[n] = dp;
- n++;
- }
- }
-
- if (dpv) {
- struct dirent *xp;
-
- /*
- * This sort must be stable.
- */
- mergesort(dpv, n, sizeof(*dpv),
- opendir_compar);
-
- dpv[n] = NULL;
- xp = NULL;
-
- /*
- * Scan through the buffer in sort order,
- * zapping the inode number of any
- * duplicate names.
- */
- for (n = 0; dpv[n]; n++) {
- struct dirent *dp = dpv[n];
-
- if ((xp == NULL) ||
- strcmp(dp->d_name, xp->d_name)) {
- xp = dp;
- } else {
- dp->d_fileno = 0;
- }
- if (dp->d_type == DT_WHT &&
- (flags & DTF_HIDEW))
- dp->d_fileno = 0;
- }
-
- free(dpv);
- break;
- } else {
- dpv = malloc((n+1) * sizeof(struct dirent *));
- if (dpv == NULL)
- break;
- }
- }
-
- dirp->dd_len = len;
- dirp->dd_size = ddptr - dirp->dd_buf;
+ if (!_filldir(dirp, use_current_pos))
+ goto fail;
+ dirp->dd_flags |= __DTF_READALL;
} else {
dirp->dd_len = incr;
- dirp->dd_size = 0;
dirp->dd_buf = malloc(dirp->dd_len);
if (dirp->dd_buf == NULL)
goto fail;
- dirp->dd_seek = 0;
+ if (use_current_pos) {
+ /*
+ * Read the first batch of directory entries
+ * to prime dd_seek. This also checks if the
+ * fd passed to fdopendir() is a directory.
+ */
+ dirp->dd_size = _getdirentries(dirp->dd_fd,
+ dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
+ if (dirp->dd_size < 0) {
+ if (errno == EINVAL)
+ errno = ENOTDIR;
+ goto fail;
+ }
+ dirp->dd_flags |= __DTF_SKIPREAD;
+ } else {
+ dirp->dd_size = 0;
+ dirp->dd_seek = 0;
+ }
}
- dirp->dd_loc = 0;
- dirp->dd_fd = fd;
- dirp->dd_flags = flags;
- dirp->dd_lock = NULL;
-
- /*
- * Set up seek point for rewinddir.
- */
- dirp->dd_rewind = telldir(dirp);
-
return (dirp);
fail:
saved_errno = errno;
- if (fd2 != -1)
- _close(fd2);
+ free(dirp->dd_buf);
free(dirp);
errno = saved_errno;
return (NULL);
Modified: head/lib/libc/gen/readdir.c
==============================================================================
--- head/lib/libc/gen/readdir.c Fri Jul 11 14:34:29 2014 (r268530)
+++ head/lib/libc/gen/readdir.c Fri Jul 11 16:16:26 2014 (r268531)
@@ -61,12 +61,14 @@ _readdir_unlocked(dirp, skip)
return (NULL);
dirp->dd_loc = 0;
}
- if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
+ if (dirp->dd_loc == 0 &&
+ !(dirp->dd_flags & (__DTF_READALL | __DTF_SKIPREAD))) {
dirp->dd_size = _getdirentries(dirp->dd_fd,
dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
if (dirp->dd_size <= 0)
return (NULL);
}
+ dirp->dd_flags &= ~__DTF_SKIPREAD;
dp = (struct dirent *)(dirp->dd_buf + dirp->dd_loc);
if ((long)dp & 03L) /* bogus pointer check */
return (NULL);
Modified: head/lib/libc/gen/rewinddir.c
==============================================================================
--- head/lib/libc/gen/rewinddir.c Fri Jul 11 14:34:29 2014 (r268530)
+++ head/lib/libc/gen/rewinddir.c Fri Jul 11 16:16:26 2014 (r268531)
@@ -33,9 +33,14 @@ static char sccsid[] = "@(#)rewinddir.c
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
+#include "namespace.h"
#include <sys/types.h>
#include <dirent.h>
+#include <pthread.h>
+#include <unistd.h>
+#include "un-namespace.h"
+#include "libc_private.h"
#include "gen-private.h"
#include "telldir.h"
@@ -44,6 +49,15 @@ rewinddir(dirp)
DIR *dirp;
{
- _seekdir(dirp, dirp->dd_rewind);
- dirp->dd_rewind = telldir(dirp);
+ if (__isthreaded)
+ _pthread_mutex_lock(&dirp->dd_lock);
+ if (dirp->dd_flags & __DTF_READALL)
+ _filldir(dirp, false);
+ else if (dirp->dd_seek != 0) {
+ (void) lseek(dirp->dd_fd, 0, SEEK_SET);
+ dirp->dd_seek = 0;
+ }
+ dirp->dd_loc = 0;
+ if (__isthreaded)
+ _pthread_mutex_unlock(&dirp->dd_lock);
}
Modified: head/lib/libc/gen/telldir.h
==============================================================================
--- head/lib/libc/gen/telldir.h Fri Jul 11 14:34:29 2014 (r268530)
+++ head/lib/libc/gen/telldir.h Fri Jul 11 16:16:26 2014 (r268531)
@@ -36,6 +36,7 @@
#define _TELLDIR_H_
#include <sys/queue.h>
+#include <stdbool.h>
/*
* One of these structures is malloced to describe the current directory
@@ -59,6 +60,7 @@ struct _telldir {
long td_loccnt; /* index of entry for sequential readdir's */
};
+bool _filldir(DIR *, bool);
struct dirent *_readdir_unlocked(DIR *, int);
void _reclaim_telldir(DIR *);
void _seekdir(DIR *, long);
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