#include <sys/param.h>
#include <sys/mount.h>
#include <sys/stat.h>
+#include <sys/sysctl.h>
#include <dirent.h>
#include <errno.h>
#include "telldir.h"
-static DIR * __opendir_common(int, const char *, int);
+static bool
+__kernel_supports_unionfs(void)
+{
+ static int8_t kernel_supports_unionfs = -1;
+ if (kernel_supports_unionfs == -1) {
+ int value = 0;
+ size_t len = sizeof(value);
+ sysctlbyname("kern.secure_kernel", &value, &len, NULL, 0);
+ kernel_supports_unionfs = !value;
+ }
+ return kernel_supports_unionfs;
+}
+
+static int
+__fd_is_on_union_mount(int fd)
+{
+ struct statfs stbuf;
+ int rc;
+
+ rc = fstatfs(fd, &stbuf);
+ if (rc < 0) {
+ return rc;
+ }
+ return (stbuf.f_flags & MNT_UNION) != 0;
+}
+
+static DIR * __opendir_common(int, int, bool);
/*
* Open a directory.
errno = ENOTDIR;
return (NULL);
}
+ /* Make sure CLOEXEC is set on the fd */
if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
return (NULL);
- return (__opendir_common(fd, NULL, DTF_HIDEW|DTF_NODUP));
+ return (__opendir_common(fd, DTF_HIDEW|DTF_NODUP, true));
}
DIR *
__opendir2(const char *name, int flags)
{
int fd;
+ 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);
- return __opendir_common(fd, name, flags);
+ dir = __opendir_common(fd, flags, false);
+ if (dir == NULL) {
+ saved_errno = errno;
+ _close(fd);
+ errno = saved_errno;
+ }
+ return (dir);
}
static int
}
/*
- * Common routine for opendir(3), __opendir2(3) and fdopendir(3).
+ * 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.
*/
-static DIR *
-__opendir_common(int fd, const char *name, int flags)
+bool
+_filldir(DIR *dirp, bool use_current_pos)
{
- DIR *dirp;
- int incr;
- int saved_errno;
- int unionstack;
-
- if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
- return (NULL);
-
- dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
- LIST_INIT(&dirp->dd_td->td_locq);
- dirp->dd_td->td_loccnt = 0;
+ 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.
incr = DIRBLKSIZ;
/*
- * Determine whether this directory is the top of a union stack.
+ * 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 (flags & DTF_NODUP) {
- struct statfs sfb;
-
- if (_fstatfs(fd, &sfb) < 0)
- goto fail;
- unionstack = !strcmp(sfb.f_fstypename, "unionfs")
- || (sfb.f_flags & MNT_UNION);
- } else {
- unionstack = 0;
+ 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);
+ }
}
- if (unionstack) {
- int len = 0;
- int space = 0;
- char *buf = 0;
- char *ddptr = 0;
- char *ddeptr;
- int n;
- struct dirent **dpv;
-
+ do {
/*
- * 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.
+ * Always make at least DIRBLKSIZ bytes
+ * available to _getdirentries
*/
-
- 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);
+ 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);
+ }
#if __DARWIN_64_BIT_INO_T
- n = (int)__getdirentries64(fd, ddptr, space, &dirp->dd_td->seekoff);
+ n = (int)__getdirentries64(fd2, ddptr, space, &dirp->dd_td->seekoff);
#else /* !__DARWIN_64_BIT_INO_T */
- n = _getdirentries(fd, ddptr, space, &dirp->dd_seek);
+ n = _getdirentries(fd2, ddptr, space, &dirp->dd_seek);
#endif /* __DARWIN_64_BIT_INO_T */
- if (n > 0) {
- ddptr += n;
- space -= n;
- }
- } while (n > 0);
+ 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;
- flags |= __DTF_READALL;
+ ddeptr = ddptr;
- /*
- * Re-open the directory.
- * This has the effect of rewinding back to the
- * top of the union stack and is needed by
- * programs which plan to fchdir to a descriptor
- * which has also been read -- see fts.c.
- */
- if (flags & DTF_REWIND) {
- (void)_close(fd);
- if ((fd = _open(name, O_RDONLY | O_DIRECTORY)) == -1) {
- saved_errno = errno;
- free(buf);
- free(dirp);
- errno = saved_errno;
- return (NULL);
+ /*
+ * 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 = NULL;;) {
+ 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++;
}
}
- /*
- * There is now a buffer full of (possibly) duplicate
- * names.
- */
- dirp->dd_buf = buf;
+ if (dpv) {
+ struct dirent *xp;
- /*
- * 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++;
- }
- }
+ /*
+ * This sort must be stable.
+ */
+ mergesort(dpv, n, sizeof(*dpv), opendir_compar);
+
+ dpv[n] = NULL;
+ xp = NULL;
- 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;
+ /*
+ * 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);
+ free(dpv);
+ break;
+ } else {
+ dpv = malloc((n+1) * sizeof(struct dirent *));
+ if (dpv == NULL)
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);
+}
+
- dirp->dd_len = len;
- dirp->dd_size = ddptr - dirp->dd_buf;
+/*
+ * Common routine for opendir(3), __opendir2(3) and fdopendir(3).
+ */
+static DIR *
+__opendir_common(int fd, int flags, bool use_current_pos)
+{
+ DIR *dirp;
+ int saved_errno;
+ int unionstack;
+
+ 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 = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
+ dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
+ LIST_INIT(&dirp->dd_td->td_locq);
+ dirp->dd_td->td_loccnt = 0;
+
+ /*
+ * Determine whether this directory is the top of a union stack.
+ */
+ if ((flags & DTF_NODUP) && __kernel_supports_unionfs()) {
+ unionstack = __fd_is_on_union_mount(fd);
+ if (unionstack < 0)
+ goto fail;
} else {
- dirp->dd_len = incr;
- dirp->dd_size = 0;
+ unionstack = 0;
+ }
+
+ if (unionstack) {
+ if (!_filldir(dirp, use_current_pos))
+ goto fail;
+ dirp->dd_flags |= __DTF_READALL;
+ } else {
+ /*
+ * Start with a small-ish size to avoid allocating full pages.
+ * readdir() will allocate a larger buffer if it didn't fit
+ * to stay fast for large directories.
+ */
+ _Static_assert(GETDIRENTRIES64_EXTENDED_BUFSIZE <= READDIR_INITIAL_SIZE,
+ "Make sure we'll get extended metadata");
+ dirp->dd_len = READDIR_INITIAL_SIZE;
dirp->dd_buf = malloc(dirp->dd_len);
if (dirp->dd_buf == NULL)
goto fail;
+ 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.
+ */
+#if __DARWIN_64_BIT_INO_T
+ /*
+ * sufficiently recent kernels when the buffer is large enough,
+ * will use the last bytes of the buffer to return status.
+ *
+ * To support older kernels:
+ * - make sure it's 0 initialized
+ * - make sure it's past `dd_size` before reading it
+ */
+ getdirentries64_flags_t *gdeflags =
+ (getdirentries64_flags_t *)(dirp->dd_buf + dirp->dd_len -
+ sizeof(getdirentries64_flags_t));
+ *gdeflags = 0;
+ dirp->dd_size = (long)__getdirentries64(dirp->dd_fd,
+ dirp->dd_buf, dirp->dd_len, &dirp->dd_td->seekoff);
+ if (dirp->dd_size >= 0 &&
+ dirp->dd_size <= dirp->dd_len - sizeof(getdirentries64_flags_t)) {
+ if (*gdeflags & GETDIRENTRIES64_EOF) {
+ dirp->dd_flags |= __DTF_ATEND;
+ }
+ }
+#else /* !__DARWIN_64_BIT_INO_T */
+ dirp->dd_size = _getdirentries(dirp->dd_fd,
+ dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
+#endif /* __DARWIN_64_BIT_INO_T */
+ if (dirp->dd_size < 0) {
+ if (errno == EINVAL)
+ errno = ENOTDIR;
+ goto fail;
+ }
+ dirp->dd_flags |= __DTF_SKIPREAD;
+ } else {
+ dirp->dd_size = 0;
#if __DARWIN_64_BIT_INO_T
- dirp->dd_td->seekoff = 0;
+ dirp->dd_td->seekoff = 0;
#else /* !__DARWIN_64_BIT_INO_T */
- dirp->dd_seek = 0;
+ dirp->dd_seek = 0;
#endif /* __DARWIN_64_BIT_INO_T */
- flags &= ~DTF_REWIND;
+ }
}
- dirp->dd_loc = 0;
- dirp->dd_fd = fd;
- dirp->dd_flags = flags;
- dirp->dd_lock = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
-
- /*
- * Set up seek point for rewinddir.
- */
- dirp->dd_rewind = telldir(dirp);
-
return (dirp);
fail:
saved_errno = errno;
+ free(dirp->dd_buf);
free(dirp);
- (void)_close(fd);
errno = saved_errno;
return (NULL);
}
projects / apple / libc.git / blobdiff