diff options
Diffstat (limited to 'sys/miscfs/union/libc.opendir.c')
| -rw-r--r-- | sys/miscfs/union/libc.opendir.c | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/sys/miscfs/union/libc.opendir.c b/sys/miscfs/union/libc.opendir.c new file mode 100644 index 0000000..99ed58b --- /dev/null +++ b/sys/miscfs/union/libc.opendir.c @@ -0,0 +1,225 @@ +/* + * Copyright (c) 1983, 1993, 1994 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#if defined(LIBC_SCCS) && !defined(lint) +static char orig_sccsid[] = "@(#)opendir.c 8.2 (Berkeley) 2/12/94"; +static char sccsid[] = "@(#)libc.opendir.c 8.1 (Berkeley) 2/15/94"; +#endif /* LIBC_SCCS and not lint */ + +#include <sys/param.h> +#include <sys/mount.h> + +#include <dirent.h> +#include <fcntl.h> +#include <stdlib.h> +#include <unistd.h> + +/* + * open a directory. + */ +DIR * +opendir(name) + const char *name; +{ + DIR *dirp; + int fd; + int incr; + struct statfs sfb; + + if ((fd = open(name, 0)) == -1) + return (NULL); + if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 || + (dirp = (DIR *)malloc(sizeof(DIR))) == NULL) { + close(fd); + return (NULL); + } + + /* + * If CLBYTES is an exact multiple of DIRBLKSIZ, use a CLBYTES + * buffer that it cluster boundary aligned. + * Hopefully this can be a big win someday by allowing page + * trades trade to user space to be done by getdirentries() + */ + if ((CLBYTES % DIRBLKSIZ) == 0) + incr = CLBYTES; + else + incr = DIRBLKSIZ; + +#ifdef MOUNT_UNION + /* + * Determine whether this directory is the top of a union stack. + */ + if (fstatfs(fd, &sfb) < 0) { + free(dirp); + close(fd); + return (NULL); + } + + if (sfb.f_type == MOUNT_UNION) { + int len = 0; + int space = 0; + char *buf = 0; + char *ddptr = 0; + 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. + */ + + /* + * Fixup dd_loc to be non-zero to fake out readdir + */ + dirp->dd_loc = sizeof(void *); + + do { + /* + * Always make at least DIRBLKSIZ bytes + * available to getdirentries + */ + if (space < DIRBLKSIZ) { + space += incr; + len += incr; + buf = realloc(buf, len); + if (buf == NULL) { + free(dirp); + close(fd); + return (NULL); + } + ddptr = buf + (len - space) + dirp->dd_loc; + } + + n = getdirentries(fd, ddptr, space, &dirp->dd_seek); + if (n > 0) { + ddptr += n; + space -= n; + } + } while (n > 0); + + /* + * 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 + dirp->dd_loc; + while (ddptr < buf + len) { + struct dirent *dp; + + dp = (struct dirent *) ddptr; + if ((int)dp & 03) + break; + if ((dp->d_reclen <= 0) || + (dp->d_reclen > (buf + len + 1 - ddptr))) + break; + ddptr += dp->d_reclen; + if (dp->d_fileno) { + if (dpv) + dpv[n] = dp; + n++; + } + } + + if (dpv) { + struct dirent *xp; + + /* + * If and when whiteouts happen, + * this sort would need to be stable. + */ + heapsort(dpv, n, sizeof(*dpv), alphasort); + + 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; + } + + 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; + } else +#endif /* MOUNT_UNION */ + { + dirp->dd_len = incr; + dirp->dd_buf = malloc(dirp->dd_len); + if (dirp->dd_buf == NULL) { + free(dirp); + close (fd); + return (NULL); + } + dirp->dd_seek = 0; + dirp->dd_loc = 0; + } + + dirp->dd_fd = fd; + + /* + * Set up seek point for rewinddir. + */ + dirp->dd_rewind = telldir(dirp); + + return (dirp); +} |
