/* $NetBSD: initdir.c,v 1.5 2021/07/11 16:30:41 kre Exp $ */ /* * Copyright (c) 1983, 1993 * 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. 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. */ #include <sys/cdefs.h> #if defined(LIBC_SCCS) && !defined(lint) __RCSID("$NetBSD: initdir.c,v 1.5 2021/07/11 16:30:41 kre Exp $"); #endif /* LIBC_SCCS and not lint */ #include "namespace.h" #include "reentrant.h" #include "extern.h" #include <sys/param.h> #include <assert.h> #include <dirent.h> #include <errno.h> #include <fcntl.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include "dirent_private.h" #define MAXITERATIONS 100 int _initdir(DIR *dirp, int fd, const char *name) { int flags = dirp->dd_flags; int pagesz; int incr; /* * If the machine's page size is an exact multiple of DIRBLKSIZ, * use a buffer that is cluster boundary aligned. * Hopefully this can be a big win someday by allowing page trades * to user space to be done by getdents() */ if (((pagesz = getpagesize()) % DIRBLKSIZ) == 0) incr = pagesz; else incr = DIRBLKSIZ; if ((flags & DTF_REWIND) && name == NULL) { return EINVAL; } if ((flags & __DTF_READALL) != 0) { size_t len; size_t space; char *buf, *nbuf; char *ddptr; char *ddeptr; int n; struct dirent **dpv; int i; /* * The strategy here for directories on top of a union stack * is to read all the directory entries into a buffer, sort * the buffer, and remove duplicate entries by setting the * inode number to zero. * * For directories on an NFS mounted filesystem, we try * to get a consistent snapshot by trying until we have * successfully read all of the directory without errors * (i.e. 'bad cookie' errors from the server because * the directory was modified). These errors should not * happen often, but need to be dealt with. */ i = 0; retry: len = 0; space = 0; buf = 0; ddptr = 0; do { /* * Always make at least DIRBLKSIZ bytes * available to getdents */ if (space < DIRBLKSIZ) { space += incr; len += incr; nbuf = realloc(buf, len); if (nbuf == NULL) { dirp->dd_buf = buf; return errno; } buf = nbuf; ddptr = buf + (len - space); } dirp->dd_seek = lseek(fd, (off_t)0, SEEK_CUR); n = getdents(fd, ddptr, space); /* * For NFS: EINVAL means a bad cookie error * from the server. Keep trying to get a * consistent view, in this case this means * starting all over again. */ if (n == -1 && errno == EINVAL && (flags & __DTF_RETRY_ON_BADCOOKIE) != 0) { free(buf); lseek(fd, (off_t)0, SEEK_SET); if (++i > MAXITERATIONS) return EINVAL; goto retry; } if (n > 0) { ddptr += n; space -= n; } } while (n > 0); 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_CLOEXEC)) == -1) { dirp->dd_buf = buf; return errno; } } /* * 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. */ if ((flags & DTF_NODUP) != 0) { for (dpv = 0;;) { for (n = 0, ddptr = buf; ddptr < ddeptr;) { struct dirent *dp; dp = (struct dirent *)(void *)ddptr; if ((long)dp & _DIRENT_ALIGN(dp)) break; /* * d_reclen is unsigned, * so no need to compare <= 0 */ if (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, (size_t)n, sizeof(*dpv), (int (*)(const void *, const void *))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; 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; } } } _DIAGASSERT(__type_fit(int, len)); dirp->dd_len = (int)len; dirp->dd_size = ddptr - dirp->dd_buf; } else { dirp->dd_len = incr; dirp->dd_size = 0; dirp->dd_buf = malloc((size_t)dirp->dd_len); if (dirp->dd_buf == NULL) return errno; dirp->dd_seek = 0; flags &= ~DTF_REWIND; } dirp->dd_loc = 0; dirp->dd_fd = fd; dirp->dd_flags = flags; /* * Set up seek point for rewinddir. */ (void)_telldir_unlocked(dirp); return 0; } void _finidir(DIR *dirp) { struct dirpos *poslist; free(dirp->dd_buf); /* free seekdir/telldir storage */ for (poslist = dirp->dd_internal; poslist; ) { struct dirpos *nextpos = poslist->dp_next; free(poslist); poslist = nextpos; } dirp->dd_internal = NULL; }
