/*- * SPDX-License-Identifier: BSD-3-Clause * * 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 "namespace.h" #include <sys/param.h> #include <sys/queue.h> #include <dirent.h> #include <pthread.h> #include <stdlib.h> #include <unistd.h> #include "un-namespace.h" #include "libc_private.h" #include "gen-private.h" #include "telldir.h" /* * return a pointer into a directory */ long telldir(DIR *dirp) { struct ddloc_mem *lp, *flp; union ddloc_packed ddloc; if (__isthreaded) _pthread_mutex_lock(&dirp->dd_lock); /* * Outline: * 1) If the directory position fits in a packed structure, return that. * 2) Otherwise, see if it's already been recorded in the linked list * 3) Otherwise, malloc a new one */ if (dirp->dd_seek < (off_t)(1l << DD_SEEK_BITS) && dirp->dd_loc < (1l << DD_LOC_BITS)) { ddloc.s.is_packed = 1; ddloc.s.loc = dirp->dd_loc; ddloc.s.seek = dirp->dd_seek; goto out; } flp = NULL; LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { if (lp->loc_seek == dirp->dd_seek) { if (flp == NULL) flp = lp; if (lp->loc_loc == dirp->dd_loc) break; } else if (flp != NULL) { lp = NULL; break; } } if (lp == NULL) { lp = malloc(sizeof(struct ddloc_mem)); if (lp == NULL) { if (__isthreaded) _pthread_mutex_unlock(&dirp->dd_lock); return (-1); } lp->loc_index = dirp->dd_td->td_loccnt++; lp->loc_seek = dirp->dd_seek; lp->loc_loc = dirp->dd_loc; if (flp != NULL) LIST_INSERT_BEFORE(flp, lp, loc_lqe); else LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe); } ddloc.i.is_packed = 0; /* * Technically this assignment could overflow on 32-bit architectures, * but we would get ENOMEM long before that happens. */ ddloc.i.index = lp->loc_index; out: if (__isthreaded) _pthread_mutex_unlock(&dirp->dd_lock); return (ddloc.l); } /* * seek to an entry in a directory. * Only values returned by "telldir" should be passed to seekdir. */ void _seekdir(DIR *dirp, long loc) { struct ddloc_mem *lp; struct dirent *dp; union ddloc_packed ddloc; off_t loc_seek; size_t loc_loc; ddloc.l = loc; if (ddloc.s.is_packed) { loc_seek = ddloc.s.seek; loc_loc = ddloc.s.loc; } else { LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { if (lp->loc_index == ddloc.i.index) break; } if (lp == NULL) return; loc_seek = lp->loc_seek; loc_loc = lp->loc_loc; } if (loc_loc == dirp->dd_loc && loc_seek == dirp->dd_seek) return; /* If it's within the same chunk of data, don't bother reloading. */ if (loc_seek == dirp->dd_seek) { /* * If we go back to 0 don't make the next readdir * trigger a call to getdirentries(). */ if (loc_loc == 0) dirp->dd_flags |= __DTF_SKIPREAD; dirp->dd_loc = loc_loc; return; } (void) lseek(dirp->dd_fd, (off_t)loc_seek, SEEK_SET); dirp->dd_seek = loc_seek; dirp->dd_loc = 0; dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */ while (dirp->dd_loc < loc_loc) { dp = _readdir_unlocked(dirp, 0); if (dp == NULL) break; } } /* * After readdir returns the last entry in a block, a call to telldir * returns a location that is after the end of that last entry. * However, that location doesn't refer to a valid directory entry. * Ideally, the call to telldir would return a location that refers to * the first entry in the next block. That location is not known * until the next block is read, so readdir calls this function after * fetching a new block to fix any such telldir locations. */ void _fixtelldir(DIR *dirp, off_t oldseek, size_t oldloc) { struct ddloc_mem *lp; lp = LIST_FIRST(&dirp->dd_td->td_locq); if (lp != NULL) { if (lp->loc_loc == oldloc && lp->loc_seek == oldseek) { lp->loc_seek = dirp->dd_seek; lp->loc_loc = dirp->dd_loc; } } } /* * Reclaim memory for telldir cookies which weren't used. */ void _reclaim_telldir(DIR *dirp) { struct ddloc_mem *lp; struct ddloc_mem *templp; lp = LIST_FIRST(&dirp->dd_td->td_locq); while (lp != NULL) { templp = lp; lp = LIST_NEXT(lp, loc_lqe); free(templp); } LIST_INIT(&dirp->dd_td->td_locq); }
