| /* Copyright (C) 1994, 1995, 1996, 1997, 1999 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include <errno.h> |
| #include <stddef.h> |
| #include <dirent.h> |
| #include <unistd.h> |
| #include <sys/types.h> |
| #include <stdlib.h> |
| #include "dirstream.h" |
| |
| /* Internal data structure for telldir and seekdir. */ |
| struct record |
| { |
| struct record *next; /* Link in chain. */ |
| off_t cookie; /* Value returned by `telldir'. */ |
| off_t pos; |
| size_t offset; |
| }; |
| #define NBUCKETS 32 |
| static struct record *records[32]; |
| static off_t lastpos; |
| __libc_lock_define_initialized(static, lock) /* Locks above data. */ |
| |
| |
| /* Return the current position of DIRP. */ |
| long int |
| telldir (dirp) |
| DIR *dirp; |
| { |
| struct record *new; |
| long int pos; |
| |
| new = malloc (sizeof *new); |
| if (new == NULL) |
| return -1l; |
| |
| __libc_lock_lock (lock); |
| |
| new->pos = dirp->filepos; |
| new->offset = dirp->offset; |
| new->cookie = ++lastpos; |
| new->next = records[new->cookie % NBUCKETS]; |
| records[new->cookie % NBUCKETS] = new; |
| |
| pos = new->cookie; |
| |
| __libc_lock_unlock (lock); |
| |
| return pos; |
| } |
| |
| |
| |
| /* Seek to position POS in DIRP. */ |
| void |
| seekdir (dirp, pos) |
| DIR *dirp; |
| long int pos; |
| { |
| struct record *r, **prevr; |
| |
| __libc_lock_lock (lock); |
| |
| for (prevr = &records[pos % NBUCKETS], r = *prevr; |
| r != NULL; |
| prevr = &r->next, r = r->next) |
| if (r->cookie == pos) |
| { |
| __libc_lock_lock (dirp->__lock); |
| if (dirp->filepos != r->pos || dirp->offset != r->offset) |
| { |
| dirp->size = 0; /* Must read a fresh buffer. */ |
| /* Move to the saved position. */ |
| __lseek (dirp->fd, r->pos, SEEK_SET); |
| dirp->filepos = r->pos; |
| dirp->offset = 0; |
| /* Read entries until we reach the saved offset. */ |
| while (dirp->offset < r->offset) |
| { |
| struct dirent *scan; |
| __libc_lock_unlock (dirp->__lock); |
| scan = readdir (dirp); |
| __libc_lock_lock (dirp->__lock); |
| if (! scan) |
| break; |
| } |
| } |
| __libc_lock_unlock (dirp->__lock); |
| |
| /* To prevent leaking memory, cookies returned from telldir |
| can only be used once. So free this one's record now. */ |
| *prevr = r->next; |
| free (r); |
| break; |
| } |
| |
| __libc_lock_unlock (lock); |
| |
| /* If we lost there is no way to indicate it. Oh well. */ |
| } |