diff options
author | Roland McGrath <roland@gnu.org> | 1995-02-18 01:27:10 +0000 |
---|---|---|
committer | Roland McGrath <roland@gnu.org> | 1995-02-18 01:27:10 +0000 |
commit | 28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch) | |
tree | 15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/unix/bsd/telldir.c | |
download | glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar.gz glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar.bz2 glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.zip |
initial import
Diffstat (limited to 'sysdeps/unix/bsd/telldir.c')
-rw-r--r-- | sysdeps/unix/bsd/telldir.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/sysdeps/unix/bsd/telldir.c b/sysdeps/unix/bsd/telldir.c new file mode 100644 index 0000000000..0321f954b8 --- /dev/null +++ b/sysdeps/unix/bsd/telldir.c @@ -0,0 +1,93 @@ +/* Copyright (C) 1994 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 Library General Public License as +published by the Free Software Foundation; either version 2 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 +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +#include <ansidecl.h> +#include <errno.h> +#include <stddef.h> +#include <dirent.h> +#include <unistd.h> +#include <sys/types.h> +#include <stdlib.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; + + +/* Return the current position of DIRP. */ +off_t +DEFUN(telldir, (dirp), DIR *dirp) +{ + struct record *new; + + new = malloc (sizeof *new); + if (new == NULL) + return (off_t) -1; + + new->pos = dirp->__pos; + new->offset = dirp->__offset; + new->cookie = ++lastpos; + new->next = records[new->cookie % NBUCKETS]; + records[new->cookie % NBUCKETS] = new; + + return new->cookie; +} + + + +/* Seek to position POS in DIRP. */ +void +DEFUN(seekdir, (dirp, pos), DIR *dirp AND __off_t pos) +{ + struct record *r, **prevr; + + for (prevr = &records[pos % NBUCKETS], r = *prevr; + r != NULL; + prevr = &r->next, r = r->next) + if (r->cookie == pos) + { + if (dirp->__pos != 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->__pos = r->pos; + dirp->__offset = 0; + /* Read entries until we reach the saved offset. */ + while (dirp->__offset < r->offset) + if (readdir (dirp) == NULL) + break; + } + + /* 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); + return; + } + + /* We lost, but have no way to indicate it. Oh well. */ +} |