diff options
Diffstat (limited to 'newlib/libc/posix/telldir.c')
| -rw-r--r-- | newlib/libc/posix/telldir.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/newlib/libc/posix/telldir.c b/newlib/libc/posix/telldir.c new file mode 100644 index 00000000000..90b12f99cbd --- /dev/null +++ b/newlib/libc/posix/telldir.c @@ -0,0 +1,133 @@ +#ifndef HAVE_OPENDIR + +/* + * Copyright (c) 1983 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 sccsid[] = "@(#)telldir.c 5.9 (Berkeley) 2/23/91"; +#endif /* LIBC_SCCS and not lint */ + +#include <sys/param.h> +#include <dirent.h> +#include <stdlib.h> +#include <unistd.h> + +/* + * The option SINGLEUSE may be defined to say that a telldir + * cookie may be used only once before it is freed. This option + * is used to avoid having memory usage grow without bound. + */ +#define SINGLEUSE + +/* + * One of these structures is malloced to describe the current directory + * position each time telldir is called. It records the current magic + * cookie returned by getdirentries and the offset within the buffer + * associated with that return value. + */ +struct ddloc { + struct ddloc *loc_next;/* next structure in list */ + long loc_index; /* key associated with structure */ + long loc_seek; /* magic cookie returned by getdirentries */ + long loc_loc; /* offset of entry in buffer */ +}; + +#define NDIRHASH 32 /* Num of hash lists, must be a power of 2 */ +#define LOCHASH(i) ((i)&(NDIRHASH-1)) + +static long dd_loccnt; /* Index of entry for sequential readdir's */ +static struct ddloc *dd_hash[NDIRHASH]; /* Hash list heads for ddlocs */ + +/* + * return a pointer into a directory + */ +long +telldir(dirp) + const DIR *dirp; +{ + register int index; + register struct ddloc *lp; + + if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL) + return (-1); + index = dd_loccnt++; + lp->loc_index = index; + lp->loc_seek = dirp->dd_seek; + lp->loc_loc = dirp->dd_loc; + lp->loc_next = dd_hash[LOCHASH(index)]; + dd_hash[LOCHASH(index)] = lp; + return (index); +} + +/* + * seek to an entry in a directory. + * Only values returned by "telldir" should be passed to seekdir. + */ +void +_seekdir(dirp, loc) + register DIR *dirp; + long loc; +{ + register struct ddloc *lp; + register struct ddloc **prevlp; + struct dirent *dp; + extern long lseek(); + + prevlp = &dd_hash[LOCHASH(loc)]; + lp = *prevlp; + while (lp != NULL) { + if (lp->loc_index == loc) + break; + prevlp = &lp->loc_next; + lp = lp->loc_next; + } + if (lp == NULL) + return; + if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) + goto found; + (void) lseek(dirp->dd_fd, lp->loc_seek, 0); + dirp->dd_seek = lp->loc_seek; + dirp->dd_loc = 0; + while (dirp->dd_loc < lp->loc_loc) { + dp = readdir(dirp); + if (dp == NULL) + break; + } +found: +#ifdef SINGLEUSE + *prevlp = lp->loc_next; + free((caddr_t)lp); +#endif +} + +#endif /* ! HAVE_OPENDIR */ |