bostic@OKEEFFE.BERKELEY.EDU.UUCP (03/28/87)
Subject: V7 directory reading routines
Index: lib/libc/gen
Description:
There is a bug in the directory reading compatibility
routines as originally distributed by Berkeley; readdir
fails if you have more than one directory open at a
time.
Repeat-By:
Run the program bug.c, provided in the attached shar, in
any directory containing several files.
Fix:
Unshar and install the attached; make sure you read the
README.
... cut here ...
echo x - Makefile
sed 's/^X//' >Makefile << 'END-of-Makefile'
X# @(#)Makefile 4.8 (Berkeley) 3/21/83
X
XDESTDIR =
XCFLAGS= -O
X
XOBJS= closedir.o opendir.o readdir.o scandir.o seekdir.o telldir.o
XDIST= README Makefile dir.h closedir.c opendir.c readdir.c \
X scandir.c seekdir.c telldir.c directory.3 scandir.3
X
X.c.o:
X ${CC} ${CFLAGS} -I. -c $*.c
X -ld -x -r $*.o
X mv a.out $*.o
X
Xlibndir: ${OBJS}
X ar cru libndir.a ${OBJS}
X ranlib libndir.a
X
Xinstall: libndir
X cp ndir.h ${DESTDIR}/usr/include/ndir.h
X cp libndir.a ${DESTDIR}/usr/lib/libndir.a
X ranlib ${DESTDIR}/usr/lib/libndir.a
X cp directory.3 /usr/man/man3/directory.3
X cp scandir.3 /usr/man/man3/scandir.3
X
Xclean:
X rm -f libndir.a ${OBJS}
END-of-Makefile
echo x - README
sed 's/^X//' >README << 'END-of-README'
X The purpose of this library is to simulate the new, flexible
Xlength directory names on top of the V7 style directory format, as well
Xas to provide compatibility routines for systems that do not intend to
Xconvert to the new directory format.
X These are copies of Kirk McKusick's original routines, with the
Xaddition of scandir(3), a major fix to readdir(3), and minor hacks. We
Xhave also added a define for the V7 directory structure, "struct v7direct"
Xso that both the old and new directory structures can coexist. You can
Xreplace your current system "dir.h" with "ndir.h", if you want to,
Xas long as you change every instance of "struct direct" in your current
Xsystem to "struct v7direct". This is a pain, but desirable if you want
Xthe directory reading routines to be a part of your standard library and
Xnot require special effort to access.
X There are a couple of fairly interesting situations you can get
Xinto with this package; if you are having difficulties, check to make
Xsure you're using the correct "dir.h" include file and that you're using
Xthe "DIRSIZ" macro correctly, since it changed in meaning in the new file
Xsystem. The simplest way to deal with the "DIRSIZ" problem is to change
Xevery occurrence in your system to "MAXNAMLEN"; this is compatible with
X4.3BSD.
X This package also requires that you have an entry of the form
X"typedef long u_long;" in your sys/types.h file.
X In any case, if you have problems using or installing this
Xpackage, contact me.
X Oh, yes, "bug.c" demonstrates the bug in the old readdir(3)
Xroutine.
X
X Keith Bostic 3/27/87
X seismo!keith +1 415 642 4948
X ucbvax!bostic
X bostic@ucbvax.berkeley.edu
END-of-README
echo x - bug.c
sed 's/^X//' >bug.c << 'END-of-bug.c'
X#include <sys/types.h>
X#include <ndir.h>
X
Xmain()
X{
X DIR *one,*two;
X struct direct *e_one;
X
X one = opendir(".");
X two = opendir(".");
X (void)readdir(one);
X (void)readdir(one);
X do {
X e_one = readdir(one);
X }
X while (!e_one->d_ino);
X printf("one -- %ld %s\n",e_one->d_ino,e_one->d_name);
X (void)readdir(two);
X puts("should be identical to the last print...");
X printf("one -- %ld %s\n",e_one->d_ino,e_one->d_name);
X}
END-of-bug.c
echo x - closedir.c
sed 's/^X//' >closedir.c << 'END-of-closedir.c'
X/*
X * Copyright (c) 1987 Regents of the University of California.
X * This file may be freely redistributed provided that this
X * notice remains attached.
X */
X
X#include <sys/types.h>
X#include <ndir.h>
X
X/*
X * close a directory.
X */
Xclosedir(dirp)
X register DIR *dirp;
X{
X close(dirp->dd_fd);
X dirp->dd_fd = -1;
X dirp->dd_loc = 0;
X free(dirp);
X}
END-of-closedir.c
echo x - directory.3
sed 's/^X//' >directory.3 << 'END-of-directory.3'
X.\" Copyright (c) 1983 Regents of the University of California.
X.\" All rights reserved. The Berkeley software License Agreement
X.\" specifies the terms and conditions for redistribution.
X.\"
X.\" @(#)directory.3 6.3 (Berkeley) 12/22/86
X.\"
X.TH DIRECTORY 3 "December 22, 1986"
X.UC 5
X.SH NAME
Xopendir, readdir, telldir, seekdir, rewinddir, closedir, dirfd \- directory operations
X.SH SYNOPSIS
X.B #include <sys/types.h>
X.br
X.B #include <sys/dir.h>
X.PP
X.SM
X.B DIR
X.B *opendir(filename)
X.br
X.B char *filename;
X.PP
X.B struct direct
X.B *readdir(dirp)
X.br
X.SM
X.B DIR
X.B *dirp;
X.PP
X.B long
X.B telldir(dirp)
X.br
X.SM
X.B DIR
X.B *dirp;
X.PP
X.B seekdir(dirp, loc)
X.br
X.SM
X.B DIR
X.B *dirp;
X.br
X.B long loc;
X.PP
X.B rewinddir(dirp)
X.br
X.SM
X.B DIR
X.B *dirp;
X.PP
X.B closedir(dirp)
X.br
X.SM
X.B DIR
X.B *dirp;
X.PP
X.B dirfd(dirp)
X.br
X.SM
X.B DIR
X.B *dirp;
X.SH DESCRIPTION
X.I Opendir
Xopens the directory named by
X.I filename
Xand associates a
X.I directory stream
Xwith it.
X.I Opendir
Xreturns a pointer to be used to identify the
X.I directory stream
Xin subsequent operations. The pointer
X.SM
X.B NULL
Xis returned if
X.I filename
Xcannot be accessed, or if it cannot
X.IR malloc (3)
Xenough memory to hold the whole thing.
X.PP
X.I Readdir
Xreturns a pointer to the next directory entry. It returns
X.B NULL
Xupon reaching the end of the directory or detecting an invalid
X.I seekdir
Xoperation.
X.PP
X.I Telldir
Xreturns the current location associated with the named
X.I directory stream.
X.PP
X.I Seekdir
Xsets the position of the next
X.I readdir
Xoperation on the
X.I directory stream.
XThe new position reverts to the one associated with the
X.I directory stream
Xwhen the
X.I telldir
Xoperation was performed. Values returned by
X.I telldir
Xare good only for the lifetime of the DIR pointer from which they are derived.
XIf the directory is closed and then reopened, the
X.I telldir
Xvalue may be invalidated due to undetected directory compaction.
XIt is safe to use a previous
X.I telldir
Xvalue immediately after a call to
X.I opendir
Xand before any calls to
X.I readdir.
X.PP
X.I Rewinddir
Xresets the position of the named
X.I directory stream
Xto the beginning of the directory.
X.PP
X.I Closedir
Xcloses the named
X.I directory stream
Xand frees the structure associated with the DIR pointer.
X.PP
X.I Dirfd
Xreturns the integer file descriptor associated with the named
X.I directory stream,
Xsee open(2).
X.PP
XSample code which searchs a directory for entry ``name'' is:
X.PP
X.br
X len = strlen(name);
X.br
X dirp = opendir(".");
X.br
X for (dp = readdir(dirp); dp != NULL; dp = readdir(dirp))
X.br
X if (dp->d_namlen == len && !strcmp(dp->d_name, name)) {
X.br
X closedir(dirp);
X.br
X return FOUND;
X.br
X }
X.br
X closedir(dirp);
X.br
X return NOT_FOUND;
X.SH "SEE ALSO"
Xopen(2),
Xclose(2),
Xread(2),
Xlseek(2),
Xdir(5)
END-of-directory.3
echo x - ndir.h
sed 's/^X//' >ndir.h << 'END-of-ndir.h'
X/*
X * Copyright (c) 1987 Regents of the University of California.
X * This file may be freely redistributed provided that this
X * notice remains attached.
X */
X
X#ifndef MAXNAMLEN
X#define MAXNAMLEN 14
X#endif
X
X/*
X * Actual directory structure as it appears on disk. For use by programs
X * and routines which need to know what a directory really looks like.
X * Don't use it unless you absolutely have to.
X */
Xstruct v7direct {
X ino_t d_ino;
X char d_name[MAXNAMLEN];
X};
X
X#ifndef KERNEL
X#define DIRBLKSIZ 512
X
Xstruct direct {
X u_long d_ino; /* inode number of entry */
X u_short d_reclen; /* length of this record */
X u_short d_namlen; /* length of string in d_name */
X char d_name[MAXNAMLEN+1]; /* name must be no longer than this */
X};
X
X/*
X * The DIRSIZ macro gives the minimum record length which will hold
X * the directory entry. This requires the amount of space in struct direct
X * without the d_name field, plus enough space for the name with a terminating
X * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
X */
X#undef DIRSIZ
X#define DIRSIZ(dp) \
X ((sizeof (struct direct) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
X
X/*
X * Definitions for library routines operating on directories.
X */
Xtypedef struct _dirdesc {
X int dd_fd;
X long dd_loc;
X long dd_size;
X char dd_buf[DIRBLKSIZ];
X struct direct dd_cur;
X} DIR;
X#ifndef NULL
X#define NULL 0
X#endif
Xextern DIR *opendir();
Xextern struct direct *readdir();
Xextern long telldir();
X#define rewinddir(dirp) seekdir((dirp), (long)0)
X#define dirfd(dirp) ((dirp)->dd_fd)
X#endif
END-of-ndir.h
echo x - opendir.c
sed 's/^X//' >opendir.c << 'END-of-opendir.c'
X/*
X * Copyright (c) 1987 Regents of the University of California.
X * This file may be freely redistributed provided that this
X * notice remains attached.
X */
X
X#include <sys/param.h>
X#include <ndir.h>
X
Xextern char *malloc();
X
X/*
X * open a directory.
X */
XDIR *
Xopendir(name)
X char *name;
X{
X register DIR *dirp;
X register int fd;
X char *malloc();
X
X if ((fd = open(name, 0)) == -1)
X return NULL;
X if ((dirp = (DIR *)malloc(sizeof(DIR))) == NULL) {
X close (fd);
X return NULL;
X }
X dirp->dd_fd = fd;
X dirp->dd_loc = 0;
X return dirp;
X}
END-of-opendir.c
echo x - readdir.c
sed 's/^X//' >readdir.c << 'END-of-readdir.c'
X/*
X * Copyright (c) 1987 Regents of the University of California.
X * This file may be freely redistributed provided that this
X * notice remains attached.
X */
X
X#include <sys/param.h>
X#include <ndir.h>
X
X/*
X * read a V7 directory entry and present it as a BSD4.X entry.
X */
X
X/*
X * get next entry in a directory.
X */
Xstruct direct *
Xreaddir(dirp)
X register DIR *dirp;
X{
X register struct v7direct *dp;
X
X for (;;) {
X if (dirp->dd_loc == 0) {
X dirp->dd_size = read(dirp->dd_fd, dirp->dd_buf,
X DIRBLKSIZ);
X if (dirp->dd_size <= 0)
X return NULL;
X }
X if (dirp->dd_loc >= dirp->dd_size) {
X dirp->dd_loc = 0;
X continue;
X }
X dp = (struct v7direct *)(dirp->dd_buf + dirp->dd_loc);
X dirp->dd_loc += sizeof(struct v7direct);
X if (dp->d_ino == 0)
X continue;
X /*
X * format V7 directory structure into BSD4.X
X */
X dirp->dd_cur.d_ino = dp->d_ino;
X bcopy(dp->d_name, dirp->dd_cur.d_name, MAXNAMLEN);
X /* insure null termination */
X dirp->dd_cur.d_name[MAXNAMLEN] = '\0';
X dirp->dd_cur.d_namlen = strlen(dirp->dd_cur.d_name);
X dirp->dd_cur.d_reclen = DIRBLKSIZ;
X return (&dirp->dd_cur);
X }
X}
END-of-readdir.c
echo x - scandir.3
sed 's/^X//' >scandir.3 << 'END-of-scandir.3'
X.\" Copyright (c) 1983 Regents of the University of California.
X.\" All rights reserved. The Berkeley software License Agreement
X.\" specifies the terms and conditions for redistribution.
X.\"
X.\" @(#)scandir.3 6.2 (Berkeley) 9/17/85
X.\"
X.TH SCANDIR 3 "September 17, 1985"
X.UC 5
X.SH NAME
Xscandir, alphasort \- scan a directory
X.SH SYNOPSIS
X.nf
X.B #include <sys/types.h>
X.B #include <sys/dir.h>
X.PP
X.B scandir(dirname, namelist, select, compar)
X.B char *dirname;
X.B struct direct *(*namelist[]);
X.B int (*select)();
X.B int (*compar)();
X.PP
X.B alphasort(d1, d2)
X.B struct direct **d1, **d2;
X.fi
X.SH DESCRIPTION
X.I Scandir
Xreads the directory
X.I dirname
Xand builds an array of pointers to directory
Xentries using
X.IR malloc (3).
XIt returns the number of entries in the array and a pointer to the
Xarray through
X.IR namelist .
X.PP
XThe
X.I select
Xparameter is a pointer to a user supplied subroutine which is called by
X.I scandir
Xto select which entries are to be included in the array.
XThe select routine is passed a
Xpointer to a directory entry and should return a non-zero
Xvalue if the directory entry is to be included in the array.
XIf
X.I select
Xis null, then all the directory entries will be included.
X.PP
XThe
X.I compar
Xparameter is a pointer to a user supplied subroutine which is passed to
X.IR qsort (3)
Xto sort the completed array. If this pointer is null, the array is not sorted.
X.I Alphasort
Xis a routine which can be used for the
X.I compar
Xparameter to sort the array alphabetically.
X.PP
XThe memory allocated for the array can be deallocated with
X.I free
X(see
X.IR malloc (3))
Xby freeing each pointer in the array and the array itself.
X.SH "SEE ALSO"
Xdirectory(3),
Xmalloc(3),
Xqsort(3),
Xdir(5)
X.SH DIAGNOSTICS
XReturns \-1 if the directory cannot be opened for reading or if
X.IR malloc (3)
Xcannot allocate enough memory to hold all the data structures.
END-of-scandir.3
echo x - scandir.c
sed 's/^X//' >scandir.c << 'END-of-scandir.c'
X/*
X * Copyright (c) 1987 Regents of the University of California.
X * This file may be freely redistributed provided that this
X * notice remains attached.
X */
X
X/*
X * Scan the directory dirname calling select to make a list of selected
X * directory entries then sort using qsort and compare routine dcomp.
X * Returns the number of entries and a pointer to a list of pointers to
X * struct direct (through namelist). Returns -1 if there were any errors.
X */
X
X#include <sys/types.h>
X#include <sys/stat.h>
X#include <ndir.h>
X
Xscandir(dirname, namelist, select, dcomp)
X char *dirname;
X struct direct *(*namelist[]);
X int (*select)(), (*dcomp)();
X{
X register struct direct *d, *p, **names;
X register int nitems;
X register char *cp1, *cp2;
X struct stat stb;
X int arraysz;
X DIR *dirp;
X
X if ((dirp = opendir(dirname)) == NULL)
X return(-1);
X if (fstat(dirp->dd_fd, &stb) < 0)
X return(-1);
X
X /*
X * estimate the array size by taking the size of the directory file
X * and dividing it by a multiple of the minimum size entry.
X */
X arraysz = (stb.st_size / 24);
X names = (struct direct **)malloc(arraysz * sizeof(struct direct *));
X if (names == NULL)
X return(-1);
X
X nitems = 0;
X while ((d = readdir(dirp)) != NULL) {
X if (select != NULL && !(*select)(d))
X continue; /* just selected names */
X /*
X * Make a minimum size copy of the data
X */
X p = (struct direct *)malloc(DIRSIZ(d));
X if (p == NULL)
X return(-1);
X p->d_ino = d->d_ino;
X p->d_reclen = d->d_reclen;
X p->d_namlen = d->d_namlen;
X for (cp1 = p->d_name, cp2 = d->d_name; *cp1++ = *cp2++; );
X /*
X * Check to make sure the array has space left and
X * realloc the maximum size.
X */
X if (++nitems >= arraysz) {
X if (fstat(dirp->dd_fd, &stb) < 0)
X return(-1); /* just might have grown */
X arraysz = stb.st_size / 12;
X names = (struct direct **)realloc((char *)names,
X arraysz * sizeof(struct direct *));
X if (names == NULL)
X return(-1);
X }
X names[nitems-1] = p;
X }
X closedir(dirp);
X if (nitems && dcomp != NULL)
X qsort(names, nitems, sizeof(struct direct *), dcomp);
X *namelist = names;
X return(nitems);
X}
X
X/*
X * Alphabetic order comparison routine for those who want it.
X */
Xalphasort(d1, d2)
X struct direct **d1, **d2;
X{
X return(strcmp((*d1)->d_name, (*d2)->d_name));
X}
END-of-scandir.c
echo x - seekdir.c
sed 's/^X//' >seekdir.c << 'END-of-seekdir.c'
X/*
X * Copyright (c) 1987 Regents of the University of California.
X * This file may be freely redistributed provided that this
X * notice remains attached.
X */
X
X#include <sys/param.h>
X#include <ndir.h>
X
X/*
X * seek to an entry in a directory.
X * Only values returned by "telldir" should be passed to seekdir.
X */
Xseekdir(dirp, loc)
X register DIR *dirp;
X long loc;
X{
X long curloc, base, offset;
X struct direct *dp;
X extern long lseek();
X
X curloc = telldir(dirp);
X if (loc == curloc)
X return;
X base = loc & ~(DIRBLKSIZ - 1);
X offset = loc & (DIRBLKSIZ - 1);
X lseek(dirp->dd_fd, base, 0);
X dirp->dd_loc = 0;
X while (dirp->dd_loc < offset) {
X dp = readdir(dirp);
X if (dp == NULL)
X return;
X }
X}
END-of-seekdir.c
echo x - telldir.c
sed 's/^X//' >telldir.c << 'END-of-telldir.c'
X/*
X * Copyright (c) 1987 Regents of the University of California.
X * This file may be freely redistributed provided that this
X * notice remains attached.
X */
X
X#include <sys/types.h>
X#include <ndir.h>
X
X/*
X * return a pointer into a directory
X */
Xlong
Xtelldir(dirp)
X DIR *dirp;
X{
X return (lseek(dirp->dd_fd, 0L, 1) - dirp->dd_size + dirp->dd_loc);
X}
END-of-telldir.c
exit