ref: 60cbbb123b106f7f31495514326a2b0bbcb0d75d
dir: /sys/src/ape/cmd/pax/paxdir.c/
/*
opendir -- open a directory stream
last edit: 16-Jun-1987 D A Gwyn
*/
#include <sys/errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "paxdir.h"
#ifdef BSD_SYSV
/*
<sys/_dir.h> -- definitions for 4.2,4.3BSD directories
last edit: 25-Apr-1987 D A Gwyn
A directory consists of some number of blocks of DIRBLKSIZ bytes each,
where DIRBLKSIZ is chosen such that it can be transferred to disk in a
single atomic operation (e.g., 512 bytes on most machines).
Each DIRBLKSIZ-byte block contains some number of directory entry
structures, which are of variable length. Each directory entry has the
beginning of a (struct direct) at the front of it, containing its
filesystem-unique ident number, the length of the entry, and the length
of the name contained in the entry. These are followed by the NUL-
terminated name padded to a (long) boundary with 0 bytes. The maximum
length of a name in a directory is MAXNAMELEN.
The macro DIRSIZ(dp) gives the amount of space required to represent a
directory entry. Free space in a directory is represented by entries
that have dp->d_reclen > DIRSIZ(dp). All DIRBLKSIZ bytes in a
directory block are claimed by the directory entries; this usually
results in the last entry in a directory having a large dp->d_reclen.
When entries are deleted from a directory, the space is returned to the
previous entry in the same directory block by increasing its
dp->d_reclen. If the first entry of a directory block is free, then
its dp->d_fileno is set to 0; entries other than the first in a
directory do not normally have dp->d_fileno set to 0.
prerequisite: <sys/types.h>
*/
#if defined(accel) || defined(sun) || defined(vax)
#define DIRBLKSIZ 512 /* size of directory block */
#else
#ifdef alliant
#define DIRBLKSIZ 4096 /* size of directory block */
#else
#ifdef gould
#define DIRBLKSIZ 1024 /* size of directory block */
#else
#ifdef ns32000 /* Dynix System V */
#define DIRBLKSIZ 2600 /* size of directory block */
#else /* be conservative; multiple blocks are okay
* but fractions are not */
#define DIRBLKSIZ 4096 /* size of directory block */
#endif
#endif
#endif
#endif
#define MAXNAMELEN 255 /* maximum filename length */
/* NOTE: not MAXNAMLEN, which has been preempted by SVR3 <dirent.h> */
struct direct { /* data from read()/_getdirentries() */
unsigned long d_fileno; /* unique ident of entry */
unsigned short d_reclen; /* length of this record */
unsigned short d_namlen; /* length of string in d_name */
char d_name[MAXNAMELEN + 1]; /* NUL-terminated filename */
};
/*
The DIRSIZ macro gives the minimum record length which will hold the
directory entry. This requires the amount of space in a (struct
direct) without the d_name field, plus enough space for the name with a
terminating NUL character, rounded up to a (long) boundary.
(Note that Berkeley didn't properly compensate for struct padding,
but we nevertheless have to use the same size as the actual system.)
*/
#define DIRSIZ( dp ) ((sizeof(struct direct) - (MAXNAMELEN+1) \
+ sizeof(long) + (dp)->d_namlen) \
/ sizeof(long) * sizeof(long))
#else
#include <sys/dir.h>
#ifdef SYSV3
#undef MAXNAMLEN /* avoid conflict with SVR3 */
#endif
/* Good thing we don't need to use the DIRSIZ() macro! */
#ifdef d_ino /* 4.3BSD/NFS using d_fileno */
#undef d_ino /* (not absolutely necessary) */
#else
#define d_fileno d_ino /* (struct direct) member */
#endif
#endif
#ifdef UNK
#ifndef UFS
#include "***** ERROR ***** UNK applies only to UFS"
/* One could do something similar for getdirentries(), but I didn't bother. */
#endif
#include <signal.h>
#endif
#if defined(UFS) + defined(BFS) + defined(NFS) != 1 /* sanity check */
#include "***** ERROR ***** exactly one of UFS, BFS, or NFS must be defined"
#endif
#ifdef UFS
#define RecLen( dp ) (sizeof(struct direct)) /* fixed-length entries */
#else /* BFS || NFS */
#define RecLen( dp ) ((dp)->d_reclen) /* variable-length entries */
#endif
#ifdef NFS
#ifdef BSD_SYSV
#define getdirentries _getdirentries /* package hides this system call */
#endif
extern int getdirentries();
static long dummy; /* getdirentries() needs basep */
#define GetBlock( fd, buf, n ) getdirentries( fd, buf, (unsigned)n, &dummy )
#else /* UFS || BFS */
#ifdef BSD_SYSV
#define read _read /* avoid emulation overhead */
#endif
extern int read();
#define GetBlock( fd, buf, n ) read( fd, buf, (unsigned)n )
#endif
#ifdef UNK
extern int _getdents(); /* actual system call */
#endif
extern char *strncpy();
extern int fstat();
extern OFFSET lseek();
extern int errno;
#ifndef DIRBLKSIZ
#define DIRBLKSIZ 4096 /* directory file read buffer size */
#endif
#ifndef NULL
#define NULL 0
#endif
#ifndef SEEK_CUR
#define SEEK_CUR 1
#endif
#ifndef S_ISDIR /* macro to test for directory file */
#define S_ISDIR( mode ) (((mode) & S_IFMT) == S_IFDIR)
#endif
#ifndef SEEK_CUR
#define SEEK_CUR 1
#endif
#ifdef BSD_SYSV
#define open _open /* avoid emulation overhead */
#endif
extern int getdents(); /* SVR3 system call, or emulation */
typedef char *pointer; /* (void *) if you have it */
extern void free();
extern pointer malloc();
extern int
open(), close(), fstat();
extern int errno;
extern OFFSET lseek();
#ifndef SEEK_SET
#define SEEK_SET 0
#endif
typedef int bool; /* Boolean data type */
#define false 0
#define true 1
#ifndef NULL
#define NULL 0
#endif
#ifndef O_RDONLY
#define O_RDONLY 0
#endif
#ifndef S_ISDIR /* macro to test for directory file */
#define S_ISDIR( mode ) (((mode) & S_IFMT) == S_IFDIR)
#endif
#ifdef __STDC__
DIR *opendir(char *dirname)
#else
DIR *opendir(dirname)
char *dirname; /* name of directory */
#endif
{
register DIR *dirp; /* -> malloc'ed storage */
register int fd; /* file descriptor for read */
struct stat sbuf; /* result of fstat() */
if ((fd = open(dirname, O_RDONLY)) < 0)
return ((DIR *)NULL); /* errno set by open() */
if (fstat(fd, &sbuf) != 0 || !S_ISDIR(sbuf.st_mode)) {
close(fd);
errno = ENOTDIR;
return ((DIR *)NULL); /* not a directory */
}
if ((dirp = (DIR *) malloc(sizeof(DIR))) == (DIR *)NULL
|| (dirp->dd_buf = (char *) malloc((unsigned) DIRBUF)) == (char *)NULL
) {
register int serrno = errno;
/* errno set to ENOMEM by sbrk() */
if (dirp != (DIR *)NULL)
free((pointer) dirp);
close(fd);
errno = serrno;
return ((DIR *)NULL); /* not enough memory */
}
dirp->dd_fd = fd;
dirp->dd_loc = dirp->dd_size = 0; /* refill needed */
return dirp;
}
/*
* closedir -- close a directory stream
*
* last edit: 11-Nov-1988 D A Gwyn
*/
#ifdef __STDC__
int closedir(register DIR *dirp)
#else
int closedir(dirp)
register DIR *dirp; /* stream from opendir() */
#endif
{
register int fd;
if ( dirp == (DIR *)NULL || dirp->dd_buf == (char *)NULL ) {
errno = EFAULT;
return -1; /* invalid pointer */
}
fd = dirp->dd_fd; /* bug fix thanks to R. Salz */
free( (pointer)dirp->dd_buf );
free( (pointer)dirp );
return close( fd );
}
/*
readdir -- read next entry from a directory stream
last edit: 25-Apr-1987 D A Gwyn
*/
#ifdef __STDC__
struct dirent *readdir(register DIR *dirp)
#else
struct dirent *readdir(dirp)
register DIR *dirp; /* stream from opendir() */
#endif
{
register struct dirent *dp; /* -> directory data */
if (dirp == (DIR *)NULL || dirp->dd_buf == (char *)NULL) {
errno = EFAULT;
return (struct dirent *)NULL; /* invalid pointer */
}
do {
if (dirp->dd_loc >= dirp->dd_size) /* empty or obsolete */
dirp->dd_loc = dirp->dd_size = 0;
if (dirp->dd_size == 0 /* need to refill buffer */
&& (dirp->dd_size =
getdents(dirp->dd_fd, dirp->dd_buf, (unsigned) DIRBUF)
) <= 0
)
return ((struct dirent *)NULL); /* EOF or error */
dp = (struct dirent *) & dirp->dd_buf[dirp->dd_loc];
dirp->dd_loc += dp->d_reclen;
}
while (dp->d_ino == 0L); /* don't rely on getdents() */
return dp;
}
/*
seekdir -- reposition a directory stream
last edit: 24-May-1987 D A Gwyn
An unsuccessful seekdir() will in general alter the current
directory position; beware.
NOTE: 4.nBSD directory compaction makes seekdir() & telldir()
practically impossible to do right. Avoid using them!
*/
#ifdef __STDC__
void seekdir(register DIR *dirp, register OFFSET loc)
#else
void seekdir(dirp, loc)
register DIR *dirp; /* stream from opendir() */
register OFFSET loc; /* position from telldir() */
#endif
{
register bool rewind; /* "start over when stymied" flag */
if (dirp == (DIR *)NULL || dirp->dd_buf == (char *)NULL) {
errno = EFAULT;
return; /* invalid pointer */
}
/*
* A (struct dirent)'s d_off is an invented quantity on 4.nBSD
* NFS-supporting systems, so it is not safe to lseek() to it.
*/
/* Monotonicity of d_off is heavily exploited in the following. */
/*
* This algorithm is tuned for modest directory sizes. For huge
* directories, it might be more efficient to read blocks until the first
* d_off is too large, then back up one block, or even to use binary
* search on the directory blocks. I doubt that the extra code for that
* would be worthwhile.
*/
if (dirp->dd_loc >= dirp->dd_size /* invalid index */
|| ((struct dirent *) & dirp->dd_buf[dirp->dd_loc])->d_off > loc
/* too far along in buffer */
)
dirp->dd_loc = 0; /* reset to beginning of buffer */
/* else save time by starting at current dirp->dd_loc */
for (rewind = true;;) {
register struct dirent *dp;
/* See whether the matching entry is in the current buffer. */
if ((dirp->dd_loc < dirp->dd_size /* valid index */
|| readdir(dirp) != (struct dirent *)NULL /* next buffer read */
&& (dirp->dd_loc = 0, true) /* beginning of buffer set */
)
&& (dp = (struct dirent *) & dirp->dd_buf[dirp->dd_loc])->d_off
<= loc /* match possible in this buffer */
) {
for ( /* dp initialized above */ ;
(char *) dp < &dirp->dd_buf[dirp->dd_size];
dp = (struct dirent *) ((char *) dp + dp->d_reclen)
)
if (dp->d_off == loc) { /* found it! */
dirp->dd_loc =
(char *) dp - dirp->dd_buf;
return;
}
rewind = false; /* no point in backing up later */
dirp->dd_loc = dirp->dd_size; /* set end of buffer */
} else
/* whole buffer past matching entry */ if (!rewind) { /* no point in searching
* further */
errno = EINVAL;
return; /* no entry at specified loc */
} else { /* rewind directory and start over */
rewind = false; /* but only once! */
dirp->dd_loc = dirp->dd_size = 0;
if (lseek(dirp->dd_fd, (OFFSET) 0, SEEK_SET)
!= 0
)
return; /* errno already set (EBADF) */
if (loc == 0)
return; /* save time */
}
}
}
/* telldir - report directory stream position
*
* DESCRIPTION
*
* Returns the offset of the next directory entry in the
* directory associated with dirp.
*
* NOTE: 4.nBSD directory compaction makes seekdir() & telldir()
* practically impossible to do right. Avoid using them!
*
* PARAMETERS
*
* DIR *dirp - stream from opendir()
*
* RETURNS
*
* Return offset of next entry
*/
#ifdef __STDC__
OFFSET telldir(DIR *dirp)
#else
OFFSET telldir(dirp)
DIR *dirp; /* stream from opendir() */
#endif
{
if (dirp == (DIR *)NULL || dirp->dd_buf == (char *)NULL) {
errno = EFAULT;
return -1; /* invalid pointer */
}
if (dirp->dd_loc < dirp->dd_size) /* valid index */
return ((struct dirent *) & dirp->dd_buf[dirp->dd_loc])->d_off;
else /* beginning of next directory block */
return lseek(dirp->dd_fd, (OFFSET) 0, SEEK_CUR);
}
#ifdef UFS
/*
The following routine is necessary to handle DIRSIZ-long entry names.
Thanks to Richard Todd for pointing this out.
*/
/* return # chars in embedded name */
#ifdef __STDC__
static int NameLen(char *name)
#else
static int NameLen(name)
char *name; /* -> name embedded in struct direct */
#endif
{
register char *s; /* -> name[.] */
register char *stop = &name[DIRSIZ]; /* -> past end of name field */
for (s = &name[1]; /* (empty names are impossible) */
*s != '\0' /* not NUL terminator */
&& ++s < stop; /* < DIRSIZ characters scanned */
);
return s - name; /* # valid characters in name */
}
#else /* BFS || NFS */
extern int strlen();
#define NameLen( name ) strlen( name ) /* names are always NUL-terminated */
#endif
#ifdef UNK
static enum {
maybe, no, yes
} state = maybe;
/* sig_catch - used to catch signals
*
* DESCRIPTION
*
* Used to catch signals.
*/
/*ARGSUSED*/
#ifdef __STDC__
static void sig_catch(int sig)
#else
static void sig_catch(sig)
int sig; /* must be SIGSYS */
#endif
{
state = no; /* attempted _getdents() faulted */
}
#endif
/* getdents - get directory entries
*
* DESCRIPTION
*
* Gets directory entries from the filesystem in an implemenation
* defined way.
*
* PARAMETERS
*
* int fildes - directory file descriptor
* char *buf - where to put the (struct dirent)s
* unsigned nbyte - size of buf[]
*
* RETURNS
*
* Returns number of bytes read; 0 on EOF, -1 on error
*/
#ifdef __STDC__
int getdents(int fildes, char *buf, unsigned nbyte)
#else
int getdents(fildes, buf, nbyte)
int fildes; /* directory file descriptor */
char *buf; /* where to put the (struct dirent)s */
unsigned nbyte; /* size of buf[] */
#endif
{
int serrno; /* entry errno */
OFFSET offset; /* initial directory file offset */
struct stat statb; /* fstat() info */
union {
/* directory file block buffer */
#ifdef UFS
char dblk[DIRBLKSIZ + 1];
#else
char dblk[DIRBLKSIZ];
#endif
struct direct dummy; /* just for alignment */
} u; /* (avoids having to malloc()) */
register struct direct *dp; /* -> u.dblk[.] */
register struct dirent *bp; /* -> buf[.] */
#ifdef UNK
switch (state) {
SIG_T (*shdlr)(); /* entry SIGSYS handler */
register int retval; /* return from _getdents() if any */
case yes: /* _getdents() is known to work */
return _getdents(fildes, buf, nbyte);
case maybe: /* first time only */
shdlr = signal(SIGSYS, sig_catch);
retval = _getdents(fildes, buf, nbyte); /* try it */
signal(SIGSYS, shdlr);
if (state == maybe) { /* SIGSYS did not occur */
state = yes; /* so _getdents() must have worked */
return retval;
}
/* else fall through into emulation */
/* case no: /* fall through into emulation */
}
#endif
if (buf == (char *)NULL
#ifdef ATT_SPEC
|| (unsigned long) buf % sizeof(long) != 0 /* ugh */
#endif
) {
errno = EFAULT; /* invalid pointer */
return -1;
}
if (fstat(fildes, &statb) != 0) {
return -1; /* errno set by fstat() */
}
if (!S_ISDIR(statb.st_mode)) {
errno = ENOTDIR; /* not a directory */
return -1;
}
if ((offset = lseek(fildes, (OFFSET) 0, SEEK_CUR)) < 0) {
return -1; /* errno set by lseek() */
}
#ifdef BFS /* no telling what remote hosts do */
if ((unsigned long) offset % DIRBLKSIZ != 0) {
errno = ENOENT; /* file pointer probably misaligned */
return -1;
}
#endif
serrno = errno; /* save entry errno */
for (bp = (struct dirent *) buf; bp == (struct dirent *) buf;) {
/* convert next directory block */
int size;
do {
size = GetBlock(fildes, u.dblk, DIRBLKSIZ);
} while (size == -1 && errno == EINTR);
if (size <= 0) {
return size; /* EOF or error (EBADF) */
}
for (dp = (struct direct *) u.dblk;
(char *) dp < &u.dblk[size];
dp = (struct direct *) ((char *) dp + RecLen(dp))
) {
#ifndef UFS
if (dp->d_reclen <= 0) {
errno = EIO; /* corrupted directory */
return -1;
}
#endif
if (dp->d_fileno != 0) { /* non-empty; copy to user buffer */
register int reclen =
DIRENTSIZ(NameLen(dp->d_name));
if ((char *) bp + reclen > &buf[nbyte]) {
errno = EINVAL;
return -1; /* buf too small */
}
bp->d_ino = dp->d_fileno;
bp->d_off = offset + ((char *) dp - u.dblk);
bp->d_reclen = reclen;
{
#ifdef UFS
/* Is the following kludge ugly? You bet. */
register char save = dp->d_name[DIRSIZ];
/* save original data */
dp->d_name[DIRSIZ] = '\0';
/* ensure NUL termination */
#endif
/* adds NUL padding */
strncpy(bp->d_name, dp->d_name, reclen - DIRENTBASESIZ);
#ifdef UFS
dp->d_name[DIRSIZ] = save;
/* restore original data */
#endif
}
bp = (struct dirent *) ((char *) bp + reclen);
}
}
#ifndef BFS /* 4.2BSD screwed up; fixed in 4.3BSD */
if ((char *) dp > &u.dblk[size]) {
errno = EIO; /* corrupted directory */
return -1;
}
#endif
}
errno = serrno; /* restore entry errno */
return (char *) bp - buf; /* return # bytes read */
}