106 lines
3.4 KiB
C
106 lines
3.4 KiB
C
/*
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* Copyright (c) 1986 Regents of the University of California.
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* All rights reserved. The Berkeley software License Agreement
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* specifies the terms and conditions for redistribution.
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*/
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#ifndef _DIR_
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#define _DIR_
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#ifndef MAXNAMLEN
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#define MAXNAMLEN 63
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#endif
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#define DIRBLKSIZ 1024
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/*
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* inode numbers are ino_t rather than u_long now. before, when v7direct
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* was used for the kernel, inode numbers were u_short/ino_t anyways, and since
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* everything had to be recompiled when the fs structure was changed it seemed
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* like a good idea to change the "real direct structure". SMS
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*/
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struct direct {
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ino_t d_ino; /* inode number of entry */
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u_short d_reclen; /* length of this record */
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u_short d_namlen; /* length of string in d_name */
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char d_name[MAXNAMLEN+1]; /* name must be no longer than this */
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};
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/*
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* A directory consists of some number of blocks of DIRBLKSIZ
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* bytes, where DIRBLKSIZ is chosen such that it can be transferred
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* to disk in a single atomic operation (e.g. 512 bytes on most machines).
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*
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* Each DIRBLKSIZ byte block contains some number of directory entry
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* structures, which are of variable length. Each directory entry has
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* a struct direct at the front of it, containing its inode number,
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* the length of the entry, and the length of the name contained in
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* the entry. These are followed by the name padded to a 4 byte boundary
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* with null bytes. All names are guaranteed null terminated.
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* The maximum length of a name in a directory is MAXNAMLEN.
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*
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* The macro DIRSIZ(dp) gives the amount of space required to represent
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* a directory entry. Free space in a directory is represented by
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* entries which have dp->d_reclen > DIRSIZ(dp). All DIRBLKSIZ bytes
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* in a directory block are claimed by the directory entries. This
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* usually results in the last entry in a directory having a large
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* dp->d_reclen. When entries are deleted from a directory, the
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* space is returned to the previous entry in the same directory
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* block by increasing its dp->d_reclen. If the first entry of
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* a directory block is free, then its dp->d_ino is set to 0.
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* Entries other than the first in a directory do not normally have
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* dp->d_ino set to 0.
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*/
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#undef DIRSIZ
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#define DIRSIZ(dp) \
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((((sizeof (struct direct) - (MAXNAMLEN+1)) + (dp)->d_namlen+1) + 3) &~ 3)
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/*
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* Definitions for library routines operating on directories.
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*/
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typedef struct _dirdesc {
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int dd_fd;
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long dd_loc;
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long dd_size;
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char dd_buf[DIRBLKSIZ];
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struct direct dd_cur;
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} DIR;
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#ifndef NULL
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#define NULL 0
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#endif
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#ifndef KERNEL
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extern DIR *opendir (const char *);
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extern struct direct *readdir (DIR *);
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extern long telldir (DIR *);
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extern void seekdir (DIR *, long);
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extern void closedir (DIR *);
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#define rewinddir(dirp) seekdir ((dirp), (long)0)
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#define dirfd(dirp) ((dirp)->dd_fd)
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#endif /* !KERNEL */
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/*
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* Template for manipulating directories.
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* Should use struct direct's, but the name field
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* is MAXNAMLEN - 1, and this just won't do.
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*/
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#define dotdot_ino dtdt_ino
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#define dotdot_reclen dtdt_rec
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#define dotdot_name dtdt_name
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struct dirtemplate {
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ino_t dot_ino;
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u_short dot_reclen;
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u_short dot_namlen;
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char dot_name[4]; /* must be multiple of 4 */
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ino_t dotdot_ino;
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u_short dotdot_reclen;
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u_short dotdot_namlen;
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char dotdot_name[4]; /* ditto */
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};
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#endif /* _DIR_ */
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