75 lines
2.7 KiB
C
75 lines
2.7 KiB
C
/* @(#)fsdir.h 1.1 94/10/31 SMI; from UCB 4.5 82/11/13 */
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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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#ifndef _ufs_fsdir_h
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#define _ufs_fsdir_h
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#define DIRBLKSIZ DEV_BSIZE
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#ifdef MAXNAMLEN /* posix may have forced it to be defined as ... */
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#undef MAXNAMLEN /* _MAXNAMLEN already. THis tneeds work. XXX */
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#endif
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#define MAXNAMLEN 255
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struct direct {
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u_long 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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* The DIRSIZ macro gives the minimum record length which will hold
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* the directory entry. This requires the amount of space in struct direct
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* without the d_name field, plus enough space for the name with a terminating
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* null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
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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)) + \
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(((dp)->d_namlen+1 + 3) &~ 3))
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#ifdef 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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struct dirtemplate {
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u_long dot_ino;
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short dot_reclen;
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short dot_namlen;
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char dot_name[4]; /* must be multiple of 4 */
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u_long dotdot_ino;
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short dotdot_reclen;
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short dotdot_namlen;
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char dotdot_name[4]; /* ditto */
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};
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#endif
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#endif /*!_ufs_fsdir_h*/
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