xref: /freebsd/bin/pax/tables.h (revision 13464e4a44fc58490a03bb8bfc7e3c972e9c30b2)
1  /*-
2   * Copyright (c) 1992 Keith Muller.
3   * Copyright (c) 1992, 1993
4   *	The Regents of the University of California.  All rights reserved.
5   *
6   * This code is derived from software contributed to Berkeley by
7   * Keith Muller of the University of California, San Diego.
8   *
9   * Redistribution and use in source and binary forms, with or without
10   * modification, are permitted provided that the following conditions
11   * are met:
12   * 1. Redistributions of source code must retain the above copyright
13   *    notice, this list of conditions and the following disclaimer.
14   * 2. Redistributions in binary form must reproduce the above copyright
15   *    notice, this list of conditions and the following disclaimer in the
16   *    documentation and/or other materials provided with the distribution.
17   * 3. Neither the name of the University nor the names of its contributors
18   *    may be used to endorse or promote products derived from this software
19   *    without specific prior written permission.
20   *
21   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31   * SUCH DAMAGE.
32   *
33   *	@(#)tables.h	8.1 (Berkeley) 5/31/93
34   * $FreeBSD$
35   */
36  
37  /*
38   * data structures and constants used by the different databases kept by pax
39   */
40  
41  /*
42   * Hash Table Sizes MUST BE PRIME, if set too small performance suffers.
43   * Probably safe to expect 500000 inodes per tape. Assuming good key
44   * distribution (inodes) chains of under 50 long (worse case) is ok.
45   */
46  #define L_TAB_SZ	2503		/* hard link hash table size */
47  #define F_TAB_SZ	50503		/* file time hash table size */
48  #define N_TAB_SZ	541		/* interactive rename hash table */
49  #define D_TAB_SZ	317		/* unique device mapping table */
50  #define A_TAB_SZ	317		/* ftree dir access time reset table */
51  #define MAXKEYLEN	64		/* max number of chars for hash */
52  
53  /*
54   * file hard link structure (hashed by dev/ino and chained) used to find the
55   * hard links in a file system or with some archive formats (cpio)
56   */
57  typedef struct hrdlnk {
58  	char		*name;	/* name of first file seen with this ino/dev */
59  	dev_t		dev;	/* files device number */
60  	ino_t		ino;	/* files inode number */
61  	u_long		nlink;	/* expected link count */
62  	struct hrdlnk	*fow;
63  } HRDLNK;
64  
65  /*
66   * Archive write update file time table (the -u, -C flag), hashed by filename.
67   * Filenames are stored in a scratch file at seek offset into the file. The
68   * file time (mod time) and the file name length (for a quick check) are
69   * stored in a hash table node. We were forced to use a scratch file because
70   * with -u, the mtime for every node in the archive must always be available
71   * to compare against (and this data can get REALLY large with big archives).
72   * By being careful to read only when we have a good chance of a match, the
73   * performance loss is not measurable (and the size of the archive we can
74   * handle is greatly increased).
75   */
76  typedef struct ftm {
77  	int		namelen;	/* file name length */
78  	time_t		mtime;		/* files last modification time */
79  	off_t		seek;		/* location in scratch file */
80  	struct ftm	*fow;
81  } FTM;
82  
83  /*
84   * Interactive rename table (-i flag), hashed by orig filename.
85   * We assume this will not be a large table as this mapping data can only be
86   * obtained through interactive input by the user. Nobody is going to type in
87   * changes for 500000 files? We use chaining to resolve collisions.
88   */
89  
90  typedef struct namt {
91  	char		*oname;		/* old name */
92  	char		*nname;		/* new name typed in by the user */
93  	struct namt	*fow;
94  } NAMT;
95  
96  /*
97   * Unique device mapping tables. Some protocols (e.g. cpio) require that the
98   * <c_dev,c_ino> pair will uniquely identify a file in an archive unless they
99   * are links to the same file. Appending to archives can break this. For those
100   * protocols that have this requirement we map c_dev to a unique value not seen
101   * in the archive when we append. We also try to handle inode truncation with
102   * this table. (When the inode field in the archive header are too small, we
103   * remap the dev on writes to remove accidental collisions).
104   *
105   * The list is hashed by device number using chain collision resolution. Off of
106   * each DEVT are linked the various remaps for this device based on those bits
107   * in the inode which were truncated. For example if we are just remapping to
108   * avoid a device number during an update append, off the DEVT we would have
109   * only a single DLIST that has a truncation id of 0 (no inode bits were
110   * stripped for this device so far). When we spot inode truncation we create
111   * a new mapping based on the set of bits in the inode which were stripped off.
112   * so if the top four bits of the inode are stripped and they have a pattern of
113   * 0110...... (where . are those bits not truncated) we would have a mapping
114   * assigned for all inodes that has the same 0110.... pattern (with this dev
115   * number of course). This keeps the mapping sparse and should be able to store
116   * close to the limit of files which can be represented by the optimal
117   * combination of dev and inode bits, and without creating a fouled up archive.
118   * Note we also remap truncated devs in the same way (an exercise for the
119   * dedicated reader; always wanted to say that...:)
120   */
121  
122  typedef struct devt {
123  	dev_t		dev;	/* the orig device number we now have to map */
124  	struct devt	*fow;	/* new device map list */
125  	struct dlist	*list;	/* map list based on inode truncation bits */
126  } DEVT;
127  
128  typedef struct dlist {
129  	ino_t trunc_bits;	/* truncation pattern for a specific map */
130  	dev_t dev;		/* the new device id we use */
131  	struct dlist *fow;
132  } DLIST;
133  
134  /*
135   * ftree directory access time reset table. When we are done with with a
136   * subtree we reset the access and mod time of the directory when the tflag is
137   * set. Not really explicitly specified in the pax spec, but easy and fast to
138   * do (and this may have even been intended in the spec, it is not clear).
139   * table is hashed by inode with chaining.
140   */
141  
142  typedef struct atdir {
143  	char *name;	/* name of directory to reset */
144  	dev_t dev;	/* dev and inode for fast lookup */
145  	ino_t ino;
146  	time_t mtime;	/* access and mod time to reset to */
147  	time_t atime;
148  	struct atdir *fow;
149  } ATDIR;
150  
151  /*
152   * created directory time and mode storage entry. After pax is finished during
153   * extraction or copy, we must reset directory access modes and times that
154   * may have been modified after creation (they no longer have the specified
155   * times and/or modes). We must reset time in the reverse order of creation,
156   * because entries are added  from the top of the file tree to the bottom.
157   * We MUST reset times from leaf to root (it will not work the other
158   * direction).  Entries are recorded into a spool file to make reverse
159   * reading faster.
160   */
161  
162  typedef struct dirdata {
163  	int nlen;	/* length of the directory name (includes \0) */
164  	off_t npos;	/* position in file where this dir name starts */
165  	mode_t mode;	/* file mode to restore */
166  	time_t mtime;	/* mtime to set */
167  	time_t atime;	/* atime to set */
168  	int frc_mode;	/* do we force mode settings? */
169  } DIRDATA;
170