1 #include <u.h>
2 #include <libc.h>
3 #include <venti.h>
4 #include "cvt.h"
5 
6 static int
7 checksize(int n)
8 {
9 	if(n < 256) {
10 		werrstr("bad block size %#ux", n);
11 		return -1;
12 	}
13 	return 0;
14 }
15 
16 // _VtEntryBig integer format is floating-point:
17 // (n>>5) << (n&31).
18 // Convert this number; must be exact or return -1.
19 int
20 vttobig(ulong n)
21 {
22 	int shift;
23 	ulong n0;
24 
25 	n0 = n;
26 	shift = 0;
27 	while(n >= (1<<(16 - 5))) {
28 		if(n & 1)
29 			return -1;
30 		shift++;
31 		n >>= 1;
32 	}
33 
34 	n = (n<<5) | shift;
35 	if(((n>>5)<<(n&31)) != n0)
36 		sysfatal("vttobig %#lux => %#lux failed", n0, n);
37 	return n;
38 }
39 
40 void
41 vtentrypack(VtEntry *e, uchar *p, int index)
42 {
43 	ulong t32;
44 	int flags;
45 	uchar *op;
46 	int depth;
47 	int psize, dsize;
48 
49 	p += index * VtEntrySize;
50 	op = p;
51 
52 	depth = e->type&VtTypeDepthMask;
53 	flags = (e->flags&~(_VtEntryDir|_VtEntryDepthMask));
54 	flags |= depth << _VtEntryDepthShift;
55 	if(e->type - depth == VtDirType)
56 		flags |= _VtEntryDir;
57 	U32PUT(p, e->gen);
58 	p += 4;
59 	psize = e->psize;
60 	dsize = e->dsize;
61 	if(psize >= (1<<16) || dsize >= (1<<16)) {
62 		flags |= _VtEntryBig;
63 		psize = vttobig(psize);
64 		dsize = vttobig(dsize);
65 		if(psize < 0 || dsize < 0)
66 			sysfatal("invalid entry psize/dsize: %ld/%ld", e->psize, e->dsize);
67 	}
68 	U16PUT(p, psize);
69 	p += 2;
70 	U16PUT(p, dsize);
71 	p += 2;
72 	U8PUT(p, flags);
73 	p++;
74 	memset(p, 0, 5);
75 	p += 5;
76 	U48PUT(p, e->size, t32);
77 	p += 6;
78 	memmove(p, e->score, VtScoreSize);
79 	p += VtScoreSize;
80 
81 	assert(p-op == VtEntrySize);
82 }
83 
84 int
85 vtentryunpack(VtEntry *e, uchar *p, int index)
86 {
87 	uchar *op;
88 
89 	p += index * VtEntrySize;
90 	op = p;
91 
92 	e->gen = U32GET(p);
93 	p += 4;
94 	e->psize = U16GET(p);
95 	p += 2;
96 	e->dsize = U16GET(p);
97 	p += 2;
98 	e->flags = U8GET(p);
99 	p++;
100 	if(e->flags & _VtEntryBig) {
101 		e->psize = (e->psize>>5)<<(e->psize & 31);
102 		e->dsize = (e->dsize>>5)<<(e->dsize & 31);
103 	}
104 	e->type = (e->flags&_VtEntryDir) ? VtDirType : VtDataType;
105 	e->type += (e->flags & _VtEntryDepthMask) >> _VtEntryDepthShift;
106 	e->flags &= ~(_VtEntryDir|_VtEntryDepthMask|_VtEntryBig);
107 	p += 5;
108 	e->size = U48GET(p);
109 	p += 6;
110 	memmove(e->score, p, VtScoreSize);
111 	p += VtScoreSize;
112 
113 	assert(p-op == VtEntrySize);
114 
115 	if(!(e->flags & VtEntryActive))
116 		return 0;
117 
118 	/*
119 	 * Some old vac files use psize==0 and dsize==0 when the
120 	 * file itself has size 0 or is zeros.  Just to make programs not
121 	 * have to figure out what block sizes of 0 means, rewrite them.
122 	 */
123 	if(e->psize == 0 && e->dsize == 0
124 	&& memcmp(e->score, vtzeroscore, VtScoreSize) == 0){
125 		e->psize = 4096;
126 		e->dsize = 4096;
127 	}
128 	if(checksize(e->psize) < 0 || checksize(e->dsize) < 0)
129 		return -1;
130 
131 	return 0;
132 }