1 #include <u.h>
2 #include <libc.h>
3 #include <diskfs.h>
4 
5 typedef struct DiskPart DiskPart;
6 struct DiskPart
7 {
8 	Disk disk;
9 	Disk *subdisk;
10 	u64int offset;
11 	u64int size;
12 };
13 
14 static Block*
15 diskpartread(Disk *dd, u32int len, u64int offset)
16 {
17 	DiskPart *d = (DiskPart*)dd;
18 
19 	if(offset+len > d->size){
20 		werrstr("read past end of partition %llud + %lud > %llud", offset, len, d->size);
21 		return nil;
22 	}
23 	return diskread(d->subdisk, len, offset+d->offset);
24 }
25 
26 static int
27 diskpartsync(Disk *dd)
28 {
29 	DiskPart *d = (DiskPart*)dd;
30 
31 	if(d->subdisk)
32 		return disksync(d->subdisk);
33 	return 0;
34 }
35 
36 static void
37 diskpartclose(Disk *dd)
38 {
39 	DiskPart *d = (DiskPart*)dd;
40 
41 	if(d->subdisk)
42 		diskclose(d->subdisk);
43 	free(d);
44 }
45 
46 Disk*
47 diskpart(Disk *subdisk, u64int offset, u64int size)
48 {
49 	DiskPart *d;
50 
51 	d = mallocz(sizeof(DiskPart), 1);
52 	if(d == nil)
53 		return nil;
54 
55 	d->subdisk = subdisk;
56 	d->offset = offset;
57 	d->size = size;
58 	d->disk._read = diskpartread;
59 	d->disk._sync = diskpartsync;
60 	d->disk._close = diskpartclose;
61 
62 	return &d->disk;
63 }
64 
65 void
66 diskpartabandon(Disk *d)
67 {
68 	if(d->_read != diskpartread)
69 		abort();
70 	((DiskPart*)d)->subdisk = nil;
71 }