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Minix reads Direct, Indirect, Doubly-indirect, and Triply-indirect zones

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This commit is contained in:
Stephen Marz 2020-04-25 16:39:50 -04:00
parent 3bfab82612
commit bb4e2d118a
1 changed files with 92 additions and 18 deletions
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106
risc_v/src/minixfs.rs
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@ -132,8 +132,7 @@ impl MinixFileSystem {
// have to skip the bitmaps blocks. We have a certain number of inode map blocks (imap)
// and zone map blocks (zmap).
// The inode comes to us as a NUMBER, not an index. So, we need to subtract 1.
let inode_offset =
(2 + super_block.imap_blocks + super_block.zmap_blocks) as usize * BLOCK_SIZE as usize;
let inode_offset = (2 + super_block.imap_blocks + super_block.zmap_blocks) as usize * BLOCK_SIZE as usize;
// Now, we read the inode itself.
// The block driver requires that our offset be a multiple of 512. We do that with the
@ -219,11 +218,7 @@ impl FileSystem for MinixFileSystem {
BLOCK_SIZE - offset_byte
};
unsafe {
memcpy(
buffer.add(bytes_read as usize,),
block_buffer.get().add(offset_byte as usize,),
read_this_many as usize,
);
memcpy(buffer.add(bytes_read as usize), block_buffer.get().add(offset_byte as usize), read_this_many as usize);
}
offset_byte = 0;
bytes_read += read_this_many;
@ -249,12 +244,44 @@ impl FileSystem for MinixFileSystem {
unsafe {
if izones.add(i).read() != 0 {
if offset_block <= blocks_seen {
syc_read(
desc,
block_buffer.get_mut(),
BLOCK_SIZE,
BLOCK_SIZE * izones.add(i,).read(),
);
syc_read(desc, block_buffer.get_mut(), BLOCK_SIZE, BLOCK_SIZE * izones.add(i).read());
let read_this_many = if BLOCK_SIZE - offset_byte > bytes_left {
bytes_left
}
else {
BLOCK_SIZE - offset_byte
};
memcpy(buffer.add(bytes_read as usize), block_buffer.get().add(offset_byte as usize), read_this_many as usize);
bytes_read += read_this_many;
bytes_left -= read_this_many;
offset_byte = 0;
if bytes_left == 0 {
return bytes_read;
}
}
blocks_seen += 1;
}
}
}
}
// ////////////////////////////////////////////
// // DOUBLY INDIRECT ZONES
// ////////////////////////////////////////////
if inode.zones[8] != 0 {
let mut indirect_buffer = BlockBuffer::new(BLOCK_SIZE);
let mut iindirect_buffer = BlockBuffer::new(BLOCK_SIZE);
syc_read(desc, indirect_buffer.get_mut(), BLOCK_SIZE, BLOCK_SIZE * inode.zones[8]);
let num_indirect_pointers = BLOCK_SIZE as usize / 4;
let izones = indirect_buffer.get() as *const u32;
let iizones = iindirect_buffer.get() as *const u32;
unsafe {
for i in 0..num_indirect_pointers {
if izones.add(i).read() != 0 {
syc_read(desc, iindirect_buffer.get_mut(), BLOCK_SIZE, BLOCK_SIZE * izones.add(i).read());
for j in 0..num_indirect_pointers {
if iizones.add(j).read() != 0 {
if offset_block <= blocks_seen {
syc_read(desc, block_buffer.get_mut(), BLOCK_SIZE, BLOCK_SIZE * iizones.add(j).read());
let read_this_many = if BLOCK_SIZE - offset_byte > bytes_left {
bytes_left
}
@ -278,12 +305,59 @@ impl FileSystem for MinixFileSystem {
}
}
}
// ////////////////////////////////////////////
// // DOUBLY INDIRECT ZONES
// ////////////////////////////////////////////
}
}
// ////////////////////////////////////////////
// // TRIPLY INDIRECT ZONES
// ////////////////////////////////////////////
if inode.zones[9] != 0 {
let mut indirect_buffer = BlockBuffer::new(BLOCK_SIZE);
let mut iindirect_buffer = BlockBuffer::new(BLOCK_SIZE);
let mut iiindirect_buffer = BlockBuffer::new(BLOCK_SIZE);
syc_read(desc, indirect_buffer.get_mut(), BLOCK_SIZE, BLOCK_SIZE * inode.zones[9]);
let num_indirect_pointers = BLOCK_SIZE as usize / 4;
let izones = indirect_buffer.get() as *const u32;
let iizones = iindirect_buffer.get() as *const u32;
let iiizones = iiindirect_buffer.get() as *const u32;
unsafe {
for i in 0..num_indirect_pointers {
if izones.add(i).read() != 0 {
syc_read(desc, iindirect_buffer.get_mut(), BLOCK_SIZE, BLOCK_SIZE * izones.add(i).read());
for j in 0..num_indirect_pointers {
if iizones.add(j).read() != 0 {
syc_read(desc, iiindirect_buffer.get_mut(), BLOCK_SIZE, BLOCK_SIZE * iizones.add(j).read());
for k in 0..num_indirect_pointers {
if iiizones.add(k).read() != 0 {
if offset_block <= blocks_seen {
syc_read(desc, block_buffer.get_mut(), BLOCK_SIZE, BLOCK_SIZE * iiizones.add(k).read());
let read_this_many = if BLOCK_SIZE - offset_byte > bytes_left {
bytes_left
}
else {
BLOCK_SIZE - offset_byte
};
memcpy(
buffer.add(bytes_read as usize,),
block_buffer.get().add(offset_byte as usize,),
read_this_many as usize,
);
bytes_read += read_this_many;
bytes_left -= read_this_many;
offset_byte = 0;
if bytes_left == 0 {
return bytes_read;
}
}
blocks_seen += 1;
}
}
}
}
}
}
}
}
bytes_read
}