Added dir.5 and filesys.5 manuals.

This commit is contained in:
Warren Toomey
2016-03-13 09:58:18 +10:00
parent 1829f8577f
commit cff237d445
2 changed files with 138 additions and 0 deletions
+34
View File
@@ -0,0 +1,34 @@
11/3/70 DIRECTORY (V)
NAME format of directories
SYNOPSIS
DESCRIPTION A directory behaves exactly like an ordinary file, save
that no user may write into a directory. The fact that a
file is a directory is indicated by a bit in the flag word
of its i-node entry.
Directory entries are 8 words long. The first word is the
i-node of the file represented by the entry, if non-zero;
if zero, the entry is empty.
Words 1-4 represent the (8-character) file name, space
padded on the right. These words are not necessarily
cleared for empty slots.
By convention, the first entry in each directory is
for "dd", which is the "directory directory" that holds
all the users' home directories and the "system" directory.
The "system" directory contains "init" and "sh".
FILES
SEE ALSO file system format
DIAGNOSTICS
BUGS
OWNER ken, dmr
+104
View File
@@ -0,0 +1,104 @@
11/3/70 FILE SYSTEM (V)
NAME format of file system
SYNOPSIS
DESCRIPTION The RB09 fixed head disk has 8,000 64-word blocks on
each of its two surfaces. Unix uses the second surface
(physical blocks 8,000 to 15,999) and numbers them
from logical block 0 to logical block 7,999. The following
discussion refers to logical blocks.
The Unix filesystem is divided into 8,000 blocks of 64 words
per block. Block 0 is the "sysdata" block. The first word
points to the first block of the free-storage map. Each block
in the free-storage map is structured as follows: the first
word is the block number of the next block in the free-storage
map, or zero if this is the end of the free-storage map. The
next nine words hold free block numbers, or zero (no block number).
Block 1 on the filesystem is unused. (?)
I-numbers begin at 1, and the storage for i-nodes begins at
block 2. Blocks 2 to 711 contain the i-nodes, with five
consecutive i-nodes per block. Certain i-nodes are reserved for
special files, directories and devices:
1 The core file written by "sys save" or a bad system call
2 The "dd" directory directory
3 The "system" directory
6 The "ttyin" special file
7 The "keyboard" (graphic-2) special file
8 The "pptin" (paper tape reader) special file
10 The "ttyout" special file
11 The "display" (graphic-2) special file
12 The "pptout" (paper tape punch) special file
There is only one file system which is always mounted;
it resides on the RB disk. This device is also used for
swapping. The swap areas are at the high blocks on this device:
blocks 6,400 to 7,999. These blocks do not appear in the free list.
Each i-node represents one file. The format of
an i-node is as follows, where the left column represents
the offset in words from the beginning of the i-node:
0 flags (see below)
1 first indirect block or contents block
...
7 seventh indirect block or contents block
8 user ID of owner
9 link count
10 size in words
11 unique value assigned at creation
The flags are as follows:
400000 i-node is allocated
200000 large file
?????? allocated bit (always on)
000040 special file
000020 directory
000010 read, owner
000004 write, owner
000002 read, non-owner
000001 write, non-owner
The allocated bit (flag ??????) is believed even if the i-node
map says the i-node is free; thus corruption of the map may
cause i-nodes to become unallocatable, but will not cause active
nodes to be reused.
Word number n of a file is accessed as follows: n is
divided by 64 to find its logical block number (say b) in
the file. If the file is small (flag 200000 is 0), then b
must be less than 7, and the physical block number corresponding
to b is the bth entry in the address portion of the i-node.
If the file is large, b is divided by 64 to yield a number
which must be less than 8 (or the file is too large for
UNIX to handle). The corresponding slot in the i-node
address portion gives the physical block number of an
indirect block. The residue mod 64 gives a word offset
in the indirect block, and the word found there is the
physical address of the block corresponding to b.
If block b in a file exists, it is not necessary that all
blocks less than b exist. A zero block number either in the
address words of the i-node or in an indirect block
indicates that the corresponding block has never been
allocated. Such a missing block reads as if it contained
all zero words.
FILES
SEE ALSO format of directories
DIAGNOSTICS
BUGS
OWNER