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372 lines
11 KiB
Perl
Executable File
372 lines
11 KiB
Perl
Executable File
#!/usr/bin/perl
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#
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# mkfs7: Make a PDP-7 filesystem image for SimH
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#
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# (c) 2016 Warren Toomey, GPL3
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#
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use strict;
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use warnings;
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use Data::Dumper;
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# Constants
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use constant NUMBLOCKS => 8000; # Number of blocks on a surface
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use constant WORDSPERBLK => 64; # 64 words per block
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use constant NUMINODEBLKS => 710; # Blocks 1 to 710 for i-nodes
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use constant FIRSTINODEBLK => 1; # First i-node block number
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use constant INODESIZE => 12; # Size of an i-node
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use constant INODESPERBLK => WORDSPERBLK/INODESIZE;
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use constant DIRENTSIZE => 8; # Size of an directory entry
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use constant DIRENTSPERBLK => WORDSPERBLK/DIRENTSIZE;
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use constant ROOT_UID => -1; # Native root user-id
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use constant MAXINT => 0777777; # Biggest unsigned integer
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use constant DD_INUM => 2; # I-number of the dd directory
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# i-node field offsets
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use constant I_FLAGS => 0;
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use constant I_DISKPS => 1;
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use constant I_UID => 8;
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use constant I_NLKS => 9;
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use constant I_SIZE => 10;
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use constant I_UNIQ => 11;
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use constant I_NUMBLKS => 7; # Seven block pointers in i-node
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# i-node flag masks
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use constant I_USED => 0400000;
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use constant I_LARGE => 0200000;
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use constant I_SPECIAL => 0000040;
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use constant I_DIRECTORY => 0000020;
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use constant I_OWNERREAD => 0000010;
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use constant I_OWNERWRITE => 0000004;
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use constant I_WORLDREAD => 0000010;
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use constant I_WORLDWRITE => 0000004;
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# Directory field offsets
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use constant D_INUM => 0;
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use constant D_NAME => 1;
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use constant D_UNIQ => 5;
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use constant D_NUMWORDS => 8; # Eight words in a direntry
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# Globals
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my $debug=0;
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my @Block; # Array of blocks and words in each block
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my $nextblknum= NUMINODEBLKS+1; # Next free block number
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my $nextinum= 1; # i-num 0 is never used
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my @Dirstack; # Stack of directories. Each value is a ref
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# to a [ blocknum, offset, inum ] array which
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# is the next free position in the directory
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# Debug printing
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sub dprint {
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print(@_) if ($debug);
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}
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sub dprintf {
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printf(@_) if ($debug);
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}
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# Given a size in words, allocate and return a set of block numbers
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# for the entity
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sub allocate_blocks {
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my $numwords= shift;
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my @blklist;
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my $numblocks= int( ($numwords+WORDSPERBLK-1) / WORDSPERBLK );
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die("Not enough blocks\n") if (($nextblknum+$numblocks) >= NUMBLOCKS);
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foreach my $b (1 .. $numblocks) {
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push(@blklist, $nextblknum++);
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}
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dprint("Allocated blocks for size $numwords: $blklist[0] .. $blklist[-1]\n");
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return(@blklist);
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}
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# Allocate and return either the specified i-node or the next
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# available one if there is no argument
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sub allocate_inode {
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my $inum= shift;
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return($nextinum++) if (!defined($inum));
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die("i-num $inum already allocated\n") if ($inum< $nextinum);
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$nextinum= $inum+1;
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return($inum);
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}
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# Given a list of block numbers, allocate a set of indirect blocks
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# and install block pointers into the indirect blocks. Return the
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# list of indirect block numbers.
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sub build_indirect_blocks {
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my @blklist= @_;
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my $blkcount= @blklist;
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# Divide the number of data blocks by WORDSPERBLK and round up, so
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# we know how many indirect blocks to allocate.
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my $indcount= int(($blkcount+WORDSPERBLK-1)/WORDSPERBLK);
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# Get enough indirect blocks
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my @indlist= allocate_blocks($indcount);
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# Now fill in the pointers
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my $indblock= $indlist[0];
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my $offset= 0;
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foreach my $datablock (@blklist) {
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$Block[$indblock][$offset++]= $datablock;
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if ($offset == WORDSPERBLK) {
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$offset=0; $indblock++;
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}
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}
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# Return the indirect block numbers
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dprint("Built indirect blocks $indlist[0] .. $indlist[-1]\n");
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return(@indlist);
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}
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# Return blocknumber and offset for a specific i-node
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sub get_inode_block_offset {
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my $inum= shift;
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my $blocknum= FIRSTINODEBLK + int($inum/INODESPERBLK);
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my $offset= INODESIZE * ($inum%INODESPERBLK);
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dprint("inum $inum => block $blocknum offset $offset\n");
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return($blocknum, $offset);
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}
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# Given an i-node number (possibly undef), permission, filetype, uid, size
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# and up to seven direct or indirect block numbers, fill in the given i-node
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# with the data. If the i-node number is undef, allocate an i-node number.
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# Return the i-node number used.
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sub fill_inode {
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my ($inum, $perms, $filetype, $uid, $size, @blklist)= @_;
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die("Too many blocks\n") if (@blklist>7);
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# Deal with the root user-id
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$uid= MAXINT if ($uid==ROOT_UID);
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# Calculate the block number and word offset for this
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$inum= allocate_inode() if (!defined($inum));
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my ($blocknum, $offset)= get_inode_block_offset($inum);
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# Fill in the easy fields
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$Block[$blocknum][$offset+I_UID]= $uid;
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$Block[$blocknum][$offset+I_SIZE]= $size;
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$Block[$blocknum][$offset+I_NLKS]= 1;
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my $i= $offset;
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foreach my $datablocknum (@blklist) {
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$Block[$blocknum][$i+I_DISKPS]= $datablocknum;
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}
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# Deal with the flags and see if it's a large file
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my $flags = $perms | $filetype | I_USED;
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$flags |= I_LARGE if ($size> WORDSPERBLK * I_NUMBLKS);
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$Block[$blocknum][$offset+I_FLAGS]= $flags;
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dprintf("fill inum %d: flags %06o uid %06o size %d\n", $inum, $flags, $uid, $size);
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return($inum);
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}
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# Convert an ASCII string into an array of 18-bit word values
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# where two characters are packed into each word. Put NUL in
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# if the string has an odd number of characters. Return the array
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sub ascii2words {
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my $str = shift;
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my @words;
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for ( my $i = 0 ; $i < length($str) ; $i += 2 ) {
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my $c1 = substr( $str, $i, 1 ) || "\0";
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my $c2 = substr( $str, $i + 1, 1 ) || "\0";
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push( @words, ( ord($c1) << 9 ) | ord($c2) );
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}
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return (@words);
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}
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# Add an extra block to an i-node. NOTE: for now, we don't change the size
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# in the i-node.
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sub add_block_to_inode {
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my ($blknum, $inum) = @_;
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my ($iblock, $offset)= get_inode_block_offset($inum);
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foreach my $i (1 .. I_NUMBLKS) {
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next if ($Block[$iblock][$offset+$i]!=0); # Skip in-use blocks
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$Block[$iblock][$offset+$i]= $blknum;
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return;
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}
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die("Unable to add extra block to i-node $inum\n");
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dprint("Added block $blknum to i-node $inum\n");
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}
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# Add a name and an i-node number to the current directory in the
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# directory stack.
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sub add_direntry {
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my ($name, $inum)= @_;
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dprint("Adding $name inode $inum to current directory\n");
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# Get the block and offset to the next empty slot in the directory
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my $dirref= $Dirstack[-1];
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if (!defined($dirref)) {
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print("Empty dirstack, we must be building the root dir\n");
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return;
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}
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my $blocknum= $dirref->[0];
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my $offset= $dirref->[1];
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# Convert the name into four words
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my @wlist= ascii2words($name);
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# Fill in the directory entry
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$Block[$blocknum][$offset+D_INUM]= $inum;
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$Block[$blocknum][$offset+D_NAME]= pop(@wlist);
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$Block[$blocknum][$offset+D_NAME+1]= pop(@wlist);
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$Block[$blocknum][$offset+D_NAME+2]= pop(@wlist);
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$Block[$blocknum][$offset+D_NAME+3]= pop(@wlist);
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# Move up to the next position in the directory.
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$dirref->[1] += D_NUMWORDS;
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# If we have filled the directory up, allocate another block to it
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if ($dirref->[1] == WORDSPERBLK) {
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my $nextblock= allocate_blocks(WORDSPERBLK);
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$dirref->[0]= $nextblock;
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$dirref->[1]= 0;
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# And add this new block to the directory's i-node
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add_block_to_inode($nextblock, $dirref->[2]);
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}
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}
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# Given a name, perms, a user-id and an optional i-node number, make a
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# directory. Link it to the previous directory in the directory stack.
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# Allocate blocks and i-nodes for it. Add a "dd" entry as well.
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sub make_dir {
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my ($dirname, $perms, $uid, $inum)= @_;
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# Get an i-node number or validate the one we got
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$inum= allocate_inode($inum);
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# Get a block for this directory
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my $dirblock= allocate_blocks(WORDSPERBLK);
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# Add this to the previous directory
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# and fill the i-node with the details
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add_direntry($dirname, $inum);
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fill_inode($inum, $perms, I_DIRECTORY, $uid, 0, $dirblock);
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# Make this the top directory on the dirstack
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dprint("Pushing dir block $dirblock inum $inum to dirstack\n");
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push(@Dirstack, [$dirblock, 0, $inum]);
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# Add a "dd" entry to this directory
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add_direntry("dd", DD_INUM);
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dprintf("Made directory %s perms %06o uid %d in i-node %d\n\n",
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$dirname, $perms, $uid, $inum);
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}
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# Read a word from a file in paper tape binary format.
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# Return -1 on EOF
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sub read_word {
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my $FH = shift;
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# Convert three bytes into one 18-bit word
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return(-1) if ( read( $FH, my $three, 3 ) != 3 ); # Not enough bytes read
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my ( $b1, $b2, $b3 ) = unpack( "CCC", $three );
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return ((($b1 & 077) << 12 ) |
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(($b2 & 077) << 6 ) |
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($b3 & 077));
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}
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# Given a filename, perms, user-id and an external file, add a file to the
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# filesystem. Add an entry to this file in the current directory on
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# the dirstack.
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sub add_file {
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my ($name, $perms, $uid, $extfile) = @_;
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dprintf("Adding file %s perms %06o uid %d extfile %s\n",
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$name, $perms, $uid, $extfile);
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# Open the external file
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open(my $IN, "<", $extfile) || die("Can't open $extfile: $!\n");
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# Determine if this is ASCII or binary
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my $isbinary=0;
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my $c = getc($IN);
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seek($IN, 0, 0);
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$isbinary=1 if ((ord($c) & 0300) == 0200);
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# Read the whole file into a buffer, converting from ASCII or sixbit encoding
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my @buf;
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my $size;
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while (1) {
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if ( $isbinary ) {
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# Convert three bytes into one 18-bit word
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my $result = read_word($IN);
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last if ($result == -1);
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$buf[$size++] = $result;
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}
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else {
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# Convert two ASCII characters into one 18-bit word
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my $c1 = getc($IN);
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last if ( !defined($c1) ); # No character, leave the loop
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my $word = ord($c1) << 9;
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my $c2 = getc($IN);
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$word |= ord($c2) if (defined($c2));
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$buf[$size++] = $word;
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}
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}
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# Allocate enough blocks for the file
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my @blklist= allocate_blocks($size);
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# If it's too big, allocate indirect blocks
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my $large=0;
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my @indblocks;
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if (@blklist > I_NUMBLKS) {
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$large=1;
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@indblocks= build_indirect_blocks(@blklist);
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}
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# Allocate and fill in the i-node
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my $inum= allocate_inode();
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if ($large) {
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fill_inode($inum, $perms, 0, $uid, $size, @indblocks);
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} else {
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fill_inode($inum, $perms, 0, $uid, $size, @blklist);
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}
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# and add the entry in the directory
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add_direntry($name, $inum);
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dprint("Done adding file $name as inum $inum\n\n");
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}
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# Given a name, perms, uid and i-number
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# add a special file to the filesystem
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sub add_special {
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my ($name, $perms, $uid, $inum) = @_;
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# Allocate and fill in the i-node
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my $inum= allocate_inode($inum);
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fill_inode($inum, $perms, I_SPECIAL, $uid, 0);
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# Add the entry in the directory
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add_direntry($name, $inum);
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dprint("Done adding special file $name inum $inum\n\n");
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}
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### MAIN PROGRAM
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$debug=1;
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make_dir("dd", 014, -1, 2);
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make_dir("system", 014, -1, 3);
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add_file("init", 014, -1, "proto");
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pop(@Dirstack);
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add_special("ttyin", 014, -1, 6);
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add_special("keyboard", 014, -1, 7);
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add_special("pptin", 014, -1, 8);
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add_special("ttyout", 014, -1, 10);
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add_special("display", 014, -1, 11);
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add_special("pptout", 014, -1, 12);
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add_file("as", 014, -1, "b.c");
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add_file("a7out", 014, -1, "a7out");
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add_file("oflow", 014, -1, "a7out");
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