3 files changed, 132 insertions(+), 2 deletions(-)

A fs/ar/tar.fs
A fs/doc/ar/tar.txt
M fs/xcomp/bootlo.fs

@@ 0,0 1,46 @@
+: parseoctal ( a u -- n )
+  0 swap for ( a res ) 8 * over c@ '0' - + dip 1+ | next nip ;
+
+struct[ TarRecord
+  $200 const RECORDSZ
+
+  100 sfield' zname
+  8   sfield' omode \ o prefix means "octal", ASCII octal.
+  8   sfield' ouid
+  8   sfield' ogid
+  12  sfield' ofilesz
+  12  sfield' omtime
+  8   sfield' checksum
+      sfieldb type
+  100 sfield' zlinkname
+
+  : :empty? ( self -- f ) @ not ;
+  : :dir? type '5' = ;
+  create _buf 100 allot
+  : :name ( self -- str )
+    zname 0 over 100 [c]? ( zname len )
+    2dup 1- + c@ '/' = if 1- then ( zname len )
+    dup _buf c!+ swap move _buf ;
+  : :filesize ( self -- sz ) ofilesz 11 parseoctal ;
+]struct
+
+struct[ Tar
+  sfield drv
+  sfield sec0
+  sfield sec
+  SZ &+ buf(
+  : :sec! ( sec self -- ) 2dup to sec bi buf( | drv Drive :sec@ ;
+  : :new ( sec0 drv -- tar )
+    here rot> dup , over , -1 , Drive secsz allot ( tar sec ) over :sec! ;
+  : :record ( self -- rec ) buf( ;
+  : :rewind dup sec0 swap :sec! ;
+  : :next ( self -- rec )
+    dup :record dup TarRecord :empty? if abort" end of tar chain" then
+    TarRecord :filesize TarRecord RECORDSZ /mod swap bool + 1+ ( self sec+ )
+    over sec + over :sec! :record ;
+  : :find ( name self -- rec? f ) >r \ V1=self
+    V1 :rewind V1 :record begin ( name rec )
+      dup TarRecord :empty? not while
+      TarRecord :name over s= not while ( name )
+      V1 :next repeat drop r> :record 1 else drop rdrop 0 then ;
+]struct

@@ 0,0 1,84 @@
+# Tape archive (tar) tools
+
+The /ar/tar.fs unit contains tool to manipulate archives of the "tar" format
+originating from UNIX. It does so through two structs.
+
+## TarRecord
+
+This wraps a 512 bytes tar header record containing metadata about the
+represented element. You are supposed to use it with a pointer to the actual
+data. For example, if you've read a tar header sector to "here", then "here
+TarRecord :name" will yield the name of the record.
+
+Fields:
+
+zname
+omode
+ouid
+ogid
+ofilesz
+omtime
+checksum
+zlinkname
+  Pointer to the address corresponding to the record field.
+
+type
+  Character corresponding to the record type ('5'=directory, NULL=file)
+
+Methods:
+
+:empty? ( self -- f )
+  Whether the record is empty (starts with null characters).
+
+:dir? ( self -- f )
+  Whether the record is a directory (type = '5')
+
+:name ( self -- str )
+  Name of the file or directory. If the name has a trailing '/', it is removed.
+  This name is stored in a static buffer that is overwritten at each :name call.
+
+:filesize ( self -- sz )
+  Parsed version of "ofilesz". This is the file size in bytes that follow the
+  record.
+
+## Tar
+
+This structure iterates over a Drive, interpreting sectors as tar records. At
+creation, it is supplied a Drive struct as well as an "origin" sector. Is is
+then possible to iterate over record through :next or to find a record with a
+specific name through :find.
+
+Fields:
+
+drv
+  Drive we're iterating through
+
+sec0
+  Origin sector number
+
+sec
+  Sector of the current record
+
+buf(
+  Buffer with the contents of the current sector
+
+Methods:
+
+:new ( sec0 drv -- tar )
+  Create new Tar with specified Drive and origin sector.
+
+:sec! ( sec self -- )
+  Read and set current sector.
+
+:record ( self -- rec )
+  TarRecord we're currently pointing at.
+
+:rewind ( self -- )
+  Set current sector to origin sector.
+
+:next ( self -- rec )
+  Advance current sector to next record and return it.
+
+:find ( name self -- rec? f )
+  Rewind, then iterate over record over a record of the specified name is found.
+  If found, f=1 and rec is set. Otherwise, f=0 and rec is absent.

@@ 377,8 377,8 @@ create _ 0 , EMETA_8B , EMETA_16B ,
 struct[ Drive
   sfield secsz
   sfield seccnt
-  smethod :sec@
-  smethod :sec!
+  smethod :sec@ ( sec dst drv -- )
+  smethod :sec! ( sec src drv -- )
 ]struct
 
 struct[ IO