From: Richard W.M. Jones <"Richard W.M. Jones "> Date: Fri, 9 May 2008 15:08:07 +0000 (+0100) Subject: Support for writing diskzip files. X-Git-Url: http://git.annexia.org/?a=commitdiff_plain;h=5ab383e245a0134ed7dd47dd3bbd4607838102ac;p=virt-df.git Support for writing diskzip files. --- diff --git a/diskzip/.depend b/diskzip/.depend index 18618bf..e54de33 100644 --- a/diskzip/.depend +++ b/diskzip/.depend @@ -1,2 +1,4 @@ -diskzip.cmo: ../lib/int63.cmi diskzip_gettext.cmo ../lib/diskimage.cmi -diskzip.cmx: ../lib/int63.cmx diskzip_gettext.cmx ../lib/diskimage.cmx +diskzip.cmo: ../lib/int63.cmi diskzip_gettext.cmo ../lib/diskimage.cmi \ + /usr/lib64/ocaml/bitmatch/bitmatch.cmi +diskzip.cmx: ../lib/int63.cmx diskzip_gettext.cmx ../lib/diskimage.cmx \ + /usr/lib64/ocaml/bitmatch/bitmatch.cmi diff --git a/diskzip/diskzip.ml b/diskzip/diskzip.ml index 721335a..55094e7 100644 --- a/diskzip/diskzip.ml +++ b/diskzip/diskzip.ml @@ -18,6 +18,8 @@ *) open Unix +open ExtList +open ExtString open Printf open Int63.Operators @@ -26,6 +28,9 @@ open Diskzip_gettext.Gettext type output = File of string | Dir of string type extcompress = BZip2 | GZip | External of string +let max_disks = 32 +let max_image_name = 256 + let rec main () = (* Program name changes behaviour. *) let compressing = @@ -175,9 +180,12 @@ and go_compress extcompress images = ) ); + (* Write the main header. *) + write_header machine.Diskimage.m_disks; + (* Iterate over the disks. *) - List.iter ( - fun { Diskimage.d_name = name; d_dev = disk } -> + List.iteri ( + fun disknum { Diskimage.d_name = name; d_dev = disk } -> let blocksize = disk#blocksize in let size = disk#size in (* Size in bytes. *) let nr_blocks = size /^ blocksize in (* Number of disk sectors. *) @@ -197,12 +205,12 @@ and go_compress extcompress images = in (* Look up owners for each sector in turn. *) - let rec loop blk = - if blk < nr_blocks then ( - (* The current sector (blk) is either free or not free. Look - * for a stretch of sectors which are the same. + let rec loop start_blk = + if start_blk < nr_blocks then ( + (* The current sector (start_blk) is either free or not free. + * Look for a stretch of sectors which are the same. *) - let current_free = block_is_free blk in + let current_free = block_is_free start_blk in let rec find_end blk = if blk < nr_blocks then ( if block_is_free blk = current_free then @@ -212,34 +220,35 @@ and go_compress extcompress images = ) else nr_blocks (* End of the disk image. *) in - let end_blk = find_end (Int63.succ blk) in + let end_blk = find_end (Int63.succ start_blk) in + + let len_blks = end_blk -^ start_blk in - (* Current stretch is from blk .. end_blk-1. *) + let start_offset = start_blk *^ blocksize in + let len_bytes = len_blks *^ blocksize in + + (* Current stretch is from start_blk .. end_blk-1. *) if !Diskimage.debug then - eprintf " %s stretch %s to %s-1 (%s bytes)\n" + eprintf " %s stretch %s to %s-1 (%s bytes)\n%!" (if current_free then "free" else "used") - (Int63.to_string blk) (Int63.to_string end_blk) - (Int63.to_string ((end_blk-^blk) *^ blocksize)); - + (Int63.to_string start_blk) (Int63.to_string end_blk) + (Int63.to_string (len_blks *^ blocksize)); + (* Write the stretch to stdout. *) + write_stretch_header disknum current_free start_offset len_bytes; + (* Write the data (note: we only need to write it if + * it's not marked as free!). + *) + if not current_free then write_stretch disk start_offset len_bytes; loop end_blk ) in loop ~^0 - ) machine.Diskimage.m_disks - - - - - - - - - - + ) machine.Diskimage.m_disks; + write_trailer () and go_decompress ?output extcompress args = (* Read the input, which may be a single named file, or a series of @@ -302,20 +311,75 @@ and go_decompress ?output extcompress args = -(* (* Since we have the wonderful pa_bitmatch, might as well use it to * define a robust binary format for the compressed files. + * + * These functions are in matched pairs "write_foo" / "read_foo" so + * you can check that the write and read protocols agree. *) -and write_header ... = - let bs = BITSTRING { - 0xD152 : 16; 0x01 : 8; 0x00 : 8; (* file magic, version 1.0 *) - nr_disks : 8; (* number of disks being packed *) - - - +and write_header disks = + let nr_disks = List.length disks in + assert (nr_disks > 0); - } in - + (* Don't allow large numbers of disks. *) + if nr_disks > max_disks then ( + eprintf (f_"diskzip: maximum number of disk images is limited by the current image format to %d") nr_disks; + exit 2 + ); + let names = List.map ( + fun { Diskimage.d_name = name } -> + let name = + try + let i = 1 + String.rindex name '/' in + String.sub name i (String.length name - i) + with + Invalid_string | Not_found -> name in + + let contains_dotdot = + try ignore (String.find name ".."); true + with Invalid_string | Not_found -> false in + if contains_dotdot then ( + prerr_endline (s_"diskzip: disk image names cannot contain \"..\""); + exit 2 + ); + + (* Don't allow very long names. *) + if String.length name > max_image_name then ( + eprintf (f_"diskzip: maximum length of disk image name is limited by the current image format to %d bytes") max_image_name; + exit 2 + ); + + name + ) disks in + + (* Header followed by names. *) + let header = + let header = + let bs = BITSTRING { + 0xD152 : 16; 0x01 : 8; 0x00 : 8; (* file magic, version 1.0 *) + nr_disks : 8 (* number of disks being packed *) + } in + let len = Bitmatch.bitstring_length bs in + assert (len land 7 = 0); + Bitmatch.string_of_bitstring bs in + let names = List.map ( + fun name -> + let bs = + BITSTRING { + String.length name : 16; + name : -1 : string + } in + let len = Bitmatch.bitstring_length bs in + assert (len land 7 = 0); + Bitmatch.string_of_bitstring bs + ) names in + + (* Construct the final header. *) + header ^ String.concat "" names in + + ignore (write stdout header 0 (String.length header)) + +(* and read_header () = (* Diskzip headers are limited to overall max size of 1024 bytes. *) let bs = Bitmatch.bitstring_of_file_descr_max stdin 1024 in @@ -350,4 +414,42 @@ and read_header () = exit 1 *) +and write_stretch_header disknum free start_offset len_bytes = + let start_offset = Int63.to_int64 start_offset in + let len_bytes = Int63.to_int64 len_bytes in + + let bs = BITSTRING { + (* Stretch header magic. Allows us to find synchronization errors. *) + 0xD1525555_l : 32; + free : 1; 0 : 7; (* Flags. *) + disknum : 8; (* Disk number. *) + start_offset : 64; (* Start offset in disk image (bytes)*) + len_bytes : 64 (* Length in bytes. *) + } in + + let str = Bitmatch.string_of_bitstring bs in + ignore (write stdout str 0 (String.length str)) + +and write_stretch dev start_offset len_bytes = + (* Limit size of blocks that we write, since some implementations + * of device class cannot handle large blocks. In any case I tested + * this and writing large blocks isn't any faster. + *) + let blocksize = ~^65536 in + let rec loop offset len = + if len > ~^0 then ( + let n = min blocksize len in + ignore (write stdout (dev#read offset n) 0 (Int63.to_int n)); + loop (offset+^n) (len-^n) + ) + in + loop start_offset len_bytes + +and write_trailer () = + let bs = BITSTRING { + 0xD152FFFF_l : 32 + } in + let str = Bitmatch.string_of_bitstring bs in + ignore (write stdout str 0 (String.length str)) + let () = main ()