X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;f=README.adoc;h=7bf90491d717fb3ef9a6276e47778d369b4a5afc;hb=HEAD;hp=a37d36d40c0e75d2409119e781fbc24923afe4e6;hpb=26b59ee2e0ee0a47f19153e629ce0c7a94bb134d;p=rrq%2Ffusefile.git diff --git a/README.adoc b/README.adoc index a37d36d..7bf9049 100644 --- a/README.adoc +++ b/README.adoc @@ -1,76 +1,29 @@ -fusefile -======== +# fusefile +:author: Ralph Ronnquist +:revdate: Sun, 30 Apr 2023 21:18:34 +1000 + +This project implements a "fuse" device to mount a concatenation of +fragments of one or more files as a single file. + +The __fused file__ allows writing to fragments (without changing their +sizes); of course only for writable fragment files. The fused file may +be set up with an __overlay file__ to capture changes instead of +writing the underlying fragment files. + +==== +This is a usage example to set up a fused file C consisting of files A +and B: +---- +$ fusefile C A B +---- +==== + +==== +This is an example of tearing down a fused file C: +---- +$ fusermount -u C +---- +==== + +See the +man page+ for usage details and some more examples. -This project implements a "fuse" device to mount as a single file that -is a concatenation of fragments of one or more files. By default the -fused file is read-only. - -A writeable fused file is set up by associating the mount with a -"scratch pad file" - -FUSE file mount for combining file fragments. - -== SYNOPSIS - *fusefile* [_fuse options_] *mountpoint* _filename/from-to_ ... - -## DESCRIPTION - -*fusefile* is FUSE file mount that presents a series of fragments of -other files as a contiguous concatenation. It bind mounts a driver on -top of the file mountpoint to present the nominated file fragments as -a single, contiguous file. - -The fragment arguments include the filename of a source file, and -optionally start and end byte positions. All in all there five -variations: - - * __filename__ include all of the file. - - * __filename/__ include all of the file named with "/" in the pathname. This case requires a final "/", since the last "/" separates the filename from the position details. - - * __filename/from__ include the file from the given start position, to end. - - * __filename/-to__ include the file from beginning to the given end position (not included). - - * __filename/from-to__ include the file from the given start position, up to the given end position (not included). - - * *pad=*_filename_ when this is given as first argument, the fused - file is set up as a writable random-access file, where the write - events are captured appended to the nominated "pad" file. The new - content is inserted into the fused file but not the original files, - and fragments are split up and adjusted as needed so as to make the - write events appear as insertions inteo the fused file. - -## EXAMPLES - -Insert file "y" into file "x" at position 1200: - - $ fusefile -ononempty x x/-1200 y x/1200 -The bind mount shadows the original file "x", and presents the -composite instead. - -Make file y be a swap of the beginning and end of file "x", at -position 2442: - - $ fusefile y x/2442 x/-2442 - -## NOTES - -Note that **fusefile** opens the nominated source file(s) before bind -mounting. With the fuse option __-ononempty__ it will bind over an -non-empty file, which may be useful. The source file descriptors -remain open, but the source fragments are not recomputed. If a source -file changes or reduces in size, anything may happen. - -If the mountpoint file doesn't exist, then **fusefile** creates it, -and removes it when unmounted. - -When a "pad" file is used, it is updated as an "ar" archive where each -write event is a new member appended at the end. The "pad" member has -two additional, newline-terminated text lines with the insertion -position and the member size (ascii decimal digits), before the actual -insertion event content. - -## AUTHOR - -Ralph Rönnquist