Lazy fast-import frontend authors that want to rely on the backend to
keep track of the content of the imported trees _almost_ have what
they need in the 'cat-blob' command (v1.7.4-rc0~30^2~3, 2010-11-28).
But it is not quite enough, since
(1) cat-blob can be used to retrieve the content of files, but
not their mode, and
(2) using cat-blob requires the frontend to keep track of a name
(mark number or object id) for each blob to be retrieved
Introduce an 'ls' command to complement cat-blob and take care of the
remaining needs. The 'ls' command finds what is at a given path
within a given tree-ish (tag, commit, or tree):
'ls' SP <dataref> SP <path> LF
or in fast-import's active commit:
'ls' SP <path> LF
The response is a single line sent through the cat-blob channel,
imitating ls-tree output. So for example:
FE> ls :1 Documentation
gfi> 040000 tree 9e6c2b599341d28a2a375f8207507e0a2a627fe9 Documentation
FE> ls 9e6c2b599341d28a2a375f8207507e0a2a627fe9 git-fast-import.txt
gfi> 100644 blob 4f92954396e3f0f97e75b6838a5635b583708870 git-fast-import.txt
FE> ls :1 RelNotes
gfi> 120000 blob b942e499449d97aeb50c73ca2bdc1c6e6d528743 RelNotes
FE> cat-blob b942e499449d97aeb50c73ca2bdc1c6e6d528743
gfi> b942e499449d97aeb50c73ca2bdc1c6e6d528743 blob 32
gfi> Documentation/RelNotes/1.7.4.txt
The most interesting parts of the reply are the first word, which is
a 6-digit octal mode (regular file, executable, symlink, directory,
or submodule), and the part from the second space to the tab, which is
a <dataref> that can be used in later cat-blob, ls, and filemodify (M)
commands to refer to the content (blob, tree, or commit) at that path.
If there is nothing there, the response is "missing some/path".
The intent is for this command to be used to read files from the
active commit, so a frontend can apply patches to them, and to copy
files and directories from previous revisions.
For example, proposed updates to svn-fe use this command in place of
its internal representation of the repository directory structure.
This simplifies the frontend a great deal and means support for
resuming an import in a separate fast-import run (i.e., incremental
import) is basically free.
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Improved-by: Junio C Hamano <gitster@pobox.com>
Improved-by: Sverre Rabbelier <srabbelier@gmail.com>
8dc6a373d2