Re: Kernel SCM saga..

[ross@jose.lug.udel.edu]

On Thu, Apr 07, 2005 at 09:42:04PM -0700, Linus Torvalds wrote:
> In the meantime (and because monotone really _is_ that slow), here's a
> quick challenge for you, and any crazy hacker out there: if you want to
> play with something _really_ nasty (but also very _very_ fast), take a
> look at kernel.org:/pub/linux/kernel/people/torvalds/.

Interesting.  I like it, with one modification (see below).

> First one to send me the changelog tree of sparse-git (and a tool to
> commit and push/pull further changes) gets a gold star, and an honorable
> mention. I've put a hell of a lot of clues in there (*).

Here's a partial solution.  It does depend on a modified version of
cat-file that behaves like cat.  I found it easier to have cat-file
just dump the object indicated on stdout.  Trivial patch for that is included.

Two scripts are included:

1) makechlog.sh takes an object and generates a ChangeLog file
consisting of all the parents of the given object.  It's probably
breakable, but correctly outputs the sparse-git changes when run on
HEAD.  Handles multiple parents and breaks cycles.

This adds a line to each object "me <sha1>".  This lets a change
identify itself.

It takes 35 seconds to produce all the change history on my box.  It
produces a single file named "ChangeLog".

2) chkchlog.sh uses the "me" entries to verify that #1 didn't miss any
parents.  It's mostly to prove my solution reasonably correct ::-)

The patch is below, the scripts are attached, and everything is
available here:

http://lug.udel.edu/~ross/git/

Now to see what I come up with for commit, push, and pull...

-- 
Ross Vandegrift
ross@lug.udel.edu

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
	--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37


--- cat-file.orig.c     2005-04-08 01:53:54.000000000 -0400
+++ cat-file.c  2005-04-08 01:57:51.000000000 -0400
@@ -11,18 +11,11 @@
        char type[20];
        void *buf;
        unsigned long size;
-       char template[] = "temp_git_file_XXXXXX";
-       int fd;
 
        if (argc != 2 || get_sha1_hex(argv[1], sha1))
                usage("cat-file: cat-file <sha1>");
        buf = read_sha1_file(sha1, type, &size);
        if (!buf)
                exit(1);
-       fd = mkstemp(template);
-       if (fd < 0)
-               usage("unable to create tempfile");
-       if (write(fd, buf, size) != size)
-               strcpy(type, "bad");
-       printf("%s: %s\n", template, type);
+       printf ("%s", buf);
 }

Attachment: makechlog.sh
Description: Bourne shell script

Attachment: chkchlog.sh
Description: Bourne shell script