Re: Kernel SCM saga..

ross
2005-04-08T07:17:33Z

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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);
}

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