This fixes stylistic problems and one unused variable spotted by
Petr Baudis.  The buf variable unused in prepare_alt_odb() is
gone and the "creepy" function is more heavily documented.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

<JC> Editorial Note.  We may want to include standard headers in one
of those headers everybody includes, e.g. cache.h, to reduce clutters,
but this commit is as Thomas posted to the GIT list.

Date:	Sat, 7 May 2005 10:41:41 +0200
Signed-off-by: NThomas Glanzmann <sithglan@stud.uni-erlangen.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This does not matter for commands that write just a handful SHA1 files,
but is noticeable in git-convert-cache which essentially traverses the
entire object database.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

SHA1_FILE_DIRECTORIES environment variable is a colon separated paths
used when looking for SHA1 files not found in the usual place for
reading.  Creating a new SHA1 file does not use this alternate object
database location mechanism.  This is useful to archive older, rarely
used objects into separate directories.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Now all the users have gone.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Coda doesn't like cross-directory hardlinks. So try to fall back
on a plain rename instead.

Make it much safer: we write to a temporary file, and then link that
temporary file to the final destination. This avoids all the nasty
races if several people write the same object at the same time.

It should also result in nicer on-disk layout, since it means that
objects all get created in the same subdirectory. That makes a lot
of block allocation algorithms happier, since the objects will now
be allocated from the same zone.

A new command, git-write-blob, is introduced.  This registers
the contents of any file on the filesystem as a blob in the
object database and reports its SHA1 to the standard output.
To implement it, the patch promotes index_fd() from a static
function in update-cache.c to extern and moves it to a library
source, sha1_file.c.

This command is used to update git-merge-one-file-script so that
it does not smudge the work tree.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

If somebody wants it later, we can re-do it, but for now we consider
it an experiment that wasn't worth it. Git will still honor symbolic
names, it just won't look up parents for you.

Of course, you can always do it by hand if you want to.

It uses the jit syntax, at least for now. 0-xxxx is the first parent of xxxx,
while 1-xxxx is the second, and so on. You can use just "-xxxx" for the first
parent, but a lot of commands will think that the initial '-' implies a
command line flag.

This allows the programs to use various simplified versions of
the SHA1 names, eg just say "HEAD" for the SHA1 pointed to by
the .git/HEAD file etc.

For example, this commit has been done with

	git-commit-tree $(git-write-tree) -p HEAD

instead of the traditional "$(cat .git/HEAD)" syntax.

This patch renames read_tree_with_tree_or_commit_sha1() to
read_object_with_reference() and extends it to automatically
dereference not just "commit" objects but "tag" objects.  With
this patch, you can say e.g.:

    ls-tree $tag
    read-tree -m $(merge-base $tag $HEAD) $tag $HEAD
    diff-cache $tag
    diff-tree $tag $HEAD
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Introduce xmalloc and xrealloc to die gracefully with a descriptive
message when out of memory, rather than taking a SIGSEGV. 

Signed-off-by: Christopher Li<chrislgit@chrisli.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Use "unsigned long" for the size, like we do everywhere else.

The write function now adds the header to the file by itself, so there
is no reason to duplicate it among all the users any more.

Here is how to trigger it:

   echo blob 100 > .git/objects/00/ae4e8d3208e09f2cf7a38202a126f728cadb49

Then run fsck-cache. It will try to unpack after the header to calculate 
the hash, inflate returns total_out == 0 and memcpy() dies.

The patch below seems to work with ZLIB 1.1 and 1.2.
Signed-off-by: NAndreas Gal <gal@uci.edu>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This adds two functions: one to check if an object is present in the local
database, and one to add an object to the local database by reading it
from a file descriptor and checking its hash.
Signed-Off-By: NDaniel Barkalow <barkalow@iabervon.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We really don't care about atime, and it sucks to dirty the
inode cache just for it.

This is more than a one-liner only because we need to be able to
clear the O_NOATIME flag in case some of the objects are owned
by others (in which case open will return EPERM), and because not
everybody has the O_NOATIME flag.

This patch implements read_tree_with_tree_or_commit_sha1(),
which can be used when you are interested in reading an unpacked
raw tree data but you do not know nor care if the SHA1 you
obtained your user is a tree ID or a commit ID.  Before this
function's introduction, you would have called read_sha1_file(),
examined its type, parsed it to call read_sha1_file() again if
it is a commit, and verified that the resulting object is a
tree.  Instead, this function does that for you.  It returns
NULL if the given SHA1 is not either a tree or a commit.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Avoid the compression.

And add a "convert-cache" program to convert from old-style
to new-style.

Do the usage and error reporting in "usage.c", and the sha1 file
accesses in "sha1_file.c".

Small, nice, easily separated parts. Good.