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Commit Graph

13166 Commits

Author SHA1 Message Date
Miklos Vajna
10eb64f5fd git pull manpage: don't include -n from fetch-options.txt
The -n option stands for --no-summary in git pull

[jes: reworded the description to avoid mentioning 'git-fetch';
 also exclude '-n' conditional on git-pull -- ugly because of
 the missing "else" statement in asciidoc]

Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-25 22:42:36 -08:00
Sam Vilain
2b0d1033a3 git-svn(1): update instructions for resuming a git-svn clone
git-svn expects its references under refs/remotes/*; but these will
not be copied or set by "git clone"; put in this man page the manual
fiddling that is required with current git-svn to get this to work.

Signed-off-by: Sam Vilain <sam.vilain@catalyst.net.nz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-25 22:31:52 -08:00
Jakub Narebski
3cf3237400 autoconf: define NO_SYS_SELECT_H on systems without <sys/select.h>.
Pre-POSIX.1-2001 systems don't have <sys/select.h>, but select(2)
is declared in <sys/time.h>, which git-compat-util.h includes.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-25 22:26:08 -08:00
Robert Schiele
81cc66a526 Makefile: customization for supporting HP-UX
Signed-off-by: Robert Schiele <rschiele@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-24 21:58:53 -08:00
Robert Schiele
2600973f2c pre-POSIX.1-2001 systems do not have <sys/select.h>
POSIX.1-2001 has declaration of select(2) in <sys/select.h>, but
in the previous version of SUS, it was declared in <sys/time.h>
(which is already included in git-compat-util.h).

This introduces NO_SYS_SELECT_H macro in the Makefile to be set
on older systems, to skip inclusion of <sys/select.h> that does
not exist on them.

We could check _POSIX_VERSION with 200112L and do this
automatically, but earlier it was reported that the approach
does not work well on some vintage of HP-UX.  Other systems may
get _POSIX_VERSION itself wrong.  At least for now, this manual
configuration is safer.

Signed-off-by: Robert Schiele <rschiele@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-24 14:01:28 -08:00
Junio C Hamano
cab31fa076 Merge git://repo.or.cz/git-gui
* git://repo.or.cz/git-gui:
  git-gui: Correctly cleanup msgfmt '1 message untranslated' output
  git-gui: Make the statistics of po2msg match those of msgfmt
  git-gui: Fallback to Tcl based po2msg.sh if msgfmt isn't available
  git-gui: Work around random missing scrollbar in revision list
2008-01-23 21:37:12 -08:00
Brandon Casey
5a9dd3998f git-commit: exit non-zero if we fail to commit the index
In certain rare cases, the creation of the commit object
and update of HEAD can succeed, but then installing the
updated index will fail. This is most likely caused by a
full disk or exceeded disk quota. When this happens the
new index file will be removed, and the repository will
be left with the original now-out-of-sync index. The
user can recover with a "git reset HEAD" once the disk
space issue is resolved.

We should detect this failure and offer the user some
helpful guidance.

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:10:11 -08:00
Miklos Vajna
28678b4f2f git-clone -s: document problems with git gc --prune
There is a scenario when using git clone -s and git gc --prune togother is
dangerous. Document this.

Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:09:54 -08:00
Shawn O. Pearce
3b8f19a02c git-gui: Correctly cleanup msgfmt '1 message untranslated' output
In the multiple message case we remove the word "messages" from the
statistics output of msgfmt as it looks cleaner on the tty when you
are watching the build process.  However we failed to strip the word
"message" when only 1 message was found to be untranslated or fuzzy,
as msgfmt does not produce the 's' suffix.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
gitgui-0.9.2
2008-01-22 23:56:15 -05:00
Shawn O. Pearce
2cd9ad2e71 git-gui: Make the statistics of po2msg match those of msgfmt
The strings we were showing from po2msg didn't exactly match those
of msgfmt's --statistics output so we didn't show quite the same
results when building git-gui's message files.  Now we're closer
to what msgfmt shows (at least for an en_US locale) so the make
output matches.

I noticed that the fuzzy translation count is off by one for the
current po/zh_cn.po file.  Not sure why and I'm not going to try
and debug it at this time as the po2msg is strictly a fallback,
users building from source really should prefer msgfmt.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-01-22 23:52:07 -05:00
Shawn O. Pearce
3470adabad git-gui: Fallback to Tcl based po2msg.sh if msgfmt isn't available
If msgfmt fails with exit code 127 that typically means the program
is not found in the user's PATH and thus cannot be executed by make.
In such a case we can try to fallback to the Tcl based po2msg program
that we distributed with git-gui, as it does a "good enough" job.

We still don't default to po2msg.sh however as it does not perform
a lot of the sanity checks that msgfmt does, and quite a few of
those are too useful to give up.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-01-22 23:44:36 -05:00
Shawn O. Pearce
3ddff72e58 git-gui: Work around random missing scrollbar in revision list
If the horizontal scrollbar isn't currently visible (because it has
not been needed) but we get an update to the scroll port we may find
the scrollbar window exists but the Tcl command doesn't.  Apparently
it is possible for Tk to have partially destroyed the scrollbar by
removing the Tcl procedure name but still leaving the widget name in
the window registry.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-01-22 23:37:15 -05:00
Eric Wong
3b839fd861 git-svn: default to repacking every 1000 commits
This should reduce disk space usage when doing large imports.
We'll be switching to "gc --auto" post-1.5.4 to handle
repacking for us.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-22 01:45:40 -08:00
Junio C Hamano
4f5f998fbd Clarify that http-push being temporarily disabled with older cURL
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-22 00:48:29 -08:00
Nicolas Pitre
6fc74703de pack-objects: Fix segfault when object count is less than thread count
When partitioning the work amongst threads, dividing the number of
objects by the number of threads may return 0 when there are less
objects than threads; this will cause the subsequent code to segfault
when accessing list[sub_size-1].  Allow some threads to have
zero objects to work on instead of barfing, while letting others
to have more.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-21 17:24:12 -08:00
Alex Riesen
9288bedafa Make t5710 more strict when creating nested repos
The test 'creating too deep nesting' can fail even when cloning the repos,
but is not its main purpose (it has to prepare nested repos and ensure
the last one is invalid). So split the test into the creation and
invalidity checking parts.

Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-21 17:24:12 -08:00
Gustaf Hendeby
97394ee430 send-email, fix breakage in combination with --compose
This fixes the subtile bug in git send-email that was introduced into
git send-email with aa54892f5ada8282643dc7387b33261c7135d784 (send-email:
detect invocation errors earlier), which caused no patches to be sent
out if the --compose flag was used.

Signed-off-by: Gustaf Hendeby <hendeby@isy.liu.se>
Tested-by: Seth Falcon <seth@userprimary.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-21 17:24:12 -08:00
Shawn O. Pearce
7422bac441 Document the hairy gfi_unpack_entry part of fast-import
Junio pointed out this part of fast-import wasn't very clear on
initial read, and it took some time for someone who was new to
fast-import's "dirty little tricks" to understand how this was
even working.  So a little bit of commentary in the proper place
may help future readers.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-21 01:04:12 -08:00
Shawn O. Pearce
bb23fdfa6c Teach fast-import to honor pack.compression and pack.depth
We now use the configured pack.compression and pack.depth values
within fast-import, as like builtin-pack-objects fast-import is
generating a packfile for consumption by the Git tools.

We use the same behavior as builtin-pack-objects does for these
options, allowing core.compression to supply the default value
for pack.compression.

The default setting for pack.depth within fast-import is still 10
as users will generally repack fast-import generated packfiles by
`repack -f`.  A large delta depth within the fast-import packfile
can significantly slow down such a later repack.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-21 01:04:10 -08:00
Steffen Prohaska
c4a95c9f4b submodule: Document the details of the command line syntax
Only "status" accepts "--cached" and the preferred way of
passing sub-command specific options is after the sub-command.

The documentation is adapted to reflect this.

Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-21 00:57:51 -08:00
Junio C Hamano
a2d93aea25 git-submodule: add test for the subcommand parser fix
This modifies the existing t7400 test to use 'init' as the
pathname that a submodule is bound to.  Without the earlier
subcommand parser fix, this fails.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-20 20:57:42 -08:00
Junio C Hamano
5c08dbbdf1 git-submodule: fix subcommand parser
The subcommand parser of "git submodule" made its subcommand
names reserved words.  As a consequence, a command like this:

    $ git submodule add init update

which is meant to add a submodule called 'init' at path 'update'
was misinterpreted as a request to invoke more than one mutually
incompatible subcommands and incorrectly rejected.

This patch fixes the issue by stopping the subcommand parsing at
the first subcommand word, to allow the sample command line
above to work as expected.

It also introduces the usual -- option disambiguator, so that a
submodule at path '-foo' can be updated with

    $ git submodule update -- -foo

without triggering an "unrecognized option -foo" error.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-20 20:57:42 -08:00
Junio C Hamano
23a485e3ee git-submodule: rename shell functions for consistency
This renames the shell functions used in git-submodule that
implement top-level subcommands.  The rule is that the
subcommand $foo is implemented by cmd_$foo function.

A noteworthy change is that modules_list() is now known as
cmd_status().  There is no "submodule list" command.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-20 20:57:42 -08:00
Junio C Hamano
36a189c86e Merge git://repo.or.cz/git-gui
* git://repo.or.cz/git-gui:
  git-gui: Correct encoding of glossary/fr.po to UTF-8
  git-gui: Consolidate hook execution code into a single function
  git-gui: Correct window title for hook failure dialogs
  git-gui: Honor the standard commit-msg hook
2008-01-20 20:36:16 -08:00
Shawn O. Pearce
6caaf2daf0 git-gui: Correct encoding of glossary/fr.po to UTF-8
Junio noticed this was incorrectly added in ISO-8859-1 but it should
be in UTF-8 (as the headers claim UTF-8, and our convention is to use
only UTF-8).

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-01-20 23:03:23 -05:00
Shawn O. Pearce
ed76cb70f4 git-gui: Consolidate hook execution code into a single function
The code we use to test if a hook is executable or not differs on
Cygwin from the normal POSIX case.  Rather then repeating that for
all three hooks we call in our commit code path we can place the
common logic into a global procedure and invoke it when necessary.

This also lets us get rid of the ugly "|& cat" we were using before
as we can now rely on the Tcl 8.4 feature of "2>@1" or fallback to
the "|& cat" when necessary.

The post-commit hook is now run through the same API, but its outcome
does not influence the commit status.  As a result we now show any of
the errors from the post-commit hook in a dialog window, instead of on
the user's tty that was used to launch git-gui.  This resolves a long
standing bug related to not getting errors out of the post-commit hook
when launched under git-gui.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-01-20 22:45:38 -05:00
Shawn O. Pearce
c87238e19d git-gui: Correct window title for hook failure dialogs
During i18n translation work this message was partially broken
by using "append" instead of "strcat" to join the two different
parts of the message together.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-01-20 22:45:37 -05:00
Shawn O. Pearce
fb0ca475c6 git-gui: Honor the standard commit-msg hook
Under core Git the git-commit tool will invoke the commit-msg hook
if it exists and is executable to the user running git-commit.  As
a hook it has some limited value as it cannot alter the commit, but
it can modify the message the user is attempting to commit.  It is
also able to examine the message to ensure it conforms to some local
standards/conventions.

Since the hook takes the name of a temporary file holding the message
as its only parameter we need to move the code that creates the temp
file up earlier in our commit code path, and then pass through that
file name to the latest stage (where we call git-commit-tree).  We let
the hook alter the file as it sees fit and we don't bother to look at
its content again until the commit succeeded and we need the subject
for the reflog update.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-01-20 22:45:37 -05:00
Junio C Hamano
ce33288ea6 GIT 1.5.4-rc4
Signed-off-by: Junio C Hamano <gitster@pobox.com>
v1.5.4-rc4
2008-01-20 17:05:11 -08:00
Junio C Hamano
105c21df14 Merge git://repo.or.cz/git-gui
* git://repo.or.cz/git-gui:
  git-gui: Makefile - Handle $DESTDIR on Cygwin
  git-gui: add french glossary: glossary/fr.po
  git-gui: Refresh file status description after hunk application
  git-gui: Allow 'Create New Repository' on existing directories
  git-gui: Initial french translation
  git-gui: Improve German translation.
  git-gui: Updated Swedish translation after mailing list review.
  git-gui: Fix broken revert confirmation.
  git-gui: Update German translation
  git-gui: Update glossary: add term "hunk"
2008-01-20 16:58:38 -08:00
Junio C Hamano
a41acc63ba Merge git://git.kernel.org/pub/scm/gitk/gitk
* git://git.kernel.org/pub/scm/gitk/gitk:
  [PATCH] gitk: make Ctrl "+" really increase the font size
2008-01-20 16:57:56 -08:00
Grégoire Barbier
3057ded057 http-push and http-fetch: handle URLs without trailing /
The URL to a repository http-push and http-fetch takes should
have a trailing slash.  Instead of failing the request, add it
ourselves before attempting such a request.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-20 15:18:34 -08:00
Junio C Hamano
325ce3959c http-push: clarify the reason of error from the initial PROPFIND request
The first thing http-push does is a PROPFIND to see if the other
end supports locking.  The failure message we give is always
reported as "no DAV locking support at the remote repository",
regardless of the reason why we ended up not finding the locking
support on the other end.

This moves the code to report "no DAV locking support" down the
codepath so that the message is issued only when we successfully
get a response to PROPFIND and the other end say it does not
support locking.  Other failures, such as connectivity glitches
and credential mismatches, have their own error message issued
and we will not issue "no DAV locking" error (we do not even
know if the remote end supports it).

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-20 15:17:58 -08:00
Grégoire Barbier
9bdbabade4 http-push: fail when info/refs exists and is already locked
Failing instead of silently not updating remote refs makes the things
clearer for the user when trying to push on a repository while another
person do (or while a dandling locks are waiting for a 10 minutes
timeout).

When silently not updating remote refs, the user does not even know
that git has pushed the objects but leaved the refs as they were
before (e.g. a new bunch of commits on branch "master" is uploaded,
however the branch by itsel still points on the previous head commit).

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-20 15:17:58 -08:00
Grégoire Barbier
9116de5957 http-push: fix webdav lock leak.
Releasing webdav lock even if push fails because of bad (or no)
reference on command line.

To reproduce the issue that this patch fixes, prepare a test repository
availlable over http+webdav, say at http://myhost/myrepo.git/

Then:

  $ git clone http://myhost/myrepo.git/
  $ cd myrepo
  $ git push http
  Fetching remote heads...
    refs/
    refs/heads/
    refs/tags/
  No refs in common and none specified; doing nothing.
  $ git push http
  Fetching remote heads...
    refs/
    refs/heads/
    refs/tags/
  No refs in common and none specified; doing nothing.
  $

Finally, you look at the web server logs, and will find one LOCK query
and no UNLOCK query, of course the second one will be in 423 return
code instead of 200:

1.2.3.4 - gb [19/Jan/2008:14:24:56 +0100] "LOCK /myrepo.git/info/refs HTTP/1.1" 200 465
(...)
1.2.3.4 - gb [19/Jan/2008:14:25:10 +0100] "LOCK /myrepo.git/info/refs HTTP/1.1" 423 363

With this patch, there would have be two UNLOCKs in addition of the LOCKs

From the user's point of view:

- If you realize that you should have typed e.g. "git push http
  master" instead of "git push http", you will have to wait for 10
  minutes for the lock to expire by its own.

- Furthermore, if somebody else is dumb enough to type "git push http"
  while you need to push "master" branch, then you'll need too to wait
  for 10 minutes too.

Signed-off-by: Gr.ANigoire Barbier <gb@gbarbier.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-20 15:17:58 -08:00
Martin Koegler
0a61779994 parse_commit_buffer: tighten checks while parsing
This tightens the parsing of a commit object in a couple of ways.

 - The "tree " header must end with a LF (earlier we did not
   check this condition).

 - Make sure parsing of timestamp on the "committer " header
   does not go beyond the buffer, even when (1) the "author "
   header does not end with a LF (this means that the commit
   object is malformed and lacks the committer information) or
   (2) the "committer " header does not have ">" that is the end
   of the e-mail address, or (3) the "committer " header does
   not end with a LF.

We however still keep the existing behaviour to return a parsed
commit object even when non-structural headers such as committer
and author are malformed, so that tools that need to look at
commits to clean up a history with such broken commits can still
get at the structural data (i.e. the parents chain and the tree
object).

Signed-off-by: Martin Koegler <mkoegler@auto.tuwien.ac.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-20 11:00:57 -08:00
Dan McGee
a3b811a491 Update git-completion for new 'remote rm' option
Signed-off-by: Dan McGee <dpmcgee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-19 23:06:02 -08:00
Jim Meyering
233808db15 doc typo: s/prior committing/prior to committing/
Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-19 11:25:37 -08:00
Miklos Vajna
fdcf39e59b Include rev-list options in git-log manpage.
Replace the "This manual page describes only the most frequently used options."
text with the list of rev-list options in git-log manpage. (The git-diff-tree
options are already included.)

Move these options to a separate file and include it from both
git-rev-list.txt and git-log.txt.

Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-18 15:09:08 -08:00
Grégoire Barbier
f854824bc5 http-push: disable http-push without USE_CURL_MULTI
Make http-push always fail when not compiled with USE_CURL_MULTI, since
otherwise it corrupts the remote repository (and then fails anyway).

Signed-off-by: Grégoire Barbier <gb@gbarbier.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-18 13:50:06 -08:00
Jeff King
c764a0c2b6 send-email: add no-validate option
Since we are now sanity-checking the contents of patches and
refusing to send ones with long lines, this knob provides a
way for the user to override the new behavior (if, e.g., he
knows his SMTP path will handle it).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-18 13:33:57 -08:00
Jeff King
747bbff9b9 send-email: validate patches before sending anything
We try to catch errors early so that we don't end up sending
half of a broken patch series. Right now the only validation
is checking that line-lengths are under the SMTP-mandated
limit of 998.

The validation parsing is very crude (it just checks each
line length without understanding the mailbox format) but
should work fine for this simple check.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-18 13:33:08 -08:00
Jeff King
aa54892f5a send-email: detect invocation errors earlier
We never even look at the command line arguments until after
we have prompted the user for some information. So running
"git send-email" without arguments would prompt for "from"
and "to" headers, only to then die with "No patch files
specified." Instead, let's try to do as much error checking
as possible before getting user input.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-18 13:29:32 -08:00
Jim Meyering
5a7b1b571e fast-import: Don't use a maybe-clobbered errno value
Without this change, each diagnostic could use an errno value
clobbered by the close or unlink in rollback_lock_file.

Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-18 13:19:37 -08:00
Lars Hjemli
181256442e Move sha1_file_to_archive into libgit
When the specfile (export-subst) attribute was introduced, it added a
dependency from archive-{tar|zip}.c to builtin-archive.c. This broke the
support for archive-operations in libgit.a since builtin-archive.o doesn't
belong in libgit.a.

This patch moves the functions required by libgit.a from builtin-archive.c
to the new file archive.c (which becomes part of libgit.a).

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-18 12:33:50 -08:00
Jeff King
472ca78077 color unchanged lines as "plain" in "diff --color-words"
These were mistakenly being colored in "meta" color.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-18 01:29:38 -08:00
Jakub Narebski
bfa8fccf47 autoconf: Add checking for unsetenv function
Update configure.ac (and config.mak.in) by adding test for unsetenv
(NO_UNSETENV).  Add comment about NO_UNSETENV to Makefile header, as
original commit 731043fd adding compat/unsetenv.c didn't do that.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-17 23:35:36 -08:00
Thomas Zander
5221ecbc51 core-tutorial typofix
Signed-off-by: Thomas Zander <zander@kde.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-17 22:55:25 -08:00
Junio C Hamano
5c66d0d458 Officially deprecate repo-config.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-17 22:52:40 -08:00
Shawn O. Pearce
c9ced051c3 Fix random fast-import errors when compiled with NO_MMAP
fast-import was relying on the fact that on most systems mmap() and
write() are synchronized by the filesystem's buffer cache.  We were
relying on the ability to mmap() 20 bytes beyond the current end
of the file, then later fill in those bytes with a future write()
call, then read them through the previously obtained mmap() address.

This isn't always true with some implementations of NFS, but it is
especially not true with our NO_MMAP=YesPlease build time option used
on some platforms.  If fast-import was built with NO_MMAP=YesPlease
we used the malloc()+pread() emulation and the subsequent write()
call does not update the trailing 20 bytes of a previously obtained
"mmap()" (aka malloc'd) address.

Under NO_MMAP that behavior causes unpack_entry() in sha1_file.c to
be unable to read an object header (or data) that has been unlucky
enough to be written to the packfile at a location such that it
is in the trailing 20 bytes of a window previously opened on that
same packfile.

This bug has gone unnoticed for a very long time as it is highly data
dependent.  Not only does the object have to be placed at the right
position, but it also needs to be positioned behind some other object
that has been accessed due to a branch cache invalidation.  In other
words the stars had to align just right, and if you did run into
this bug you probably should also have purchased a lottery ticket.

Fortunately the workaround is a lot easier than the bug explanation.

Before we allow unpack_entry() to read data from a pack window
that has also (possibly) been modified through write() we force
all existing windows on that packfile to be closed.  By closing
the windows we ensure that any new access via the emulated mmap()
will reread the packfile, updating to the current file content.

This comes at a slight performance degredation as we cannot reuse
previously cached windows when we update the packfile.  But it
is a fairly minor difference as the window closes happen at only
two points:

 - When the packfile is finalized and its .idx is generated:

   At this stage we are getting ready to update the refs and any
   data access into the packfile is going to be random, and is
   going after only the branch tips (to ensure they are valid).
   Our existing windows (if any) are not likely to be positioned
   at useful locations to access those final tip commits so we
   probably were closing them before anyway.

 - When the branch cache missed and we need to reload:

   At this point fast-import is getting change commands for the next
   commit and it needs to go re-read a tree object it previously
   had written out to the packfile.  What windows we had (if any)
   are not likely to cover the tree in question so we probably were
   closing them before anyway.

We do try to avoid unnecessarily closing windows in the second case
by checking to see if the packfile size has increased since the
last time we called unpack_entry() on that packfile.  If the size
has not changed then we have not written additional data, and any
existing window is still vaild.  This nicely handles the cases where
fast-import is going through a branch cache reload and needs to read
many trees at once.  During such an event we are not likely to be
updating the packfile so we do not cycle the windows between reads.

With this change in place t9301-fast-export.sh (which was broken
by c3b0dec509fe136c5417422f31898b5a4e2d5e02) finally works again.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-17 22:39:20 -08:00