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2014-06-03Merge branch 'mh/ref-transaction'Libravatar Junio C Hamano1-31/+69
Update "update-ref --stdin [-z]" and then introduce a transactional support for (multi-)reference updates. * mh/ref-transaction: (27 commits) ref_transaction_commit(): work with transaction->updates in place struct ref_update: add a type field struct ref_update: add a lock field ref_transaction_commit(): simplify code using temporary variables struct ref_update: store refname as a FLEX_ARRAY struct ref_update: rename field "ref_name" to "refname" refs: remove API function update_refs() update-ref --stdin: reimplement using reference transactions refs: add a concept of a reference transaction update-ref --stdin: harmonize error messages update-ref --stdin: improve the error message for unexpected EOF t1400: test one mistake at a time update-ref --stdin -z: deprecate interpreting the empty string as zeros update-ref.c: extract a new function, parse_next_sha1() t1400: test that stdin -z update treats empty <newvalue> as zeros update-ref --stdin: simplify error messages for missing oldvalues update-ref --stdin: make error messages more consistent update-ref --stdin: improve error messages for invalid values update-ref.c: extract a new function, parse_refname() parse_cmd_verify(): copy old_sha1 instead of evaluating <oldvalue> twice ...
2014-04-07update-ref --stdin: harmonize error messagesLibravatar Michael Haggerty1-16/+16
Make (most of) the error messages for invalid input have the same format [1]: $COMMAND [SP $REFNAME]: $MESSAGE Update the tests accordingly. [1] A few error messages are left with their old form, because $COMMAND and $REFNAME aren't passed all the way down the call stack. Maybe those sites should be changed some day, too. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07update-ref --stdin: improve the error message for unexpected EOFLibravatar Michael Haggerty1-6/+6
Distinguish this error from the error that an argument is missing for another reason. Update the tests accordingly. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07t1400: test one mistake at a timeLibravatar Michael Haggerty1-1/+7
This case wants to test passing a bad refname to the "update" command. But it also passes too few arguments to "update", which muddles the situation: which error should be diagnosed? So split this test into two: * One that passes too few arguments to update * One that passes all three arguments to "update", but with a bad refname. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07update-ref --stdin -z: deprecate interpreting the empty string as zerosLibravatar Michael Haggerty1-2/+3
In the original version of this command, for the single case of the "update" command's <newvalue>, the empty string was interpreted as being equivalent to 40 "0"s. This shorthand is unnecessary (binary input will usually be generated programmatically anyway), and it complicates the parser and the documentation. So gently deprecate this usage: remove its description from the documentation and emit a warning if it is found. But for reasons of backwards compatibility, continue to accept it. Helped-by: Brad King <brad.king@kitware.com> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07update-ref.c: extract a new function, parse_next_sha1()Libravatar Michael Haggerty1-1/+1
Replace three functions, update_store_new_sha1(), update_store_old_sha1(), and parse_next_arg(), with a single function, parse_next_sha1(). The new function takes care of a whole argument, including checking whether it is there, converting it to an SHA-1, and emitting errors on EOF or for invalid values. The return value indicates whether the argument was present or absent, which requires a bit of intelligence because absent values are represented differently depending on whether "-z" was used. The new interface means that the calling functions, parse_cmd_*(), don't have to interpret the result differently based on the line_termination mode that is in effect. It also means that parse_cmd_create() can distinguish unambiguously between an empty new value and a zeros new value, which fixes a failure in t1400. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07t1400: test that stdin -z update treats empty <newvalue> as zerosLibravatar Michael Haggerty1-0/+7
This is the (slightly inconsistent) status quo; make sure it doesn't change by accident. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07update-ref --stdin: simplify error messages for missing oldvaluesLibravatar Michael Haggerty1-3/+3
Instead of, for example, fatal: update refs/heads/master missing [<oldvalue>] NUL emit fatal: update refs/heads/master missing <oldvalue> Update the tests accordingly. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07update-ref --stdin: make error messages more consistentLibravatar Michael Haggerty1-7/+7
The old error messages emitted for invalid input sometimes said "<oldvalue>"/"<newvalue>" and sometimes said "old value"/"new value". Convert them all to the former. Update the tests accordingly. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07update-ref --stdin: improve error messages for invalid valuesLibravatar Michael Haggerty1-4/+4
If an invalid value is passed to "update-ref --stdin" as <oldvalue> or <newvalue>, include the command and the name of the reference at the beginning of the error message. Update the tests accordingly. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07t1400: add some more tests involving quoted argumentsLibravatar Michael Haggerty1-1/+25
Previously there were no good tests of C-quoted arguments. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07parse_arg(): really test that argument is properly terminatedLibravatar Michael Haggerty1-2/+2
The old parse_arg(), when fed an argument "refs/heads/a"master parsed 'refs/heads/a' off of the front of the argument and considered itself successful. It was only when parse_next_arg() tried to parse the *next* argument that a problem was noticed. But in fact, the definition of the input format requires arguments to be terminated by SP or NUL, so *this* argument is already erroneous and parse_arg() should diagnose the problem. So teach parse_arg() to verify that C-quoted arguments are terminated correctly. If not, emit a more specific error message. There is no corresponding error case of a non-C-quoted argument that is not terminated correctly, because the end of a non-quoted argument is *by definition* a space or NUL, so there is no way to insert other junk between the "end" of the argument and the argument terminator. Adjust the tests to expect the new error message. Add a docstring to the function, incorporating the comments that were formerly within the function plus some added information. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07t1400: provide more usual input to the commandLibravatar Michael Haggerty1-1/+1
The old version was passing (among other things) update SP refs/heads/c NUL NUL 0{40} NUL to "git update-ref -z --stdin" to test whether the old-value check for c is working. But the <newvalue> is empty, which is a bit off the beaten track. So, to be sure that we are testing what we want to test, provide an actual <newvalue> on the "update" line. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-07t1400: fix name and expected result of one testLibravatar Michael Haggerty1-2/+2
The test stdin -z create ref fails with zero new value actually passes an empty new value, not a zero new value. So rename the test s/zero/empty/, and change the expected error from fatal: create $c given zero new value to fatal: create $c missing <newvalue> Of course, this makes the test fail now, because although "git update-ref" tries to distinguish between these two errors, it does not succeed in this situation. Fixing it is more than a one-liner, so mark the test test_expect_failure for now. The failure will be fixed later in this patch series. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-02update-ref: fail create operation over stdin if ref already existsLibravatar Aman Gupta1-0/+11
Signed-off-by: Aman Gupta <aman@tmm1.net> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Acked-by: Brad King <brad.king@kitware.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-09-11update-ref: add test cases covering --stdin signatureLibravatar Brad King1-0/+632
Extend t/t1400-update-ref.sh to cover cases using the --stdin option. Signed-off-by: Brad King <brad.king@kitware.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-10-21Fix failure to delete a packed ref through a symrefLibravatar Johan Herland1-1/+1
When deleting a ref through a symref (e.g. using 'git update-ref -d HEAD' to delete refs/heads/master), we would remove the loose ref, but a packed version of the same ref would remain, the end result being that instead of deleting refs/heads/master we would appear to reset it to its state as of the last repack. This patch fixes the issue, by making sure we pass the correct ref name when invoking repack_without_ref() from within delete_ref(). Signed-off-by: Johan Herland <johan@herland.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-10-21t1400-update-ref: Add test verifying bug with symrefs in delete_ref()Libravatar Johan Herland1-0/+18
When deleting a ref through a symref (e.g. using 'git update-ref -d HEAD' to delete refs/heads/master), we currently fail to remove the packed version of that ref. This testcase demonstrates the bug. Signed-off-by: Johan Herland <johan@herland.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-05-06Merge branch 'jc/fix-diff-files-unmerged'Libravatar Junio C Hamano1-1/+1
* jc/fix-diff-files-unmerged: diff-files: show unmerged entries correctly diff: remove often unused parameters from diff_unmerge() diff.c: return filepair from diff_unmerge() test: use $_z40 from test-lib
2011-04-23test: use $_z40 from test-libLibravatar Junio C Hamano1-1/+1
There is no need to duplicate the definition of $_z40 and $_x40 that test-lib.sh supplies the test scripts. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-11-09t1400 (update-ref): use test_must_failLibravatar Jonathan Nieder1-3/+2
As t/README explains: When a gitcommand dies due to a segfault, test_must_fail diagnoses it as an error; "! git <command>" treats it as just another expected failure, which would let such a bug go unnoticed. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-11-09tests: add missing &&, batch 2Libravatar Jonathan Nieder1-10/+10
Same rules as before: this patch only adds " &&" to the end of some lines in the test suite. Intended to be applied on top of or squashed with the last batch if they look okay. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-03-17Tests: use test_cmp instead of diff where possibleLibravatar Miklos Vajna1-3/+3
Several old tests were written before test_cmp was introduced, convert these to test_cmp. If were are at it, fix the order of the arguments where necessary to make expected come first, so the command shows how the test result deviates from the correct output. Signed-off-by: Miklos Vajna <vmiklos@frugalware.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-10-31update-ref --no-deref -d: handle the case when the pointed ref is packedLibravatar Miklos Vajna1-0/+11
In this case we did nothing in the past, but we should delete the reference in fact. The problem was that when the symref is not packed but the referenced ref is packed, then we assumed that the symref is packed as well, but symrefs are never packed. Signed-off-by: Miklos Vajna <vmiklos@frugalware.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-10-26Fix git update-ref --no-deref -d.Libravatar Miklos Vajna1-0/+7
Till now --no-deref was just ignored when deleting refs, fix this. Signed-off-by: Miklos Vajna <vmiklos@frugalware.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-09-03tests: use "git xyzzy" form (t0000 - t3599)Libravatar Nanako Shiraishi1-5/+5
Converts tests between t0050-t3903. Signed-off-by: Nanako Shiraishi <nanako3@lavabit.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-07-13t/: Use "test_must_fail git" instead of "! git"Libravatar Stephan Beyer1-2/+2
This patch changes every occurrence of "! git" -- with the meaning that a git call has to gracefully fail -- into "test_must_fail git". This is useful to - make sure the test does not fail because of a signal, e.g. SIGSEGV, and - advertise the use of "test_must_fail" for new tests. Signed-off-by: Stephan Beyer <s-beyer@gmx.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-07-08avoid null SHA1 in oldest reflogLibravatar Jeff King1-1/+8
When the user specifies a ref by a reflog entry older than one we have (e.g., "HEAD@{20 years ago"}), we issue a warning and give them the "from" value of the oldest reflog entry. That is, we say "we don't know what happened before this entry, but before this we know we had some particular SHA1". However, the oldest reflog entry is often a creation event such as clone or branch creation. In this case, the entry claims that the ref went from "00000..." (the null sha1) to the new value, and the reflog lookup returns the null sha1. While this is technically correct (the entry tells us that the ref didn't exist at the specified time) it is not terribly useful to the end user. What they probably want instead is "the oldest useful sha1 that this ref ever had". This patch changes the behavior such that if the oldest ref would return the null sha1, it instead returns the first value the ref ever had. We never discovered this problem in the test scripts because we created "fake" reflogs that had only a specified segment of history. This patch updates the tests with a creation event at the beginning of history. Signed-off-by: Jeff King <peff@peff.net> Acked-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-06-02Make old sha1 optional with git update-ref -dLibravatar Karl Hasselström1-0/+8
Giving the old sha1 is already optional when changing a ref, and it's quite handy when running update-ref manually. So make it optional for deleting a ref too. Signed-off-by: Karl Hasselström <kha@treskal.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-27Add some tests for git update-ref -dLibravatar Karl Hasselström1-0/+16
Signed-off-by: Karl Hasselström <kha@treskal.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-02-01Sane use of test_expect_failureLibravatar Junio C Hamano1-12/+12
Originally, test_expect_failure was designed to be the opposite of test_expect_success, but this was a bad decision. Most tests run a series of commands that leads to the single command that needs to be tested, like this: test_expect_{success,failure} 'test title' ' setup1 && setup2 && setup3 && what is to be tested ' And expecting a failure exit from the whole sequence misses the point of writing tests. Your setup$N that are supposed to succeed may have failed without even reaching what you are trying to test. The only valid use of test_expect_failure is to check a trivial single command that is expected to fail, which is a minority in tests of Porcelain-ish commands. This large-ish patch rewrites all uses of test_expect_failure to use test_expect_success and rewrites the condition of what is tested, like this: test_expect_success 'test title' ' setup1 && setup2 && setup3 && ! this command should fail ' test_expect_failure is redefined to serve as a reminder that that test *should* succeed but due to a known breakage in git it currently does not pass. So if git-foo command should create a file 'bar' but you discovered a bug that it doesn't, you can write a test like this: test_expect_failure 'git-foo should create bar' ' rm -f bar && git foo && test -f bar ' This construct acts similar to test_expect_success, but instead of reporting "ok/FAIL" like test_expect_success does, the outcome is reported as "FIXED/still broken". Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-16Be more careful about updating refsLibravatar Linus Torvalds1-6/+13
This makes write_ref_sha1() more careful: it actually checks the SHA1 of the ref it is updating, and refuses to update a ref with an object that it cannot find. Perhaps more importantly, it also refuses to update a branch head with a non-commit object. I don't quite know *how* the stable series maintainers were able to corrupt their repository to have a HEAD that pointed to a tag rather than a commit object, but they did. Which results in a totally broken repository that cannot be cloned or committed on. So make it harder for people to shoot themselves in the foot like that. The test t1400-update-ref.sh is fixed at the same time, as it assumed that the commands involved in the particular test would not care about corrupted repositories whose refs point at nonexistant bogus objects. That assumption does not hold true anymore. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-11-08stop t1400 hiding errors in testsLibravatar Alex Riesen1-1/+1
The last rm in the test was lacking an "&&" before it, which caused the errors in the commands be silently hidden. Signed-off-by: Alex Riesen <raa.lkml@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-05Cleanup unnecessary file modifications in t1400-update-refLibravatar Shawn O. Pearce1-2/+0
Kristian Høgsberg pointed out that the two file modifications we were doing during the 'creating initial files' step are not even used within the test suite. This was actually confusing as we do not even need these changes for the tests to pass. All that really matters here is the specific commit dates are used so that these appear in the branch's reflog, and that the dates are different so that the branch will update when asked and the reflog entry is also updated. There is no need for the file modification. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-07-02Rewrite "git-frotz" to "git frotz"Libravatar Junio C Hamano1-37/+37
This uses the remove-dashes target to replace "git-frotz" to "git frotz". Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-01-28[PATCH] Rename git-repo-config to git-config.Libravatar Tom Prince1-2/+2
Signed-off-by: Tom Prince <tom.prince@ualberta.net> Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-01-19Extend read_ref_at() to be usable from places other than sha1_name.Libravatar Junio C Hamano1-3/+3
You can pass an extra argument to the function to receive the reflog message information. Also when the log does not go back beyond the point the user asked, the cut-off time and count are given back to the caller for emitting the error messages as appropriately. We could later add configuration for get_sha1_basic() to make it an error instead of it being just a warning. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-12-15Enable reflogs by default in any repository with a working directory.Libravatar Shawn O. Pearce1-2/+2
New and experienced Git users alike are finding out too late that they forgot to enable reflogs in the current repository, and cannot use the information stored within it to recover from an incorrectly entered command such as `git reset --hard HEAD^^^` when they really meant HEAD^^ (aka HEAD~2). So enable reflogs by default in all future versions of Git, unless the user specifically disables it with: [core] logAllRefUpdates = false in their .git/config or ~/.gitconfig. We only enable reflogs in repositories that have a working directory associated with them, as shared/bare repositories do not have an easy means to prune away old log entries, or may fail logging entirely if the user's gecos information is not valid during a push. This heuristic was suggested on the mailing list by Junio. Documentation was also updated to indicate the new default behavior. We probably should start to teach usuing the reflog to recover from mistakes in some of the tutorial material, as new users are likely to make a few along the way and will feel better knowing they can recover from them quickly and easily, without fsck-objects' lost+found features. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-09-17Fix t1400-update-ref test minimallyLibravatar Junio C Hamano1-5/+2
It depended on specific error messages to detect failure but the implementation changed and broke the test. This fixes the breakage minimally. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-09-16t1400: make test debuggable.Libravatar Junio C Hamano1-43/+43
I had a hard time figuring out why this test was failing with the packed-refs update without running it under "sh -x". This makes output from "sh t1400-update-ref.sh -v" more descriptive. Updating other tests would be a good janitorial task. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-07-28Display an error from update-ref if target ref name is invalid.Libravatar Shawn Pearce1-0/+12
Alex Riesen (raa.lkml@gmail.com) recently observed that git branch would fail with no error message due to unexpected situations with regards to refs. For example, if .git/refs/heads/gu is a file but "git branch -b refs/heads/gu/fixa HEAD" was invoked by the user it would fail silently due to refs/heads/gu being a file and not a directory. This change adds a test for trying to create a ref within a directory that is actually currently a file, and adds error printing within the ref locking routine should the resolve operation fail. The error printing code probably belongs at this level of the library as other failures within the ref locking, writing and logging code are also currently at this level of the code. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-07-11tests: Set EDITOR=: and VISUAL=: globallyLibravatar Eric Wong1-1/+0
This way we don't have to remember to set it for each test; and if we forget, we won't cause interactive editors to be spawned for non-interactive tests. Signed-off-by: Eric Wong <normalperson@yhbt.net> Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-07-10Record the type of commit operation in the reflog.Libravatar Shawn Pearce1-3/+16
If committing a merge (.git/MERGE_HEAD exists), an initial tree (no HEAD) or using --amend to amend the prior commit then denote the subtype of commit in the reflog. This helps to distinguish amended or merge commits from normal commits. In the case of --amend the prior sha1 is probably the commit which is being thrown away in favor of the new commit. Since it is likely that the old commit doesn't have any ref pointing to it anymore it can be interesting to know why that the commit was replaced and orphaned. In the case of a merge the prior sha1 is probably the first parent of the new merge commit. Consequently having its prior sha1 in the reflog is slightly less interesting but its still informative to know the commit was the result of a merge which had to be completed by hand. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-05-24Verify git-commit provides a reflog message.Libravatar Shawn Pearce1-12/+26
The reflog message from git-commit should include the first line of the commit message as supplied by the user. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-05-19Change 'master@noon' syntax to 'master@{noon}'.Libravatar Shawn Pearce1-16/+39
Its ambiguous to parse "master@2006-05-17 18:30:foo" when foo is meant as a file name and ":30" is meant as 30 minutes past 6 pm. Therefore all date specifications in a sha1 expression must now appear within brackets and the ':' splitter used for the path name in a sha1 expression ignores ':' appearing within brackets. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-05-19General ref log reading improvements.Libravatar Shawn Pearce1-0/+64
Corrected the log starting time displayed in the error message (as it was always showing the epoch due to a bad input to strtoul). Improved the log parser so we only scan backwards towards the '\n' from the end of the prior log; during this scan the last '>' is remembered to improve performance (rather than scanning forward to it). If the log record matched is the last log record in the file only use its new sha1 value if the date matches exactly; otherwise we leave the passed in sha1 alone as it already contains the current value of the ref. This way lookups of dates later than the log end to stick with the current ref value in case the ref was updated without logging. If it looks like someone changed the ref without logging it and we are going to return the sha1 which should have been valid during the missing period then warn the user that there might be log data missing and thus their query result may not be accurate. The check isn't perfect as its just based on comparing the old and new sha1 values between the two log records but its better than not checking at all. Implemented test cases based on git-rev-parse for most of the boundary conditions. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-05-17Log ref updates to logs/refs/<ref>Libravatar Shawn Pearce1-0/+112
If config parameter core.logAllRefUpdates is true or the log file already exists then append a line to ".git/logs/refs/<ref>" whenever git-update-ref <ref> is executed. Each log line contains the following information: oldsha1 <SP> newsha1 <SP> committer <LF> where committer is the current user, date, time and timezone in the standard GIT ident format. If the caller is unable to append to the log file then git-update-ref will fail without updating <ref>. An optional message may be included in the log line with the -m flag. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>