Sometimes its necessary to supply a value as a power of two in a
configuration parameter. In this case the user may want to use the
standard suffixes such as K, M, or G to indicate that the numerical
value should be multiplied by a constant base before being used.
Shell scripts/etc. can also benefit from this automatic option
parsing with `git repo-config --int`.
[jc: with a couple of test and a slight input tightening]
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Currently the update hook invoked by receive-pack has its stdin
connected to the pushing client. The hook shouldn't attempt to
read from this stream, and doing so may consume data that was
meant for receive-pack. Instead we should give the update hook
/dev/null as its stdin, ensuring that it always receives EOF and
doesn't disrupt the protocol if it attempts to read any data.
The post-update hook is similar, as it gets invoked with /dev/null
on stdin to prevent the hook from reading data from the client.
Previously we had invoked it with stdout also connected to /dev/null,
throwing away anything on stdout, to prevent client protocol errors.
Instead we should redirect stdout to stderr, like we do with the
update hook.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
If an update hook outputs to stdout then that output will be sent
back over the wire to the push client as though it were part of
the git protocol. This tends to cause protocol errors on the
client end of the connection, as the hook output is not expected
in that context. Most hook developers work around this by making
sure their hook outputs everything to stderr.
But hooks shouldn't need to perform such special behavior. Instead
we can just dup stderr to stdout prior to invoking the update hook.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
The argc parameter is never used by the run_command_v family of
functions. Instead they require that the passed argv[] be NULL
terminated so they can rely on the operating system's execvp
function to correctly pass the arguments to the new process.
Making the caller pass the argc is just confusing, as the caller
could be mislead into believing that the argc might take precendece
over the argv, or that the argv does not need to be NULL terminated.
So goodbye argc. Don't come back.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Many users find it unfriendly that they can create a bare git
repository easily with `git clone --bare` but are then unable to
run simple commands like `git log` once they cd into that newly
created bare repository. This occurs because we do not check to
see if the current working directory is a git repository.
Instead of failing out with "fatal: Not a git repository" we should
try to automatically detect if the current working directory is
a bare repository and use that for GIT_DIR, and fail out only if
that doesn't appear to be true.
We test the current working directory only after we have tried
searching up the directory tree. This is to retain backwards
compatibility with our previous behavior on the off chance that
a user has a 'refs' and 'objects' subdirectories and a 'HEAD'
file that looks like a symref, all stored within a repository's
associated working directory.
This change also consolidates the validation logic between the case
of GIT_DIR being supplied and GIT_DIR not being supplied, cleaning
up the code.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
We tend to use the nice constant GIT_DIR_ENVIRONMENT when we
are referring to the "GIT_DIR" constant, but git.c didn't do
so. Now it does.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
For easier portability we prefer PATH_MAX over seemingly random
constants like 1024. Make it so.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Many users have noticed that core.filemode doesn't appear to be
automatically set right on Cygwin when using a repository stored
on NTFS. The issue is that Cygwin and NTFS correctly supports
the executable mode bit, and Git properly detected that, but most
native Windows applications tend to create files such that Cygwin
sees the executable bit set when it probably shouldn't be.
This is especially bad if the user's favorite editor deletes the
file then recreates it whenever they save (vs. just overwriting)
as now a file that was created with mode 0644 by checkout-index
appears to have mode 0755.
So we introduce NO_TRUSTABLE_FILEMODE, settable at compile time.
Setting this option forces core.filemode to false, even if the
detection code would have returned true. This option should be
enabled by default on Cygwin.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
The line:
[remote "<remote>"]
was getting swallowed up by asciidoc, causing a critical line in the
explanation for how to store the .git/remotes information in .git/config
to go missing from the git-fetch, git-pull, and git-push manpages.
Put all of the examples into delimited blocks to fix this problem and to
make them look nicer.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Junio C Hamano <junkio@cox.net>
In very obscure cases, a merge can hit an unexpected code path (where the
original code went as far as saying that this was a bug). This failing
merge was noticed by Alexandre Juillard.
The problem is that the original file contains something like this:
-- snip --
two non-empty lines
before two empty lines
after two empty lines
-- snap --
and this snippet is reduced to _one_ empty line in _both_ new files.
However, it is ambiguous as to which hunk takes the empty line: the first
or the second one?
Indeed in Alexandre's example files, the xdiff algorithm attributes the
empty line to the first hunk in one case, and to the second hunk in the
other case.
(Trimming down the example files _changes_ that behaviour!)
Thus, the call to xdl_merge_cmp_lines() has no chance to realize that the
change is actually identical in both new files. Therefore,
xdl_refine_conflicts() finds an empty diff script, which was not expected
there, because (the original author of xdl_merge() thought)
xdl_merge_cmp_lines() would catch that case earlier.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
After re-coding the commit message into the encoding the user
specified (either with core.logoutputencidng or --encoding
option), this drops the "encoding" header altogether. The
output is after re-coding as the user asked (either with the
config or --encoding=<encoding> option), and the extra header
becomes redundant information.
Signed-off-by: Junio C Hamano <junkio@cox.net>
People can spell config.commitencoding differently from what we
internally have ("utf-8") to mean UTF-8. Try to accept them and
treat them equally.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Telling the git-log family not to do any character conversion is
done with --encoding=none, which sets log_output_encoding to an
empty string. However, logmsg_reencode() confused this with
log_output_encoding and commit_encoding set to NULL. The latter
means we should use the default encoding (i.e. utf-8).
Signed-off-by: Junio C Hamano <junkio@cox.net>
send-pack builds a pipeline that runs "rev-list | pack-objects"
and sends the output from pack-objects to the other side, while
feeding the input side of that pipe from itself. However, the
file descriptor that is given to this pipeline (so that it can
be dup2(2)'ed into file descriptor 1 of pack-objects) is closed
by the caller before the complex fork+exec dance! Worse yet,
the caller already dup2's it to 1, so the child process did not
even have to.
I do not understand how this code could possibly have been
working, but it somehow was working by accident.
Merging the sliding mmap() code reveals this problem, presumably
because it keeps one extra file descriptor open for a packfile
and changes the way file descriptors are allocated. I am too
tired to diagnose the problem now, but this seems to be a
sensible fix.
Signed-off-by: Junio C Hamano <junkio@cox.net>
I do not have any proof that this matters to any existing
problems I am seeing, but I do not think of any reason not to do
this.
Signed-off-by: Junio C Hamano <junkio@cox.net>
The code calls use_pack() to make that the variably encoded
offset fits in the mmap'ed window, but it forgot that the
operation gives the pointer to the beginning of the asked
region.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Junio noticed that 'non-trivial' pushes were failing if executed
using the sliding window mmap changes. This was somewhat difficult
to track down as the failure was appearing randomly.
It turns out this was a failure caused by the delta base reference
(either ref or offset format) spanning over the end of a mmap window.
The error in pack-objects was we were not recalling use_pack
after the object header was unpacked, and therefore we did not
get the promise of at least 20 bytes in the buffer for the delta
base parsing. This would case later memcmp() calls to walk into
unassigned address space at the end of the window.
The reason Junio and I had hard time tracking this down in current
Git repositories is we were both probably packing with offset deltas,
which minimized the odds of the delta base reference spanning over
the end of the mmap window. Stepping back and repacking with
version 1.3.3 (which only supported reference deltas) increased
the likelyhood of seeing the bug.
The correct technique (as used in sha1_file.c) is to invoke
use_pack() after unpack_object_header_gently to ensure we have
enough data available for the delta base decoding.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
When I converted the mmap() call to xmmap() I failed to cleanup the
way this routine handles errors and left some crufty code behind.
This is a small cleanup, suggested by Johannes.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
In some cases we did not even bother to check the return value of
mmap() and just assume it worked. This is bad, because if we are
out of virtual address space the kernel returned MAP_FAILED and we
would attempt to dereference that address, segfaulting without any
real error output to the user.
We are replacing all calls to mmap() with xmmap() and moving all
MAP_FAILED checking into that single location. If a mmap call
fails we try to release enough least-recently-used pack windows
to possibly succeed, then retry the mmap() attempt. If we cannot
mmap even after releasing pack memory then we die() as none of our
callers have any reasonable recovery strategy for a failed mmap.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
If we are about to fail because this process has run out of memory we
should first try to automatically control our appetite for address
space by releasing enough least-recently-used pack windows to gain
back enough memory such that we might actually be able to meet the
current allocation request.
This should help users who have fairly large repositories but are
working on systems with relatively small virtual address space.
Many times we see reports on the mailing list of these users running
out of memory during various Git operations. Dynamically decreasing
the amount of pack memory used when the demand for heap memory is
increasing is an intelligent solution to this problem.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
If the compiler has asked us to disable use of mmap() on their
platform then we are forced to use git_mmap and its emulation via
pread. In this case large (e.g. 32 MiB) windows for pack access
are simply too big as a command will wind up reading a lot more
data than it will ever need, significantly reducing response time.
To prevent a high latency when NO_MMAP has been selected we now
use a default of 1 MiB for core.packedGitWindowSize. Credit goes
to Linus and Junio for recommending this more reasonable setting.
[jc: upcased the name of the symbolic constant, and made another
hardcoded constant into a symbolic constant while at it. ]
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This is a basic set of tests for the sliding window mmap. We mostly
focus on the verify-pack and pack-objects implementations (including
delta reuse) as these commands appear to cover the bulk of the
affected portions of sha1_file.c.
The test cases don't verify the virtual memory size used, as
this can differ from system to system. Instead it just verifies
that we can run with very low values for core.packedGitLimit and
core.packedGitWindowSize.
Adding pack_report() to the end of both builtin-verify-pack.c and
builtin-pack-objects.c and manually inspecting the statistics output
can help to verify that the total virtual memory size attributed
to pack mmap usage is what one might expect on the current system.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Much like the alloc_report() function can be useful to report on
object allocation statistics while debugging the new pack_report()
function can be useful to report on the behavior of the mmap window
code used for packfile access.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
If a command opens a packfile for only temporary access and does not
install the struct packed_git* into the global packed_git list then
we are unable to unmap any inactive windows within that packed_git,
causing the overall process to exceed core.packedGitLimit.
We cannot force the callers to install their temporary packfile
into the packed_git chain as doing so would allow that (possibly
corrupt but currently being verified) temporary packfile to become
part of the local ODB, which may allow it to be considered for
object resolution when it may not actually be a valid packfile.
So to support unmapping the windows of these temporary packfiles we
also scan the windows of the struct packed_git which was supplied
to use_pack(). Since commands only work with one temporary packfile
at a time scanning the one supplied to use_pack() and all packs
installed into packed_git should cover everything available in
memory.
We also have to be careful to not close the file descriptor of
the packed_git which was handed to use_pack() when all of that
packfile's windows have been unmapped, as we are already past the
open call that would open the packfile and need the file descriptor
to be ready for mmap() after unuse_one_window returns.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
If we are unable to mmap the a region of the packfile with the mmap()
system call there may be a good reason why, such as a closed file
descriptor or out of address space. Reporting the system level
error message can help to debug such problems.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
We cannot allow a window to be smaller than 2 system pages.
This limitation is necessary to support the feature of use_pack()
where we always supply at least 20 bytes after the offset to help
the object header and delta base parsing routines.
If packedGitWindowSize were allowed to be as small as 1 system page
then we would be completely unable to access an object header which
spanned over a page as we would never be able to arrange a mapping
such that the header was contiguous in virtual memory.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Now that our pack access code's behavior may be altered by the
setting of core.packedGitWindowSize or core.packedGitLimit we need
to make sure these values are set as configured in the repository's
configuration file rather than to their defaults.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This finally turns on the sliding window behavior for packfile data
access by mapping limited size windows and chaining them under the
packed_git->windows list.
We consider a given byte offset to be within the window only if there
would be at least 20 bytes (one hash worth of data) accessible after
the requested offset. This range selection relates to the contract
that use_pack() makes with its callers, allowing them to access
one hash or one object header without needing to call use_pack()
for every byte of data obtained.
In the worst case scenario we will map the same page of data twice
into memory: once at the end of one window and once again at the
start of the next window. This duplicate page mapping will happen
only when an object header or a delta base reference is spanned
over the end of a window and is always limited to just one page of
duplication, as no sane operating system will ever have a page size
smaller than a hash.
I am assuming that the possible wasted page of virtual address
space is going to perform faster than the alternatives, which
would be to copy the object header or ref delta into a temporary
buffer prior to parsing, or to check the window range on every byte
during header parsing. We may decide to revisit this decision in
the future since this is just a gut instinct decision and has not
actually been proven out by experimental testing.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
To support multiple windows per packfile we need to unmap only one
window at a time from that packfile, leaving any other windows in
place and available for reference.
We treat all windows from all packfiles equally; the least recently
used, not-in-use window across all packfiles will always be closed
first.
If we have unmapped all windows in a packfile then we can also close
the packfile's file descriptor as its possible we won't need to map
any window from that file in the near future. This decision about
when to close the pack file descriptor may need to be revisited in
the future after additional testing on several different platforms
can be performed.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
When we parse the object header or the delta base reference we
don't bother to loop over use_pack() calls. The reason we don't
need to bother with calling use_pack for each byte accessed is that
use_pack will always promise us at least 20 bytes (really the hash
size) after the offset. This promise from use_pack simplifies a
lot of code in the header parsing logic, as well as helps out the
zlib library by ensuring there's always some data for it to consume
during an inflate call.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
When multiple mmaps start getting used for all pack file access it
is not possible to get all data associated with a specific object
in one contiguous memory region. This limitation prevents simply
passing a single address and length to SHA1_Update or to inflate.
Instead we need to loop until we have processed all data of interest.
As we loop over the data we are always interested in reusing the same
window 'cursor', as the prior window will no longer be of any use
to us. This allows the use_pack() call to automatically decrement
the use count of the prior window before setting up access for us
to the next window.
Within each loop we need to make use of the available length output
parameter of use_pack() to tell us how many bytes are available in
the current memory region, as we cannot tell otherwise.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Part of the implementation concept of the sliding mmap window for
pack access is to permit multiple windows per pack to be mapped
independently. Since the inuse_cnt is associated with the mmap and
not with the file, this value is in struct pack_window and needs to
be incremented/decremented for each pack_window accessed by any code.
To faciliate that implementation we need to replace all uses of
use_packed_git() and unuse_packed_git() with a different API that
follows struct pack_window objects rather than struct packed_git.
The way this works is when we need to start accessing a pack for
the first time we should setup a new window 'cursor' by declaring
a local and setting it to NULL:
struct pack_windows *w_curs = NULL;
To obtain the memory region which contains a specific section of
the pack file we invoke use_pack(), supplying the address of our
current window cursor:
unsigned int len;
unsigned char *addr = use_pack(p, &w_curs, offset, &len);
the returned address `addr` will be the first byte at `offset`
within the pack file. The optional variable len will also be
updated with the number of bytes remaining following the address.
Multiple calls to use_pack() with the same window cursor will
update the window cursor, moving it from one window to another
when necessary. In this way each window cursor variable maintains
only one struct pack_window inuse at a time.
Finally before exiting the scope which originally declared the window
cursor we must invoke unuse_pack() to unuse the current window (which
may be different from the one that was first obtained from use_pack):
unuse_pack(&w_curs);
This implementation is still not complete with regards to multiple
windows, as only one window per pack file is supported right now.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
To efficiently support mmaping of multiple regions of the same pack
file we want to keep the pack's file descriptor open while we are
actively working with that pack. So we are now keeping that file
descriptor in packed_git.pack_fd and closing it only after we unmap
the last window.
This is going to increase the number of file descriptors that are
in use at once, however that will be bounded by the total number of
pack files present and therefore should not be very high. It is
a small tradeoff which we may need to revisit after some testing
can be done on various repositories and systems.
For code clarity we also want to seperate out the implementation
of how we open a pack file from the implementation which locates
a suitable window (or makes a new one) from the given pack file.
Since this is a rather large delta I'm taking advantage of doing
it now, in a fairly isolated change.
When we open a pack file we need to examine the header and trailer
without having a mmap in place, as we may only need to mmap
the middle section of this particular pack. Consequently the
verification code has been refactored to make use of the new
read_or_die function.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Like write_or_die read_or_die reads the entire length requested
or it kills the current process with a die call.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Since the index_size and pack_size members of struct packed_git
are the lengths of those corresponding files we should use the
off_t size of the operating system to store these file lengths,
rather than an unsigned long. This would help in the future should
we ever resurrect Junio's 64 bit index implementation.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
The idea behind the sliding mmap window pack reader implementation
is to have multiple mmap regions active against the same pack file,
thereby allowing the process to mmap in only the active/hot sections
of the pack and reduce overall virtual address space usage.
To implement this we need to refactor the mmap related data
(pack_base, pack_use_cnt) out of struct packed_git and move them
into a new struct pack_window.
We are refactoring the code to support a single struct pack_window
per packfile, thereby emulating the prior behavior of mmap'ing the
entire pack file.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Rather than hardcoding the maximum number of bytes which can be
mmapped from pack files we should make this value configurable,
allowing the end user to increase or decrease this limit on a
per-repository basis depending on the size of the repository
and the capabilities of their operating system.
In general users should not need to manually tune such a low-level
setting within the core code, but being able to artifically limit
the number of bytes which we can mmap at once from pack files will
make it easier to craft test cases for the new mmap sliding window
implementation.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
The unpack_entry_gently function currently has only two callers:
the delta base resolution in sha1_file.c and the main loop of
pack-check.c. Both of these must change to using unpack_entry
directly when we implement sliding window mmap logic, so I'm doing
it earlier to help break down the change set.
This may cause a slight performance decrease for delta base
resolution as well as for pack-check.c's verify_packfile(), as
the pack use counter will be incremented and decremented for every
object that is unpacked.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
When '*.ig' is ignored, and you have two files f.ig and d.ig/foo
in the working tree,
$ git add .
correctly ignored f.ig but failed to ignore d.ig/foo. This was
caused by a thinko in an earlier commit 4888c534, when we tried
to allow adding otherwise ignored files.
After reverting that commit, this takes a much simpler approach.
When we have an unmatched pathspec that talks about an existing
pathname, we know it is an ignored path the user tried to add,
so we include it in the set of paths directory walker returned.
This does not let you say "git add -f D" on an ignored directory
D and add everything under D. People can submit a patch to
further allow it if they want to, but I think it is a saner
behaviour to require explicit paths to be spelled out in such a
case.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Not that this reveals anything new, but I did test_tick shell
function in test-lib and found it rather cute and nice.
Signed-off-by: Junio C Hamano <junkio@cox.net>
By switching from merge-resolve to merge-recursive in the 3-way
fallback behavior of git-am we gain a few benefits:
* renames are automatically handled, like in rebase -m;
* conflict hunks can reference the patch name;
* its faster on Cygwin (less forks).
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
To support wider use cases, such as from within `git am -3`, the
merge-recursive utility needs to accept not just commit-ish but
also tree-ish as arguments on its command line.
If given a tree-ish then merge-recursive will create a virtual commit
wrapping it, with the subject of the commit set to the best name we
can derive for that tree, which is either the command line string
(probably the SHA1), or whatever string appears in GITHEAD_*.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
