In particular, the git__mmap() and git__munmap() routines provide
the interface to platform specific memory-mapped file facilities.
We provide implementations for unix and win32, which can be found
in their own sub-directories.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
On windows, unless we use the O_BINARY flag in the open()
call, the file I/O routines will perform line ending
conversion (\r\n => \n on input, \n => \r\n on output).
In addition to the performance penalty, most files in the
object database are binary and will, therefore, become
corrupted by this conversion.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
In particular, conditional expressions which contain an
assignment statement, where the expression type is not
explicitly made to be boolean, elicits the following
message:
warning 2: possible unintended assignment
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
In particular, using pointer arithmetic on void pointers,
despite being quite useful, is not legal in standard C.
Avoiding non-standard C constructs will help in porting
the library to other compilers/platforms.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Paul agreed to the GCC-exception license by email:
|
| From: Paul Kocher <paul@cryptography.com>
| Date: Sun, 15 Mar 2009 11:37:23 -0700
| Subject: Re: Adding Mozilla SHA1 implementation to libgit2
|
| Yes - that's fine.
|
| At 01:56 AM 3/5/2009, Andreas Ericsson wrote:
| > Hi Paul. We spoke earlier about this, if you remember?
| > We'd like to add the GCC-exception to the GPL license
| > for these files.
Signed-off-by: Paul Kocher <paul@cryptography.com>
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This function determines if the given object can be found
in the object database. At present, only the local object
database is searched.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
In particular, the test for z-stream input completion
(zs.avail_in != 0) logically belongs with the test for
the Z_STREAM_END stream status. This is also consistent
with the identical check in finish_inflate().
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
At present, it is sufficient to ensure that an error return
from inflateInit() is not ignored. Most error returns, like
Z_VERSION_ERROR and Z_STREAM_ERROR, indicate programming or
build errors. These errors could, perhaps, be handled with
simple asserts. However, for a Z_MEM_ERROR, we may want to
perform some further error handling in the future.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
In particular, neglecting to call inflateEnd() along various
codepaths in the inflate_tail() routine, would result in the
failure to release zlib internal state.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
These routines are intended to extract the directory and
base name from a path string. Note that these routines
do not interact with any filesystem and work only on the
text of the path.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
In particular, the git__delta_apply() function has not been
declared prior to it's definition. In order to suppress the
warning, include the delta-apply.h header which provides the
public interface. This ensures that the declaration and
definition are consistent.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The git__delta_apply() function can be used to apply a Git style
delta, such as those used in pack files or in git patch files,
to recover the original object stream.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The fanout table is fairly commonly accessed, we need to read it
twice for each object we lookup in any given pack file. Most of
the processors running Git are running in little-endian mode, as
they are variants of the x86 platform, so reading the fanout is
a costly operation as we need to convert from network byte order
to local byte order. By decoding the fanout table into a malloc
obtained buffer we can save these 2 decode operations per lookup
and make search go more quickly.
This also cleans up the initialization of the search functions
by cutting out a few instructions, saving a small amount of time.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The index data is mapped into memory and then scanned using a
binary search algorithm to locate the matching entry for the
supplied git_oid. The standard fanout hash trick is applied to
reduce the search space by 8 iterations.
Since the v1 and v2 file formats differ in their search function,
due to the different layouts used for the object records, we use
two different search implementations and a virtual function pointer
to jump to the correct version of code for the current pack index.
The single function jump per-pack should be faster then computing
a branch point inside the inner loop of a common binary search.
To improve concurrency during read operations the pack lock is only
held while verifying the index is actually open, or while opening
the index for the first time. This permits multiple concurrent
readers to scan through the same index.
If an invalid index file is opened we close it and mark the
git_pack's invalid bit to true. The git_pack structure is kept
around in its parent git_packlist, but the invalid bit will cause
all future readers to skip over the pack entirely. Pruning the
invalid entries is relatively unimportant because they shouldn't
be very common, a $GIT_DIRECTORY/objects/pack directory tends to
only have valid pack files.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Win32 has a variant of mmap that is harder to use than POSIX, but
to run natively and efficiently on Win32 we need some form of it.
gitfo_map_ro() provides a basic mmap function for use in locations
where we need read-only random data access to large ranges of a file,
such as a pack-*.idx.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Using an atomic reference counter is difficult to make
cross-platform, as the reference count implementations
are generally processor specific. Its also hard to do
a proper multi-read/single-write implementation.
We now use a simple mutex around the reference count for the list
of packs. Readers grab the mutex and either build the list, or
increment the existing one's reference count. When the reader is
done with the list, the reference count is decremented. In this way
parallel readers are able to operate on the list without worrying
about it being deallocated out from under them.
Individual pack structures are held by reference counts, but we
only care about the list the pack structure is held in. There is
no need to increment/decrement the pack reference counts as we
scan through them during a read operation, the caller holds the
git_packlist and that is sufficient to hold the packs it references.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
As far as gcc is concerned, the "z size specifier" is available as
an extension to the language, which is available with or without any
-std= switch. (I think you have to go back to 2.95 for a version
of gcc which doesn't work.) Many other compilers have this as an
extension as well (ie without the equivalent of -std=c99).
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
These headers aren't always available; they typically come from the
Linux kernel, but aren't supposed to be exported into the userspace
/usr/include. Modern kernels won't install these and some distros
rm -rf the directory post kernel header install.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Currently we only catalog the available pack files into a table,
storing their path names relative to the pack directory.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
When scanning the pack directory we need to see if the path
name is present for ".idx" when we discover a ".pack" file.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Checking the return value of snprintf is a pain, as it must be
>= 0 and < sizeof(buffer). git__fmt is a simple wrapper to
perform these checks.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Our fileops API is currently private. We aren't planning on supplying
a cross-platform file API to applications that link to us. If we did,
we'd probably whole-sale publish fileops, not just the dirent code.
By moving it to be private we can also change the call signature to
permit the buffer to be passed down through the call chain. This is
very helpful when we are doing a recursive scan as we can reuse just
one buffer in all stack frames, reducing the impact the recursion has
on the stack frames in the data cache.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We grab the lock while accessing the alternates list, ensuring that
we only initialize it once for the given git_odb.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
These abstractions can be used to implement an efficient resource
reference counter and simple mutual exclusion. On pthreads we use
pthread_mutex_t, except when we are also on glibc and can directly
use its asm/atomic.h definitions.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If we are using threads we need to make sure pthread.h comes
in before just about anything else. Some platforms enable
macros that alter what other headers define.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This error code indicates the OS error code has a better value
describing the last error, as it is likely a network or local
file IO problem identified by a C library function call.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We now forbid direct use of malloc, strdup or calloc within the
library and instead use wrapper functions git__malloc, etc. to
invoke the underlying library malloc and set git_errno to a no
memory error code if the allocation fails.
In the future once we have pack objects in memory we are likely
to enhance these routines with garbage collection logic to purge
cached pack data when allocations fail. Because the size of the
function will grow somewhat large, we don't want to mark them for
inline as gcc tends to aggressively inline, creating larger than
expected executables.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We're likely to add additional path data, like the path of the
refs or the path to the config file into the git_odb structure,
as it may grow into the repository wrapper. Changing the name
of the objects directory reference makes it more clear should
we later add something else.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We didn't search for the object, so we cannot possibly promise it
to the caller of git_odb_read().
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This is the correct C99 format code for the size_t type when passed
as an argument to the *printf family. If the platform doesn't
define it, we assume %lu and just cross our fingers that its the
proper setting for a size_t on this system. On most sane platforms,
"unsigned long" is the underlying type of "size_t".
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The Mach-O format does not permit gcc to implement the __thread
TLS specification, so we must instead emulate it using a single
int cell allocated from memory and stored inside of the thread
specific data associated with the current pthread.
What makes this tricky is git_errno must be a valid lvalue, so
we really need to return a pointer to the caller and deference it
as part of the git_errno macro.
The GCC-specific __attribute__((constructor)) extension is used
to ensure the pthread_key_t is allocated before any Git functions
are executed in the library, as this is necessary to access our
thread specific storage.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
[sp: Changed signature for output to use git_oid, and added
a test case to verify an allocated git_hash_ctx can be
reinitialized and reused.]
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
In particular, when asked to read an empty file, this function
calls malloc() with a zero size allocation request. Standard C
says that the behaviour of malloc() in this case is implementation
defined.
[C99, 7.20.3 says "... If the size of the space requested is zero,
the behavior is implementation-defined: either a null pointer is
returned, or the behavior is as if the size were some nonzero
value, except that the returned pointer shall not be used to
access an object."]
Finesse the issue by over-allocating by one byte. Setting the extra
byte to '\0' may also provide a useful sentinel for text files.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
In particular, the gitfo_read_file() routine can be used to slurp
the complete file contents into an gitfo_buf structure. The buffer
content will be allocated by malloc() and may be released by the
gitfo_free_buf() routine. The io buffer type can be initialised
on the stack with the GITFO_BUF_INIT macro.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
In particular, the warning relates to malloc(), which is
declared in <stdlib.h>. This header is now included,
indirectly, via the "common.h" header.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The PATH_MAX symbol is often, but not always, defined
in the <limits.h> header. In particular, on cygwin you
need to include this header to avoid a compilation error.
However, some systems define PATH_MAX to be something as
small as 256, which POSIX is happy to allow, while others
allow much larger values. In general it can vary from
one filesystem to another.
In order to avoid the vagaries of different systems, define
our own symbol.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
[sp: Credit for some of this implementation goes to Pieter, I
started off a patch he proposed for libgit2 but reworked
enough of it that I don't want to blame him for any bugs.]
Suggested-by: Pieter de Bie <pdebie@ai.rug.nl>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
commit dff79e27d3 renamed
the (small object) "git_sobj" to a plain "git_obj", but
neglected to update some of the documentation to reflect
that change.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Since at least MS have something like GetFirstDirEnt() and
GetNextDirEnt() (presumably with superior performance), we
can let MS hackers add support for a dirent walker using
that API instead, while we stick with the posix-style
readdir() calls.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The idea is taken from Junio's work in read-cache.c, where
it's used for writing out the index without tap-dancing on
the poor harddrive. Since it's almost certainly useful for
cached writing of packfiles too, we turn it into a generic
API, making it perfectly simple to reuse it later.
gitfo_write_cached() has the same contract as gitfo_write(), it
returns GIT_SUCCESS if all bytes are successfully written (or were
at least buffered for later writing), and <0 if an error occurs
during buffer writing.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Since it doesn't make sense to make the disk access stuff
portable *AND* public (that's a job for each application
imo), we can take a shortcut and just support unixy stuff
for now and get away with coding most of it as macros.
Since we go with an internal API for starters and only
provide higher-level API's to the libgit users, we'll be
ok with this approach.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Since it's being added when we install the headers anyway,
we might as well get rid of it. If anything, we should point
coders to the COPYING file in the project's root directory
instead of duplicating the same (large-ish) text everywhere.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This adds the per-thread global variable git_errno to the
system, which callers can examine to get information about
an error.
Two helper functions are added to reduce LoC-count for the
library code itself.
Also, some exceptions are made for running sparse on GIT_TLS
definitions, since it doesn't grok thread-local variables at
all.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
ARRAY_SIZE() et al go in util.h, included from common.h
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This one pulls in compiler compatibility macros, some
common header files, and also the public common.h header.
C source files are modified to use the private common.h
in favour of the public one.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Otherwise their prototypes don't match their declarations.
Detected by 'sparse', which is obviously good to run
before each commit.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Using it in the first place means something's wrong.
This patch replaces it with an internal header which
carries the previously "protected" code instead.
Internal source-files simply include "commit.h" and
they're done. The internal header includes the public
one to make sure we always use the proper prototype.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
It doesn't cover all cases, but we can work on those as
we go along. For now, gcc, MSVC++, Intel C/C++, IBM XL C/C++,
Sun Studio C/C++ and Borland C++ Builder are the supported
compilers (although we boldly assume that they all are of
a recent enough version to support thread-local storage).
This is intended to be used in upcoming patches that implement
graceful (but TLS-dependant) error-handling in the library.
As an added bonus, we also bring the online_cpus() function
from git.git to detect the number of usable cpu's.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
It's arguably smoother to keep them close to the source,
as that's where one's working when modifying them. More
importantly, though, is the ability to use private headers
in the src/ dir that simply include "git/$samename.h" to
get to the public API at the same time.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
git_revp is something I personally can't stop pronouncing
"rev pointer". I'm sure others would suffer the same
problem.
Also, rename the git_revp_ sub-api "gitrp_". This is the
first of many such renames, primarily done to prevent
extreme inflation in the "git_" namespace, which we'd like
to reserve for a higher-level API.
While we're at it, we remove the noise-char "c" from a lot
of functions. Since revision walking is all about commits,
the common case should be that we're dealing with commits.
Exceptions can get a more mnemonic description as needed.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The 's' never really made sense, since it's not a "small"
object at all, but rather a plain object. As such, it should
have a "plain" object name.
Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We never want to accept a short read or a short write when
transferring data to or from a local file.
Either the entire read (or write) completes or the operation
failed and we will not recover gracefully from it.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
These are easily built off the standard C library functions memcpy
and memcmp. By marking these inline we stand a good chance of
the C compiler replacing the entire thing with tight machine code,
because many compilers will actually inline a memcmp or memcpy when
the 3rd argument (the size) is a constant value.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This way we can start to write IO code to read and write files in the
Git object database, but provide a hook to inject native Win32 APIs
instead so libgit2 can be ported to run natively on that platform.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This isn't the best idea I've head. Pierre Habouzit was suggesting
a technique of assigning a unique integer to each commit and then
allocating storage out of auxiliary pools, using the commit's unique
integer to index into any auxiliary pool in constant time. This way
both applications and the library can efficiently attach arbitrary
data onto a commit, such as rewritten parents, or flags, and have
them disconnected from the main object hash table.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This way only structures we ask the caller to allocate on their
call stack or which we want to allow them to use members from
are shown in the API docs.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Most read calls will use the small object format, as the
majority of the content within the database is very small
objects (under 20 KB when inflated).
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
