/*
* libgit2 "general" example - shows basic libgit2 concepts
*
* Written by the libgit2 contributors
*
* To the extent possible under law, the author(s) have dedicated all copyright
* and related and neighboring rights to this software to the public domain
* worldwide. This software is distributed without any warranty.
*
* You should have received a copy of the CC0 Public Domain Dedication along
* with this software. If not, see
* <http://creativecommons.org/publicdomain/zero/1.0/>.
*/
/**
* [**libgit2**][lg] is a portable, pure C implementation of the Git core
* methods provided as a re-entrant linkable library with a solid API,
* allowing you to write native speed custom Git applications in any
* language which supports C bindings.
*
* This file is an example of using that API in a real, compilable C file.
* As the API is updated, this file will be updated to demonstrate the new
* functionality.
*
* If you're trying to write something in C using [libgit2][lg], you should
* also check out the generated [API documentation][ap]. We try to link to
* the relevant sections of the API docs in each section in this file.
*
* **libgit2** (for the most part) only implements the core plumbing
* functions, not really the higher level porcelain stuff. For a primer on
* Git Internals that you will need to know to work with Git at this level,
* check out [Chapter 10][pg] of the Pro Git book.
*
* [lg]: http://libgit2.github.com
* [ap]: http://libgit2.github.com/libgit2
* [pg]: https://git-scm.com/book/en/v2/Git-Internals-Plumbing-and-Porcelain
*/
/**
* ### Includes
*
* Including the `git2.h` header will include all the other libgit2 headers
* that you need. It should be the only thing you need to include in order
* to compile properly and get all the libgit2 API.
*/
#include <git2.h>
#include <stdio.h>
#include <string.h>
static void oid_parsing(git_oid *out);
static void object_database(git_repository *repo, git_oid *oid);
static void commit_writing(git_repository *repo);
static void commit_parsing(git_repository *repo);
static void tag_parsing(git_repository *repo);
static void tree_parsing(git_repository *repo);
static void blob_parsing(git_repository *repo);
static void revwalking(git_repository *repo);
static void index_walking(git_repository *repo);
static void reference_listing(git_repository *repo);
static void config_files(const char *repo_path, git_repository *repo);
/**
* Almost all libgit2 functions return 0 on success or negative on error.
* This is not production quality error checking, but should be sufficient
* as an example.
*/
static void check_error(int error_code, const char *action)
{
const git_error *error = giterr_last();
if (!error_code)
return;
printf("Error %d %s - %s\n", error_code, action,
(error && error->message) ? error->message : "???");
exit(1);
}
int main (int argc, char** argv)
{
int error;
git_oid oid;
char *repo_path;
git_repository *repo;
/**
* Initialize the library, this will set up any global state which libgit2 needs
* including threading and crypto
*/
git_libgit2_init();
/**
* ### Opening the Repository
*
* There are a couple of methods for opening a repository, this being the
* simplest. There are also [methods][me] for specifying the index file
* and work tree locations, here we assume they are in the normal places.
*
* (Try running this program against tests/resources/testrepo.git.)
*
* [me]: http://libgit2.github.com/libgit2/#HEAD/group/repository
*/
repo_path = (argc > 1) ? argv[1] : "/opt/libgit2-test/.git";
error = git_repository_open(&repo, repo_path);
check_error(error, "opening repository");
oid_parsing(&oid);
object_database(repo, &oid);
commit_writing(repo);
commit_parsing(repo);
tag_parsing(repo);
tree_parsing(repo);
blob_parsing(repo);
revwalking(repo);
index_walking(repo);
reference_listing(repo);
config_files(repo_path, repo);
/**
* Finally, when you're done with the repository, you can free it as well.
*/
git_repository_free(repo);
return 0;
}
/**
* ### SHA-1 Value Conversions
*/
static void oid_parsing(git_oid *oid)
{
char out[GIT_OID_HEXSZ+1];
char hex[] = "4a202b346bb0fb0db7eff3cffeb3c70babbd2045";
printf("*Hex to Raw*\n");
/**
* For our first example, we will convert a 40 character hex value to the
* 20 byte raw SHA1 value.
*
* The `git_oid` is the structure that keeps the SHA value. We will use
* this throughout the example for storing the value of the current SHA
* key we're working with.
*/
git_oid_fromstr(oid, hex);
// Once we've converted the string into the oid value, we can get the raw
// value of the SHA by accessing `oid.id`
// Next we will convert the 20 byte raw SHA1 value to a human readable 40
// char hex value.
printf("\n*Raw to Hex*\n");
out[GIT_OID_HEXSZ] = '\0';
/**
* If you have a oid, you can easily get the hex value of the SHA as well.
*/
git_oid_fmt(out, oid);
/**
* If you have a oid, you can easily get the hex value of the SHA as well.
*/
git_oid_fmt(out, oid);
printf("SHA hex string: %s\n", out);
}
/**
* ### Working with the Object Database
*
* **libgit2** provides [direct access][odb] to the object database. The
* object database is where the actual objects are stored in Git. For
* working with raw objects, we'll need to get this structure from the
* repository.
*
* [odb]: http://libgit2.github.com/libgit2/#HEAD/group/odb
*/
static void object_database(git_repository *repo, git_oid *oid)
{
char oid_hex[GIT_OID_HEXSZ+1] = { 0 };
const unsigned char *data;
const char *str_type;
int error;
git_odb_object *obj;
git_odb *odb;
git_otype otype;
git_repository_odb(&odb, repo);
/**
* #### Raw Object Reading
*/
printf("\n*Raw Object Read*\n");
/**
* We can read raw objects directly from the object database if we have
* the oid (SHA) of the object. This allows us to access objects without
* knowing their type and inspect the raw bytes unparsed.
*/
error = git_odb_read(&obj, odb, oid);
check_error(error, "finding object in repository");
/**
* A raw object only has three properties - the type (commit, blob, tree
* or tag), the size of the raw data and the raw, unparsed data itself.
* For a commit or tag, that raw data is human readable plain ASCII
* text. For a blob it is just file contents, so it could be text or
* binary data. For a tree it is a special binary format, so it's unlikely
* to be hugely helpful as a raw object.
*/
data = (const unsigned char *)git_odb_object_data(obj);
otype = git_odb_object_type(obj);
/**
* We provide methods to convert from the object type which is an enum, to
* a string representation of that value (and vice-versa).
*/
str_type = git_object_type2string(otype);
printf("object length and type: %d, %s\nobject data: %s\n",
(int)git_odb_object_size(obj),
str_type, data);
/**
* For proper memory management, close the object when you are done with
* it or it will leak memory.
*/
git_odb_object_free(obj);
/**
* #### Raw Object Writing
*/
printf("\n*Raw Object Write*\n");
/**
* You can also write raw object data to Git. This is pretty cool because
* it gives you direct access to the key/value properties of Git. Here
* we'll write a new blob object that just contains a simple string.
* Notice that we have to specify the object type as the `git_otype` enum.
*/
git_odb_write(oid, odb, "test data", sizeof("test data") - 1, GIT_OBJ_BLOB);
/**
* Now that we've written the object, we can check out what SHA1 was
* generated when the object was written to our database.
*/
git_oid_fmt(oid_hex, oid);
printf("Written Object: %s\n", oid_hex);
/**
* Free the object database after usage.
*/
git_odb_free(odb);
}
/**
* #### Writing Commits
*
* libgit2 provides a couple of methods to create commit objects easily as
* well. There are four different create signatures, we'll just show one
* of them here. You can read about the other ones in the [commit API
* docs][cd].
*
* [cd]: http://libgit2.github.com/libgit2/#HEAD/group/commit
*/
static void commit_writing(git_repository *repo)
{
git_oid tree_id, parent_id, commit_id;
git_tree *tree;
git_commit *parent;
git_signature *author, *committer;
char oid_hex[GIT_OID_HEXSZ+1] = { 0 };
printf("\n*Commit Writing*\n");
/**
* Creating signatures for an authoring identity and time is simple. You
* will need to do this to specify who created a commit and when. Default
* values for the name and email should be found in the `user.name` and
* `user.email` configuration options. See the `config` section of this
* example file to see how to access config values.
*/
git_signature_new(&author,
"Scott Chacon", "schacon@gmail.com", 123456789, 60);
git_signature_new(&committer,
"Scott A Chacon", "scott@github.com", 987654321, 90);
/**
* Commit objects need a tree to point to and optionally one or more
* parents. Here we're creating oid objects to create the commit with,
* but you can also use
*/
git_oid_fromstr(&tree_id, "f60079018b664e4e79329a7ef9559c8d9e0378d1");
git_tree_lookup(&tree, repo, &tree_id);
git_oid_fromstr(&parent_id, "5b5b025afb0b4c913b4c338a42934a3863bf3644");
git_commit_lookup(&parent, repo, &parent_id);
/**
* Here we actually create the commit object with a single call with all
* the values we need to create the commit. The SHA key is written to the
* `commit_id` variable here.
*/
git_commit_create_v(
&commit_id, /* out id */
repo,
NULL, /* do not update the HEAD */
author,
committer,
NULL, /* use default message encoding */
"example commit",
tree,
1, parent);
/**
* Now we can take a look at the commit SHA we've generated.
*/
git_oid_fmt(oid_hex, &commit_id);
printf("New Commit: %s\n", oid_hex);
/**
* Free all objects used in the meanwhile.
*/
git_tree_free(tree);
git_commit_free(parent);
git_signature_free(author);
git_signature_free(committer);
}
/**
* ### Object Parsing
*
* libgit2 has methods to parse every object type in Git so you don't have
* to work directly with the raw data. This is much faster and simpler
* than trying to deal with the raw data yourself.
*/
/**
* #### Commit Parsing
*
* [Parsing commit objects][pco] is simple and gives you access to all the
* data in the commit - the author (name, email, datetime), committer
* (same), tree, message, encoding and parent(s).
*
* [pco]: http://libgit2.github.com/libgit2/#HEAD/group/commit
*/
static void commit_parsing(git_repository *repo)
{
const git_signature *author, *cmtter;
git_commit *commit, *parent;
git_oid oid;
char oid_hex[GIT_OID_HEXSZ+1];
const char *message;
unsigned int parents, p;
int error;
time_t time;
printf("\n*Commit Parsing*\n");
git_oid_fromstr(&oid, "8496071c1b46c854b31185ea97743be6a8774479");
error = git_commit_lookup(&commit, repo, &oid);
check_error(error, "looking up commit");
/**
* Each of the properties of the commit object are accessible via methods,
* including commonly needed variations, such as `git_commit_time` which
* returns the author time and `git_commit_message` which gives you the
* commit message (as a NUL-terminated string).
*/
message = git_commit_message(commit);
author = git_commit_author(commit);
cmtter = git_commit_committer(commit);
time = git_commit_time(commit);
/**
* The author and committer methods return [git_signature] structures,
* which give you name, email and `when`, which is a `git_time` structure,
* giving you a timestamp and timezone offset.
*/
printf("Author: %s (%s)\nCommitter: %s (%s)\nDate: %s\nMessage: %s\n",
author->name, author->email,
cmtter->name, cmtter->email,
ctime(&time), message);
/**
* Commits can have zero or more parents. The first (root) commit will
* have no parents, most commits will have one (i.e. the commit it was
* based on) and merge commits will have two or more. Commits can
* technically have any number, though it's rare to have more than two.
*/
parents = git_commit_parentcount(commit);
for (p = 0;p < parents;p++) {
memset(oid_hex, 0, sizeof(oid_hex));
git_commit_parent(&parent, commit, p);
git_oid_fmt(oid_hex, git_commit_id(parent));
printf("Parent: %s\n", oid_hex);
git_commit_free(parent);
}
git_commit_free(commit);
}
/**
* #### Tag Parsing
*
* You can parse and create tags with the [tag management API][tm], which
* functions very similarly to the commit lookup, parsing and creation
* methods, since the objects themselves are very similar.
*
* [tm]: http://libgit2.github.com/libgit2/#HEAD/group/tag
*/
static void tag_parsing(git_repository *repo)
{
git_commit *commit;
git_otype type;
git_tag *tag;
git_oid oid;
const char *name, *message;
int error;
printf("\n*Tag Parsing*\n");
/**
* We create an oid for the tag object if we know the SHA and look it up
* the same way that we would a commit (or any other object).
*/
git_oid_fromstr(&oid, "b25fa35b38051e4ae45d4222e795f9df2e43f1d1");
error = git_tag_lookup(&tag, repo, &oid);
check_error(error, "looking up tag");
/**
* Now that we have the tag object, we can extract the information it
* generally contains: the target (usually a commit object), the type of
* the target object (usually 'commit'), the name ('v1.0'), the tagger (a
* git_signature - name, email, timestamp), and the tag message.
*/
git_tag_target((git_object **)&commit, tag);
name = git_tag_name(tag); /* "test" */
type = git_tag_target_type(tag); /* GIT_OBJ_COMMIT (otype enum) */
message = git_tag_message(tag); /* "tag message\n" */
printf("Tag Name: %s\nTag Type: %s\nTag Message: %s\n",
name, git_object_type2string(type), message);
/**
* Free both the commit and tag after usage.
*/
git_commit_free(commit);
git_tag_free(tag);
}
/**
* #### Tree Parsing
*
* [Tree parsing][tp] is a bit different than the other objects, in that
* we have a subtype which is the tree entry. This is not an actual
* object type in Git, but a useful structure for parsing and traversing
* tree entries.
*
* [tp]: http://libgit2.github.com/libgit2/#HEAD/group/tree
*/
static void tree_parsing(git_repository *repo)
{
const git_tree_entry *entry;
size_t cnt;
git_object *obj;
git_tree *tree;
git_oid oid;
printf("\n*Tree Parsing*\n");
/**
* Create the oid and lookup the tree object just like the other objects.
*/
git_oid_fromstr(&oid, "f60079018b664e4e79329a7ef9559c8d9e0378d1");
git_tree_lookup(&tree, repo, &oid);
/**
* Getting the count of entries in the tree so you can iterate over them
* if you want to.
*/
cnt = git_tree_entrycount(tree); /* 2 */
printf("tree entries: %d\n", (int) cnt);
entry = git_tree_entry_byindex(tree, 0);
printf("Entry name: %s\n", git_tree_entry_name(entry)); /* "README" */
/**
* You can also access tree entries by name if you know the name of the
* entry you're looking for.
*/
entry = git_tree_entry_byname(tree, "README");
git_tree_entry_name(entry); /* "README" */
/**
* Once you have the entry object, you can access the content or subtree
* (or commit, in the case of submodules) that it points to. You can also
* get the mode if you want.
*/
git_tree_entry_to_object(&obj, repo, entry); /* blob */
/**
* Remember to close the looked-up object and tree once you are done using it
*/
git_object_free(obj);
git_tree_free(tree);
}
/**
* #### Blob Parsing
*
* The last object type is the simplest and requires the least parsing
* help. Blobs are just file contents and can contain anything, there is
* no structure to it. The main advantage to using the [simple blob
* api][ba] is that when you're creating blobs you don't have to calculate
* the size of the content. There is also a helper for reading a file
* from disk and writing it to the db and getting the oid back so you
* don't have to do all those steps yourself.
*
* [ba]: http://libgit2.github.com/libgit2/#HEAD/group/blob
*/
static void blob_parsing(git_repository *repo)
{
git_blob *blob;
git_oid oid;
printf("\n*Blob Parsing*\n");
git_oid_fromstr(&oid, "1385f264afb75a56a5bec74243be9b367ba4ca08");
git_blob_lookup(&blob, repo, &oid);
/**
* You can access a buffer with the raw contents of the blob directly.
* Note that this buffer may not be contain ASCII data for certain blobs
* (e.g. binary files): do not consider the buffer a NULL-terminated
* string, and use the `git_blob_rawsize` attribute to find out its exact
* size in bytes
* */
printf("Blob Size: %ld\n", (long)git_blob_rawsize(blob)); /* 8 */
git_blob_rawcontent(blob); /* "content" */
/**
* Free the blob after usage.
*/
git_blob_free(blob);
}
/**
* ### Revwalking
*
* The libgit2 [revision walking api][rw] provides methods to traverse the
* directed graph created by the parent pointers of the commit objects.
* Since all commits point back to the commit that came directly before
* them, you can walk this parentage as a graph and find all the commits
* that were ancestors of (reachable from) a given starting point. This
* can allow you to create `git log` type functionality.
*
* [rw]: http://libgit2.github.com/libgit2/#HEAD/group/revwalk
*/
static void revwalking(git_repository *repo)
{
const git_signature *cauth;
const char *cmsg;
int error;
git_revwalk *walk;
git_commit *wcommit;
git_oid oid;
printf("\n*Revwalking*\n");
git_oid_fromstr(&oid, "5b5b025afb0b4c913b4c338a42934a3863bf3644");
/**
* To use the revwalker, create a new walker, tell it how you want to sort
* the output and then push one or more starting points onto the walker.
* If you want to emulate the output of `git log` you would push the SHA
* of the commit that HEAD points to into the walker and then start
* traversing them. You can also 'hide' commits that you want to stop at
* or not see any of their ancestors. So if you want to emulate `git log
* branch1..branch2`, you would push the oid of `branch2` and hide the oid
* of `branch1`.
*/
git_revwalk_new(&walk, repo);
git_revwalk_sorting(walk, GIT_SORT_TOPOLOGICAL | GIT_SORT_REVERSE);
git_revwalk_push(walk, &oid);
/**
* Now that we have the starting point pushed onto the walker, we start
* asking for ancestors. It will return them in the sorting order we asked
* for as commit oids. We can then lookup and parse the committed pointed
* at by the returned OID; note that this operation is specially fast
* since the raw contents of the commit object will be cached in memory
*/
while ((git_revwalk_next(&oid, walk)) == 0) {
error = git_commit_lookup(&wcommit, repo, &oid);
check_error(error, "looking up commit during revwalk");
cmsg = git_commit_message(wcommit);
cauth = git_commit_author(wcommit);
printf("%s (%s)\n", cmsg, cauth->email);
git_commit_free(wcommit);
}
/**
* Like the other objects, be sure to free the revwalker when you're done
* to prevent memory leaks. Also, make sure that the repository being
* walked it not deallocated while the walk is in progress, or it will
* result in undefined behavior
*/
git_revwalk_free(walk);
}
/**
* ### Index File Manipulation *
* The [index file API][gi] allows you to read, traverse, update and write
* the Git index file (sometimes thought of as the staging area).
*
* [gi]: http://libgit2.github.com/libgit2/#HEAD/group/index
*/
static void index_walking(git_repository *repo)
{
git_index *index;
unsigned int i, ecount;
printf("\n*Index Walking*\n");
/**
* You can either open the index from the standard location in an open
* repository, as we're doing here, or you can open and manipulate any
* index file with `git_index_open_bare()`. The index for the repository
* will be located and loaded from disk.
*/
git_repository_index(&index, repo);
/**
* For each entry in the index, you can get a bunch of information
* including the SHA (oid), path and mode which map to the tree objects
* that are written out. It also has filesystem properties to help
* determine what to inspect for changes (ctime, mtime, dev, ino, uid,
* gid, file_size and flags) All these properties are exported publicly in
* the `git_index_entry` struct
*/
ecount = git_index_entrycount(index);
for (i = 0; i < ecount; ++i) {
const git_index_entry *e = git_index_get_byindex(index, i);
printf("path: %s\n", e->path);
printf("mtime: %d\n", (int)e->mtime.seconds);
printf("fs: %d\n", (int)e->file_size);
}
git_index_free(index);
}
/**
* ### References
*
* The [reference API][ref] allows you to list, resolve, create and update
* references such as branches, tags and remote references (everything in
* the .git/refs directory).
*
* [ref]: http://libgit2.github.com/libgit2/#HEAD/group/reference
*/
static void reference_listing(git_repository *repo)
{
git_strarray ref_list;
unsigned i;
printf("\n*Reference Listing*\n");
/**
* Here we will implement something like `git for-each-ref` simply listing
* out all available references and the object SHA they resolve to.
*
* Now that we have the list of reference names, we can lookup each ref
* one at a time and resolve them to the SHA, then print both values out.
*/
git_reference_list(&ref_list, repo);
for (i = 0; i < ref_list.count; ++i) {
git_reference *ref;
char oid_hex[GIT_OID_HEXSZ+1] = GIT_OID_HEX_ZERO;
const char *refname;
refname = ref_list.strings[i];
git_reference_lookup(&ref, repo, refname);
switch (git_reference_type(ref)) {
case GIT_REF_OID:
git_oid_fmt(oid_hex, git_reference_target(ref));
printf("%s [%s]\n", refname, oid_hex);
break;
case GIT_REF_SYMBOLIC:
printf("%s => %s\n", refname, git_reference_symbolic_target(ref));
break;
default:
fprintf(stderr, "Unexpected reference type\n");
exit(1);
}
git_reference_free(ref);
}
git_strarray_free(&ref_list);
}
/**
* ### Config Files
*
* The [config API][config] allows you to list and updatee config values
* in any of the accessible config file locations (system, global, local).
*
* [config]: http://libgit2.github.com/libgit2/#HEAD/group/config
*/
static void config_files(const char *repo_path, git_repository* repo)
{
const char *email;
char config_path[256];
int32_t autocorrect;
git_config *cfg;
git_config *snap_cfg;
printf("\n*Config Listing*\n");
/**
* Open a config object so we can read global values from it.
*/
sprintf(config_path, "%s/config", repo_path);
check_error(git_config_open_ondisk(&cfg, config_path), "opening config");
if (git_config_get_int32(&autocorrect, cfg, "help.autocorrect") == 0)
printf("Autocorrect: %d\n", autocorrect);
check_error(git_repository_config_snapshot(&snap_cfg, repo), "config snapshot");
git_config_get_string(&email, snap_cfg, "user.email");
printf("Email: %s\n", email);
/**
* Remember to free the configurations after usage.
*/
git_config_free(cfg);
git_config_free(snap_cfg);
}