{{ message }}
Repository navigation
Expand file tree
/
Copy pathgeneral.c
More file actions
451 lines (365 loc) · 18.3 KB
/
Copy pathgeneral.c
File metadata and controls
451 lines (365 loc) · 18.3 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
// [**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 will also want
// to check out the generated [API documentation][ap] and the [Usage Guide][ug]. We've
// tried to link to the relevant sections of the API docs in each section in this file.
//
// **libgit2** 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 9][pg] of the Pro Git book.
//
// [lg]: http://libgit2.github.com
// [ap]: http://libgit2.github.com/libgit2
// [ug]: http://libgit2.github.com/api.html
// [pg]: http://progit.org/book/ch9-0.html
// ### 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>
int main (int argc, char** argv)
{
// ### 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 are assuming they are in the normal places.
//
// [me]: http://libgit2.github.com/libgit2/#HEAD/group/repository
git_repository *repo;
if (argc > 1) {
git_repository_open(&repo, argv[1]);
} else {
git_repository_open(&repo, "/opt/libgit2-test/.git");
}
// ### SHA-1 Value Conversions
// For our first example, we will convert a 40 character hex value to the 20 byte raw SHA1 value.
printf("*Hex to Raw*\n");
char hex[] = "fd6e612585290339ea8bf39c692a7ff6a29cb7c3";
// 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 oid;
git_oid_fromstr(&oid, hex);
// Once we've converted the string into the oid value, we can get the raw value of the SHA.
printf("Raw 20 bytes: [%.20s]\n", (&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");
char out[41];
out[40] = '\0';
// 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
git_odb *odb;
git_repository_odb(&odb, repo);
// #### Raw Object Reading
printf("\n*Raw Object Read*\n");
git_odb_object *obj;
git_otype otype;
const unsigned char *data;
const char *str_type;
int error;
// 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 thier type and inspect
// the raw bytes unparsed.
error = git_odb_read(&obj, odb, &oid);
// 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\n",
(int)git_odb_object_size(obj),
str_type);
// 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(out, &oid);
printf("Written Object: %s\n", out);
// ### 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
printf("\n*Commit Parsing*\n");
git_commit *commit;
git_oid_fromstr(&oid, "f0877d0b841d75172ec404fc9370173dfffc20d1");
error = git_commit_lookup(&commit, repo, &oid);
const git_signature *author, *cmtter;
const char *message;
time_t ctime;
unsigned int parents, p;
// 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 `_message`
// which gives you the commit message.
message = git_commit_message(commit);
author = git_commit_author(commit);
cmtter = git_commit_committer(commit);
ctime = 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)\n", author->name, author->email);
// Commits can have zero or more parents. The first (root) commit will have no parents, most commits
// will have one, which is the commit it was based on, and merge commits will have two or more.
// Commits can technically have any number, though it's pretty rare to have more than two.
parents = git_commit_parentcount(commit);
for (p = 0;p < parents;p++) {
git_commit *parent;
git_commit_parent(&parent, commit, p);
git_oid_fmt(out, git_commit_id(parent));
printf("Parent: %s\n", out);
git_commit_free(parent);
}
// Don't forget to close the object to prevent memory leaks. You will have to do this for
// all the objects you open and parse.
git_commit_free(commit);
// #### 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
printf("\n*Commit Writing*\n");
git_oid tree_id, parent_id, commit_id;
git_tree *tree;
git_commit *parent;
// Creating signatures for an authoring identity and time is pretty simple - you will need to have
// this to create a commit in order to specify who created it 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((git_signature **)&author, "Scott Chacon", "schacon@gmail.com",
123456789, 60);
git_signature_new((git_signature **)&cmtter, "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, "28873d96b4e8f4e33ea30f4c682fd325f7ba56ac");
git_tree_lookup(&tree, repo, &tree_id);
git_oid_fromstr(&parent_id, "f0877d0b841d75172ec404fc9370173dfffc20d1");
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,
cmtter,
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(out, &commit_id);
printf("New Commit: %s\n", out);
// #### 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
printf("\n*Tag Parsing*\n");
git_tag *tag;
const char *tmessage, *tname;
git_otype ttype;
// We create an oid for the tag object if we know the SHA and look it up in the repository the same
// way that we would a commit (or any other) object.
git_oid_fromstr(&oid, "bc422d45275aca289c51d79830b45cecebff7c3a");
error = git_tag_lookup(&tag, repo, &oid);
// 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);
tname = git_tag_name(tag); // "test"
ttype = git_tag_target_type(tag); // GIT_OBJ_COMMIT (otype enum)
tmessage = git_tag_message(tag); // "tag message\n"
printf("Tag Message: %s\n", tmessage);
git_commit_free(commit);
// #### 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
printf("\n*Tree Parsing*\n");
const git_tree_entry *entry;
git_object *objt;
// Create the oid and lookup the tree object just like the other objects.
git_oid_fromstr(&oid, "2a741c18ac5ff082a7caaec6e74db3075a1906b5");
git_tree_lookup(&tree, repo, &oid);
// Getting the count of entries in the tree so you can iterate over them if you want to.
size_t cnt = git_tree_entrycount(tree); // 3
printf("tree entries: %d\n", (int)cnt);
entry = git_tree_entry_byindex(tree, 0);
printf("Entry name: %s\n", git_tree_entry_name(entry)); // "hello.c"
// 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, "hello.c");
git_tree_entry_name(entry); // "hello.c"
// 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(&objt, repo, entry); // blob
// Remember to close the looked-up object once you are done using it
git_object_free(objt);
// #### 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
printf("\n*Blob Parsing*\n");
git_blob *blob;
git_oid_fromstr(&oid, "af7574ea73f7b166f869ef1a39be126d9a186ae0");
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"
// ### 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
printf("\n*Revwalking*\n");
git_revwalk *walk;
git_commit *wcommit;
git_oid_fromstr(&oid, "f0877d0b841d75172ec404fc9370173dfffc20d1");
// 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);
const git_signature *cauth;
const char *cmsg;
// Now that we have the starting point pushed onto the walker, we can 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 commited 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);
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
printf("\n*Index Walking*\n");
git_index *index;
unsigned int i, ecount;
// 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
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.
git_strarray ref_list;
git_reference_list(&ref_list, repo, GIT_REF_LISTALL);
const char *refname;
git_reference *ref;
// 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.
for (i = 0; i < ref_list.count; ++i) {
refname = ref_list.strings[i];
git_reference_lookup(&ref, repo, refname);
switch (git_reference_type(ref)) {
case GIT_REF_OID:
git_oid_fmt(out, git_reference_target(ref));
printf("%s [%s]\n", refname, out);
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_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
printf("\n*Config Listing*\n");
const char *email;
int32_t j;
git_config *cfg;
// Open a config object so we can read global values from it.
git_config_open_ondisk(&cfg, "~/.gitconfig");
git_config_get_int32(&j, cfg, "help.autocorrect");
printf("Autocorrect: %d\n", j);
git_config_get_string(&email, cfg, "user.email");
printf("Email: %s\n", email);
// Finally, when you're done with the repository, you can free it as well.
git_repository_free(repo);
return 0;
}
You can’t perform that action at this time.