Merge pull request #4040 from tiennou/examples/merge

Merge example

7 files changed, 447 insertions, 36 deletions

diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index a6f26c7a6..99e2ba9c1 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -1,7 +1,7 @@
 LINK_DIRECTORIES(${LIBGIT2_LIBDIRS})
 INCLUDE_DIRECTORIES(${LIBGIT2_INCLUDES})
 
-FILE(GLOB_RECURSE SRC_EXAMPLE_GIT2 network/*.c network/*.h)
+FILE(GLOB_RECURSE SRC_EXAMPLE_GIT2 network/*.c network/*.h common.?)
 ADD_EXECUTABLE(cgit2 ${SRC_EXAMPLE_GIT2})
 IF(WIN32 OR ANDROID)
 	TARGET_LINK_LIBRARIES(cgit2 git2)
diff --git a/examples/common.c b/examples/common.c
index 96f5eaa8e..118072044 100644
--- a/examples/common.c
+++ b/examples/common.c
@@ -235,3 +235,13 @@ void treeish_to_tree(
 	git_object_free(obj);
 }
 
+void *xrealloc(void *oldp, size_t newsz)
+{
+	void *p = realloc(oldp, newsz);
+	if (p == NULL) {
+		fprintf(stderr, "Cannot allocate memory, exiting.\n");
+		exit(1);
+	}
+	return p;
+}
+
diff --git a/examples/common.h b/examples/common.h
index adea0d318..af42324c2 100644
--- a/examples/common.h
+++ b/examples/common.h
@@ -103,3 +103,8 @@ extern int diff_output(
  */
 extern void treeish_to_tree(
 	git_tree **out, git_repository *repo, const char *treeish);
+
+/**
+ * A realloc that exits on failure
+ */
+extern void *xrealloc(void *oldp, size_t newsz);
diff --git a/examples/describe.c b/examples/describe.c
index 4cdf61f75..2005de4ae 100644
--- a/examples/describe.c
+++ b/examples/describe.c
@@ -47,16 +47,6 @@ typedef struct {
 
 typedef struct args_info args_info;
 
-static void *xrealloc(void *oldp, size_t newsz)
-{
-	void *p = realloc(oldp, newsz);
-	if (p == NULL) {
-		fprintf(stderr, "Cannot allocate memory, exiting.\n");
-		exit(1);
-	}
-	return p;
-}
-
 static void opts_add_commit(describe_options *opts, const char *commit)
 {
 	size_t sz;
diff --git a/examples/merge.c b/examples/merge.c
new file mode 100644
index 000000000..59982cb9b
--- /dev/null
+++ b/examples/merge.c
@@ -0,0 +1,396 @@
+/*
+ * libgit2 "merge" example - shows how to perform merges
+ *
+ * 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/>.
+ */
+
+#include "common.h"
+#include <assert.h>
+
+#ifdef _MSC_VER
+#define snprintf sprintf_s
+#endif
+
+/** The following example demonstrates how to do merges with libgit2.
+ *
+ * It will merge whatever commit-ish you pass in into the current branch.
+ *
+ * Recognized options are :
+ *  --no-commit: don't actually commit the merge.
+ *
+ */
+
+typedef struct {
+	const char **heads;
+	size_t heads_count;
+
+	git_annotated_commit **annotated;
+	size_t annotated_count;
+
+	int no_commit : 1;
+} merge_options;
+
+static void print_usage(void)
+{
+	fprintf(stderr, "usage: merge [--no-commit] <commit...>\n");
+	exit(1);
+}
+
+static void merge_options_init(merge_options *opts)
+{
+	memset(opts, 0, sizeof(*opts));
+
+	opts->heads = NULL;
+	opts->heads_count = 0;
+	opts->annotated = NULL;
+	opts->annotated_count = 0;
+}
+
+static void opts_add_refish(merge_options *opts, const char *refish)
+{
+	size_t sz;
+
+	assert(opts != NULL);
+
+	sz = ++opts->heads_count * sizeof(opts->heads[0]);
+	opts->heads = xrealloc(opts->heads, sz);
+	opts->heads[opts->heads_count - 1] = refish;
+}
+
+static void parse_options(const char **repo_path, merge_options *opts, int argc, char **argv)
+{
+	struct args_info args = ARGS_INFO_INIT;
+
+	if (argc <= 1)
+		print_usage();
+
+	for (args.pos = 1; args.pos < argc; ++args.pos) {
+		const char *curr = argv[args.pos];
+
+		if (curr[0] != '-') {
+			opts_add_refish(opts, curr);
+		} else if (!strcmp(curr, "--no-commit")) {
+			opts->no_commit = 1;
+		} else if (match_str_arg(repo_path, &args, "--git-dir")) {
+			continue;
+		} else {
+			print_usage();
+		}
+	}
+}
+
+static int resolve_refish(git_annotated_commit **commit, git_repository *repo, const char *refish)
+{
+	git_reference *ref;
+	int err = 0;
+	git_oid oid;
+
+	assert(commit != NULL);
+
+	err = git_reference_dwim(&ref, repo, refish);
+	if (err == GIT_OK) {
+		git_annotated_commit_from_ref(commit, repo, ref);
+		git_reference_free(ref);
+		return 0;
+	}
+
+	err = git_oid_fromstr(&oid, refish);
+	if (err == GIT_OK) {
+		err = git_annotated_commit_lookup(commit, repo, &oid);
+	}
+
+	return err;
+}
+
+static int resolve_heads(git_repository *repo, merge_options *opts)
+{
+	git_annotated_commit **annotated = calloc(opts->heads_count, sizeof(git_annotated_commit *));
+	size_t annotated_count = 0, i;
+	int err = 0;
+
+	for (i = 0; i < opts->heads_count; i++) {
+		err = resolve_refish(&annotated[annotated_count++], repo, opts->heads[i]);
+		if (err != 0) {
+			fprintf(stderr, "failed to resolve refish %s: %s\n", opts->heads[i], giterr_last()->message);
+			annotated_count--;
+			continue;
+		}
+	}
+
+	if (annotated_count != opts->heads_count) {
+		fprintf(stderr, "unable to parse some refish\n");
+		free(annotated);
+		return -1;
+	}
+
+	opts->annotated = annotated;
+	opts->annotated_count = annotated_count;
+	return 0;
+}
+
+static int perform_fastforward(git_repository *repo, const git_oid *target_oid, int is_unborn)
+{
+	git_checkout_options ff_checkout_options = GIT_CHECKOUT_OPTIONS_INIT;
+	git_reference *target_ref;
+	git_reference *new_target_ref;
+	git_object *target = NULL;
+	int err = 0;
+
+	if (is_unborn) {
+		const char *symbolic_ref;
+		git_reference *head_ref;
+
+		/* HEAD reference is unborn, lookup manually so we don't try to resolve it */
+		err = git_reference_lookup(&head_ref, repo, "HEAD");
+		if (err != 0) {
+			fprintf(stderr, "failed to lookup HEAD ref\n");
+			return -1;
+		}
+
+		/* Grab the reference HEAD should be pointing to */
+		symbolic_ref = git_reference_symbolic_target(head_ref);
+
+		/* Create our master reference on the target OID */
+		err = git_reference_create(&target_ref, repo, symbolic_ref, target_oid, 0, NULL);
+		if (err != 0) {
+			fprintf(stderr, "failed to create master reference\n");
+			return -1;
+		}
+
+		git_reference_free(head_ref);
+	} else {
+		/* HEAD exists, just lookup and resolve */
+		err = git_repository_head(&target_ref, repo);
+		if (err != 0) {
+			fprintf(stderr, "failed to get HEAD reference\n");
+			return -1;
+		}
+	}
+
+	/* Lookup the target object */
+	err = git_object_lookup(&target, repo, target_oid, GIT_OBJ_COMMIT);
+	if (err != 0) {
+		fprintf(stderr, "failed to lookup OID %s\n", git_oid_tostr_s(target_oid));
+		return -1;
+	}
+
+	/* Checkout the result so the workdir is in the expected state */
+	ff_checkout_options.checkout_strategy = GIT_CHECKOUT_SAFE;
+	err = git_checkout_tree(repo, target, &ff_checkout_options);
+	if (err != 0) {
+		fprintf(stderr, "failed to checkout HEAD reference\n");
+		return -1;
+	}
+
+	/* Move the target reference to the target OID */
+	err = git_reference_set_target(&new_target_ref, target_ref, target_oid, NULL);
+	if (err != 0) {
+		fprintf(stderr, "failed to move HEAD reference\n");
+		return -1;
+	}
+
+	git_reference_free(target_ref);
+	git_reference_free(new_target_ref);
+	git_object_free(target);
+
+	return 0;
+}
+
+static void output_conflicts(git_index *index)
+{
+	git_index_conflict_iterator *conflicts;
+	const git_index_entry *ancestor;
+	const git_index_entry *our;
+	const git_index_entry *their;
+	int err = 0;
+
+	check_lg2(git_index_conflict_iterator_new(&conflicts, index), "failed to create conflict iterator", NULL);
+
+	while ((err = git_index_conflict_next(&ancestor, &our, &their, conflicts)) == 0) {
+		fprintf(stderr, "conflict: a:%s o:%s t:%s\n",
+		        ancestor ? ancestor->path : "NULL",
+		        our->path ? our->path : "NULL",
+		        their->path ? their->path : "NULL");
+	}
+
+	if (err != GIT_ITEROVER) {
+		fprintf(stderr, "error iterating conflicts\n");
+	}
+
+	git_index_conflict_iterator_free(conflicts);
+}
+
+static int create_merge_commit(git_repository *repo, git_index *index, merge_options *opts)
+{
+	git_oid tree_oid, commit_oid;
+	git_tree *tree;
+	git_signature *sign;
+	git_reference *merge_ref = NULL;
+	git_annotated_commit *merge_commit;
+	git_reference *head_ref;
+	git_commit **parents = calloc(opts->annotated_count + 1, sizeof(git_commit *));
+	const char *msg_target = NULL;
+	size_t msglen = 0;
+	char *msg;
+	size_t i;
+	int err;
+
+	/* Grab our needed references */
+	check_lg2(git_repository_head(&head_ref, repo), "failed to get repo HEAD", NULL);
+	if (resolve_refish(&merge_commit, repo, opts->heads[0])) {
+		fprintf(stderr, "failed to resolve refish %s", opts->heads[0]);
+		return -1;
+	}
+
+	/* Maybe that's a ref, so DWIM it */
+	err = git_reference_dwim(&merge_ref, repo, opts->heads[0]);
+	check_lg2(err, "failed to DWIM reference", giterr_last()->message);
+
+	/* Grab a signature */
+	check_lg2(git_signature_now(&sign, "Me", "me@example.com"), "failed to create signature", NULL);
+
+#define MERGE_COMMIT_MSG "Merge %s '%s'"
+	/* Prepare a standard merge commit message */
+	if (merge_ref != NULL) {
+		check_lg2(git_branch_name(&msg_target, merge_ref), "failed to get branch name of merged ref", NULL);
+	} else {
+		msg_target = git_oid_tostr_s(git_annotated_commit_id(merge_commit));
+	}
+
+	msglen = snprintf(NULL, 0, MERGE_COMMIT_MSG, (merge_ref ? "branch" : "commit"), msg_target);
+	if (msglen > 0) msglen++;
+	msg = malloc(msglen);
+	err = snprintf(msg, msglen, MERGE_COMMIT_MSG, (merge_ref ? "branch" : "commit"), msg_target);
+
+	/* This is only to silence the compiler */
+	if (err < 0) goto cleanup;
+
+	/* Setup our parent commits */
+	err = git_reference_peel((git_object **)&parents[0], head_ref, GIT_OBJ_COMMIT);
+	check_lg2(err, "failed to peel head reference", NULL);
+	for (i = 0; i < opts->annotated_count; i++) {
+		git_commit_lookup(&parents[i + 1], repo, git_annotated_commit_id(opts->annotated[i]));
+	}
+
+	/* Prepare our commit tree */
+	check_lg2(git_index_write_tree(&tree_oid, index), "failed to write merged tree", NULL);
+	check_lg2(git_tree_lookup(&tree, repo, &tree_oid), "failed to lookup tree", NULL);
+
+	/* Commit time ! */
+	err = git_commit_create(&commit_oid,
+	                        repo, git_reference_name(head_ref),
+	                        sign, sign,
+	                        NULL, msg,
+	                        tree,
+	                        opts->annotated_count + 1, (const git_commit **)parents);
+	check_lg2(err, "failed to create commit", NULL);
+
+	/* We're done merging, cleanup the repository state */
+	git_repository_state_cleanup(repo);
+
+cleanup:
+	free(parents);
+	return err;
+}
+
+int main(int argc, char **argv)
+{
+	git_repository *repo = NULL;
+	merge_options opts;
+	git_index *index;
+	git_repository_state_t state;
+	git_merge_analysis_t analysis;
+	git_merge_preference_t preference;
+	const char *path = ".";
+	int err = 0;
+
+	merge_options_init(&opts);
+	parse_options(&path, &opts, argc, argv);
+
+	git_libgit2_init();
+
+	check_lg2(git_repository_open_ext(&repo, path, 0, NULL),
+	          "Could not open repository", NULL);
+
+	state = git_repository_state(repo);
+	if (state != GIT_REPOSITORY_STATE_NONE) {
+		fprintf(stderr, "repository is in unexpected state %d\n", state);
+		goto cleanup;
+	}
+
+	err = resolve_heads(repo, &opts);
+	if (err != 0)
+		goto cleanup;
+
+	err = git_merge_analysis(&analysis, &preference,
+	                         repo,
+	                         (const git_annotated_commit **)opts.annotated,
+	                         opts.annotated_count);
+	check_lg2(err, "merge analysis failed", NULL);
+
+	if (analysis & GIT_MERGE_ANALYSIS_UP_TO_DATE) {
+		printf("Already up-to-date\n");
+		return 0;
+	} else if (analysis & GIT_MERGE_ANALYSIS_UNBORN ||
+	          (analysis & GIT_MERGE_ANALYSIS_FASTFORWARD &&
+	          !(preference & GIT_MERGE_PREFERENCE_NO_FASTFORWARD))) {
+		const git_oid *target_oid;
+		if (analysis & GIT_MERGE_ANALYSIS_UNBORN) {
+			printf("Unborn\n");
+		} else {
+			printf("Fast-forward\n");
+		}
+
+		/* Since this is a fast-forward, there can be only one merge head */
+		target_oid = git_annotated_commit_id(opts.annotated[0]);
+		assert(opts.annotated_count == 1);
+
+		return perform_fastforward(repo, target_oid, (analysis & GIT_MERGE_ANALYSIS_UNBORN));
+	} else if (analysis & GIT_MERGE_ANALYSIS_NORMAL) {
+		git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
+		git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
+
+		merge_opts.flags = 0;
+		merge_opts.file_flags = GIT_MERGE_FILE_STYLE_DIFF3;
+
+		checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE|GIT_CHECKOUT_ALLOW_CONFLICTS;
+
+		if (preference & GIT_MERGE_PREFERENCE_FASTFORWARD_ONLY) {
+			printf("Fast-forward is preferred, but only a merge is possible\n");
+			return -1;
+		}
+
+		err = git_merge(repo,
+		                (const git_annotated_commit **)opts.annotated, opts.annotated_count,
+		                &merge_opts, &checkout_opts);
+		check_lg2(err, "merge failed", NULL);
+	}
+
+	/* If we get here, we actually performed the merge above */
+
+	check_lg2(git_repository_index(&index, repo), "failed to get repository index", NULL);
+
+	if (git_index_has_conflicts(index)) {
+		/* Handle conflicts */
+		output_conflicts(index);
+	} else if (!opts.no_commit) {
+		create_merge_commit(repo, index, &opts);
+		printf("Merge made\n");
+	}
+
+cleanup:
+	free(opts.heads);
+	free(opts.annotated);
+	git_repository_free(repo);
+	git_libgit2_shutdown();
+
+	return 0;
+}
diff --git a/examples/network/fetch.c b/examples/network/fetch.c
index 10974a9f1..76b301193 100644
--- a/examples/network/fetch.c
+++ b/examples/network/fetch.c
@@ -8,13 +8,6 @@
 # include <unistd.h>
 #endif
 
-struct dl_data {
-	git_remote *remote;
-	git_fetch_options *fetch_opts;
-	int ret;
-	int finished;
-};
-
 static int progress_cb(const char *str, int len, void *data)
 {
 	(void)data;
diff --git a/examples/network/git2.c b/examples/network/git2.c
index 448103c46..1d3d27b1b 100644
--- a/examples/network/git2.c
+++ b/examples/network/git2.c
@@ -2,10 +2,11 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "../common.h"
 #include "common.h"
 
-// This part is not strictly libgit2-dependent, but you can use this
-// as a starting point for a git-like tool
+/* This part is not strictly libgit2-dependent, but you can use this
+ * as a starting point for a git-like tool */
 
 struct {
 	char *name;
@@ -18,20 +19,12 @@ struct {
 	{ NULL, NULL}
 };
 
-static int run_command(git_cb fn, int argc, char **argv)
+static int run_command(git_cb fn, git_repository *repo, struct args_info args)
 {
 	int error;
-	git_repository *repo;
-
-	// Before running the actual command, create an instance of the local
-	// repository and pass it to the function.
-
-	error = git_repository_open(&repo, ".git");
-	if (error < 0)
-		repo = NULL;
 
-	// Run the command. If something goes wrong, print the error message to stderr
-	error = fn(repo, argc, argv);
+	/* Run the command. If something goes wrong, print the error message to stderr */
+	error = fn(repo, args.argc - args.pos, &args.argv[args.pos]);
 	if (error < 0) {
 		if (giterr_last() == NULL)
 			fprintf(stderr, "Error without message");
@@ -39,9 +32,6 @@ static int run_command(git_cb fn, int argc, char **argv)
 			fprintf(stderr, "Bad news:\n %s\n", giterr_last()->message);
 	}
 
-	if(repo)
-		git_repository_free(repo);
-
 	return !!error;
 }
 
@@ -49,6 +39,10 @@ int main(int argc, char **argv)
 {
 	int i;
 	int return_code = 1;
+	int error;
+	git_repository *repo;
+	struct args_info args = ARGS_INFO_INIT;
+	const char *git_dir = NULL;
 
 	if (argc < 2) {
 		fprintf(stderr, "usage: %s <cmd> [repo]\n", argv[0]);
@@ -57,9 +51,30 @@ int main(int argc, char **argv)
 
 	git_libgit2_init();
 
+	for (args.pos = 1; args.pos < args.argc; ++args.pos) {
+		char *a = args.argv[args.pos];
+
+		if (a[0] != '-') {
+			/* non-arg */
+			break;
+		} else if (optional_str_arg(&git_dir, &args, "--git-dir", ".git")) {
+			continue;
+		} else if (!strcmp(a, "--")) {
+			/* arg separator */
+			break;
+		}
+	}
+
+	/* Before running the actual command, create an instance of the local
+	 * repository and pass it to the function. */
+
+	error = git_repository_open(&repo, git_dir);
+	if (error < 0)
+		repo = NULL;
+
 	for (i = 0; commands[i].name != NULL; ++i) {
-		if (!strcmp(argv[1], commands[i].name)) {
-			return_code = run_command(commands[i].fn, --argc, ++argv);
+		if (!strcmp(args.argv[args.pos], commands[i].name)) {
+			return_code = run_command(commands[i].fn, repo, args);
 			goto shutdown;
 		}
 	}
@@ -67,6 +82,8 @@ int main(int argc, char **argv)
 	fprintf(stderr, "Command not found: %s\n", argv[1]);
 
 shutdown:
+	git_repository_free(repo);
+
 	git_libgit2_shutdown();
 
 	return return_code;