commit-graph: create git-commit-graph builtin

Teach git the 'commit-graph' builtin that will be used for writing and
reading packed graph files. The current implementation is mostly
empty, except for an '--object-dir' option.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

8 files changed, 53 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 833ef3b0b7..e82f90184d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -34,6 +34,7 @@
 /git-clone
 /git-column
 /git-commit
+/git-commit-graph
 /git-commit-tree
 /git-config
 /git-count-objects
diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
new file mode 100644
index 0000000000..f3b34622a8
--- /dev/null
+++ b/Documentation/git-commit-graph.txt
@@ -0,0 +1,10 @@
+git-commit-graph(1)
+===================
+
+NAME
+----
+git-commit-graph - Write and verify Git commit graph files
+
+GIT
+---
+Part of the linkgit:git[1] suite
diff --git a/Makefile b/Makefile
index c56fdc14ca..2e4956f0a3 100644
--- a/Makefile
+++ b/Makefile
@@ -946,6 +946,7 @@ BUILTIN_OBJS += builtin/clone.o
 BUILTIN_OBJS += builtin/column.o
 BUILTIN_OBJS += builtin/commit-tree.o
 BUILTIN_OBJS += builtin/commit.o
+BUILTIN_OBJS += builtin/commit-graph.o
 BUILTIN_OBJS += builtin/config.o
 BUILTIN_OBJS += builtin/count-objects.o
 BUILTIN_OBJS += builtin/credential.o
diff --git a/builtin.h b/builtin.h
index 42378f3aa4..079855b6d4 100644
--- a/builtin.h
+++ b/builtin.h
@@ -149,6 +149,7 @@ extern int cmd_clone(int argc, const char **argv, const char *prefix);
 extern int cmd_clean(int argc, const char **argv, const char *prefix);
 extern int cmd_column(int argc, const char **argv, const char *prefix);
 extern int cmd_commit(int argc, const char **argv, const char *prefix);
+extern int cmd_commit_graph(int argc, const char **argv, const char *prefix);
 extern int cmd_commit_tree(int argc, const char **argv, const char *prefix);
 extern int cmd_config(int argc, const char **argv, const char *prefix);
 extern int cmd_count_objects(int argc, const char **argv, const char *prefix);
diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
new file mode 100644
index 0000000000..b466ecd781
--- /dev/null
+++ b/builtin/commit-graph.c
@@ -0,0 +1,36 @@
+#include "builtin.h"
+#include "config.h"
+#include "parse-options.h"
+
+static char const * const builtin_commit_graph_usage[] = {
+	N_("git commit-graph [--object-dir <objdir>]"),
+	NULL
+};
+
+static struct opts_commit_graph {
+	const char *obj_dir;
+} opts;
+
+
+int cmd_commit_graph(int argc, const char **argv, const char *prefix)
+{
+	static struct option builtin_commit_graph_options[] = {
+		OPT_STRING(0, "object-dir", &opts.obj_dir,
+			N_("dir"),
+			N_("The object directory to store the graph")),
+		OPT_END(),
+	};
+
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage_with_options(builtin_commit_graph_usage,
+				   builtin_commit_graph_options);
+
+	git_config(git_default_config, NULL);
+	argc = parse_options(argc, argv, prefix,
+			     builtin_commit_graph_options,
+			     builtin_commit_graph_usage,
+			     PARSE_OPT_STOP_AT_NON_OPTION);
+
+	usage_with_options(builtin_commit_graph_usage,
+			   builtin_commit_graph_options);
+}
diff --git a/command-list.txt b/command-list.txt
index a1fad28fd8..835c5890be 100644
--- a/command-list.txt
+++ b/command-list.txt
@@ -34,6 +34,7 @@ git-clean                               mainporcelain
 git-clone                               mainporcelain           init
 git-column                              purehelpers
 git-commit                              mainporcelain           history
+git-commit-graph                        plumbingmanipulators
 git-commit-tree                         plumbingmanipulators
 git-config                              ancillarymanipulators
 git-count-objects                       ancillaryinterrogators
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 88813e9124..b060b6ff6e 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -841,6 +841,7 @@ __git_list_porcelain_commands ()
 		check-ref-format) : plumbing;;
 		checkout-index)   : plumbing;;
 		column)           : internal helper;;
+		commit-graph)     : plumbing;;
 		commit-tree)      : plumbing;;
 		count-objects)    : infrequent;;
 		credential)       : credentials;;
@@ -2419,6 +2420,7 @@ _git_config ()
 		core.bigFileThreshold
 		core.checkStat
 		core.commentChar
+		core.commitGraph
 		core.compression
 		core.createObject
 		core.deltaBaseCacheLimit
diff --git a/git.c b/git.c
index c870b9719c..c7b5adae7b 100644
--- a/git.c
+++ b/git.c
@@ -388,6 +388,7 @@ static struct cmd_struct commands[] = {
 	{ "clone", cmd_clone },
 	{ "column", cmd_column, RUN_SETUP_GENTLY },
 	{ "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
+	{ "commit-graph", cmd_commit_graph, RUN_SETUP },
 	{ "commit-tree", cmd_commit_tree, RUN_SETUP },
 	{ "config", cmd_config, RUN_SETUP_GENTLY },
 	{ "count-objects", cmd_count_objects, RUN_SETUP },