thodg/libgit2

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 90ecc92..763bd43 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,6 +18,7 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PROJECT_SOURCE_DIR}/cmake")
 # Optional subsystems
 option(BUILD_SHARED_LIBS       "Build Shared Library (OFF for Static)"                  ON)
 option(BUILD_TESTS             "Build Tests using the Clar suite"                       ON)
+option(BUILD_CLI               "Build the command-line interface"                       ON)
 option(BUILD_EXAMPLES          "Build library usage example apps"                      OFF)
 option(BUILD_FUZZERS           "Build the fuzz targets"                                OFF)
 
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 8b0d7f4..72ec410 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -178,6 +178,10 @@ configure_file(features.h.in git2/sys/features.h)
 add_subdirectory(libgit2)
 add_subdirectory(util)
 
+if(BUILD_CLI)
+	add_subdirectory(cli)
+endif()
+
 # re-export these to the root so that peer projects (tests, fuzzers,
 # examples) can use them
 set(LIBGIT2_INCLUDES ${LIBGIT2_INCLUDES} PARENT_SCOPE)
diff --git a/src/README.md b/src/README.md
index 12e0d0e..10b86c1 100644
--- a/src/README.md
+++ b/src/README.md
@@ -3,6 +3,8 @@
 This is the source that makes up the core of libgit2 and its related
 projects.
 
+* `cli`  
+  A git-compatible command-line interface that uses libgit2.
 * `libgit2`  
   This is the libgit2 project, a cross-platform, linkable library
   implementation of Git that you can use in your application.
diff --git a/src/cli/CMakeLists.txt b/src/cli/CMakeLists.txt
new file mode 100644
index 0000000..4f347e9
--- /dev/null
+++ b/src/cli/CMakeLists.txt
@@ -0,0 +1,53 @@
+set(CLI_INCLUDES
+	"${libgit2_BINARY_DIR}/src"
+	"${libgit2_SOURCE_DIR}/src/util"
+	"${libgit2_SOURCE_DIR}/src/cli"
+	"${libgit2_SOURCE_DIR}/include")
+
+if(WIN32 AND NOT CYGWIN)
+	file(GLOB CLI_SRC_OS win32/*.c)
+	list(SORT CLI_SRC_OS)
+else()
+	file(GLOB CLI_SRC_OS unix/*.c)
+	list(SORT CLI_SRC_OS)
+endif()
+
+file(GLOB CLI_SRC_C *.c *.h)
+list(SORT CLI_SRC_C)
+
+#
+# The CLI currently needs to be statically linked against libgit2 because
+# the utility library uses libgit2's thread-local error buffers.  TODO:
+# remove this dependency and allow us to dynamically link against libgit2.
+#
+
+if(BUILD_CLI STREQUAL "dynamic")
+	set(CLI_LIBGIT2_LIBRARY libgit2package)
+else()
+	set(CLI_LIBGIT2_OBJECTS $<TARGET_OBJECTS:libgit2>)
+endif()
+
+#
+# Compile and link the CLI
+#
+
+add_executable(git2_cli ${CLI_SRC_C} ${CLI_SRC_OS} ${CLI_OBJECTS}
+	$<TARGET_OBJECTS:util>
+	${CLI_LIBGIT2_OBJECTS}
+	${LIBGIT2_DEPENDENCY_OBJECTS})
+target_link_libraries(git2_cli ${CLI_LIBGIT2_LIBRARY} ${LIBGIT2_SYSTEM_LIBS})
+
+set_target_properties(git2_cli PROPERTIES C_STANDARD 90)
+set_target_properties(git2_cli PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${libgit2_BINARY_DIR})
+
+ide_split_sources(git2_cli)
+
+target_include_directories(git2_cli PRIVATE ${CLI_INCLUDES})
+
+if(MSVC_IDE)
+	# Precompiled headers
+	set_target_properties(git2_cli PROPERTIES COMPILE_FLAGS "/Yuprecompiled.h /FIprecompiled.h")
+	set_source_files_properties(win32/precompiled.c COMPILE_FLAGS "/Ycprecompiled.h")
+endif()
+
+install(TARGETS git2_cli RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
diff --git a/src/cli/README.md b/src/cli/README.md
new file mode 100644
index 0000000..eefd2ff
--- /dev/null
+++ b/src/cli/README.md
@@ -0,0 +1,3 @@
+# cli
+
+A git-compatible command-line interface that uses libgit2.
diff --git a/src/cli/cli.h b/src/cli/cli.h
new file mode 100644
index 0000000..a27081d
--- /dev/null
+++ b/src/cli/cli.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#ifndef CLI_cli_h__
+#define CLI_cli_h__
+
+#define PROGRAM_NAME "git2"
+
+#include "git2_util.h"
+
+#include "error.h"
+#include "opt.h"
+
+#endif /* CLI_cli_h__ */
diff --git a/src/cli/error.h b/src/cli/error.h
new file mode 100644
index 0000000..cce7a54
--- /dev/null
+++ b/src/cli/error.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#ifndef CLI_error_h__
+#define CLI_error_h__
+
+#include "cli.h"
+#include <stdio.h>
+
+#define CLI_EXIT_OK      0
+#define CLI_EXIT_ERROR   1
+#define CLI_EXIT_OS    128
+#define CLI_EXIT_GIT   128
+#define CLI_EXIT_USAGE 129
+
+#define cli_error__print(fmt) do { \
+		va_list ap; \
+		va_start(ap, fmt); \
+		fprintf(stderr, "%s: ", PROGRAM_NAME); \
+		vfprintf(stderr, fmt, ap); \
+		fprintf(stderr, "\n"); \
+		va_end(ap); \
+	} while(0)
+
+GIT_INLINE(int) cli_error(const char *fmt, ...)
+{
+	cli_error__print(fmt);
+	return CLI_EXIT_ERROR;
+}
+
+GIT_INLINE(int) cli_error_usage(const char *fmt, ...)
+{
+	cli_error__print(fmt);
+	return CLI_EXIT_USAGE;
+}
+
+GIT_INLINE(int) cli_error_git(void)
+{
+	const git_error *err = git_error_last();
+	fprintf(stderr, "%s: %s\n", PROGRAM_NAME,
+	        err ? err->message : "unknown error");
+	return CLI_EXIT_GIT;
+}
+
+#define cli_error_os() (perror(PROGRAM_NAME), CLI_EXIT_OS)
+
+#endif /* CLI_error_h__ */
diff --git a/src/cli/main.c b/src/cli/main.c
new file mode 100644
index 0000000..709f6b4
--- /dev/null
+++ b/src/cli/main.c
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include <stdio.h>
+#include <git2.h>
+#include "cli.h"
+
+static int show_version = 0;
+
+static const cli_opt_spec common_opts[] = {
+	{ CLI_OPT_TYPE_SWITCH,  "version",   0, &show_version, 1,
+	  CLI_OPT_USAGE_DEFAULT, NULL,      "display the version" },
+	{ 0 }
+};
+
+int main(int argc, char **argv)
+{
+	cli_opt_parser optparser;
+	cli_opt opt;
+	int ret = 0;
+
+	if (git_libgit2_init() < 0) {
+		cli_error("failed to initialize libgit2");
+		exit(CLI_EXIT_GIT);
+	}
+
+	cli_opt_parser_init(&optparser, common_opts, argv + 1, argc - 1, CLI_OPT_PARSE_GNU);
+
+	/* Parse the top-level (common) options and command information */
+	while (cli_opt_parser_next(&opt, &optparser)) {
+		if (!opt.spec) {
+			cli_opt_status_fprint(stderr, PROGRAM_NAME, &opt);
+			cli_opt_usage_fprint(stderr, PROGRAM_NAME, common_opts);
+			ret = CLI_EXIT_USAGE;
+			goto done;
+		}
+	}
+
+	if (show_version) {
+		printf("%s version %s\n", PROGRAM_NAME, LIBGIT2_VERSION);
+		goto done;
+	}
+
+done:
+	git_libgit2_shutdown();
+	return ret;
+}
diff --git a/src/cli/opt.c b/src/cli/opt.c
new file mode 100644
index 0000000..11faa92
--- /dev/null
+++ b/src/cli/opt.c
@@ -0,0 +1,750 @@
+/*
+ * Copyright (c), Edward Thomson <ethomson@edwardthomson.com>
+ * All rights reserved.
+ *
+ * This file is part of adopt, distributed under the MIT license.
+ * For full terms and conditions, see the included LICENSE file.
+ *
+ * THIS FILE IS AUTOMATICALLY GENERATED; DO NOT EDIT.
+ *
+ * This file was produced by using the `rename.pl` script included with
+ * adopt.  The command-line specified was:
+ *
+ * ./rename.pl cli_opt --filename=opt --include=cli.h --inline=GIT_INLINE --header-guard=CLI_opt_h__ --lowercase-status
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <limits.h>
+#include <assert.h>
+
+#include "cli.h"
+#include "opt.h"
+
+#ifdef _WIN32
+# include <Windows.h>
+#else
+# include <fcntl.h>
+# include <sys/ioctl.h>
+#endif
+
+#ifdef _MSC_VER
+# define alloca _alloca
+#endif
+
+#define spec_is_option_type(x) \
+	((x)->type == CLI_OPT_TYPE_BOOL || \
+	 (x)->type == CLI_OPT_TYPE_SWITCH || \
+	 (x)->type == CLI_OPT_TYPE_VALUE)
+
+GIT_INLINE(const cli_opt_spec *) spec_for_long(
+	int *is_negated,
+	int *has_value,
+	const char **value,
+	const cli_opt_parser *parser,
+	const char *arg)
+{
+	const cli_opt_spec *spec;
+	char *eql;
+	size_t eql_pos;
+
+	eql = strchr(arg, '=');
+	eql_pos = (eql = strchr(arg, '=')) ? (size_t)(eql - arg) : strlen(arg);
+
+	for (spec = parser->specs; spec->type; ++spec) {
+		/* Handle -- (everything after this is literal) */
+		if (spec->type == CLI_OPT_TYPE_LITERAL && arg[0] == '\0')
+			return spec;
+
+		/* Handle --no-option arguments for bool types */
+		if (spec->type == CLI_OPT_TYPE_BOOL &&
+		    strncmp(arg, "no-", 3) == 0 &&
+		    strcmp(arg + 3, spec->name) == 0) {
+			*is_negated = 1;
+			return spec;
+		}
+
+		/* Handle the typical --option arguments */
+		if (spec_is_option_type(spec) &&
+		    spec->name &&
+		    strcmp(arg, spec->name) == 0)
+			return spec;
+
+		/* Handle --option=value arguments */
+		if (spec->type == CLI_OPT_TYPE_VALUE &&
+		    eql &&
+		    strncmp(arg, spec->name, eql_pos) == 0 &&
+		    spec->name[eql_pos] == '\0') {
+			*has_value = 1;
+			*value = arg[eql_pos + 1] ? &arg[eql_pos + 1] : NULL;
+			return spec;
+		}
+	}
+
+	return NULL;
+}
+
+GIT_INLINE(const cli_opt_spec *) spec_for_short(
+	const char **value,
+	const cli_opt_parser *parser,
+	const char *arg)
+{
+	const cli_opt_spec *spec;
+
+	for (spec = parser->specs; spec->type; ++spec) {
+		/* Handle -svalue short options with a value */
+		if (spec->type == CLI_OPT_TYPE_VALUE &&
+		    arg[0] == spec->alias &&
+		    arg[1] != '\0') {
+			*value = &arg[1];
+			return spec;
+		}
+
+		/* Handle typical -s short options */
+		if (arg[0] == spec->alias) {
+			*value = NULL;
+			return spec;
+		}
+	}
+
+	return NULL;
+}
+
+GIT_INLINE(const cli_opt_spec *) spec_for_arg(cli_opt_parser *parser)
+{
+	const cli_opt_spec *spec;
+	size_t args = 0;
+
+	for (spec = parser->specs; spec->type; ++spec) {
+		if (spec->type == CLI_OPT_TYPE_ARG) {
+			if (args == parser->arg_idx) {
+				parser->arg_idx++;
+				return spec;
+			}
+
+			args++;
+		}
+
+		if (spec->type == CLI_OPT_TYPE_ARGS && args == parser->arg_idx)
+			return spec;
+	}
+
+	return NULL;
+}
+
+GIT_INLINE(int) spec_is_choice(const cli_opt_spec *spec)
+{
+	return ((spec + 1)->type &&
+	       ((spec + 1)->usage & CLI_OPT_USAGE_CHOICE));
+}
+
+/*
+ * If we have a choice with switches and bare arguments, and we see
+ * the switch, then we no longer expect the bare argument.
+ */
+GIT_INLINE(void) consume_choices(const cli_opt_spec *spec, cli_opt_parser *parser)
+{
+	/* back up to the beginning of the choices */
+	while (spec->type && (spec->usage & CLI_OPT_USAGE_CHOICE))
+		--spec;
+
+	if (!spec_is_choice(spec))
+		return;
+
+	do {
+		if (spec->type == CLI_OPT_TYPE_ARG)
+			parser->arg_idx++;
+		++spec;
+	} while(spec->type && (spec->usage & CLI_OPT_USAGE_CHOICE));
+}
+
+static cli_opt_status_t parse_long(cli_opt *opt, cli_opt_parser *parser)
+{
+	const cli_opt_spec *spec;
+	char *arg = parser->args[parser->idx++];
+	const char *value = NULL;
+	int is_negated = 0, has_value = 0;
+
+	opt->arg = arg;
+
+	if ((spec = spec_for_long(&is_negated, &has_value, &value, parser, &arg[2])) == NULL) {
+		opt->spec = NULL;
+		opt->status = CLI_OPT_STATUS_UNKNOWN_OPTION;
+		goto done;
+	}
+
+	opt->spec = spec;
+
+	/* Future options parsed as literal */
+	if (spec->type == CLI_OPT_TYPE_LITERAL)
+		parser->in_literal = 1;
+
+	/* --bool or --no-bool */
+	else if (spec->type == CLI_OPT_TYPE_BOOL && spec->value)
+		*((int *)spec->value) = !is_negated;
+
+	/* --accumulate */
+	else if (spec->type == CLI_OPT_TYPE_ACCUMULATOR && spec->value)
+		*((int *)spec->value) += spec->switch_value ? spec->switch_value : 1;
+
+	/* --switch */
+	else if (spec->type == CLI_OPT_TYPE_SWITCH && spec->value)
+		*((int *)spec->value) = spec->switch_value;
+
+	/* Parse values as "--foo=bar" or "--foo bar" */
+	else if (spec->type == CLI_OPT_TYPE_VALUE) {
+		if (has_value)
+			opt->value = (char *)value;
+		else if ((parser->idx + 1) <= parser->args_len)
+			opt->value = parser->args[parser->idx++];
+
+		if (spec->value)
+			*((char **)spec->value) = opt->value;
+	}
+
+	/* Required argument was not provided */
+	if (spec->type == CLI_OPT_TYPE_VALUE &&
+	    !opt->value &&
+	    !(spec->usage & CLI_OPT_USAGE_VALUE_OPTIONAL))
+		opt->status = CLI_OPT_STATUS_MISSING_VALUE;
+	else
+		opt->status = CLI_OPT_STATUS_OK;
+
+	consume_choices(opt->spec, parser);
+
+done:
+	return opt->status;
+}
+
+static cli_opt_status_t parse_short(cli_opt *opt, cli_opt_parser *parser)
+{
+	const cli_opt_spec *spec;
+	char *arg = parser->args[parser->idx++];
+	const char *value;
+
+	opt->arg = arg;
+
+	if ((spec = spec_for_short(&value, parser, &arg[1 + parser->in_short])) == NULL) {
+		opt->spec = NULL;
+		opt->status = CLI_OPT_STATUS_UNKNOWN_OPTION;
+		goto done;
+	}
+
+	opt->spec = spec;
+
+	if (spec->type == CLI_OPT_TYPE_BOOL && spec->value)
+		*((int *)spec->value) = 1;
+
+	else if (spec->type == CLI_OPT_TYPE_ACCUMULATOR && spec->value)
+		*((int *)spec->value) += spec->switch_value ? spec->switch_value : 1;
+
+	else if (spec->type == CLI_OPT_TYPE_SWITCH && spec->value)
+		*((int *)spec->value) = spec->switch_value;
+
+	/* Parse values as "-ifoo" or "-i foo" */
+	else if (spec->type == CLI_OPT_TYPE_VALUE) {
+		if (value)
+			opt->value = (char *)value;
+		else if ((parser->idx + 1) <= parser->args_len)
+			opt->value = parser->args[parser->idx++];
+
+		if (spec->value)
+			*((char **)spec->value) = opt->value;
+	}
+
+	/*
+	 * Handle compressed short arguments, like "-fbcd"; see if there's
+	 * another character after the one we processed.  If not, advance
+	 * the parser index.
+	 */
+	if (spec->type != CLI_OPT_TYPE_VALUE && arg[2 + parser->in_short] != '\0') {
+		parser->in_short++;
+		parser->idx--;
+	} else {
+		parser->in_short = 0;
+	}
+
+	/* Required argument was not provided */
+	if (spec->type == CLI_OPT_TYPE_VALUE && !opt->value)
+		opt->status = CLI_OPT_STATUS_MISSING_VALUE;
+	else
+		opt->status = CLI_OPT_STATUS_OK;
+
+	consume_choices(opt->spec, parser);
+
+done:
+	return opt->status;
+}
+
+static cli_opt_status_t parse_arg(cli_opt *opt, cli_opt_parser *parser)
+{
+	const cli_opt_spec *spec = spec_for_arg(parser);
+
+	opt->spec = spec;
+	opt->arg = parser->args[parser->idx];
+
+	if (!spec) {
+		parser->idx++;
+		opt->status = CLI_OPT_STATUS_UNKNOWN_OPTION;
+	} else if (spec->type == CLI_OPT_TYPE_ARGS) {
+		if (spec->value)
+			*((char ***)spec->value) = &parser->args[parser->idx];
+
+		/*
+		 * We have started a list of arguments; the remainder of
+		 * given arguments need not be examined.
+		 */
+		parser->in_args = (parser->args_len - parser->idx);
+		parser->idx = parser->args_len;
+		opt->args_len = parser->in_args;
+		opt->status = CLI_OPT_STATUS_OK;
+	} else {
+		if (spec->value)
+			*((char **)spec->value) = parser->args[parser->idx];
+
+		parser->idx++;
+		opt->status = CLI_OPT_STATUS_OK;
+	}
+
+	return opt->status;
+}
+
+static int support_gnu_style(unsigned int flags)
+{
+	if ((flags & CLI_OPT_PARSE_FORCE_GNU) != 0)
+		return 1;
+
+	if ((flags & CLI_OPT_PARSE_GNU) == 0)
+		return 0;
+
+	/* TODO: Windows */
+#if defined(_WIN32) && defined(UNICODE)
+	if (_wgetenv(L"POSIXLY_CORRECT") != NULL)
+		return 0;
+#else
+	if (getenv("POSIXLY_CORRECT") != NULL)
+		return 0;
+#endif
+
+	return 1;
+}
+
+void cli_opt_parser_init(
+	cli_opt_parser *parser,
+	const cli_opt_spec specs[],
+	char **args,
+	size_t args_len,
+	unsigned int flags)
+{
+	assert(parser);
+
+	memset(parser, 0x0, sizeof(cli_opt_parser));
+
+	parser->specs = specs;
+	parser->args = args;
+	parser->args_len = args_len;
+	parser->flags = flags;
+
+	parser->needs_sort = support_gnu_style(flags);
+}
+
+GIT_INLINE(const cli_opt_spec *) spec_for_sort(
+	int *needs_value,
+	const cli_opt_parser *parser,
+	const char *arg)
+{
+	int is_negated, has_value = 0;
+	const char *value;
+	const cli_opt_spec *spec = NULL;
+	size_t idx = 0;
+
+	*needs_value = 0;
+
+	if (strncmp(arg, "--", 2) == 0) {
+		spec = spec_for_long(&is_negated, &has_value, &value, parser, &arg[2]);
+		*needs_value = !has_value;
+	}
+
+	else if (strncmp(arg, "-", 1) == 0) {
+		spec = spec_for_short(&value, parser, &arg[1]);
+
+		/*
+		 * Advance through compressed short arguments to see if
+		 * the last one has a value, eg "-xvffilename".
+		 */
+		while (spec && !value && arg[1 + ++idx] != '\0')
+			spec = spec_for_short(&value, parser, &arg[1 + idx]);
+
+		*needs_value = (value == NULL);
+	}
+
+	return spec;
+}
+
+/*
+ * Some parsers allow for handling arguments like "file1 --help file2";
+ * this is done by re-sorting the arguments in-place; emulate that.
+ */
+static int sort_gnu_style(cli_opt_parser *parser)
+{
+	size_t i, j, insert_idx = parser->idx, offset;
+	const cli_opt_spec *spec;
+	char *option, *value;
+	int needs_value, changed = 0;
+
+	parser->needs_sort = 0;
+
+	for (i = parser->idx; i < parser->args_len; i++) {
+		spec = spec_for_sort(&needs_value, parser, parser->args[i]);
+
+		/* Not a "-" or "--" prefixed option.  No change. */
+		if (!spec)
+			continue;
+
+		/* A "--" alone means remaining args are literal. */
+		if (spec->type == CLI_OPT_TYPE_LITERAL)
+			break;
+
+		option = parser->args[i];
+
+		/*
+		 * If the argument is a value type and doesn't already
+		 * have a value (eg "--foo=bar" or "-fbar") then we need
+		 * to copy the next argument as its value.
+		 */
+		if (spec->type == CLI_OPT_TYPE_VALUE && needs_value) {
+			/*
+			 * A required value is not provided; set parser
+			 * index to this value so that we fail on it.
+			 */
+			if (i + 1 >= parser->args_len) {
+				parser->idx = i;
+				return 1;
+			}
+
+			value = parser->args[i + 1];
+			offset = 1;
+		} else {
+			value = NULL;
+			offset = 0;
+		}
+
+		/* Caller error if args[0] is an option. */
+		if (i == 0)
+			return 0;
+
+		/* Shift args up one (or two) and insert the option */
+		for (j = i; j > insert_idx; j--)
+			parser->args[j + offset] = parser->args[j - 1];
+
+		parser->args[insert_idx] = option;
+
+		if (value)
+			parser->args[insert_idx + 1] = value;
+
+		insert_idx += (1 + offset);
+		i += offset;
+
+		changed = 1;
+	}
+
+	return changed;
+}
+
+cli_opt_status_t cli_opt_parser_next(cli_opt *opt, cli_opt_parser *parser)
+{
+	assert(opt && parser);
+
+	memset(opt, 0x0, sizeof(cli_opt));
+
+	if (parser->idx >= parser->args_len) {
+		opt->args_len = parser->in_args;
+		return CLI_OPT_STATUS_DONE;
+	}
+
+	/* Handle options in long form, those beginning with "--" */
+	if (strncmp(parser->args[parser->idx], "--", 2) == 0 &&
+	    !parser->in_short &&
+	    !parser->in_literal)
+		return parse_long(opt, parser);
+
+	/* Handle options in short form, those beginning with "-" */
+	else if (parser->in_short ||
+	         (strncmp(parser->args[parser->idx], "-", 1) == 0 &&
+		  !parser->in_literal))
+		return parse_short(opt, parser);
+
+	/*
+	 * We've reached the first "bare" argument.  In POSIX mode, all
+	 * remaining items on the command line are arguments.  In GNU
+	 * mode, there may be long or short options after this.  Sort any
+	 * options up to this position then re-parse the current position.
+	 */
+	if (parser->needs_sort && sort_gnu_style(parser))
+		return cli_opt_parser_next(opt, parser);
+
+	return parse_arg(opt, parser);
+}
+
+GIT_INLINE(int) spec_included(const cli_opt_spec **specs, const cli_opt_spec *spec)
+{
+	const cli_opt_spec **i;
+
+	for (i = specs; *i; ++i) {
+		if (spec == *i)
+			return 1;
+	}
+
+	return 0;
+}
+
+static cli_opt_status_t validate_required(
+	cli_opt *opt,
+	const cli_opt_spec specs[],
+	const cli_opt_spec **given_specs)
+{
+	const cli_opt_spec *spec, *required;
+	int given;
+
+	/*
+	 * Iterate over the possible specs to identify requirements and
+	 * ensure that those have been given on the command-line.
+	 * Note that we can have required *choices*, where one in a
+	 * list of choices must be specified.
+	 */
+	for (spec = specs, required = NULL, given = 0; spec->type; ++spec) {
+		if (!required && (spec->usage & CLI_OPT_USAGE_REQUIRED)) {
+			required = spec;
+			given = 0;
+		} else if (!required) {
+			continue;
+		}
+
+		if (!given)
+			given = spec_included(given_specs, spec);
+
+		/*
+		 * Validate the requirement unless we're in a required
+		 * choice.  In that case, keep the required state and
+		 * validate at the end of the choice list.
+		 */
+		if (!spec_is_choice(spec)) {
+			if (!given) {
+				opt->spec = required;
+				opt->status = CLI_OPT_STATUS_MISSING_ARGUMENT;
+				break;
+			}
+
+			required = NULL;
+			given = 0;
+		}
+	}
+
+	return opt->status;
+}
+
+cli_opt_status_t cli_opt_parse(
+	cli_opt *opt,
+	const cli_opt_spec specs[],
+	char **args,
+	size_t args_len,
+	unsigned int flags)
+{
+	cli_opt_parser parser;
+	const cli_opt_spec **given_specs;
+	size_t given_idx = 0;
+
+	cli_opt_parser_init(&parser, specs, args, args_len, flags);
+
+	given_specs = alloca(sizeof(const cli_opt_spec *) * (args_len + 1));
+
+	while (cli_opt_parser_next(opt, &parser)) {
+		if (opt->status != CLI_OPT_STATUS_OK &&
+		    opt->status != CLI_OPT_STATUS_DONE)
+			return opt->status;
+
+		if ((opt->spec->usage & CLI_OPT_USAGE_STOP_PARSING))
+			return (opt->status = CLI_OPT_STATUS_DONE);
+
+		given_specs[given_idx++] = opt->spec;
+	}
+
+	given_specs[given_idx] = NULL;
+
+	return validate_required(opt, specs, given_specs);
+}
+
+static int spec_name_fprint(FILE *file, const cli_opt_spec *spec)
+{
+	int error;
+
+	if (spec->type == CLI_OPT_TYPE_ARG)
+		error = fprintf(file, "%s", spec->value_name);
+	else if (spec->type == CLI_OPT_TYPE_ARGS)
+		error = fprintf(file, "%s", spec->value_name);
+	else if (spec->alias && !(spec->usage & CLI_OPT_USAGE_SHOW_LONG))
+		error = fprintf(file, "-%c", spec->alias);
+	else
+		error = fprintf(file, "--%s", spec->name);
+
+	return error;
+}
+
+int cli_opt_status_fprint(
+	FILE *file,
+	const char *command,
+	const cli_opt *opt)
+{
+	const cli_opt_spec *choice;
+	int error;
+
+	if (command && (error = fprintf(file, "%s: ", command)) < 0)
+		return error;
+
+	switch (opt->status) {
+	case CLI_OPT_STATUS_DONE:
+		error = fprintf(file, "finished processing arguments (no error)\n");
+		break;
+	case CLI_OPT_STATUS_OK:
+		error = fprintf(file, "no error\n");
+		break;
+	case CLI_OPT_STATUS_UNKNOWN_OPTION:
+		error = fprintf(file, "unknown option: %s\n", opt->arg);
+		break;
+	case CLI_OPT_STATUS_MISSING_VALUE:
+		if ((error = fprintf(file, "argument '")) < 0 ||
+		    (error = spec_name_fprint(file, opt->spec)) < 0 ||
+		    (error = fprintf(file, "' requires a value.\n")) < 0)
+			break;
+		break;
+	case CLI_OPT_STATUS_MISSING_ARGUMENT:
+		if (spec_is_choice(opt->spec)) {
+			int is_choice = 1;
+
+			if (spec_is_choice((opt->spec)+1))
+				error = fprintf(file, "one of");
+			else
+				error = fprintf(file, "either");
+
+			if (error < 0)
+				break;
+
+			for (choice = opt->spec; is_choice; ++choice) {
+				is_choice = spec_is_choice(choice);
+
+				if (!is_choice)
+					error = fprintf(file, " or");
+				else if (choice != opt->spec)
+					error = fprintf(file, ",");
+
+				if ((error < 0) ||
+				    (error = fprintf(file, " '")) < 0 ||
+				    (error = spec_name_fprint(file, choice)) < 0 ||
+				    (error = fprintf(file, "'")) < 0)
+					break;
+
+				if (!spec_is_choice(choice))
+					break;
+			}
+
+			if ((error < 0) ||
+			    (error = fprintf(file, " is required.\n")) < 0)
+				break;
+		} else {
+			if ((error = fprintf(file, "argument '")) < 0 ||
+			    (error = spec_name_fprint(file, opt->spec)) < 0 ||
+			    (error = fprintf(file, "' is required.\n")) < 0)
+				break;
+		}
+
+		break;
+	default:
+		error = fprintf(file, "unknown status: %d\n", opt->status);
+		break;
+	}
+
+	return error;
+}
+
+int cli_opt_usage_fprint(
+	FILE *file,
+	const char *command,
+	const cli_opt_spec specs[])
+{
+	const cli_opt_spec *spec;
+	int choice = 0, next_choice = 0, optional = 0;
+	int error;
+
+	if ((error = fprintf(file, "usage: %s", command)) < 0)
+		goto done;
+
+	for (spec = specs; spec->type; ++spec) {
+		if (!choice)
+			optional = !(spec->usage & CLI_OPT_USAGE_REQUIRED);
+
+		next_choice = !!((spec + 1)->usage & CLI_OPT_USAGE_CHOICE);
+
+		if (spec->usage & CLI_OPT_USAGE_HIDDEN)
+			continue;
+
+		if (choice)
+			error = fprintf(file, "|");
+		else
+			error = fprintf(file, " ");
+
+		if (error < 0)
+			goto done;
+
+		if (optional && !choice && (error = fprintf(file, "[")) < 0)
+			error = fprintf(file, "[");
+		if (!optional && !choice && next_choice)
+			error = fprintf(file, "(");
+
+		if (error < 0)
+			goto done;
+
+		if (spec->type == CLI_OPT_TYPE_VALUE && spec->alias &&
+		    !(spec->usage & CLI_OPT_USAGE_VALUE_OPTIONAL) &&
+		    !(spec->usage & CLI_OPT_USAGE_SHOW_LONG))
+			error = fprintf(file, "-%c <%s>", spec->alias, spec->value_name);
+		else if (spec->type == CLI_OPT_TYPE_VALUE && spec->alias &&
+		         !(spec->usage & CLI_OPT_USAGE_SHOW_LONG))
+			error = fprintf(file, "-%c [<%s>]", spec->alias, spec->value_name);
+		else if (spec->type == CLI_OPT_TYPE_VALUE &&
+		         !(spec->usage & CLI_OPT_USAGE_VALUE_OPTIONAL))
+			error = fprintf(file, "--%s[=<%s>]", spec->name, spec->value_name);
+		else if (spec->type == CLI_OPT_TYPE_VALUE)
+			error = fprintf(file, "--%s=<%s>", spec->name, spec->value_name);
+		else if (spec->type == CLI_OPT_TYPE_ARG)
+			error = fprintf(file, "<%s>", spec->value_name);
+		else if (spec->type == CLI_OPT_TYPE_ARGS)
+			error = fprintf(file, "<%s>...", spec->value_name);
+		else if (spec->type == CLI_OPT_TYPE_LITERAL)
+			error = fprintf(file, "--");
+		else if (spec->alias && !(spec->usage & CLI_OPT_USAGE_SHOW_LONG))
+			error = fprintf(file, "-%c", spec->alias);
+		else
+			error = fprintf(file, "--%s", spec->name);
+
+		if (error < 0)
+			goto done;
+
+		if (!optional && choice && !next_choice)
+			error = fprintf(file, ")");
+		else if (optional && !next_choice)
+			error = fprintf(file, "]");
+
+		if (error < 0)
+			goto done;
+
+		choice = next_choice;
+	}
+
+	error = fprintf(file, "\n");
+
+done:
+	error = (error < 0) ? -1 : 0;
+	return error;
+}
+
diff --git a/src/cli/opt.h b/src/cli/opt.h
new file mode 100644
index 0000000..f7b6b93
--- /dev/null
+++ b/src/cli/opt.h
@@ -0,0 +1,362 @@
+/*
+ * Copyright (c), Edward Thomson <ethomson@edwardthomson.com>
+ * All rights reserved.
+ *
+ * This file is part of adopt, distributed under the MIT license.
+ * For full terms and conditions, see the included LICENSE file.
+ *
+ * THIS FILE IS AUTOMATICALLY GENERATED; DO NOT EDIT.
+ *
+ * This file was produced by using the `rename.pl` script included with
+ * adopt.  The command-line specified was:
+ *
+ * ./rename.pl cli_opt --filename=opt --include=cli.h --inline=GIT_INLINE --header-guard=CLI_opt_h__ --lowercase-status
+ */
+
+#ifndef CLI_opt_h__
+#define CLI_opt_h__
+
+#include <stdio.h>
+#include <stdint.h>
+
+/**
+ * The type of argument to be parsed.
+ */
+typedef enum {
+	CLI_OPT_TYPE_NONE = 0,
+
+	/**
+	 * An option that, when specified, sets a given value to true.
+	 * This is useful for options like "--debug".  A negation
+	 * option (beginning with "no-") is implicitly specified; for
+	 * example "--no-debug".  The `value` pointer in the returned
+	 * option will be set to `1` when this is specified, and set to
+	 * `0` when the negation "no-" option is specified.
+	 */
+	CLI_OPT_TYPE_BOOL,
+
+	/**
+	 * An option that, when specified, sets the given `value` pointer
+	 * to the specified `switch_value`.  This is useful for booleans
+	 * where you do not want the implicit negation that comes with an
+	 * `CLI_OPT_TYPE_BOOL`, or for switches that multiplex a value, like
+	 * setting a mode.  For example, `--read` may set the `value` to
+	 * `MODE_READ` and `--write` may set the `value` to `MODE_WRITE`.
+	 */
+	CLI_OPT_TYPE_SWITCH,
+
+	/**
+	 * An option that, when specified, increments the given
+	 * `value` by the given `switch_value`.  This can be specified
+	 * multiple times to continue to increment the `value`.
+	 * (For example, "-vvv" to set verbosity to 3.)
+	 */
+	CLI_OPT_TYPE_ACCUMULATOR,
+
+	/**
+	 * An option that takes a value, for example `-n value`,
+	 * `-nvalue`, `--name value` or `--name=value`.
+	 */
+	CLI_OPT_TYPE_VALUE,
+
+	/**
+	 * A bare "--" that indicates that arguments following this are
+	 * literal.  This allows callers to specify things that might
+	 * otherwise look like options, for example to operate on a file
+	 * named "-rf" then you can invoke "program -- -rf" to treat
+	 * "-rf" as an argument not an option.
+	 */
+	CLI_OPT_TYPE_LITERAL,
+
+	/**
+	 * A single argument, not an option.  When options are exhausted,
+	 * arguments will be matches in the order that they're specified
+	 * in the spec list.  For example, if two `CLI_OPT_TYPE_ARGS` are
+	 * specified, `input_file` and `output_file`, then the first bare
+	 * argument on the command line will be `input_file` and the
+	 * second will be `output_file`.
+	 */
+	CLI_OPT_TYPE_ARG,
+
+	/**
+	 * A collection of arguments.  This is useful when you want to take
+	 * a list of arguments, for example, multiple paths.  When specified,
+	 * the value will be set to the first argument in the list.
+	 */
+	CLI_OPT_TYPE_ARGS,
+} cli_opt_type_t;
+
+/**
+ * Additional information about an option, including parsing
+ * restrictions and usage information to be displayed to the end-user.
+ */
+typedef enum {
+	/** Defaults for the argument. */
+	CLI_OPT_USAGE_DEFAULT  = 0,
+
+	/** This argument is required. */
+	CLI_OPT_USAGE_REQUIRED = (1u << 0),
+
+	/**
+	 * This is a multiple choice argument, combined with the previous
+	 * argument.  For example, when the previous argument is `-f` and
+	 * this optional is applied to an argument of type `-b` then one
+	 * of `-f` or `-b` may be specified.
+	 */
+	CLI_OPT_USAGE_CHOICE = (1u << 1),
+
+	/**
+	 * This argument short-circuits the remainder of parsing.
+	 * Useful for arguments like `--help`.
+	 */
+	CLI_OPT_USAGE_STOP_PARSING = (1u << 2),
+
+	/** The argument's value is optional ("-n" or "-n foo") */
+	CLI_OPT_USAGE_VALUE_OPTIONAL = (1u << 3),
+
+	/** This argument should not be displayed in usage. */
+	CLI_OPT_USAGE_HIDDEN = (1u << 4),
+
+	/** In usage, show the long format instead of the abbreviated format. */
+	CLI_OPT_USAGE_SHOW_LONG = (1u << 5),
+} cli_opt_usage_t;
+
+typedef enum {
+	/** Default parsing behavior. */
+	CLI_OPT_PARSE_DEFAULT  = 0,
+
+	/**
+	 * Parse with GNU `getopt_long` style behavior, where options can
+	 * be intermixed with arguments at any position (for example,
+	 * "file1 --help file2".)  Like `getopt_long`, this can mutate the
+	 * arguments given.
+	 */
+	CLI_OPT_PARSE_GNU = (1u << 0),
+
+	/**
+	 * Force GNU `getopt_long` style behavior; the `POSIXLY_CORRECT`
+	 * environment variable is ignored.
+	 */
+	CLI_OPT_PARSE_FORCE_GNU = (1u << 1),
+} cli_opt_flag_t;
+
+/** Specification for an available option. */
+typedef struct cli_opt_spec {
+	/** Type of option expected. */
+	cli_opt_type_t type;
+
+	/** Name of the long option. */
+	const char *name;
+
+	/** The alias is the short (one-character) option alias. */
+	const char alias;
+
+	/**
+	 * If this spec is of type `CLI_OPT_TYPE_BOOL`, this is a pointer
+	 * to an `int` that will be set to `1` if the option is specified.
+	 *
+	 * If this spec is of type `CLI_OPT_TYPE_SWITCH`, this is a pointer
+	 * to an `int` that will be set to the opt's `switch_value` (below)
+	 * when this option is specified.
+	 *
+	 * If this spec is of type `CLI_OPT_TYPE_ACCUMULATOR`, this is a
+	 * pointer to an `int` that will be incremented by the opt's
+	 * `switch_value` (below).  If no `switch_value` is provided then
+	 * the value will be incremented by 1.
+	 *
+	 * If this spec is of type `CLI_OPT_TYPE_VALUE`,
+	 * `CLI_OPT_TYPE_VALUE_OPTIONAL`, or `CLI_OPT_TYPE_ARG`, this is
+	 * a pointer to a `char *` that will be set to the value
+	 * specified on the command line.
+	 *
+	 * If this spec is of type `CLI_OPT_TYPE_ARGS`, this is a pointer
+	 * to a `char **` that will be set to the remaining values
+	 * specified on the command line.
+	 */
+	void *value;
+
+	/**
+	 * If this spec is of type `CLI_OPT_TYPE_SWITCH`, this is the value
+	 * to set in the option's `value` pointer when it is specified.  If
+	 * this spec is of type `CLI_OPT_TYPE_ACCUMULATOR`, this is the value
+	 * to increment in the option's `value` pointer when it is
+	 * specified.  This is ignored for other opt types.
+	 */
+	int switch_value;
+
+	/**
+	 * Optional usage flags that change parsing behavior and how
+	 * usage information is shown to the end-user.
+	 */
+	uint32_t usage;
+
+	/**
+	 * The name of the value, provided when creating usage information.
+	 * This is required only for the functions that display usage
+	 * information and only when a spec is of type `CLI_OPT_TYPE_VALUE,
+	 * `CLI_OPT_TYPE_ARG` or `CLI_OPT_TYPE_ARGS``.
+	 */
+	const char *value_name;
+
+	/**
+	 * Optional short description of the option to display to the
+	 * end-user.  This is only used when creating usage information.
+	 */
+	const char *help;
+} cli_opt_spec;
+
+/** Return value for `cli_opt_parser_next`. */
+typedef enum {
+	/** Parsing is complete; there are no more arguments. */
+	CLI_OPT_STATUS_DONE = 0,
+
+	/**
+	 * This argument was parsed correctly; the `opt` structure is
+	 * populated and the value pointer has been set.
+	 */
+	CLI_OPT_STATUS_OK = 1,
+
+	/**
+	 * The argument could not be parsed correctly, it does not match
+	 * any of the specifications provided.
+	 */
+	CLI_OPT_STATUS_UNKNOWN_OPTION = 2,
+
+	/**
+	 * The argument matched a spec of type `CLI_OPT_VALUE`, but no value
+	 * was provided.
+	 */
+	CLI_OPT_STATUS_MISSING_VALUE = 3,
+
+	/** A required argument was not provided. */
+	CLI_OPT_STATUS_MISSING_ARGUMENT = 4,
+} cli_opt_status_t;
+
+/** An option provided on the command-line. */
+typedef struct cli_opt {
+	/** The status of parsing the most recent argument. */
+	cli_opt_status_t status;
+
+	/**
+	 * The specification that was provided on the command-line, or
+	 * `NULL` if the argument did not match an `cli_opt_spec`.
+	 */
+	const cli_opt_spec *spec;
+
+	/**
+	 * The argument as it was specified on the command-line, including
+	 * dashes, eg, `-f` or `--foo`.
+	 */
+	char *arg;
+
+	/**
+	 * If the spec is of type `CLI_OPT_VALUE` or `CLI_OPT_VALUE_OPTIONAL`,
+	 * this is the value provided to the argument.
+	 */
+	char *value;
+
+	/**
+	 * If the argument is of type `CLI_OPT_ARGS`, this is the number of
+	 * arguments remaining.  This value is persisted even when parsing
+	 * is complete and `status` == `CLI_OPT_STATUS_DONE`.
+	 */
+	size_t args_len;
+} cli_opt;
+
+/* The internal parser state.  Callers should not modify this structure. */
+typedef struct cli_opt_parser {
+	const cli_opt_spec *specs;
+	char **args;
+	size_t args_len;
+	unsigned int flags;
+
+	/* Parser state */
+	size_t idx;
+	size_t arg_idx;
+	size_t in_args;
+	size_t in_short;
+	int needs_sort : 1,
+	    in_literal : 1;
+} cli_opt_parser;
+
+/**
+ * Parses all the command-line arguments and updates all the options using
+ * the pointers provided.  Parsing stops on any invalid argument and
+ * information about the failure will be provided in the opt argument.
+ *
+ * This is the simplest way to parse options; it handles the initialization
+ * (`parser_init`) and looping (`parser_next`).
+ *
+ * @param opt The The `cli_opt` information that failed parsing
+ * @param specs A NULL-terminated array of `cli_opt_spec`s that can be parsed
+ * @param args The arguments that will be parsed
+ * @param args_len The length of arguments to be parsed
+ * @param flags The `cli_opt_flag_t flags for parsing
+ */
+cli_opt_status_t cli_opt_parse(
+    cli_opt *opt,
+    const cli_opt_spec specs[],
+    char **args,
+    size_t args_len,
+    unsigned int flags);
+
+/**
+ * Initializes a parser that parses the given arguments according to the
+ * given specifications.
+ *
+ * @param parser The `cli_opt_parser` that will be initialized
+ * @param specs A NULL-terminated array of `cli_opt_spec`s that can be parsed
+ * @param args The arguments that will be parsed
+ * @param args_len The length of arguments to be parsed
+ * @param flags The `cli_opt_flag_t flags for parsing
+ */
+void cli_opt_parser_init(
+	cli_opt_parser *parser,
+	const cli_opt_spec specs[],
+	char **args,
+	size_t args_len,
+	unsigned int flags);
+
+/**
+ * Parses the next command-line argument and places the information about
+ * the argument into the given `opt` data.
+ *
+ * @param opt The `cli_opt` information parsed from the argument
+ * @param parser An `cli_opt_parser` that has been initialized with
+ *        `cli_opt_parser_init`
+ * @return true if the caller should continue iterating, or 0 if there are
+ *         no arguments left to process.
+ */
+cli_opt_status_t cli_opt_parser_next(
+	cli_opt *opt,
+	cli_opt_parser *parser);
+
+/**
+ * Prints the status after parsing the most recent argument.  This is
+ * useful for printing an error message when an unknown argument was
+ * specified, or when an argument was specified without a value.
+ *
+ * @param file The file to print information to
+ * @param command The name of the command to use when printing (optional)
+ * @param opt The option that failed to parse
+ * @return 0 on success, -1 on failure
+ */
+int cli_opt_status_fprint(
+	FILE *file,
+	const char *command,
+	const cli_opt *opt);
+
+/**
+ * Prints usage information to the given file handle.
+ *
+ * @param file The file to print information to
+ * @param command The name of the command to use when printing
+ * @param specs The specifications allowed by the command
+ * @return 0 on success, -1 on failure
+ */
+int cli_opt_usage_fprint(
+	FILE *file,
+	const char *command,
+	const cli_opt_spec specs[]);
+
+#endif /* CLI_opt_h__ */
diff --git a/src/cli/win32/precompiled.c b/src/cli/win32/precompiled.c
new file mode 100644
index 0000000..5f656a4
--- /dev/null
+++ b/src/cli/win32/precompiled.c
@@ -0,0 +1 @@
+#include "precompiled.h"
diff --git a/src/cli/win32/precompiled.h b/src/cli/win32/precompiled.h
new file mode 100644
index 0000000..b0309b8
--- /dev/null
+++ b/src/cli/win32/precompiled.h
@@ -0,0 +1,3 @@
+#include <git2.h>
+
+#include "cli.h"