Extract common example helpers and reorg examples

This reorganizes a few of the examples so that the main function
comes first with the argument parsing extracted into a helper
that can come at the end of the file (so the example focuses more
on the use of libgit2 instead of command line support).  This also
creates a shared examples/common.[ch] so that useful helper funcs
can be shared across examples instead of repeated.

examples/CMakeLists.txt

@@ -9,6 +9,8 @@ ENDIF()
 FILE(GLOB SRC_EXAMPLE_APPS RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} *.c)
 FOREACH(src_app ${SRC_EXAMPLE_APPS})
 	STRING(REPLACE ".c" "" app_name ${src_app})
-	ADD_EXECUTABLE(${app_name} ${src_app})
-	TARGET_LINK_LIBRARIES(${app_name} git2)
+	IF(NOT ${app_name} STREQUAL "common")
+		ADD_EXECUTABLE(${app_name} ${src_app} "common.c")
+		TARGET_LINK_LIBRARIES(${app_name} git2)
+	ENDIF()
 ENDFOREACH()

examples/Makefile

@@ -8,7 +8,7 @@ APPS = general showindex diff rev-list cat-file status log rev-parse init
 all: $(APPS)
 
 % : %.c
-	$(CC) -o $@ $(CFLAGS) $< $(LFLAGS)
+	$(CC) -o $@ common.c $(CFLAGS) $< $(LFLAGS)
 
 clean:
 	$(RM) $(APPS)

examples/common.c

+/*
+ * 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 "common.h"
+
+void check_lg2(int error, const char *message, const char *extra)
+{
+	const git_error *lg2err;
+	const char *lg2msg = "", *lg2spacer = "";
+
+	if (!error)
+		return;
+
+	if ((lg2err = giterr_last()) != NULL && lg2err->message != NULL) {
+		lg2msg = lg2err->message;
+		lg2spacer = " - ";
+	}
+
+	if (extra)
+		fprintf(stderr, "%s '%s' [%d]%s%s\n",
+			message, extra, error, lg2spacer, lg2msg);
+	else
+		fprintf(stderr, "%s [%d]%s%s\n",
+			message, error, lg2spacer, lg2msg);
+
+	exit(1);
+}
+
+void fatal(const char *message, const char *extra)
+{
+	if (extra)
+		fprintf(stderr, "%s %s\n", message, extra);
+	else
+		fprintf(stderr, "%s\n", message);
+
+	exit(1);
+}
+
+size_t is_prefixed(const char *str, const char *pfx)
+{
+	size_t len = strlen(pfx);
+	return strncmp(str, pfx, len) ? 0 : len;
+}
+
+int match_str_arg(
+	const char **out, struct args_info *args, const char *opt)
+{
+	const char *found = args->argv[args->pos];
+	size_t len = is_prefixed(found, opt);
+
+	if (!len)
+		return 0;
+
+	if (!found[len]) {
+		if (args->pos + 1 == args->argc)
+			fatal("expected value following argument", opt);
+		args->pos += 1;
+		*out = args->argv[args->pos];
+		return 1;
+	}
+
+	if (found[len] == '=') {
+		*out = found + len + 1;
+		return 1;
+	}
+
+	return 0;
+}
+
+static const char *match_numeric_arg(struct args_info *args, const char *opt)
+{
+	const char *found = args->argv[args->pos];
+	size_t len = is_prefixed(found, opt);
+
+	if (!len)
+		return NULL;
+
+	if (!found[len]) {
+		if (args->pos + 1 == args->argc)
+			fatal("expected numeric value following argument", opt);
+		args->pos += 1;
+		found = args->argv[args->pos];
+	} else {
+		found = found + len;
+		if (*found == '=')
+			found++;
+	}
+
+	return found;
+}
+
+int match_uint16_arg(
+	uint16_t *out, struct args_info *args, const char *opt)
+{
+	const char *found = match_numeric_arg(args, opt);
+	uint16_t val;
+	char *endptr = NULL;
+
+	if (!found)
+		return 0;
+
+	val = (uint16_t)strtoul(found, &endptr, 0);
+	if (!endptr || *endptr != '\0')
+		fatal("expected number after argument", opt);
+
+	if (out)
+		*out = val;
+	return 1;
+}
+
+static int match_int_internal(
+	int *out, const char *str, int allow_negative, const char *opt)
+{
+	char *endptr = NULL;
+	int	  val = (int)strtol(str, &endptr, 10);
+
+	if (!endptr || *endptr != '\0')
+		fatal("expected number", opt);
+	else if (val < 0 && !allow_negative)
+		fatal("negative values are not allowed", opt);
+
+	if (out)
+		*out = val;
+
+	return 1;
+}
+
+int is_integer(int *out, const char *str, int allow_negative)
+{
+	return match_int_internal(out, str, allow_negative, NULL);
+}
+
+int match_int_arg(
+	int *out, struct args_info *args, const char *opt, int allow_negative)
+{
+	const char *found = match_numeric_arg(args, opt);
+	if (!found)
+		return 0;
+	return match_int_internal(out, found, allow_negative, opt);
+}
+
+int diff_output(
+	const git_diff_delta *d,
+	const git_diff_hunk *h,
+	const git_diff_line *l,
+	void *p)
+{
+	FILE *fp = p;
+
+	(void)d; (void)h;
+
+	if (!fp)
+		fp = stdout;
+
+	if (l->origin == GIT_DIFF_LINE_CONTEXT ||
+		l->origin == GIT_DIFF_LINE_ADDITION ||
+		l->origin == GIT_DIFF_LINE_DELETION)
+		fputc(l->origin, fp);
+
+	fwrite(l->content, 1, l->content_len, fp);
+
+	return 0;
+}
+
+void treeish_to_tree(
+	git_tree **out, git_repository *repo, const char *treeish)
+{
+	git_object *obj = NULL;
+
+	check_lg2(
+		git_revparse_single(&obj, repo, treeish),
+		"looking up object", treeish);
+
+	check_lg2(
+		git_object_peel((git_object **)out, obj, GIT_OBJ_TREE),
+		"resolving object to tree", treeish);
+
+	git_object_free(obj);
+}
+

examples/common.h

+/*
+ * 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 <string.h>
+#include <stdlib.h>
+#include <git2.h>
+
+/**
+ * Check libgit2 error code, printing error to stderr on failure and
+ * exiting the program.
+ */
+extern void check_lg2(int error, const char *message, const char *extra);
+
+/**
+ * Exit the program, printing error to stderr
+ */
+extern void fatal(const char *message, const char *extra);
+
+/**
+ * Check if a string has the given prefix.  Returns 0 if not prefixed
+ * or the length of the prefix if it is.
+ */
+extern size_t is_prefixed(const char *str, const char *pfx);
+
+/**
+ * Match an integer string, returning 1 if matched, 0 if not.
+ */
+extern int is_integer(int *out, const char *str, int allow_negative);
+
+struct args_info {
+	int    argc;
+	char **argv;
+	int    pos;
+};
+#define ARGS_INFO_INIT { argc, argv, 0 }
+
+/**
+ * Check current `args` entry against `opt` string.  If it matches
+ * exactly, take the next arg as a string; if it matches as a prefix with
+ * an equal sign, take the remainder as a string; otherwise return 0.
+ */
+extern int match_str_arg(
+	const char **out, struct args_info *args, const char *opt);
+
+/**
+ * Check current `args` entry against `opt` string parsing as uint16.  If
+ * `opt` matches exactly, take the next arg as a uint16_t value; if `opt`
+ * is a prefix (equal sign optional), take the remainder of the arg as a
+ * uint16_t value; otherwise return 0.
+ */
+extern int match_uint16_arg(
+	uint16_t *out, struct args_info *args, const char *opt);
+
+/**
+ * Check current `args` entry against `opt` string parsing as int.  If
+ * `opt` matches exactly, take the next arg as an int value; if it matches
+ * as a prefix (equal sign optional), take the remainder of the arg as a
+ * int value; otherwise return 0.
+ */
+extern int match_int_arg(
+	int *out, struct args_info *args, const char *opt, int allow_negative);
+
+/**
+ * Basic output function for plain text diff output
+ * Pass `FILE*` such as `stdout` or `stderr` as payload (or NULL == `stdout`)
+ */
+extern int diff_output(
+	const git_diff_delta*, const git_diff_hunk*, const git_diff_line*, void*);
+
+/**
+ * Convert a treeish argument to an actual tree; this will call check_lg2
+ * and exit the program if `treeish` cannot be resolved to a tree
+ */
+extern void treeish_to_tree(
+	git_tree **out, git_repository *repo, const char *treeish);

examples/diff.c

-#include <stdio.h>
-#include <git2.h>
-#include <stdlib.h>
-#include <string.h>
+/*
+ * 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 "common.h"
+
+/*
+ * This example demonstrates the use of the libgit2 diff APIs to
+ * create `git_diff` objects and display them, emulating a number of
+ * core Git `diff` command line options.
+ *
+ * This covers on a portion of the core Git diff options and doesn't
+ * have particularly good error handling, but it should show most of
+ * the core libgit2 diff APIs, including various types of diffs and
+ * how to do renaming detection and patch formatting.
+ */
+
+static const char *colors[] = {
+	"\033[m", /* reset */
+	"\033[1m", /* bold */
+	"\033[31m", /* red */
+	"\033[32m", /* green */
+	"\033[36m" /* cyan */
+};
 
-static void check(int error, const char *message)
-{
-	if (error) {
-		fprintf(stderr, "%s (%d)\n", message, error);
-		exit(1);
-	}
-}
+/* this implements very rudimentary colorized output */
+static int color_printer(
+	const git_diff_delta*, const git_diff_hunk*, const git_diff_line*, void*);
+
+/* the 'opts' struct captures all the various parsed command line options */
+struct opts {
+	git_diff_options diffopts;
+	git_diff_find_options findopts;
+	int color;
+	int cached;
+	git_diff_format_t format;
+	const char *treeish1;
+	const char *treeish2;
+	const char *dir;
+};
+
+static void parse_opts(struct opts *o, int argc, char *argv[]);
 
-static int resolve_to_tree(
-	git_repository *repo, const char *identifier, git_tree **tree)
+int main(int argc, char *argv[])
 {
-	int err = 0;
-	git_object *obj = NULL;
-
-	if ((err = git_revparse_single(&obj, repo, identifier)) < 0)
-		return err;
-
-	switch (git_object_type(obj)) {
-	case GIT_OBJ_TREE:
-		*tree = (git_tree *)obj;
-		break;
-	case GIT_OBJ_COMMIT:
-		err = git_commit_tree(tree, (git_commit *)obj);
-		git_object_free(obj);
-		break;
-	default:
-		err = GIT_ENOTFOUND;
+	git_repository *repo = NULL;
+	git_tree *t1 = NULL, *t2 = NULL;
+	git_diff *diff;
+	struct opts o = {
+		GIT_DIFF_OPTIONS_INIT, GIT_DIFF_FIND_OPTIONS_INIT,
+		-1, 0, GIT_DIFF_FORMAT_PATCH, NULL, NULL, "."
+	};
+
+	git_threads_init();
+
+	parse_opts(&o, argc, argv);
+
+	check_lg2(git_repository_open_ext(&repo, o.dir, 0, NULL),
+		"Could not open repository", o.dir);
+
+	/* Possible argument patterns:
+	 *   <sha1> <sha2>
+	 *   <sha1> --cached
+	 *   <sha1>
+	 *   --cached
+	 *   nothing
+	 *
+	 * Currently ranged arguments like <sha1>..<sha2> and <sha1>...<sha2>
+	 * are not supported in this example
+	 */
+
+	if (o.treeish1)
+		treeish_to_tree(&t1, repo, o.treeish1);
+	if (o.treeish2)
+		treeish_to_tree(&t2, repo, o.treeish2);
+
+	if (t1 && t2)
+		check_lg2(
+			git_diff_tree_to_tree(&diff, repo, t1, t2, &o.diffopts),
+			"diff trees", NULL);
+	else if (t1 && o.cached)
+		check_lg2(
+			git_diff_tree_to_index(&diff, repo, t1, NULL, &o.diffopts),
+			"diff tree to index", NULL);
+	else if (t1)
+		check_lg2(
+			git_diff_tree_to_workdir_with_index(&diff, repo, t1, &o.diffopts),
+			"diff tree to working directory", NULL);
+	else if (o.cached) {
+		treeish_to_tree(&t1, repo, "HEAD");
+		check_lg2(
+			git_diff_tree_to_index(&diff, repo, t1, NULL, &o.diffopts),
+			"diff tree to index", NULL);
 	}
+	else
+		check_lg2(
+			git_diff_index_to_workdir(&diff, repo, NULL, &o.diffopts),
+			"diff index to working directory", NULL);
+
+	/* apply rename and copy detection if requested */
+
+	if ((o.findopts.flags & GIT_DIFF_FIND_ALL) != 0)
+		check_lg2(
+			git_diff_find_similar(diff, &o.findopts),
+			"finding renames and copies", NULL);
+
+	/* generate simple output using libgit2 display helper */
 
-	return err;
+	if (o.color >= 0)
+		fputs(colors[0], stdout);
+
+	check_lg2(
+		git_diff_print(diff, o.format, color_printer, &o.color),
+		"displaying diff", NULL);
+
+	if (o.color >= 0)
+		fputs(colors[0], stdout);
+
+	/* cleanup before exiting */
+
+	git_diff_free(diff);
+	git_tree_free(t1);
+	git_tree_free(t2);
+	git_repository_free(repo);
+
+	git_threads_shutdown();
+
+	return 0;
 }
 
-char *colors[] = {
-	"\033[m", /* reset */
-	"\033[1m", /* bold */
-	"\033[31m", /* red */
-	"\033[32m", /* green */
-	"\033[36m" /* cyan */
-};
+static void usage(const char *message, const char *arg)
+{
+	if (message && arg)
+		fprintf(stderr, "%s: %s\n", message, arg);
+	else if (message)
+		fprintf(stderr, "%s\n", message);
+	fprintf(stderr, "usage: diff [<tree-oid> [<tree-oid>]]\n");
+	exit(1);
+}
 
-static int printer(
+static int color_printer(
 	const git_diff_delta *delta,
 	const git_diff_hunk *hunk,
 	const git_diff_line *line,
@@ -63,6 +161,7 @@ static int printer(
 		case GIT_DIFF_LINE_HUNK_HDR:  color = 4; break;
 		default: break;
 		}
+
 		if (color != *last_color) {
 			if (*last_color == 1 || color == 1)
 				fputs(colors[0], stdout);
@@ -71,186 +170,79 @@ static int printer(
 		}
 	}
 
-	if (line->origin == GIT_DIFF_LINE_CONTEXT ||
-		line->origin == GIT_DIFF_LINE_ADDITION ||
-		line->origin == GIT_DIFF_LINE_DELETION)
-		fputc(line->origin, stdout);
-
-	fwrite(line->content, 1, line->content_len, stdout);
-
-	return 0;
-}
-
-static int check_uint16_param(const char *arg, const char *pattern, uint16_t *val)
-{
-	size_t len = strlen(pattern);
-	uint16_t strval;
-	char *endptr = NULL;
-	if (strncmp(arg, pattern, len))
-		return 0;
-	if (arg[len] == '\0' && pattern[len - 1] != '=')
-		return 1;
-	if (arg[len] == '=')
-		len++;
-	strval = strtoul(arg + len, &endptr, 0);
-	if (endptr == arg)
-		return 0;
-	*val = strval;
-	return 1;
+	return diff_output(delta, hunk, line, stdout);
 }
 
-static int check_str_param(const char *arg, const char *pattern, const char **val)
+static void parse_opts(struct opts *o, int argc, char *argv[])
 {
-	size_t len = strlen(pattern);
-	if (strncmp(arg, pattern, len))
-		return 0;
-	*val = (const char *)(arg + len);
-	return 1;
-}
-
-static void usage(const char *message, const char *arg)
-{
-	if (message && arg)
-		fprintf(stderr, "%s: %s\n", message, arg);
-	else if (message)
-		fprintf(stderr, "%s\n", message);
-	fprintf(stderr, "usage: diff [<tree-oid> [<tree-oid>]]\n");
-	exit(1);
-}
-
-int main(int argc, char *argv[])
-{
-	git_repository *repo = NULL;
-	git_tree *t1 = NULL, *t2 = NULL;
-	git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
-	git_diff_find_options findopts = GIT_DIFF_FIND_OPTIONS_INIT;
-	git_diff *diff;
-	int i, color = -1, cached = 0;
-	git_diff_format_t format = GIT_DIFF_FORMAT_PATCH;
-	char *a, *treeish1 = NULL, *treeish2 = NULL;
-	const char *dir = ".";
-
-	git_threads_init();
+	struct args_info args = ARGS_INFO_INIT;
 
 	/* parse arguments as copied from git-diff */
 
-	for (i = 1; i < argc; ++i) {
-		a = argv[i];
+	for (args.pos = 1; args.pos < argc; ++args.pos) {
+		const char *a = argv[args.pos];
 
 		if (a[0] != '-') {
-			if (treeish1 == NULL)
-				treeish1 = a;
-			else if (treeish2 == NULL)
-				treeish2 = a;
+			if (o->treeish1 == NULL)
+				o->treeish1 = a;
+			else if (o->treeish2 == NULL)
+				o->treeish2 = a;
 			else
 				usage("Only one or two tree identifiers can be provided", NULL);
 		}
 		else if (!strcmp(a, "-p") || !strcmp(a, "-u") ||
 			!strcmp(a, "--patch"))
-			format = GIT_DIFF_FORMAT_PATCH;
+			o->format = GIT_DIFF_FORMAT_PATCH;
 		else if (!strcmp(a, "--cached"))
-			cached = 1;
+			o->cached = 1;
 		else if (!strcmp(a, "--name-only"))
-			format = GIT_DIFF_FORMAT_NAME_ONLY;
+			o->format = GIT_DIFF_FORMAT_NAME_ONLY;
 		else if (!strcmp(a, "--name-status"))
-			format = GIT_DIFF_FORMAT_NAME_STATUS;
+			o->format = GIT_DIFF_FORMAT_NAME_STATUS;
 		else if (!strcmp(a, "--raw"))
-			format = GIT_DIFF_FORMAT_RAW;
+			o->format = GIT_DIFF_FORMAT_RAW;
 		else if (!strcmp(a, "--color"))
-			color = 0;
+			o->color = 0;
 		else if (!strcmp(a, "--no-color"))
-			color = -1;
+			o->color = -1;
 		else if (!strcmp(a, "-R"))
-			opts.flags |= GIT_DIFF_REVERSE;
+			o->diffopts.flags |= GIT_DIFF_REVERSE;
 		else if (!strcmp(a, "-a") || !strcmp(a, "--text"))
-			opts.flags |= GIT_DIFF_FORCE_TEXT;
+			o->diffopts.flags |= GIT_DIFF_FORCE_TEXT;
 		else if (!strcmp(a, "--ignore-space-at-eol"))
-			opts.flags |= GIT_DIFF_IGNORE_WHITESPACE_EOL;
+			o->diffopts.flags |= GIT_DIFF_IGNORE_WHITESPACE_EOL;
 		else if (!strcmp(a, "-b") || !strcmp(a, "--ignore-space-change"))
-			opts.flags |= GIT_DIFF_IGNORE_WHITESPACE_CHANGE;
+			o->diffopts.flags |= GIT_DIFF_IGNORE_WHITESPACE_CHANGE;
 		else if (!strcmp(a, "-w") || !strcmp(a, "--ignore-all-space"))
-			opts.flags |= GIT_DIFF_IGNORE_WHITESPACE;
+			o->diffopts.flags |= GIT_DIFF_IGNORE_WHITESPACE;
 		else if (!strcmp(a, "--ignored"))
-			opts.flags |= GIT_DIFF_INCLUDE_IGNORED;
+			o->diffopts.flags |= GIT_DIFF_INCLUDE_IGNORED;
 		else if (!strcmp(a, "--untracked"))
-			opts.flags |= GIT_DIFF_INCLUDE_UNTRACKED;
-		else if (check_uint16_param(a, "-M", &findopts.rename_threshold) ||
-				 check_uint16_param(a, "--find-renames",
-					&findopts.rename_threshold))
-			findopts.flags |= GIT_DIFF_FIND_RENAMES;
-		else if (check_uint16_param(a, "-C", &findopts.copy_threshold) ||
-				 check_uint16_param(a, "--find-copies",
-					&findopts.copy_threshold))
-			findopts.flags |= GIT_DIFF_FIND_COPIES;
+			o->diffopts.flags |= GIT_DIFF_INCLUDE_UNTRACKED;
+		else if (match_uint16_arg(
+				&o->findopts.rename_threshold, &args, "-M") ||
+			match_uint16_arg(
+				&o->findopts.rename_threshold, &args, "--find-renames"))
+			o->findopts.flags |= GIT_DIFF_FIND_RENAMES;
+		else if (match_uint16_arg(
+				&o->findopts.copy_threshold, &args, "-C") ||
+			match_uint16_arg(
+				&o->findopts.copy_threshold, &args, "--find-copies"))
+			o->findopts.flags |= GIT_DIFF_FIND_COPIES;
 		else if (!strcmp(a, "--find-copies-harder"))
-			findopts.flags |= GIT_DIFF_FIND_COPIES_FROM_UNMODIFIED;
-		else if (!strncmp(a, "-B", 2) || !strncmp(a, "--break-rewrites", 16)) {
+			o->findopts.flags |= GIT_DIFF_FIND_COPIES_FROM_UNMODIFIED;
+		else if (is_prefixed(a, "-B") || is_prefixed(a, "--break-rewrites"))
 			/* TODO: parse thresholds */
-			findopts.flags |= GIT_DIFF_FIND_REWRITES;
-		}
-		else if (!check_uint16_param(a, "-U", &opts.context_lines) &&
-			!check_uint16_param(a, "--unified=", &opts.context_lines) &&
-			!check_uint16_param(a, "--inter-hunk-context=",
-				&opts.interhunk_lines) &&
-			!check_str_param(a, "--src-prefix=", &opts.old_prefix) &&
-			!check_str_param(a, "--dst-prefix=", &opts.new_prefix) &&
-			!check_str_param(a, "--git-dir=", &dir))
-			usage("Unknown arg", a);
-	}
-
-	/* open repo */
-
-	check(git_repository_open_ext(&repo, dir, 0, NULL),
-		"Could not open repository");
-
-	if (treeish1)
-		check(resolve_to_tree(repo, treeish1, &t1), "Looking up first tree");
-	if (treeish2)
-		check(resolve_to_tree(repo, treeish2, &t2), "Looking up second tree");
-
-	/* <sha1> <sha2> */
-	/* <sha1> --cached */
-	/* <sha1> */
-	/* --cached */
-	/* nothing */
-
-	if (t1 && t2)
-		check(git_diff_tree_to_tree(&diff, repo, t1, t2, &opts), "Diff");
-	else if (t1 && cached)
-		check(git_diff_tree_to_index(&diff, repo, t1, NULL, &opts), "Diff");
-	else if (t1) {
-		git_diff *diff2;
-		check(git_diff_tree_to_index(&diff, repo, t1, NULL, &opts), "Diff");
-		check(git_diff_index_to_workdir(&diff2, repo, NULL, &opts), "Diff");
-		check(git_diff_merge(diff, diff2), "Merge diffs");
-		git_diff_free(diff2);
+			o->findopts.flags |= GIT_DIFF_FIND_REWRITES;
+		else if (!match_uint16_arg(
+				&o->diffopts.context_lines, &args, "-U") &&
+			!match_uint16_arg(
+				&o->diffopts.context_lines, &args, "--unified") &&
+			!match_uint16_arg(
+				&o->diffopts.interhunk_lines, &args, "--inter-hunk-context") &&
+			!match_str_arg(&o->diffopts.old_prefix, &args, "--src-prefix") &&
+			!match_str_arg(&o->diffopts.new_prefix, &args, "--dst-prefix") &&
+			!match_str_arg(&o->dir, &args, "--git-dir"))
+			usage("Unknown command line argument", a);
 	}
-	else if (cached) {
-		check(resolve_to_tree(repo, "HEAD", &t1), "looking up HEAD");
-		check(git_diff_tree_to_index(&diff, repo, t1, NULL, &opts), "Diff");
-	}
-	else
-		check(git_diff_index_to_workdir(&diff, repo, NULL, &opts), "Diff");
-
-	if ((findopts.flags & GIT_DIFF_FIND_ALL) != 0)
-		check(git_diff_find_similar(diff, &findopts),
-			"finding renames and copies ");
-
-	if (color >= 0)
-		fputs(colors[0], stdout);
-
-	check(git_diff_print(diff, format, printer, &color), "Displaying diff");
-
-	if (color >= 0)
-		fputs(colors[0], stdout);
-
-	git_diff_free(diff);
-	git_tree_free(t1);
-	git_tree_free(t2);
-	git_repository_free(repo);
-
-	git_threads_shutdown();
-
-	return 0;
 }
-

examples/log.c

-#include <stdio.h>
-#include <git2.h>
-#include <stdlib.h>
-#include <string.h>
-
-static void check(int error, const char *message, const char *arg)
-{
-	if (!error)
-		return;
-	if (arg)
-		fprintf(stderr, "%s '%s' (%d)\n", message, arg, error);
-	else
-		fprintf(stderr, "%s (%d)\n", message, error);
-	exit(1);
-}
-
-static void usage(const char *message, const char *arg)
-{
-	if (message && arg)
-		fprintf(stderr, "%s: %s\n", message, arg);
-	else if (message)
-		fprintf(stderr, "%s\n", message);
-	fprintf(stderr, "usage: log [<options>]\n");
-	exit(1);
-}
-
+/*
+ * 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 "common.h"
+
+/*
+ * This example demonstrates the libgit2 rev walker APIs to roughly
+ * simulate the output of `git log` and a few of command line arguments.
+ * `git log` has many many options and this only shows a few of them.
+ *
+ * This does not have:
+ * - Robust error handling
+ * - Colorized or paginated output formatting
+ * - Most of the `git log` options
+ *
+ * This does have:
+ * - Examples of translating command line arguments to equivalent libgit2
+ *   revwalker configuration calls
+ * - Simplified options to apply pathspec limits and to show basic diffs
+ */
+
+/* log_state represents walker being configured while handling options */
 struct log_state {
 	git_repository *repo;
 	const char *repodir;
 	git_revwalk *walker;
 	int hide;
 	int sorting;
+	int revisions;
 };
 
-static void set_sorting(struct log_state *s, unsigned int sort_mode)
+/* utility functions that are called to configure the walker */
+static void set_sorting(struct log_state *s, unsigned int sort_mode);
+static void push_rev(struct log_state *s, git_object *obj, int hide);
+static int add_revision(struct log_state *s, const char *revstr);
+
+/* log_options holds other command line options that affect log output */
+struct log_options {
+	int show_diff;
+	int skip, limit;
+	int min_parents, max_parents;
+	git_time_t before;
+	git_time_t after;
+	char *author;
+	char *committer;
+};
+
+/* utility functions that parse options and help with log output */
+static int parse_options(
+	struct log_state *s, struct log_options *opt, int argc, char **argv);
+static void print_time(const git_time *intime, const char *prefix);
+static void print_commit(git_commit *commit);
+static int match_with_parent(git_commit *commit, int i, git_diff_options *);
+
+
+int main(int argc, char *argv[])
 {
-	if (!s->repo) {
-		if (!s->repodir) s->repodir = ".";
-		check(git_repository_open_ext(&s->repo, s->repodir, 0, NULL),
-			"Could not open repository", s->repodir);
-	}
+	int i, count = 0, printed = 0, parents, last_arg;
+	struct log_state s;
+	struct log_options opt;
+	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
+	git_oid oid;
+	git_commit *commit = NULL;
+	git_pathspec *ps = NULL;
 
-	if (!s->walker)
-		check(git_revwalk_new(&s->walker, s->repo),
-			"Could not create revision walker", NULL);
+	git_threads_init();
 
-	if (sort_mode == GIT_SORT_REVERSE)
-		s->sorting = s->sorting ^ GIT_SORT_REVERSE;
-	else
-		s->sorting = sort_mode | (s->sorting & GIT_SORT_REVERSE);
+	/* parse arguments and set up revwalker */
 
-	git_revwalk_sorting(s->walker, s->sorting);
+	last_arg = parse_options(&s, &opt, argc, argv);
+
+	diffopts.pathspec.strings = &argv[last_arg];
+	diffopts.pathspec.count	  = argc - last_arg;
+	if (diffopts.pathspec.count > 0)
+		check_lg2(git_pathspec_new(&ps, &diffopts.pathspec),
+			"Building pathspec", NULL);
+
+	if (!s.revisions)
+		add_revision(&s, NULL);
+
+	/* use the revwalker to traverse the history */
+
+	printed = count = 0;
+
+	for (; !git_revwalk_next(&oid, s.walker); git_commit_free(commit)) {
+		check_lg2(git_commit_lookup(&commit, s.repo, &oid),
+			"Failed to look up commit", NULL);
+
+		parents = (int)git_commit_parentcount(commit);
+		if (parents < opt.min_parents)
+			continue;
+		if (opt.max_parents > 0 && parents > opt.max_parents)
+			continue;
+
+		if (diffopts.pathspec.count > 0) {
+			int unmatched = parents;
+
+			if (parents == 0) {
+				git_tree *tree;
+				check_lg2(git_commit_tree(&tree, commit), "Get tree", NULL);
+				if (git_pathspec_match_tree(
+						NULL, tree, GIT_PATHSPEC_NO_MATCH_ERROR, ps) != 0)
+					unmatched = 1;
+				git_tree_free(tree);
+			} else if (parents == 1) {
+				unmatched = match_with_parent(commit, 0, &diffopts) ? 0 : 1;
+			} else {
+				for (i = 0; i < parents; ++i) {
+					if (match_with_parent(commit, i, &diffopts))
+						unmatched--;
+				}
+			}
+
+			if (unmatched > 0)
+				continue;
+		}
+
+		if (count++ < opt.skip)
+			continue;
+		if (opt.limit != -1 && printed++ >= opt.limit) {
+			git_commit_free(commit);
+			break;
+		}
+
+		print_commit(commit);
+
+		if (opt.show_diff) {
+			git_tree *a = NULL, *b = NULL;
+			git_diff *diff = NULL;
+
+			if (parents > 1)
+				continue;
+			check_lg2(git_commit_tree(&b, commit), "Get tree", NULL);
+			if (parents == 1) {
+				git_commit *parent;
+				check_lg2(git_commit_parent(&parent, commit, 0), "Get parent", NULL);
+				check_lg2(git_commit_tree(&a, parent), "Tree for parent", NULL);
+				git_commit_free(parent);
+			}
+
+			check_lg2(git_diff_tree_to_tree(
+				&diff, git_commit_owner(commit), a, b, &diffopts),
+				"Diff commit with parent", NULL);
+			check_lg2(
+                git_diff_print(diff, GIT_DIFF_FORMAT_PATCH, diff_output, NULL),
+				"Displaying diff", NULL);
+
+			git_diff_free(diff);
+			git_tree_free(a);
+			git_tree_free(b);
+		}
+	}
+
+	git_pathspec_free(ps);
+	git_revwalk_free(s.walker);
+	git_repository_free(s.repo);
+	git_threads_shutdown();
+
+	return 0;
 }
 
+/* push object (for hide or show) onto revwalker */
 static void push_rev(struct log_state *s, git_object *obj, int hide)
 {
 	hide = s->hide ^ hide;
 
+	/* create revwalker on demand if it doesn't already exist */
 	if (!s->walker) {
-		check(git_revwalk_new(&s->walker, s->repo),
+		check_lg2(git_revwalk_new(&s->walker, s->repo),
 			"Could not create revision walker", NULL);
 		git_revwalk_sorting(s->walker, s->sorting);
 	}
 
 	if (!obj)
-		check(git_revwalk_push_head(s->walker),
+		check_lg2(git_revwalk_push_head(s->walker),
 			"Could not find repository HEAD", NULL);
 	else if (hide)
-		check(git_revwalk_hide(s->walker, git_object_id(obj)),
+		check_lg2(git_revwalk_hide(s->walker, git_object_id(obj)),
 			"Reference does not refer to a commit", NULL);
 	else
-		check(git_revwalk_push(s->walker, git_object_id(obj)),
+		check_lg2(git_revwalk_push(s->walker, git_object_id(obj)),
 			"Reference does not refer to a commit", NULL);
 
 	git_object_free(obj);
 }
 
+/* parse revision string and add revs to walker */
 static int add_revision(struct log_state *s, const char *revstr)
 {
 	git_revspec revs;
 	int hide = 0;
 
+	/* open repo on demand if it isn't already open */
 	if (!s->repo) {
 		if (!s->repodir) s->repodir = ".";
-		check(git_repository_open_ext(&s->repo, s->repodir, 0, NULL),
+		check_lg2(git_repository_open_ext(&s->repo, s->repodir, 0, NULL),
 			"Could not open repository", s->repodir);
 	}
 
@@ -107,10 +222,11 @@ static int add_revision(struct log_state *s, const char *revstr)
 
 		if ((revs.flags & GIT_REVPARSE_MERGE_BASE) != 0) {
 			git_oid base;
-			check(git_merge_base(&base, s->repo,
+			check_lg2(git_merge_base(&base, s->repo,
 				git_object_id(revs.from), git_object_id(revs.to)),
 				"Could not find merge base", revstr);
-			check(git_object_lookup(&revs.to, s->repo, &base, GIT_OBJ_COMMIT),
+			check_lg2(
+				git_object_lookup(&revs.to, s->repo, &base, GIT_OBJ_COMMIT),
 				"Could not find merge base commit", NULL);
 
 			push_rev(s, revs.to, hide);
@@ -122,6 +238,30 @@ static int add_revision(struct log_state *s, const char *revstr)
 	return 0;
 }
 
+/* update revwalker with sorting mode */
+static void set_sorting(struct log_state *s, unsigned int sort_mode)
+{
+	/* open repo on demand if it isn't already open */
+	if (!s->repo) {
+		if (!s->repodir) s->repodir = ".";
+		check_lg2(git_repository_open_ext(&s->repo, s->repodir, 0, NULL),
+			"Could not open repository", s->repodir);
+	}
+
+	/* create revwalker on demand if it doesn't already exist */
+	if (!s->walker)
+		check_lg2(git_revwalk_new(&s->walker, s->repo),
+			"Could not create revision walker", NULL);
+
+	if (sort_mode == GIT_SORT_REVERSE)
+		s->sorting = s->sorting ^ GIT_SORT_REVERSE;
+	else
+		s->sorting = sort_mode | (s->sorting & GIT_SORT_REVERSE);
+
+	git_revwalk_sorting(s->walker, s->sorting);
+}
+
+/* helper to format a git_time value like Git */
 static void print_time(const git_time *intime, const char *prefix)
 {
 	char sign, out[32];
@@ -148,6 +288,7 @@ static void print_time(const git_time *intime, const char *prefix)
 	printf("%s%s %c%02d%02d\n", prefix, out, sign, hours, minutes);
 }
 
+/* helper to print a commit object */
 static void print_commit(git_commit *commit)
 {
 	char buf[GIT_OID_HEXSZ + 1];
@@ -182,54 +323,21 @@ static void print_commit(git_commit *commit)
 	printf("\n");
 }
 
-static int print_diff(
-	const git_diff_delta *delta,
-	const git_diff_hunk *hunk,
-	const git_diff_line *line,
-	void *data)
-{
-	(void)delta; (void)hunk; (void)data;
-
-	if (line->origin == GIT_DIFF_LINE_CONTEXT ||
-		line->origin == GIT_DIFF_LINE_ADDITION ||
-		line->origin == GIT_DIFF_LINE_DELETION)
-		fputc(line->origin, stdout);
-
-	fwrite(line->content, 1, line->content_len, stdout);
-	return 0;
-}
-
-static int match_int(int *value, const char *arg, int allow_negative)
-{
-	char *found;
-	*value = (int)strtol(arg, &found, 10);
-	return (found && *found == '\0' && (allow_negative || *value >= 0));
-}
-
-static int match_int_arg(
-	int *value, const char *arg, const char *pfx, int allow_negative)
-{
-	size_t pfxlen = strlen(pfx);
-	if (strncmp(arg, pfx, pfxlen) != 0)
-		return 0;
-	if (!match_int(value, arg + pfxlen, allow_negative))
-		usage("Invalid value after argument", arg);
-	return 1;
-}
-
-static int match_with_parent(
-	git_commit *commit, int i, git_diff_options *opts)
+/* helper to find how many files in a commit changed from its nth parent */
+static int match_with_parent(git_commit *commit, int i, git_diff_options *opts)
 {
 	git_commit *parent;
 	git_tree *a, *b;
 	git_diff *diff;
 	int ndeltas;
 
-	check(git_commit_parent(&parent, commit, (size_t)i), "Get parent", NULL);
-	check(git_commit_tree(&a, parent), "Tree for parent", NULL);
-	check(git_commit_tree(&b, commit), "Tree for commit", NULL);
-	check(git_diff_tree_to_tree(&diff, git_commit_owner(commit), a, b, opts),
-		  "Checking diff between parent and commit", NULL);
+	check_lg2(
+		git_commit_parent(&parent, commit, (size_t)i), "Get parent", NULL);
+	check_lg2(git_commit_tree(&a, parent), "Tree for parent", NULL);
+	check_lg2(git_commit_tree(&b, commit), "Tree for commit", NULL);
+	check_lg2(
+		git_diff_tree_to_tree(&diff, git_commit_owner(commit), a, b, opts),
+		"Checking diff between parent and commit", NULL);
 
 	ndeltas = (int)git_diff_num_deltas(diff);
 
@@ -241,170 +349,76 @@ static int match_with_parent(
 	return ndeltas > 0;
 }
 
-struct log_options {
-	int show_diff;
-	int skip, limit;
-	int min_parents, max_parents;
-	git_time_t before;
-	git_time_t after;
-	char *author;
-	char *committer;
-};
-
-int main(int argc, char *argv[])
+/* print a usage message for the program */
+static void usage(const char *message, const char *arg)
 {
-	int i, count = 0, printed = 0, parents;
-	char *a;
-	struct log_state s;
-	struct log_options opt;
-	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
-	git_oid oid;
-	git_commit *commit = NULL;
-	git_pathspec *ps = NULL;
+	if (message && arg)
+		fprintf(stderr, "%s: %s\n", message, arg);
+	else if (message)
+		fprintf(stderr, "%s\n", message);
+	fprintf(stderr, "usage: log [<options>]\n");
+	exit(1);
+}
 
-	git_threads_init();
+/* parse some log command line options */
+static int parse_options(
+	struct log_state *s, struct log_options *opt, int argc, char **argv)
+{
+	struct args_info args = ARGS_INFO_INIT;
 
-	memset(&s, 0, sizeof(s));
-	s.sorting = GIT_SORT_TIME;
+	memset(s, 0, sizeof(*s));
+	s->sorting = GIT_SORT_TIME;
 
-	memset(&opt, 0, sizeof(opt));
-	opt.max_parents = -1;
- 	opt.limit = -1;
+	memset(opt, 0, sizeof(*opt));
+	opt->max_parents = -1;
+	opt->limit = -1;
 
-	for (i = 1; i < argc; ++i) {
-		a = argv[i];
+	for (args.pos = 1; args.pos < argc; ++args.pos) {
+		const char *a = argv[args.pos];
 
 		if (a[0] != '-') {
-			if (!add_revision(&s, a))
-				++count;
+			if (!add_revision(s, a))
+				s->revisions++;
 			else /* try failed revision parse as filename */
 				break;
 		} else if (!strcmp(a, "--")) {
-			++i;
+			++args.pos;
 			break;
 		}
 		else if (!strcmp(a, "--date-order"))
-			set_sorting(&s, GIT_SORT_TIME);
+			set_sorting(s, GIT_SORT_TIME);
 		else if (!strcmp(a, "--topo-order"))
-			set_sorting(&s, GIT_SORT_TOPOLOGICAL);
+			set_sorting(s, GIT_SORT_TOPOLOGICAL);
 		else if (!strcmp(a, "--reverse"))
-			set_sorting(&s, GIT_SORT_REVERSE);
-		else if (!strncmp(a, "--git-dir=", strlen("--git-dir=")))
-			s.repodir = a + strlen("--git-dir=");
-		else if (match_int_arg(&opt.skip, a, "--skip=", 0))
+			set_sorting(s, GIT_SORT_REVERSE);
+		else if (match_str_arg(&s->repodir, &args, "--git-dir"))
+			/* found git-dir */;
+		else if (match_int_arg(&opt->skip, &args, "--skip", 0))
 			/* found valid --skip */;
-		else if (match_int_arg(&opt.limit, a, "--max-count=", 0))
+		else if (match_int_arg(&opt->limit, &args, "--max-count", 0))
 			/* found valid --max-count */;
-		else if (a[1] >= '0' && a[1] <= '9') {
-			if (!match_int(&opt.limit, a + 1, 0))
-				usage("Invalid limit on number of commits", a);
-		} else if (!strcmp(a, "-n")) {
-			if (i + 1 == argc || !match_int(&opt.limit, argv[i + 1], 0))
-				usage("Argument -n not followed by valid count", argv[i + 1]);
-			else
-				++i;
-		}
+		else if (a[1] >= '0' && a[1] <= '9')
+			is_integer(&opt->limit, a + 1, 0);
+		else if (match_int_arg(&opt->limit, &args, "-n", 0))
+			/* found valid -n */;
 		else if (!strcmp(a, "--merges"))
-			opt.min_parents = 2;
+			opt->min_parents = 2;
 		else if (!strcmp(a, "--no-merges"))
-			opt.max_parents = 1;
+			opt->max_parents = 1;
 		else if (!strcmp(a, "--no-min-parents"))
-			opt.min_parents = 0;
+			opt->min_parents = 0;
 		else if (!strcmp(a, "--no-max-parents"))
-			opt.max_parents = -1;
-		else if (match_int_arg(&opt.max_parents, a, "--max-parents=", 1))
+			opt->max_parents = -1;
+		else if (match_int_arg(&opt->max_parents, &args, "--max-parents=", 1))
 			/* found valid --max-parents */;
-		else if (match_int_arg(&opt.min_parents, a, "--min-parents=", 0))
+		else if (match_int_arg(&opt->min_parents, &args, "--min-parents=", 0))
 			/* found valid --min_parents */;
 		else if (!strcmp(a, "-p") || !strcmp(a, "-u") || !strcmp(a, "--patch"))
-			opt.show_diff = 1;
+			opt->show_diff = 1;
 		else
 			usage("Unsupported argument", a);
 	}
 
-	if (!count)
-		add_revision(&s, NULL);
-
-	diffopts.pathspec.strings = &argv[i];
-	diffopts.pathspec.count   = argc - i;
-	if (diffopts.pathspec.count > 0)
-		check(git_pathspec_new(&ps, &diffopts.pathspec),
-			"Building pathspec", NULL);
-
-	printed = count = 0;
-
-	for (; !git_revwalk_next(&oid, s.walker); git_commit_free(commit)) {
-		check(git_commit_lookup(&commit, s.repo, &oid),
-			"Failed to look up commit", NULL);
-
-		parents = (int)git_commit_parentcount(commit);
-		if (parents < opt.min_parents)
-			continue;
-		if (opt.max_parents > 0 && parents > opt.max_parents)
-			continue;
-
-		if (diffopts.pathspec.count > 0) {
-			int unmatched = parents;
-
-			if (parents == 0) {
-				git_tree *tree;
-				check(git_commit_tree(&tree, commit), "Get tree", NULL);
-				if (git_pathspec_match_tree(
-						NULL, tree, GIT_PATHSPEC_NO_MATCH_ERROR, ps) != 0)
-					unmatched = 1;
-				git_tree_free(tree);
-			} else if (parents == 1) {
-				unmatched = match_with_parent(commit, 0, &diffopts) ? 0 : 1;
-			} else {
-				for (i = 0; i < parents; ++i) {
-					if (match_with_parent(commit, i, &diffopts))
-						unmatched--;
-				}
-			}
-
-			if (unmatched > 0)
-				continue;
-		}
-
-		if (count++ < opt.skip)
-			continue;
-		if (opt.limit != -1 && printed++ >= opt.limit) {
-			git_commit_free(commit);
-			break;
-		}
-
-		print_commit(commit);
-
-		if (opt.show_diff) {
-			git_tree *a = NULL, *b = NULL;
-			git_diff *diff = NULL;
-
-			if (parents > 1)
-				continue;
-			check(git_commit_tree(&b, commit), "Get tree", NULL);
-			if (parents == 1) {
-				git_commit *parent;
-				check(git_commit_parent(&parent, commit, 0), "Get parent", NULL);
-				check(git_commit_tree(&a, parent), "Tree for parent", NULL);
-				git_commit_free(parent);
-			}
-
-			check(git_diff_tree_to_tree(
-				&diff, git_commit_owner(commit), a, b, &diffopts),
-				"Diff commit with parent", NULL);
-			check(git_diff_print(diff, GIT_DIFF_FORMAT_PATCH, print_diff, NULL),
-				"Displaying diff", NULL);
-
-			git_diff_free(diff);
-			git_tree_free(a);
-			git_tree_free(b);
-		}
-	}
-
-	git_pathspec_free(ps);
-	git_revwalk_free(s.walker);
-	git_repository_free(s.repo);
-	git_threads_shutdown();
-
-	return 0;
+	return args.pos;
 }
+

examples/status.c

@@ -4,18 +4,8 @@
  * 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 <git2.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 
-enum {
-	FORMAT_DEFAULT   = 0,
-	FORMAT_LONG      = 1,
-	FORMAT_SHORT     = 2,
-	FORMAT_PORCELAIN = 3,
-};
-#define MAX_PATHSPEC 8
+#include "common.h"
 
 /*
  * This example demonstrates the use of the libgit2 status APIs,
@@ -35,32 +25,83 @@ enum {
  * - A sample status formatter that matches the "short" format
  */
 
-static void check(int error, const char *message, const char *extra)
+enum {
+	FORMAT_DEFAULT   = 0,
+	FORMAT_LONG      = 1,
+	FORMAT_SHORT     = 2,
+	FORMAT_PORCELAIN = 3,
+};
+
+#define MAX_PATHSPEC 8
+
+struct opts {
+    git_status_options statusopt;
+    char *repodir;
+    char *pathspec[MAX_PATHSPEC];
+    int npaths;
+    int format;
+    int zterm;
+    int showbranch;
+};
+
+static void parse_opts(struct opts *o, int argc, char *argv[]);
+static void show_branch(git_repository *repo, int format);
+static void print_long(git_repository *repo, git_status_list *status);
+static void print_short(git_repository *repo, git_status_list *status);
+
+int main(int argc, char *argv[])
 {
-	const git_error *lg2err;
-	const char *lg2msg = "", *lg2spacer = "";
+	git_repository *repo = NULL;
+	git_status_list *status;
+	struct opts o = { GIT_STATUS_OPTIONS_INIT, "." };
 
-	if (!error)
-		return;
+	git_threads_init();
 
-	if ((lg2err = giterr_last()) != NULL && lg2err->message != NULL) {
-		lg2msg = lg2err->message;
-		lg2spacer = " - ";
-	}
+	o.statusopt.show  = GIT_STATUS_SHOW_INDEX_AND_WORKDIR;
+	o.statusopt.flags = GIT_STATUS_OPT_INCLUDE_UNTRACKED |
+		GIT_STATUS_OPT_RENAMES_HEAD_TO_INDEX |
+		GIT_STATUS_OPT_SORT_CASE_SENSITIVELY;
+
+	parse_opts(&o, argc, argv);
+
+	/*
+	 * Try to open the repository at the given path (or at the current
+	 * directory if none was given).
+	 */
+	check_lg2(git_repository_open_ext(&repo, o.repodir, 0, NULL),
+		  "Could not open repository", o.repodir);
+
+	if (git_repository_is_bare(repo))
+		fatal("Cannot report status on bare repository",
+			git_repository_path(repo));
+
+	/*
+	 * Run status on the repository
+	 *
+	 * Because we want to simluate a full "git status" run and want to
+	 * support some command line options, we use `git_status_foreach_ext()`
+	 * instead of just the plain status call.  This allows (a) iterating
+	 * over the index and then the workdir and (b) extra flags that control
+	 * which files are included.  If you just want simple status (e.g. to
+	 * enumerate files that are modified) then you probably don't need the
+	 * extended API.
+	 */
+	check_lg2(git_status_list_new(&status, repo, &o.statusopt),
+		  "Could not get status", NULL);
 
-	if (extra)
-		fprintf(stderr, "%s '%s' [%d]%s%s\n",
-			message, extra, error, lg2spacer, lg2msg);
+	if (o.showbranch)
+		show_branch(repo, o.format);
+
+	if (o.format == FORMAT_LONG)
+		print_long(repo, status);
 	else
-		fprintf(stderr, "%s [%d]%s%s\n",
-			message, error, lg2spacer, lg2msg);
+		print_short(repo, status);
 
-	exit(1);
-}
+	git_status_list_free(status);
+	git_repository_free(repo);
+	git_threads_shutdown();
 
-static void fail(const char *message)
-{
-	check(-1, message, NULL);
+	return 0;
 }
 
 static void show_branch(git_repository *repo, int format)
@@ -78,7 +119,7 @@ static void show_branch(git_repository *repo, int format)
 		if (!strncmp(branch, "refs/heads/", strlen("refs/heads/")))
 			branch += strlen("refs/heads/");
 	} else
-		check(error, "failed to get current branch", NULL);
+		check_lg2(error, "failed to get current branch", NULL);
 
 	if (format == FORMAT_LONG)
 		printf("# On branch %s\n",
@@ -341,103 +382,58 @@ static void print_short(git_repository *repo, git_status_list *status)
 	}
 }
 
-int main(int argc, char *argv[])
+static void parse_opts(struct opts *o, int argc, char *argv[])
 {
-	git_repository *repo = NULL;
-	int i, npaths = 0, format = FORMAT_DEFAULT, zterm = 0, showbranch = 0;
-	git_status_options opt = GIT_STATUS_OPTIONS_INIT;
-	git_status_list *status;
-	char *repodir = ".", *pathspec[MAX_PATHSPEC];
+	struct args_info args = ARGS_INFO_INIT;
 
-	opt.show  = GIT_STATUS_SHOW_INDEX_AND_WORKDIR;
-	opt.flags = GIT_STATUS_OPT_INCLUDE_UNTRACKED |
-		GIT_STATUS_OPT_RENAMES_HEAD_TO_INDEX |
-		GIT_STATUS_OPT_SORT_CASE_SENSITIVELY;
+	for (args.pos = 1; args.pos < argc; ++args.pos) {
+		char *a = argv[args.pos];
 
-	for (i = 1; i < argc; ++i) {
-		if (argv[i][0] != '-') {
-			if (npaths < MAX_PATHSPEC)
-				pathspec[npaths++] = argv[i];
+		if (a[0] != '-') {
+			if (o->npaths < MAX_PATHSPEC)
+				o->pathspec[o->npaths++] = a;
 			else
-				fail("Example only supports a limited pathspec");
+				fatal("Example only supports a limited pathspec", NULL);
 		}
-		else if (!strcmp(argv[i], "-s") || !strcmp(argv[i], "--short"))
-			format = FORMAT_SHORT;
-		else if (!strcmp(argv[i], "--long"))
-			format = FORMAT_LONG;
-		else if (!strcmp(argv[i], "--porcelain"))
-			format = FORMAT_PORCELAIN;
-		else if (!strcmp(argv[i], "-b") || !strcmp(argv[i], "--branch"))
-			showbranch = 1;
-		else if (!strcmp(argv[i], "-z")) {
-			zterm = 1;
-			if (format == FORMAT_DEFAULT)
-				format = FORMAT_PORCELAIN;
+		else if (!strcmp(a, "-s") || !strcmp(a, "--short"))
+			o->format = FORMAT_SHORT;
+		else if (!strcmp(a, "--long"))
+			o->format = FORMAT_LONG;
+		else if (!strcmp(a, "--porcelain"))
+			o->format = FORMAT_PORCELAIN;
+		else if (!strcmp(a, "-b") || !strcmp(a, "--branch"))
+			o->showbranch = 1;
+		else if (!strcmp(a, "-z")) {
+			o->zterm = 1;
+			if (o->format == FORMAT_DEFAULT)
+				o->format = FORMAT_PORCELAIN;
 		}
-		else if (!strcmp(argv[i], "--ignored"))
-			opt.flags |= GIT_STATUS_OPT_INCLUDE_IGNORED;
-		else if (!strcmp(argv[i], "-uno") ||
-				 !strcmp(argv[i], "--untracked-files=no"))
-			opt.flags &= ~GIT_STATUS_OPT_INCLUDE_UNTRACKED;
-		else if (!strcmp(argv[i], "-unormal") ||
-				 !strcmp(argv[i], "--untracked-files=normal"))
-			opt.flags |= GIT_STATUS_OPT_INCLUDE_UNTRACKED;
-		else if (!strcmp(argv[i], "-uall") ||
-				 !strcmp(argv[i], "--untracked-files=all"))
-			opt.flags |= GIT_STATUS_OPT_INCLUDE_UNTRACKED |
+		else if (!strcmp(a, "--ignored"))
+			o->statusopt.flags |= GIT_STATUS_OPT_INCLUDE_IGNORED;
+		else if (!strcmp(a, "-uno") ||
+				 !strcmp(a, "--untracked-files=no"))
+			o->statusopt.flags &= ~GIT_STATUS_OPT_INCLUDE_UNTRACKED;
+		else if (!strcmp(a, "-unormal") ||
+				 !strcmp(a, "--untracked-files=normal"))
+			o->statusopt.flags |= GIT_STATUS_OPT_INCLUDE_UNTRACKED;
+		else if (!strcmp(a, "-uall") ||
+				 !strcmp(a, "--untracked-files=all"))
+			o->statusopt.flags |= GIT_STATUS_OPT_INCLUDE_UNTRACKED |
 				GIT_STATUS_OPT_RECURSE_UNTRACKED_DIRS;
-		else if (!strcmp(argv[i], "--ignore-submodules=all"))
-			opt.flags |= GIT_STATUS_OPT_EXCLUDE_SUBMODULES;
-		else if (!strncmp(argv[i], "--git-dir=", strlen("--git-dir=")))
-			repodir = argv[i] + strlen("--git-dir=");
+		else if (!strcmp(a, "--ignore-submodules=all"))
+			o->statusopt.flags |= GIT_STATUS_OPT_EXCLUDE_SUBMODULES;
+		else if (!strncmp(a, "--git-dir=", strlen("--git-dir=")))
+			o->repodir = a + strlen("--git-dir=");
 		else
-			check(-1, "Unsupported option", argv[i]);
+			check_lg2(-1, "Unsupported option", a);
 	}
 
-	if (format == FORMAT_DEFAULT)
-		format = FORMAT_LONG;
-	if (format == FORMAT_LONG)
-		showbranch = 1;
-	if (npaths > 0) {
-		opt.pathspec.strings = pathspec;
-		opt.pathspec.count   = npaths;
+	if (o->format == FORMAT_DEFAULT)
+		o->format = FORMAT_LONG;
+	if (o->format == FORMAT_LONG)
+		o->showbranch = 1;
+	if (o->npaths > 0) {
+		o->statusopt.pathspec.strings = o->pathspec;
+		o->statusopt.pathspec.count   = o->npaths;
 	}
-
-	/*
-	 * Try to open the repository at the given path (or at the current
-	 * directory if none was given).
-	 */
-	check(git_repository_open_ext(&repo, repodir, 0, NULL),
-		  "Could not open repository", repodir);
-
-	if (git_repository_is_bare(repo))
-		fail("Cannot report status on bare repository");
-
-	/*
-	 * Run status on the repository
-	 *
-	 * Because we want to simluate a full "git status" run and want to
-	 * support some command line options, we use `git_status_foreach_ext()`
-	 * instead of just the plain status call.  This allows (a) iterating
-	 * over the index and then the workdir and (b) extra flags that control
-	 * which files are included.  If you just want simple status (e.g. to
-	 * enumerate files that are modified) then you probably don't need the
-	 * extended API.
-	 */
-	check(git_status_list_new(&status, repo, &opt),
-		  "Could not get status", NULL);
-
-	if (showbranch)
-		show_branch(repo, format);
-
-	if (format == FORMAT_LONG)
-		print_long(repo, status);
-	else
-		print_short(repo, status);
-
-	git_status_list_free(status);
-	git_repository_free(repo);
-
-	return 0;
 }
-