diff.c 7.45 KB
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/*
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 * libgit2 "diff" example - shows how to use the diff API
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 *
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 * 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/>.
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 */

#include "common.h"

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/**
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 * 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 */
};
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/** The 'opts' struct captures all the various parsed command line options. */
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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;
};

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/** These functions are implemented at the end */
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static void parse_opts(struct opts *o, int argc, char *argv[]);
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static int color_printer(
	const git_diff_delta*, const git_diff_hunk*, const git_diff_line*, void*);
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int main(int argc, char *argv[])
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{
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	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);

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	/**
	 * Possible argument patterns:
	 *
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	 *  * &lt;sha1&gt; &lt;sha2&gt;
	 *  * &lt;sha1&gt; --cached
	 *  * &lt;sha1&gt;
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	 *  * --cached
	 *  * nothing
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	 *
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	 * Currently ranged arguments like &lt;sha1&gt;..&lt;sha2&gt; and &lt;sha1&gt;...&lt;sha2&gt;
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	 * 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);
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	}
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	else
		check_lg2(
			git_diff_index_to_workdir(&diff, repo, NULL, &o.diffopts),
			"diff index to working directory", NULL);

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	/** Apply rename and copy detection if requested. */
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	if ((o.findopts.flags & GIT_DIFF_FIND_ALL) != 0)
		check_lg2(
			git_diff_find_similar(diff, &o.findopts),
			"finding renames and copies", NULL);

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	/** Generate simple output using libgit2 display helper. */
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	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);

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	/** Cleanup before exiting. */
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	git_diff_free(diff);
	git_tree_free(t1);
	git_tree_free(t2);
	git_repository_free(repo);

	git_threads_shutdown();

	return 0;
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}

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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);
}
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/** This implements very rudimentary colorized output. */
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static int color_printer(
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	const git_diff_delta *delta,
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	const git_diff_hunk *hunk,
	const git_diff_line *line,
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	void *data)
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{
	int *last_color = data, color = 0;

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	(void)delta; (void)hunk;
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	if (*last_color >= 0) {
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		switch (line->origin) {
		case GIT_DIFF_LINE_ADDITION:  color = 3; break;
		case GIT_DIFF_LINE_DELETION:  color = 2; break;
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		case GIT_DIFF_LINE_ADD_EOFNL: color = 3; break;
		case GIT_DIFF_LINE_DEL_EOFNL: color = 2; break;
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		case GIT_DIFF_LINE_FILE_HDR:  color = 1; break;
		case GIT_DIFF_LINE_HUNK_HDR:  color = 4; break;
		default: break;
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		}
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		if (color != *last_color) {
			if (*last_color == 1 || color == 1)
				fputs(colors[0], stdout);
			fputs(colors[color], stdout);
			*last_color = color;
		}
	}

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	return diff_output(delta, hunk, line, stdout);
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}

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/** Parse arguments as copied from git-diff. */
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static void parse_opts(struct opts *o, int argc, char *argv[])
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{
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	struct args_info args = ARGS_INFO_INIT;
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	for (args.pos = 1; args.pos < argc; ++args.pos) {
		const char *a = argv[args.pos];
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		if (a[0] != '-') {
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			if (o->treeish1 == NULL)
				o->treeish1 = a;
			else if (o->treeish2 == NULL)
				o->treeish2 = a;
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			else
				usage("Only one or two tree identifiers can be provided", NULL);
		}
		else if (!strcmp(a, "-p") || !strcmp(a, "-u") ||
			!strcmp(a, "--patch"))
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			o->format = GIT_DIFF_FORMAT_PATCH;
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		else if (!strcmp(a, "--cached"))
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			o->cached = 1;
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		else if (!strcmp(a, "--name-only"))
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			o->format = GIT_DIFF_FORMAT_NAME_ONLY;
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		else if (!strcmp(a, "--name-status"))
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			o->format = GIT_DIFF_FORMAT_NAME_STATUS;
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		else if (!strcmp(a, "--raw"))
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			o->format = GIT_DIFF_FORMAT_RAW;
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		else if (!strcmp(a, "--color"))
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			o->color = 0;
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		else if (!strcmp(a, "--no-color"))
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			o->color = -1;
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		else if (!strcmp(a, "-R"))
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			o->diffopts.flags |= GIT_DIFF_REVERSE;
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		else if (!strcmp(a, "-a") || !strcmp(a, "--text"))
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			o->diffopts.flags |= GIT_DIFF_FORCE_TEXT;
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		else if (!strcmp(a, "--ignore-space-at-eol"))
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			o->diffopts.flags |= GIT_DIFF_IGNORE_WHITESPACE_EOL;
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		else if (!strcmp(a, "-b") || !strcmp(a, "--ignore-space-change"))
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			o->diffopts.flags |= GIT_DIFF_IGNORE_WHITESPACE_CHANGE;
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		else if (!strcmp(a, "-w") || !strcmp(a, "--ignore-all-space"))
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			o->diffopts.flags |= GIT_DIFF_IGNORE_WHITESPACE;
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		else if (!strcmp(a, "--ignored"))
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			o->diffopts.flags |= GIT_DIFF_INCLUDE_IGNORED;
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		else if (!strcmp(a, "--untracked"))
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			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;
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		else if (!strcmp(a, "--find-copies-harder"))
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			o->findopts.flags |= GIT_DIFF_FIND_COPIES_FROM_UNMODIFIED;
		else if (is_prefixed(a, "-B") || is_prefixed(a, "--break-rewrites"))
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			/* TODO: parse thresholds */
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			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);
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	}
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}