kc3-lang/libgit2/examples/describe.c

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• Author : Etienne Samson
  Date : 2019-11-06 11:08:49
  Hash : 313908f9
  Message : examples: normalize decls and usage of options structs

• examples/describe.c

• /*
   * libgit2 "describe" example - shows how to describe commits
   *
   * Written by the libgit2 contributors
   *
   * To the extent possible under law, the author(s) have dedicated all copyright
   * and related and neighboring rights to this software to the public domain
   * worldwide. This software is distributed without any warranty.
   *
   * You should have received a copy of the CC0 Public Domain Dedication along
   * with this software. If not, see
   * <http://creativecommons.org/publicdomain/zero/1.0/>.
   */
  
  #include "common.h"
  
  /**
   * The following example partially reimplements the `git describe` command
   * and some of its options.
   *
   * These commands should work:
  
   * - Describe HEAD with default options (`describe`)
   * - Describe specified revision (`describe master~2`)
   * - Describe specified revisions (`describe master~2 HEAD~3`)
   * - Describe HEAD with dirty state suffix (`describe --dirty=*`)
   * - Describe consider all refs (`describe --all master`)
   * - Describe consider lightweight tags (`describe --tags temp-tag`)
   * - Describe show non-default abbreviated size (`describe --abbrev=10`)
   * - Describe always output the long format if matches a tag (`describe --long v1.0`)
   * - Describe consider only tags of specified pattern (`describe --match v*-release`)
   * - Describe show the fallback result (`describe --always`)
   * - Describe follow only the first parent commit (`describe --first-parent`)
   *
   * The command line parsing logic is simplified and doesn't handle
   * all of the use cases.
   */
  
  /** describe_options represents the parsed command line options */
  struct describe_options {
  	const char **commits;
  	size_t commit_count;
  	git_describe_options describe_options;
  	git_describe_format_options format_options;
  };
  
  static void opts_add_commit(struct describe_options *opts, const char *commit)
  {
  	size_t sz;
  
  	assert(opts != NULL);
  
  	sz = ++opts->commit_count * sizeof(opts->commits[0]);
  	opts->commits = xrealloc((void *) opts->commits, sz);
  	opts->commits[opts->commit_count - 1] = commit;
  }
  
  static void do_describe_single(git_repository *repo, struct describe_options *opts, const char *rev)
  {
  	git_object *commit;
  	git_describe_result *describe_result;
  	git_buf buf = { 0 };
  
  	if (rev) {
  		check_lg2(git_revparse_single(&commit, repo, rev),
  			"Failed to lookup rev", rev);
  
  		check_lg2(git_describe_commit(&describe_result, commit, &opts->describe_options),
  			"Failed to describe rev", rev);
  	}
  	else
  		check_lg2(git_describe_workdir(&describe_result, repo, &opts->describe_options),
  			"Failed to describe workdir", NULL);
  
  	check_lg2(git_describe_format(&buf, describe_result, &opts->format_options),
  			"Failed to format describe rev", rev);
  
  	printf("%s\n", buf.ptr);
  }
  
  static void do_describe(git_repository *repo, struct describe_options *opts)
  {
  	if (opts->commit_count == 0)
  		do_describe_single(repo, opts, NULL);
  	else
  	{
  		size_t i;
  		for (i = 0; i < opts->commit_count; i++)
  			do_describe_single(repo, opts, opts->commits[i]);
  	}
  }
  
  static void print_usage(void)
  {
  	fprintf(stderr, "usage: see `git help describe`\n");
  	exit(1);
  }
  
  /** Parse command line arguments */
  static void parse_options(struct describe_options *opts, int argc, char **argv)
  {
  	struct args_info args = ARGS_INFO_INIT;
  
  	for (args.pos = 1; args.pos < argc; ++args.pos) {
  		const char *curr = argv[args.pos];
  
  		if (curr[0] != '-') {
  			opts_add_commit(opts, curr);
  		} else if (!strcmp(curr, "--all")) {
  			opts->describe_options.describe_strategy = GIT_DESCRIBE_ALL;
  		} else if (!strcmp(curr, "--tags")) {
  			opts->describe_options.describe_strategy = GIT_DESCRIBE_TAGS;
  		} else if (!strcmp(curr, "--exact-match")) {
  			opts->describe_options.max_candidates_tags = 0;
  		} else if (!strcmp(curr, "--long")) {
  			opts->format_options.always_use_long_format = 1;
  		} else if (!strcmp(curr, "--always")) {
  			opts->describe_options.show_commit_oid_as_fallback = 1;
  		} else if (!strcmp(curr, "--first-parent")) {
  			opts->describe_options.only_follow_first_parent = 1;
  		} else if (optional_str_arg(&opts->format_options.dirty_suffix, &args, "--dirty", "-dirty")) {
  		} else if (match_int_arg((int *)&opts->format_options.abbreviated_size, &args, "--abbrev", 0)) {
  		} else if (match_int_arg((int *)&opts->describe_options.max_candidates_tags, &args, "--candidates", 0)) {
  		} else if (match_str_arg(&opts->describe_options.pattern, &args, "--match")) {
  		} else {
  			print_usage();
  		}
  	}
  
  	if (opts->commit_count > 0) {
  		if (opts->format_options.dirty_suffix)
  			fatal("--dirty is incompatible with commit-ishes", NULL);
  	}
  	else {
  		if (!opts->format_options.dirty_suffix || !opts->format_options.dirty_suffix[0]) {
  			opts_add_commit(opts, "HEAD");
  		}
  	}
  }
  
  /** Initialize describe_options struct */
  static void describe_options_init(struct describe_options *opts)
  {
  	memset(opts, 0, sizeof(*opts));
  
  	opts->commits = NULL;
  	opts->commit_count = 0;
  	git_describe_options_init(&opts->describe_options, GIT_DESCRIBE_OPTIONS_VERSION);
  	git_describe_format_options_init(&opts->format_options, GIT_DESCRIBE_FORMAT_OPTIONS_VERSION);
  }
  
  int lg2_describe(git_repository *repo, int argc, char **argv)
  {
  	struct describe_options opts;
  
  	describe_options_init(&opts);
  	parse_options(&opts, argc, argv);
  
  	do_describe(repo, &opts);
  
  	return 0;
  }