thodg/libgit2/examples/rev-parse.c

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• Hash : ead10785
  Author :
  Date : 2019-01-24T11:31:49
  

  examples: create common lg2 executable
  
  Inside of our networking example code, we have a git2 executable
  that acts as an entry point to all the different network
  examples. As such, it is kind of the same like the normal git(1)
  executable in that it simply arbitrates to the respective
  subcommands.
  
  Let's extend this approach and merge all examples into a single
  standalone lg2 executable. Instead of building an executable
  for all the existing examples we have, we now bundle them all
  inside of the lg2 one and let them be callable via subcommands.
  
  In the process, we can get rid of duplicated library
  initialization, deinitialization and repository discovery code.
  Instead of having each subcommand handle these on its own, we
  simply do it inside of the single main function now.
  

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• examples/rev-parse.c

• /*
   * libgit2 "rev-parse" example - shows how to parse revspecs
   *
   * 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"
  
  /** Forward declarations for helpers. */
  struct parse_state {
  	const char *repodir;
  	const char *spec;
  	int not;
  };
  static void parse_opts(struct parse_state *ps, int argc, char *argv[]);
  static int parse_revision(git_repository *repo, struct parse_state *ps);
  
  int lg2_rev_parse(git_repository *repo, int argc, char *argv[])
  {
  	struct parse_state ps = {0};
  
  	parse_opts(&ps, argc, argv);
  
  	check_lg2(parse_revision(repo, &ps), "Parsing", NULL);
  
  	return 0;
  }
  
  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: rev-parse [ --option ] <args>...\n");
  	exit(1);
  }
  
  static void parse_opts(struct parse_state *ps, int argc, char *argv[])
  {
  	struct args_info args = ARGS_INFO_INIT;
  
  	for (args.pos=1; args.pos < argc; ++args.pos) {
  		const char *a = argv[args.pos];
  
  		if (a[0] != '-') {
  			if (ps->spec)
  				usage("Too many specs", a);
  			ps->spec = a;
  		} else if (!strcmp(a, "--not"))
  			ps->not = !ps->not;
  		else if (!match_str_arg(&ps->repodir, &args, "--git-dir"))
  			usage("Cannot handle argument", a);
  	}
  }
  
  static int parse_revision(git_repository *repo, struct parse_state *ps)
  {
  	git_revspec rs;
  	char str[GIT_OID_HEXSZ + 1];
  
  	check_lg2(git_revparse(&rs, repo, ps->spec), "Could not parse", ps->spec);
  
  	if ((rs.flags & GIT_REVPARSE_SINGLE) != 0) {
  		git_oid_tostr(str, sizeof(str), git_object_id(rs.from));
  		printf("%s\n", str);
  		git_object_free(rs.from);
  	}
  	else if ((rs.flags & GIT_REVPARSE_RANGE) != 0) {
  		git_oid_tostr(str, sizeof(str), git_object_id(rs.to));
  		printf("%s\n", str);
  		git_object_free(rs.to);
  
  		if ((rs.flags & GIT_REVPARSE_MERGE_BASE) != 0) {
  			git_oid base;
  			check_lg2(git_merge_base(&base, repo,
  						git_object_id(rs.from), git_object_id(rs.to)),
  					"Could not find merge base", ps->spec);
  
  			git_oid_tostr(str, sizeof(str), &base);
  			printf("%s\n", str);
  		}
  
  		git_oid_tostr(str, sizeof(str), git_object_id(rs.from));
  		printf("^%s\n", str);
  		git_object_free(rs.from);
  	}
  	else {
  		fatal("Invalid results from git_revparse", ps->spec);
  	}
  
  	return 0;
  }
  
  

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