thodg/libgit2/examples/init.c

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• Hash : 2ba7dbbe
  Author :
  Date : 2019-06-24T14:55:15
  

  Resolve static check warnings in example code Using cppcheck on libgit2 sources indicated two warnings in example code. merge.c was reported as having a memory leak. Fix applied was to `free()` memory pointed to by `parents`. init.c was reported as having a null pointer dereference on variable arg. Function 'usage' was being called with a null variable. Changed supplied parameter to empty string.

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• examples/init.c

• /*
   * libgit2 "init" example - shows how to initialize a new repo
   *
   * 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"
  
  /**
   * This is a sample program that is similar to "git init".  See the
   * documentation for that (try "git help init") to understand what this
   * program is emulating.
   *
   * This demonstrates using the libgit2 APIs to initialize a new repository.
   *
   * This also contains a special additional option that regular "git init"
   * does not support which is "--initial-commit" to make a first empty commit.
   * That is demonstrated in the "create_initial_commit" helper function.
   */
  
  /** Forward declarations of helpers */
  struct opts {
  	int no_options;
  	int quiet;
  	int bare;
  	int initial_commit;
  	uint32_t shared;
  	const char *template;
  	const char *gitdir;
  	const char *dir;
  };
  static void create_initial_commit(git_repository *repo);
  static void parse_opts(struct opts *o, int argc, char *argv[]);
  
  int lg2_init(git_repository *repo, int argc, char *argv[])
  {
  	struct opts o = { 1, 0, 0, 0, GIT_REPOSITORY_INIT_SHARED_UMASK, 0, 0, 0 };
  
  	parse_opts(&o, argc, argv);
  
  	/* Initialize repository. */
  
  	if (o.no_options) {
  		/**
  		 * No options were specified, so let's demonstrate the default
  		 * simple case of git_repository_init() API usage...
  		 */
  		check_lg2(git_repository_init(&repo, o.dir, 0),
  			"Could not initialize repository", NULL);
  	}
  	else {
  		/**
  		 * Some command line options were specified, so we'll use the
  		 * extended init API to handle them
  		 */
  		git_repository_init_options initopts = GIT_REPOSITORY_INIT_OPTIONS_INIT;
  		initopts.flags = GIT_REPOSITORY_INIT_MKPATH;
  
  		if (o.bare)
  			initopts.flags |= GIT_REPOSITORY_INIT_BARE;
  
  		if (o.template) {
  			initopts.flags |= GIT_REPOSITORY_INIT_EXTERNAL_TEMPLATE;
  			initopts.template_path = o.template;
  		}
  
  		if (o.gitdir) {
  			/**
  			 * If you specified a separate git directory, then initialize
  			 * the repository at that path and use the second path as the
  			 * working directory of the repository (with a git-link file)
  			 */
  			initopts.workdir_path = o.dir;
  			o.dir = o.gitdir;
  		}
  
  		if (o.shared != 0)
  			initopts.mode = o.shared;
  
  		check_lg2(git_repository_init_ext(&repo, o.dir, &initopts),
  				"Could not initialize repository", NULL);
  	}
  
  	/** Print a message to stdout like "git init" does. */
  
  	if (!o.quiet) {
  		if (o.bare || o.gitdir)
  			o.dir = git_repository_path(repo);
  		else
  			o.dir = git_repository_workdir(repo);
  
  		printf("Initialized empty Git repository in %s\n", o.dir);
  	}
  
  	/**
  	 * As an extension to the basic "git init" command, this example
  	 * gives the option to create an empty initial commit.  This is
  	 * mostly to demonstrate what it takes to do that, but also some
  	 * people like to have that empty base commit in their repo.
  	 */
  	if (o.initial_commit) {
  		create_initial_commit(repo);
  		printf("Created empty initial commit\n");
  	}
  
  	git_repository_free(repo);
  
  	return 0;
  }
  
  /**
   * Unlike regular "git init", this example shows how to create an initial
   * empty commit in the repository.  This is the helper function that does
   * that.
   */
  static void create_initial_commit(git_repository *repo)
  {
  	git_signature *sig;
  	git_index *index;
  	git_oid tree_id, commit_id;
  	git_tree *tree;
  
  	/** First use the config to initialize a commit signature for the user. */
  
  	if (git_signature_default(&sig, repo) < 0)
  		fatal("Unable to create a commit signature.",
  		      "Perhaps 'user.name' and 'user.email' are not set");
  
  	/* Now let's create an empty tree for this commit */
  
  	if (git_repository_index(&index, repo) < 0)
  		fatal("Could not open repository index", NULL);
  
  	/**
  	 * Outside of this example, you could call git_index_add_bypath()
  	 * here to put actual files into the index.  For our purposes, we'll
  	 * leave it empty for now.
  	 */
  
  	if (git_index_write_tree(&tree_id, index) < 0)
  		fatal("Unable to write initial tree from index", NULL);
  
  	git_index_free(index);
  
  	if (git_tree_lookup(&tree, repo, &tree_id) < 0)
  		fatal("Could not look up initial tree", NULL);
  
  	/**
  	 * Ready to create the initial commit.
  	 *
  	 * Normally creating a commit would involve looking up the current
  	 * HEAD commit and making that be the parent of the initial commit,
  	 * but here this is the first commit so there will be no parent.
  	 */
  
  	if (git_commit_create_v(
  			&commit_id, repo, "HEAD", sig, sig,
  			NULL, "Initial commit", tree, 0) < 0)
  		fatal("Could not create the initial commit", NULL);
  
  	/** Clean up so we don't leak memory. */
  
  	git_tree_free(tree);
  	git_signature_free(sig);
  }
  
  static void usage(const char *error, const char *arg)
  {
  	fprintf(stderr, "error: %s '%s'\n", error, arg);
  	fprintf(stderr,
  			"usage: init [-q | --quiet] [--bare] [--template=<dir>]\n"
  			"            [--shared[=perms]] [--initial-commit]\n"
  			"            [--separate-git-dir] <directory>\n");
  	exit(1);
  }
  
  /** Parse the tail of the --shared= argument. */
  static uint32_t parse_shared(const char *shared)
  {
  	if (!strcmp(shared, "false") || !strcmp(shared, "umask"))
  		return GIT_REPOSITORY_INIT_SHARED_UMASK;
  
  	else if (!strcmp(shared, "true") || !strcmp(shared, "group"))
  		return GIT_REPOSITORY_INIT_SHARED_GROUP;
  
  	else if (!strcmp(shared, "all") || !strcmp(shared, "world") ||
  			 !strcmp(shared, "everybody"))
  		return GIT_REPOSITORY_INIT_SHARED_ALL;
  
  	else if (shared[0] == '0') {
  		long val;
  		char *end = NULL;
  		val = strtol(shared + 1, &end, 8);
  		if (end == shared + 1 || *end != 0)
  			usage("invalid octal value for --shared", shared);
  		return (uint32_t)val;
  	}
  
  	else
  		usage("unknown value for --shared", shared);
  
  	return 0;
  }
  
  static void parse_opts(struct opts *o, int argc, char *argv[])
  {
  	struct args_info args = ARGS_INFO_INIT;
  	const char *sharedarg;
  
  	/** Process arguments. */
  
  	for (args.pos = 1; args.pos < argc; ++args.pos) {
  		char *a = argv[args.pos];
  
  		if (a[0] == '-')
  			o->no_options = 0;
  
  		if (a[0] != '-') {
  			if (o->dir != NULL)
  				usage("extra argument", a);
  			o->dir = a;
  		}
  		else if (!strcmp(a, "-q") || !strcmp(a, "--quiet"))
  			o->quiet = 1;
  		else if (!strcmp(a, "--bare"))
  			o->bare = 1;
  		else if (!strcmp(a, "--shared"))
  			o->shared = GIT_REPOSITORY_INIT_SHARED_GROUP;
  		else if (!strcmp(a, "--initial-commit"))
  			o->initial_commit = 1;
  		else if (match_str_arg(&sharedarg, &args, "--shared"))
  			o->shared = parse_shared(sharedarg);
  		else if (!match_str_arg(&o->template, &args, "--template") ||
  		         !match_str_arg(&o->gitdir, &args, "--separate-git-dir"))
  			usage("unknown option", a);
  	}
  
  	if (!o->dir)
  		usage("must specify directory to init", "");
  }
  

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