thodg/libgit2/src/cli/main.c

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• Hash : 3a3ab065
  Author :
  Date : 2020-05-03T23:13:28
  

  cli: infrastructure for a cli project
  
  Introduce a command-line interface for libgit2.  The goal is for it to
  be git-compatible.
  
  1. The libgit2 developers can more easily dogfood libgit2 to find bugs,
     and performance issues.
  
  2. There is growing usage of libgit2's examples as a client; libgit2's
     examples should be exactly that - simple code samples that illustrate
     libgit2's usage.  This satisfies that need directly.
  
  3. By producing a client ourselves, we can better understand the needs
     of client creators, possibly producing a shared "middleware" for
     commonly-used pieces of client functionality like interacting with
     external tools.
  
  4. Since git is the reference implementation, we may be able to benefit
     from git's unit tests, running their test suite against our CLI to
     ensure correct behavior.
  
  This commit introduces a simple infrastructure for the CLI.
  
  The CLI is currently links libgit2 statically; this is because the
  utility layer is required for libgit2 _but_ shares the error state
  handling with libgit2 itself.  There's no obviously good solution
  here without introducing annoying indirection or more complexity.
  Until we can untangle that dependency, this is a good step forward.
  
  In the meantime, we link the libgit2 object files, but we do not include
  the (private) libgit2 headers.  This constrains the CLI to the public
  libgit2 interfaces.
  

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• src/cli/main.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 <stdio.h>
  #include <git2.h>
  #include "cli.h"
  #include "cmd.h"
  
  static int show_help = 0;
  static int show_version = 0;
  static char *command = NULL;
  static char **args = NULL;
  
  const cli_opt_spec cli_common_opts[] = {
  	{ CLI_OPT_TYPE_SWITCH,    "help",      0, &show_help,    1,
  	  CLI_OPT_USAGE_DEFAULT,   NULL,      "display help information" },
  	{ CLI_OPT_TYPE_SWITCH,    "version",   0, &show_version, 1,
  	  CLI_OPT_USAGE_DEFAULT,   NULL,      "display the version" },
  	{ CLI_OPT_TYPE_ARG,       "command",   0, &command,      0,
  	  CLI_OPT_USAGE_REQUIRED, "command", "the command to run" },
  	{ CLI_OPT_TYPE_ARGS,      "args",      0, &args,         0,
  	  CLI_OPT_USAGE_DEFAULT,  "args",    "arguments for the command" },
  	{ 0 }
  };
  
  const cli_cmd_spec cli_cmds[] = {
  	{ "cat-file",    cmd_cat_file,    "Display an object in the repository" },
  	{ "hash-object", cmd_hash_object, "Hash a raw object and product its object ID" },
  	{ "help",        cmd_help,        "Display help information" },
  	{ NULL }
  };
  
  int main(int argc, char **argv)
  {
  	const cli_cmd_spec *cmd;
  	cli_opt_parser optparser;
  	cli_opt opt;
  	char *help_args[3] = { NULL };
  	int help_args_len;
  	int args_len = 0;
  	int ret = 0;
  
  	if (git_libgit2_init() < 0) {
  		cli_error("failed to initialize libgit2");
  		exit(CLI_EXIT_GIT);
  	}
  
  	cli_opt_parser_init(&optparser, cli_common_opts, argv + 1, argc - 1, CLI_OPT_PARSE_GNU);
  
  	/* Parse the top-level (common) options and command information */
  	while (cli_opt_parser_next(&opt, &optparser)) {
  		if (!opt.spec) {
  			cli_opt_status_fprint(stderr, PROGRAM_NAME, &opt);
  			cli_opt_usage_fprint(stderr, PROGRAM_NAME, NULL, cli_common_opts);
  			ret = CLI_EXIT_USAGE;
  			goto done;
  		}
  
  		/*
  		 * When we see a command, stop parsing and capture the
  		 * remaining arguments as args for the command itself.
  		 */
  		if (command) {
  			args = &argv[optparser.idx];
  			args_len = (int)(argc - optparser.idx);
  			break;
  		}
  	}
  
  	if (show_version) {
  		printf("%s version %s\n", PROGRAM_NAME, LIBGIT2_VERSION);
  		goto done;
  	}
  
  	/*
  	 * If `--help <command>` is specified, delegate to that command's
  	 * `--help` option.  If no command is specified, run the `help`
  	 * command.  Do this by updating the args to emulate that behavior.
  	 */
  	if (!command || show_help) {
  		help_args[0] = command ? (char *)command : "help";
  		help_args[1] = command ? "--help" : NULL;
  		help_args_len = command ? 2 : 1;
  
  		command = help_args[0];
  		args = help_args;
  		args_len = help_args_len;
  	}
  
  	if ((cmd = cli_cmd_spec_byname(command)) == NULL) {
  		ret = cli_error("'%s' is not a %s command. See '%s help'.",
  		                command, PROGRAM_NAME, PROGRAM_NAME);
  		goto done;
  	}
  
  	ret = cmd->fn(args_len, args);
  
  done:
  	git_libgit2_shutdown();
  	return ret;
  }
  

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