text: /*
   * builtin-help.c
   *
   * Builtin help command
   */
  #include "cache.h"
  #include "builtin.h"
  #include "exec_cmd.h"
  #include "parse-options.h"
  #include "run-command.h"
  #include "column.h"
  #include "help.h"
  
  #ifndef DEFAULT_HELP_FORMAT
  #define DEFAULT_HELP_FORMAT "man"
  #endif
  
  static struct man_viewer_list {
  	struct man_viewer_list *next;
  	char name[FLEX_ARRAY];
  } *man_viewer_list;
  
  static struct man_viewer_info_list {
  	struct man_viewer_info_list *next;
  	const char *info;
  	char name[FLEX_ARRAY];
  } *man_viewer_info_list;
  
  enum help_format {
  	HELP_FORMAT_NONE,
  	HELP_FORMAT_MAN,
  	HELP_FORMAT_INFO,
  	HELP_FORMAT_WEB
  };
  
  static const char *html_path;
  
  static int show_all = 0;
  static int show_guides = 0;
  static unsigned int colopts;
  static enum help_format help_format = HELP_FORMAT_NONE;
  static struct option builtin_help_options[] = {
  	OPT_BOOL('a', "all", &show_all, N_("print all available commands")),
  	OPT_BOOL('g', "guides", &show_guides, N_("print list of useful guides")),
  	OPT_SET_INT('m', "man", &help_format, N_("show man page"), HELP_FORMAT_MAN),
  	OPT_SET_INT('w', "web", &help_format, N_("show manual in web browser"),
  			HELP_FORMAT_WEB),
  	OPT_SET_INT('i', "info", &help_format, N_("show info page"),
  			HELP_FORMAT_INFO),
  	OPT_END(),
  };
  
  static const char * const builtin_help_usage[] = {
  	N_("git help [--all] [--guides] [--man|--web|--info] [command]"),
  	NULL
  };
  
  static enum help_format parse_help_format(const char *format)
  {
  	if (!strcmp(format, "man"))
  		return HELP_FORMAT_MAN;
  	if (!strcmp(format, "info"))
  		return HELP_FORMAT_INFO;
  	if (!strcmp(format, "web") || !strcmp(format, "html"))
  		return HELP_FORMAT_WEB;
  	die(_("unrecognized help format '%s'"), format);
  }
  
  static const char *get_man_viewer_info(const char *name)
  {
  	struct man_viewer_info_list *viewer;
  
  	for (viewer = man_viewer_info_list; viewer; viewer = viewer->next)
  	{
  		if (!strcasecmp(name, viewer->name))
  			return viewer->info;
  	}
  	return NULL;
  }
  
  static int check_emacsclient_version(void)
  {
  	struct strbuf buffer = STRBUF_INIT;
  	struct child_process ec_process;
  	const char *argv_ec[] = { "emacsclient", "--version", NULL };
  	int version;
  
  	/* emacsclient prints its version number on stderr */
  	memset(&ec_process, 0, sizeof(ec_process));
  	ec_process.argv = argv_ec;
  	ec_process.err = -1;
  	ec_process.stdout_to_stderr = 1;
  	if (start_command(&ec_process))
  		return error(_("Failed to start emacsclient."));
  
  	strbuf_read(&buffer, ec_process.err, 20);
  	close(ec_process.err);
  
  	/*
  	 * Don't bother checking return value, because "emacsclient --version"
  	 * seems to always exits with code 1.
  	 */
  	finish_command(&ec_process);
  
  	if (prefixcmp(buffer.buf, "emacsclient")) {
  		strbuf_release(&buffer);
  		return error(_("Failed to parse emacsclient version."));
  	}
  
  	strbuf_remove(&buffer, 0, strlen("emacsclient"));
  	version = atoi(buffer.buf);
  
  	if (version < 22) {
  		strbuf_release(&buffer);
  		return error(_("emacsclient version '%d' too old (< 22)."),
  			version);
  	}
  
  	strbuf_release(&buffer);
  	return 0;
  }
  
  static void exec_woman_emacs(const char *path, const char *page)
  {
  	if (!check_emacsclient_version()) {
  		/* This works only with emacsclient version >= 22. */
  		struct strbuf man_page = STRBUF_INIT;
  
  		if (!path)
  			path = "emacsclient";
  		strbuf_addf(&man_page, "(woman \"%s\")", page);
  		execlp(path, "emacsclient", "-e", man_page.buf, (char *)NULL);
  		warning(_("failed to exec '%s': %s"), path, strerror(errno));
  	}
  }
  
  static void exec_man_konqueror(const char *path, const char *page)
  {
  	const char *display = getenv("DISPLAY");
  	if (display && *display) {
  		struct strbuf man_page = STRBUF_INIT;
  		const char *filename = "kfmclient";
  
  		/* It's simpler to launch konqueror using kfmclient. */
  		if (path) {
  			const char *file = strrchr(path, '/');
  			if (file && !strcmp(file + 1, "konqueror")) {
  				char *new = xstrdup(path);
  				char *dest = strrchr(new, '/');
  
  				/* strlen("konqueror") == strlen("kfmclient") */
  				strcpy(dest + 1, "kfmclient");
  				path = new;
  			}
  			if (file)
  				filename = file;
  		} else
  			path = "kfmclient";
  		strbuf_addf(&man_page, "man:%s(1)", page);
  		execlp(path, filename, "newTab", man_page.buf, (char *)NULL);
  		warning(_("failed to exec '%s': %s"), path, strerror(errno));
  	}
  }
  
  static void exec_man_man(const char *path, const char *page)
  {
  	if (!path)
  		path = "man";
  	execlp(path, "man", page, (char *)NULL);
  	warning(_("failed to exec '%s': %s"), path, strerror(errno));
  }
  
  static void exec_man_cmd(const char *cmd, const char *page)
  {
  	struct strbuf shell_cmd = STRBUF_INIT;
  	strbuf_addf(&shell_cmd, "%s %s", cmd, page);
  	execl("/bin/sh", "sh", "-c", shell_cmd.buf, (char *)NULL);
  	warning(_("failed to exec '%s': %s"), cmd, strerror(errno));
  }
  
  static void add_man_viewer(const char *name)
  {
  	struct man_viewer_list **p = &man_viewer_list;
  	size_t len = strlen(name);
  
  	while (*p)
  		p = &((*p)->next);
  	*p = xcalloc(1, (sizeof(**p) + len + 1));
  	strncpy((*p)->name, name, len);
  }
  
  static int supported_man_viewer(const char *name, size_t len)
  {
  	return (!strncasecmp("man", name, len) ||
  		!strncasecmp("woman", name, len) ||
  		!strncasecmp("konqueror", name, len));
  }
  
  static void do_add_man_viewer_info(const char *name,
  				   size_t len,
  				   const char *value)
  {
  	struct man_viewer_info_list *new = xcalloc(1, sizeof(*new) + len + 1);
  
  	strncpy(new->name, name, len);
  	new->info = xstrdup(value);
  	new->next = man_viewer_info_list;
  	man_viewer_info_list = new;
  }
  
  static int add_man_viewer_path(const char *name,
  			       size_t len,
  			       const char *value)
  {
  	if (supported_man_viewer(name, len))
  		do_add_man_viewer_info(name, len, value);
  	else
  		warning(_("'%s': path for unsupported man viewer.\n"
  			  "Please consider using 'man.<tool>.cmd' instead."),
  			name);
  
  	return 0;
  }
  
  static int add_man_viewer_cmd(const char *name,
  			      size_t len,
  			      const char *value)
  {
  	if (supported_man_viewer(name, len))
  		warning(_("'%s': cmd for supported man viewer.\n"
  			  "Please consider using 'man.<tool>.path' instead."),
  			name);
  	else
  		do_add_man_viewer_info(name, len, value);
  
  	return 0;
  }
  
  static int add_man_viewer_info(const char *var, const char *value)
  {
  	const char *name, *subkey;
  	int namelen;
  
  	if (parse_config_key(var, "man", &name, &namelen, &subkey) < 0 || !name)
  		return 0;
  
  	if (!strcmp(subkey, "path")) {
  		if (!value)
  			return config_error_nonbool(var);
  		return add_man_viewer_path(name, namelen, value);
  	}
  	if (!strcmp(subkey, "cmd")) {
  		if (!value)
  			return config_error_nonbool(var);
  		return add_man_viewer_cmd(name, namelen, value);
  	}
  
  	return 0;
  }
  
  static int git_help_config(const char *var, const char *value, void *cb)
  {
  	if (!prefixcmp(var, "column."))
  		return git_column_config(var, value, "help", &colopts);
  	if (!strcmp(var, "help.format")) {
  		if (!value)
  			return config_error_nonbool(var);
  		help_format = parse_help_format(value);
  		return 0;
  	}
  	if (!strcmp(var, "help.htmlpath")) {
  		if (!value)
  			return config_error_nonbool(var);
  		html_path = xstrdup(value);
  		return 0;
  	}
  	if (!strcmp(var, "man.viewer")) {
  		if (!value)
  			return config_error_nonbool(var);
  		add_man_viewer(value);
  		return 0;
  	}
  	if (!prefixcmp(var, "man."))
  		return add_man_viewer_info(var, value);
  
  	return git_default_config(var, value, cb);
  }
  
  static struct cmdnames main_cmds, other_cmds;
  
  static int is_git_command(const char *s)
  {
  	return is_in_cmdlist(&main_cmds, s) ||
  		is_in_cmdlist(&other_cmds, s);
  }
  
  static const char *prepend(const char *prefix, const char *cmd)
  {
  	size_t pre_len = strlen(prefix);
  	size_t cmd_len = strlen(cmd);
  	char *p = xmalloc(pre_len + cmd_len + 1);
  	memcpy(p, prefix, pre_len);
  	strcpy(p + pre_len, cmd);
  	return p;
  }
  
  static const char *cmd_to_page(const char *git_cmd)
  {
  	if (!git_cmd)
  		return "git";
  	else if (!prefixcmp(git_cmd, "git"))
  		return git_cmd;
  	else if (is_git_command(git_cmd))
  		return prepend("git-", git_cmd);
  	else
  		return prepend("git", git_cmd);
  }
  
  static void setup_man_path(void)
  {
  	struct strbuf new_path = STRBUF_INIT;
  	const char *old_path = getenv("MANPATH");
  
  	/* We should always put ':' after our path. If there is no
  	 * old_path, the ':' at the end will let 'man' to try
  	 * system-wide paths after ours to find the manual page. If
  	 * there is old_path, we need ':' as delimiter. */
  	strbuf_addstr(&new_path, system_path(GIT_MAN_PATH));
  	strbuf_addch(&new_path, ':');
  	if (old_path)
  		strbuf_addstr(&new_path, old_path);
  
  	setenv("MANPATH", new_path.buf, 1);
  
  	strbuf_release(&new_path);
  }
  
  static void exec_viewer(const char *name, const char *page)
  {
  	const char *info = get_man_viewer_info(name);
  
  	if (!strcasecmp(name, "man"))
  		exec_man_man(info, page);
  	else if (!strcasecmp(name, "woman"))
  		exec_woman_emacs(info, page);
  	else if (!strcasecmp(name, "konqueror"))
  		exec_man_konqueror(info, page);
  	else if (info)
  		exec_man_cmd(info, page);
  	else
  		warning(_("'%s': unknown man viewer."), name);
  }
  
  static void show_man_page(const char *git_cmd)
  {
  	struct man_viewer_list *viewer;
  	const char *page = cmd_to_page(git_cmd);
  	const char *fallback = getenv("GIT_MAN_VIEWER");
  
  	setup_man_path();
  	for (viewer = man_viewer_list; viewer; viewer = viewer->next)
  	{
  		exec_viewer(viewer->name, page); /* will return when unable */
  	}
  	if (fallback)
  		exec_viewer(fallback, page);
  	exec_viewer("man", page);
  	die(_("no man viewer handled the request"));
  }
  
  static void show_info_page(const char *git_cmd)
  {
  	const char *page = cmd_to_page(git_cmd);
  	setenv("INFOPATH", system_path(GIT_INFO_PATH), 1);
  	execlp("info", "info", "gitman", page, (char *)NULL);
  	die(_("no info viewer handled the request"));
  }
  
  static void get_html_page_path(struct strbuf *page_path, const char *page)
  {
  	struct stat st;
  	if (!html_path)
  		html_path = system_path(GIT_HTML_PATH);
  
  	/* Check that we have a git documentation directory. */
  	if (!strstr(html_path, "://")) {
  		if (stat(mkpath("%s/git.html", html_path), &st)
  		    || !S_ISREG(st.st_mode))
  			die("'%s': not a documentation directory.", html_path);
  	}
  
  	strbuf_init(page_path, 0);
  	strbuf_addf(page_path, "%s/%s.html", html_path, page);
  }
  
  /*
   * If open_html is not defined in a platform-specific way (see for
   * example compat/mingw.h), we use the script web--browse to display
   * HTML.
   */
  #ifndef open_html
  static void open_html(const char *path)
  {
  	execl_git_cmd("web--browse", "-c", "help.browser", path, (char *)NULL);
  }
  #endif
  
  static void show_html_page(const char *git_cmd)
  {
  	const char *page = cmd_to_page(git_cmd);
  	struct strbuf page_path; /* it leaks but we exec bellow */
  
  	get_html_page_path(&page_path, page);
  
  	open_html(page_path.buf);
  }
  
  static struct {
  	const char *name;
  	const char *help;
  } common_guides[] = {
  	{ "attributes", N_("Defining attributes per path") },
  	{ "glossary", N_("A Git glossary") },
  	{ "ignore", N_("Specifies intentionally untracked files to ignore") },
  	{ "modules", N_("Defining submodule properties") },
  	{ "revisions", N_("Specifying revisions and ranges for Git") },
  	{ "tutorial", N_("A tutorial introduction to Git (for version 1.5.1 or newer)") },
  	{ "workflows", N_("An overview of recommended workflows with Git") },
  };
  
  static void list_common_guides_help(void)
  {
  	int i, longest = 0;
  
  	for (i = 0; i < ARRAY_SIZE(common_guides); i++) {
  		if (longest < strlen(common_guides[i].name))
  			longest = strlen(common_guides[i].name);
  	}
  
  	puts(_("The common Git guides are:\n"));
  	for (i = 0; i < ARRAY_SIZE(common_guides); i++) {
  		printf("   %s   ", common_guides[i].name);
  		mput_char(' ', longest - strlen(common_guides[i].name));
  		puts(_(common_guides[i].help));
  	}
  	putchar('\n');
  }
  
  int cmd_help(int argc, const char **argv, const char *prefix)
  {
  	int nongit;
  	const char *alias;
  	enum help_format parsed_help_format;
  	load_command_list("git-", &main_cmds, &other_cmds);
  
  	argc = parse_options(argc, argv, prefix, builtin_help_options,
  			builtin_help_usage, 0);
  	parsed_help_format = help_format;
  
  	if (show_all) {
  		git_config(git_help_config, NULL);
  		printf(_("usage: %s%s"), _(git_usage_string), "\n\n");
  		list_commands(colopts, &main_cmds, &other_cmds);
  	}
  
  	if (show_guides)
  		list_common_guides_help();
  
  	if (show_all || show_guides) {
  		printf("%s\n", _(git_more_info_string));
  		/*
  		* We're done. Ignore any remaining args
  		*/
  		return 0;
  	}
  
  	if (!argv[0]) {
  		printf(_("usage: %s%s"), _(git_usage_string), "\n\n");
  		list_common_cmds_help();
  		printf("\n%s\n", _(git_more_info_string));
  		return 0;
  	}
  
  	setup_git_directory_gently(&nongit);
  	git_config(git_help_config, NULL);
  
  	if (parsed_help_format != HELP_FORMAT_NONE)
  		help_format = parsed_help_format;
  	if (help_format == HELP_FORMAT_NONE)
  		help_format = parse_help_format(DEFAULT_HELP_FORMAT);
  
  	alias = alias_lookup(argv[0]);
  	if (alias && !is_git_command(argv[0])) {
  		printf_ln(_("`git %s' is aliased to `%s'"), argv[0], alias);
  		return 0;
  	}
  
  	switch (help_format) {
  	case HELP_FORMAT_NONE:
  	case HELP_FORMAT_MAN:
  		show_man_page(argv[0]);
  		break;
  	case HELP_FORMAT_INFO:
  		show_info_page(argv[0]);
  		break;
  	case HELP_FORMAT_WEB:
  		show_html_page(argv[0]);
  		break;
  	}
  
  	return 0;
  }
  