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f4fcd74a6

Denys Vlasenko

2021-10-11

SUCCESS Duration: 155s

Subject

shell: do not read user database for every prompt - only for those which need it

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

libbb/lineedit.c +46 -27

libbb/lineedit.c+46 -27

@@ -135,10 +135,6 @@ enum {
	: 0x7ff0
	};

-	#if ENABLE_USERNAME_OR_HOMEDIR
-	static const char null_str[] ALIGN1 = "";
-	#endif
-
	/* We try to minimize both static and stack usage. */
	struct lineedit_statics {
	line_input_t *state;
@@ -161,12 +157,13 @@ struct lineedit_statics {

	#if ENABLE_USERNAME_OR_HOMEDIR
	char *user_buf;
-	char home_pwd_buf; / = (char)null_str; /
+	char *home_pwd_buf;
+	smallint got_user_strings;
	#endif

	#if ENABLE_FEATURE_TAB_COMPLETION
-	char **matches;
	unsigned num_matches;
+	char **matches;
	#endif

	#if ENABLE_FEATURE_EDITING_WINCH
@@ -207,8 +204,9 @@ extern struct lineedit_statics *BB_GLOBAL_CONST lineedit_ptr_to_statics;
	#define prompt_last_line (S.prompt_last_line)
	#define user_buf (S.user_buf )
	#define home_pwd_buf (S.home_pwd_buf )
-	#define matches (S.matches )
+	#define got_user_strings (S.got_user_strings)
	#define num_matches (S.num_matches )
+	#define matches (S.matches )
	#define delptr (S.delptr )
	#define newdelflag (S.newdelflag )
	#define delbuf (S.delbuf )
@@ -226,14 +224,47 @@ static void deinit_S(void)
	#endif
	#if ENABLE_USERNAME_OR_HOMEDIR
	free(user_buf);
-	if (home_pwd_buf != null_str)
-	free(home_pwd_buf);
+	free(home_pwd_buf);
	#endif
	free(lineedit_ptr_to_statics);
	}
	#define DEINIT_S() deinit_S()


+	#if ENABLE_USERNAME_OR_HOMEDIR
+	/* Call getpwuid() only if necessary.
+	* E.g. if PS1=':', no user database reading is needed to generate prompt.
+	* (Unfortunately, default PS1='\w \$' needs it, \w abbreviates homedir
+	* as ~/... - for that it needs to know the homedir...)
+	*/
+	static void get_user_strings(void)
+	{
+	struct passwd *entry;
+
+	got_user_strings = 1;
+	entry = getpwuid(geteuid());
+	if (entry) {
+	user_buf = xstrdup(entry->pw_name);
+	home_pwd_buf = xstrdup(entry->pw_dir);
+	}
+	}
+
+	static const char *get_username_str(void)
+	{
+	if (!got_user_strings)
+	get_user_strings();
+	return user_buf ? user_buf : "";
+	/* btw, bash uses "I have no name!" string if uid has no entry */
+	}
+
+	static NOINLINE const char *get_homedir_or_NULL(void)
+	{
+	if (!got_user_strings)
+	get_user_strings();
+	return home_pwd_buf;
+	}
+	#endif
+
	#if ENABLE_UNICODE_SUPPORT
	static size_t load_string(const char *src)
	{
@@ -691,11 +722,11 @@ static char username_path_completion(char ud)
	{
	struct passwd *entry;
	char *tilde_name = ud;
-	char *home = NULL;
+	const char *home = NULL;

	ud++; /* skip ~ */
	if (ud == '/') { / "~/..." */
-	home = home_pwd_buf;
+	home = get_homedir_or_NULL();
	} else {
	/* "~user/..." */
	ud = strchr(ud, '/');
@@ -1971,7 +2002,7 @@ static void parse_and_put_prompt(const char *prmt_ptr)

	switch (c) {
	case 'u':
-	pbuf = user_buf ? user_buf : (char*)"";
+	pbuf = (char*)get_username_str();
	break;
	case 'H':
	case 'h':
@@ -1993,14 +2024,15 @@ static void parse_and_put_prompt(const char *prmt_ptr)
	case 'w': /* current dir */
	case 'W': /* basename of cur dir */
	if (!cwd_buf) {
+	const char *home;
	cwd_buf = xrealloc_getcwd_or_warn(NULL);
	if (!cwd_buf)
	cwd_buf = (char *)bb_msg_unknown;
-	else if (home_pwd_buf[0]) {
+	else if ((home = get_homedir_or_NULL()) != NULL && home[0]) {
	char *after_home_user;

	/* /home/user[/something] -> ~[/something] */
-	after_home_user = is_prefixed_with(cwd_buf, home_pwd_buf);
+	after_home_user = is_prefixed_with(cwd_buf, home);
	if (after_home_user
	&& (after_home_user == '/' \|\| after_home_user == '\0')
	) {
@@ -2399,7 +2431,6 @@ int FAST_FUNC read_line_input(line_input_t st, const char prompt, char *comman
	//command_len = 0; - done by INIT_S()
	//cmdedit_y = 0; /* quasireal y, not true if line > xtyt /
	cmdedit_termw = 80;
-	IF_USERNAME_OR_HOMEDIR(home_pwd_buf = (char*)null_str;)
	IF_FEATURE_EDITING_VI(delptr = delbuf;)

	n = get_termios_and_make_raw(STDIN_FILENO, &new_settings, &initial_settings, 0
@@ -2459,18 +2490,6 @@ int FAST_FUNC read_line_input(line_input_t st, const char prompt, char *comman

	tcsetattr_stdin_TCSANOW(&new_settings);

-	#if ENABLE_USERNAME_OR_HOMEDIR
-	{
-	struct passwd *entry;
-
-	entry = getpwuid(geteuid());
-	if (entry) {
-	user_buf = xstrdup(entry->pw_name);
-	home_pwd_buf = xstrdup(entry->pw_dir);
-	}
-	}
-	#endif
-
	#if 0
	for (i = 0; i <= state->max_history; i++)
	bb_error_msg("history[%d]:'%s'", i, state->history[i]);