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

function                                             old     new   delta
get_user_strings                                       -      52     +52
get_homedir_or_NULL                                    -      23     +23
parse_and_put_prompt                                 823     838     +15
null_str                                               1       -      -1
complete_cmd_dir_file                                814     812      -2
deinit_S                                              51      42      -9
read_line_input                                     3059    3015     -44
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 1/3 up/down: 90/-56)             Total: 34 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-10-11 23:08:31 +02:00
parent 6ba1f2d0bc
commit f4fcd74a6e

View File

@ -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 )
@ -226,7 +224,6 @@ static void deinit_S(void)
#endif
#if ENABLE_USERNAME_OR_HOMEDIR
free(user_buf);
if (home_pwd_buf != null_str)
free(home_pwd_buf);
#endif
free(lineedit_ptr_to_statics);
@ -234,6 +231,40 @@ static void deinit_S(void)
#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 > xt*yt */
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]);