lineedit: stop using both data/bss and tons of stack.

stack usage was ~10 kb!
unfortunately, noticeable code size growth:
   text    data     bss     dec     hex filename
   9252      12     181    9445    24e5 busybox.t7/libbb/lineedit.o
   9714       4       0    9718    25f6 busybox.t8/libbb/lineedit.o

1 files changed, 166 insertions, 93 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index f65e852b1..4d33834ce 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -41,7 +41,6 @@
 #define ENABLE_FEATURE_TAB_COMPLETION 0
 #define ENABLE_FEATURE_USERNAME_COMPLETION 0
 #define ENABLE_FEATURE_NONPRINTABLE_INVERSE_PUT 0
-#define ENABLE_FEATURE_CLEAN_UP 0
 
 #endif  /* TEST */
 
@@ -56,35 +55,117 @@
 #endif
 
 #define ENABLE_FEATURE_GETUSERNAME_AND_HOMEDIR \
-(ENABLE_FEATURE_USERNAME_COMPLETION || ENABLE_FEATURE_EDITING_FANCY_PROMPT)
+        (ENABLE_FEATURE_USERNAME_COMPLETION || ENABLE_FEATURE_EDITING_FANCY_PROMPT)
+#define USE_FEATURE_GETUSERNAME_AND_HOMEDIR(...)
+#if ENABLE_FEATURE_GETUSERNAME_AND_HOMEDIR
+#undef USE_FEATURE_GETUSERNAME_AND_HOMEDIR
+#define USE_FEATURE_GETUSERNAME_AND_HOMEDIR(...) __VA_ARGS__
+#endif
 
-enum { MAX_LINELEN = CONFIG_FEATURE_EDITING_MAX_LEN };
+enum {
+        /* We use int16_t for positions, need to limit line len */
+        MAX_LINELEN = CONFIG_FEATURE_EDITING_MAX_LEN < 0x7ff0
+                      ? CONFIG_FEATURE_EDITING_MAX_LEN
+                      : 0x7ff0
+};
+
+#if ENABLE_FEATURE_GETUSERNAME_AND_HOMEDIR
+static const char null_str[] ALIGN1 = "";
+#endif
 
-static line_input_t *state;
+/* We try to minimize both static and stack usage. */
+struct statics {
+        line_input_t *state;
 
-static struct termios initial_settings, new_settings;
+        volatile unsigned cmdedit_termw; /* = 80; */ /* actual terminal width */
+        sighandler_t previous_SIGWINCH_handler;
 
-static volatile unsigned cmdedit_termw = 80;        /* actual terminal width */
 
-static int cmdedit_x;           /* real x terminal position */
-static int cmdedit_y;           /* pseudoreal y terminal position */
-static int cmdedit_prmt_len;    /* length of prompt (without colors etc) */
+        int cmdedit_x;           /* real x terminal position */
+        int cmdedit_y;           /* pseudoreal y terminal position */
+        int cmdedit_prmt_len;    /* length of prompt (without colors etc) */
 
-static unsigned cursor;
-static unsigned command_len;
-static char *command_ps;
-static const char *cmdedit_prompt;
+        unsigned cursor;
+        unsigned command_len;
+        char *command_ps;
 
+        const char *cmdedit_prompt;
 #if ENABLE_FEATURE_EDITING_FANCY_PROMPT
-static char *hostname_buf;
-static int num_ok_lines = 1;
+        char *hostname_buf;
+        int num_ok_lines; /* = 1; */
+#endif
+
+#if ENABLE_FEATURE_GETUSERNAME_AND_HOMEDIR
+        char *user_buf;
+        char *home_pwd_buf; /* = (char*)null_str; */
+#endif
+
+#if ENABLE_FEATURE_TAB_COMPLETION
+        char **matches;
+        unsigned num_matches;
 #endif
 
+#if ENABLE_FEATURE_EDITING_VI
+#define DELBUFSIZ 128
+        char *delptr;
+        smallint newdelflag;     /* whether delbuf should be reused yet */
+        char delbuf[DELBUFSIZ];  /* a place to store deleted characters */
+#endif
+
+        /* Formerly these were big buffers on stack: */
+#if ENABLE_FEATURE_TAB_COMPLETION
+        char exe_n_cwd_tab_completion__dirbuf[MAX_LINELEN];
+        char input_tab__matchBuf[MAX_LINELEN];
+        int16_t find_match__int_buf[MAX_LINELEN + 1]; /* need to have 9 bits at least */
+        int16_t find_match__pos_buf[MAX_LINELEN + 1];
+#endif
+};
+
+static struct statics *const ptr_to_statics __attribute__ ((section (".data")));
+
+#define S (*ptr_to_statics)
+#define state            (S.state           )
+#define cmdedit_termw    (S.cmdedit_termw   )
+#define previous_SIGWINCH_handler (S.previous_SIGWINCH_handler)
+#define cmdedit_x        (S.cmdedit_x       )
+#define cmdedit_y        (S.cmdedit_y       )
+#define cmdedit_prmt_len (S.cmdedit_prmt_len)
+#define cursor           (S.cursor          )
+#define command_len      (S.command_len     )
+#define command_ps       (S.command_ps      )
+#define cmdedit_prompt   (S.cmdedit_prompt  )
+#define hostname_buf     (S.hostname_buf    )
+#define num_ok_lines     (S.num_ok_lines    )
+#define user_buf         (S.user_buf        ) 
+#define home_pwd_buf     (S.home_pwd_buf    )
+#define matches          (S.matches         )
+#define num_matches      (S.num_matches     )
+#define delptr           (S.delptr          )
+#define newdelflag       (S.newdelflag      )
+#define delbuf           (S.delbuf          )
+
+#define INIT_S() do { \
+        (*(struct statics**)&ptr_to_statics) = xzalloc(sizeof(S)); \
+        cmdedit_termw = 80; \
+        USE_FEATURE_EDITING_FANCY_PROMPT(num_ok_lines = 1;) \
+        USE_FEATURE_GETUSERNAME_AND_HOMEDIR(home_pwd_buf = (char*)null_str;) \
+} while (0)
+static void deinit_S(void)
+{
+#if ENABLE_FEATURE_EDITING_FANCY_PROMPT
+        free(hostname_buf);
+        /* This one is allocated only if FANCY_PROMPT is on
+         * (otherwise it points to verbatim prompt (NOT malloced) */
+        free((char*)cmdedit_prompt);
+#endif
 #if ENABLE_FEATURE_GETUSERNAME_AND_HOMEDIR
-static const char null_str[] = "";
-static char *user_buf;
-static char *home_pwd_buf = (char*)null_str;
+        free(user_buf);
+        if (home_pwd_buf != null_str)
+                free(home_pwd_buf);
 #endif
+        free(ptr_to_statics);
+}
+#define DEINIT_S() deinit_S()
 
 /* Put 'command_ps[cursor]', cursor++.
  * Advance cursor on screen. If we reached right margin, scroll text up
@@ -110,8 +191,7 @@ static void cmdedit_set_out_char(int next_char)
         } else
 #endif
         {
-                if (initial_settings.c_lflag & ECHO)
-                        bb_putchar(c);
+                bb_putchar(c);
         }
         if (++cmdedit_x >= cmdedit_termw) {
                 /* terminal is scrolled down */
@@ -204,13 +284,6 @@ static void redraw(int y, int back_cursor)
         input_backward(back_cursor);
 }
 
-#if ENABLE_FEATURE_EDITING_VI
-#define DELBUFSIZ 128
-static char *delbuf;  /* a (malloced) place to store deleted characters */
-static char *delp;
-static char newdelflag;      /* whether delbuf should be reused yet */
-#endif
-
 /* Delete the char in front of the cursor, optionally saving it
  * for later putback */
 static void input_delete(int save)
@@ -223,14 +296,11 @@ static void input_delete(int save)
 #if ENABLE_FEATURE_EDITING_VI
         if (save) {
                 if (newdelflag) {
-                        if (!delbuf)
-                                delbuf = malloc(DELBUFSIZ);
-                        /* safe if malloc fails */
-                        delp = delbuf;
+                        delptr = delbuf;
                         newdelflag = 0;
                 }
-                if (delbuf && (delp - delbuf < DELBUFSIZ))
-                        *delp++ = command_ps[j];
+                if ((delptr - delbuf) < DELBUFSIZ)
+                        *delptr++ = command_ps[j];
         }
 #endif
 
@@ -245,7 +315,7 @@ static void input_delete(int save)
 static void put(void)
 {
         int ocursor;
-        int j = delp - delbuf;
+        int j = delptr - delbuf;
 
         if (j == 0)
                 return;
@@ -275,12 +345,8 @@ static void input_forward(void)
                 cmdedit_set_out_char(command_ps[cursor + 1]);
 }
 
-
 #if ENABLE_FEATURE_TAB_COMPLETION
 
-static char **matches;
-static unsigned num_matches;
-
 static void free_tab_completion_data(void)
 {
         if (matches) {
@@ -329,11 +395,8 @@ static void username_tab_completion(char *ud, char *with_shash_flg)
                 }
                 if (home) {
                         if ((userlen + strlen(home) + 1) < MAX_LINELEN) {
-                                char temp2[MAX_LINELEN];     /* argument size */
-
                                 /* /home/user/... */
-                                sprintf(temp2, "%s%s", home, ud);
-                                strcpy(sav_ud, temp2);
+                                sprintf(sav_ud, "%s%s", home, ud);
                         }
                 }
         } else {
@@ -411,7 +474,6 @@ static void exe_n_cwd_tab_completion(char *command, int type)
 {
         DIR *dir;
         struct dirent *next;
-        char dirbuf[MAX_LINELEN];
         struct stat st;
         char *path1[1];
         char **paths = path1;
@@ -419,6 +481,8 @@ static void exe_n_cwd_tab_completion(char *command, int type)
         int i;
         char *found;
         char *pfind = strrchr(command, '/');
+/*      char dirbuf[MAX_LINELEN]; */
+#define dirbuf (S.exe_n_cwd_tab_completion__dirbuf)
 
         npaths = 1;
         path1[0] = (char*)".";
@@ -492,21 +556,25 @@ static void exe_n_cwd_tab_completion(char *command, int type)
                 free(paths[0]);                 /* allocated memory only in first member */
                 free(paths);
         }
+#undef dirbuf
 }
 
 #define QUOT (UCHAR_MAX+1)
 
-#define collapse_pos(is, in) { \
-        memmove(int_buf+(is), int_buf+(in), (MAX_LINELEN+1-(is)-(in))*sizeof(int)); \
-        memmove(pos_buf+(is), pos_buf+(in), (MAX_LINELEN+1-(is)-(in))*sizeof(int)); }
+#define collapse_pos(is, in) do { \
+        memmove(int_buf+(is), int_buf+(in), (MAX_LINELEN+1-(is)-(in)) * sizeof(pos_buf[0])); \
+        memmove(pos_buf+(is), pos_buf+(in), (MAX_LINELEN+1-(is)-(in)) * sizeof(pos_buf[0])); \
+} while (0)
 
 static int find_match(char *matchBuf, int *len_with_quotes)
 {
         int i, j;
         int command_mode;
         int c, c2;
-        int int_buf[MAX_LINELEN + 1];
-        int pos_buf[MAX_LINELEN + 1];
+/*      int16_t int_buf[MAX_LINELEN + 1]; */
+/*      int16_t pos_buf[MAX_LINELEN + 1]; */
+#define int_buf (S.find_match__int_buf)
+#define pos_buf (S.find_match__pos_buf)
 
         /* set to integer dimension characters and own positions */
         for (i = 0;; i++) {
@@ -622,8 +690,8 @@ static int find_match(char *matchBuf, int *len_with_quotes)
         for (i = 0; int_buf[i]; i++)
                 if (int_buf[i] == ' ' || int_buf[i] == '<' || int_buf[i] == '>') {
                         if (int_buf[i] == ' ' && command_mode == FIND_EXE_ONLY
-                         && matchBuf[pos_buf[0]]=='c'
-                         && matchBuf[pos_buf[1]]=='d'
+                         && matchBuf[pos_buf[0]] == 'c'
+                         && matchBuf[pos_buf[1]] == 'd'
                         ) {
                                 command_mode = FIND_DIR_ONLY;
                         } else {
@@ -657,11 +725,13 @@ static int find_match(char *matchBuf, int *len_with_quotes)
                 matchBuf[c++] = matchBuf[pos_buf[i]];
                 j = pos_buf[i] + 1;
         }
-        matchBuf[c] = 0;
+        matchBuf[c] = '\0';
         /* old length matchBuf with quotes symbols */
         *len_with_quotes = j ? j - pos_buf[0] : 0;
 
         return command_mode;
+#undef int_buf
+#undef pos_buf
 }
 
 /*
@@ -724,7 +794,7 @@ static int match_compare(const void *a, const void *b)
 }
 
 /* Do TAB completion */
-static void input_tab(int *lastWasTab)
+static void input_tab(smallint *lastWasTab)
 {
         if (!(state->flags & TAB_COMPLETION))
                 return;
@@ -732,7 +802,8 @@ static void input_tab(int *lastWasTab)
         if (!*lastWasTab) {
                 char *tmp, *tmp1;
                 int len_found;
-                char matchBuf[MAX_LINELEN];
+/*              char matchBuf[MAX_LINELEN]; */
+#define matchBuf (S.input_tab__matchBuf)
                 int find_type;
                 int recalc_pos;
 
@@ -782,7 +853,6 @@ static void input_tab(int *lastWasTab)
                         if (!matches)
                                 return;         /* not found */
                         /* find minimal match */
-                // ash: yet another failure in trying to achieve "we don't die on OOM"
                         tmp1 = xstrdup(matches[0]);
                         for (tmp = tmp1; *tmp; tmp++)
                                 for (len_found = 1; len_found < num_matches; len_found++)
@@ -811,7 +881,7 @@ static void input_tab(int *lastWasTab)
                 /* have space to placed match? */
                 if ((len_found - strlen(matchBuf) + command_len) < MAX_LINELEN) {
                         /* before word for match   */
-                        command_ps[cursor - recalc_pos] = 0;
+                        command_ps[cursor - recalc_pos] = '\0';
                         /* save   tail line        */
                         strcpy(matchBuf, command_ps + cursor);
                         /* add    match            */
@@ -828,6 +898,7 @@ static void input_tab(int *lastWasTab)
                         redraw(cmdedit_y, command_len - recalc_pos);
                 }
                 free(tmp);
+#undef matchBuf
         } else {
                 /* Ok -- the last char was a TAB.  Since they
                  * just hit TAB again, print a list of all the
@@ -843,8 +914,6 @@ static void input_tab(int *lastWasTab)
         }
 }
 
-#else
-#define input_tab(a) ((void)0)
 #endif  /* FEATURE_COMMAND_TAB_COMPLETION */
 
 
@@ -1079,14 +1148,14 @@ vi_back_motion(char *command)
  */
 
 #if !ENABLE_FEATURE_EDITING_FANCY_PROMPT
-static void parse_prompt(const char *prmt_ptr)
+static void parse_and_put_prompt(const char *prmt_ptr)
 {
         cmdedit_prompt = prmt_ptr;
         cmdedit_prmt_len = strlen(prmt_ptr);
         put_prompt();
 }
 #else
-static void parse_prompt(const char *prmt_ptr)
+static void parse_and_put_prompt(const char *prmt_ptr)
 {
         int prmt_len = 0;
         size_t cur_prmt_len = 0;
@@ -1114,7 +1183,7 @@ static void parse_prompt(const char *prmt_ptr)
 
                         c = bb_process_escape_sequence(&prmt_ptr);
                         if (prmt_ptr == cp) {
-                                if (*cp == 0)
+                                if (*cp == '\0')
                                         break;
                                 c = *prmt_ptr++;
                                 switch (c) {
@@ -1147,7 +1216,7 @@ static void parse_prompt(const char *prmt_ptr)
                                         if (l != 0
                                          && strncmp(home_pwd_buf, pbuf, l) == 0
                                          && (pbuf[l]=='/' || pbuf[l]=='\0')
-                                         && strlen(pwd_buf+l)<PATH_MAX
+                                         && strlen(pwd_buf+l) < PATH_MAX
                                         ) {
                                                 pbuf = buf2;
                                                 *pbuf = '~';
@@ -1188,7 +1257,7 @@ static void parse_prompt(const char *prmt_ptr)
                                         break;
                                 case '[': case ']':
                                         if (c == flg_not_length) {
-                                                flg_not_length = flg_not_length == '[' ? ']' : '[';
+                                                flg_not_length = (flg_not_length == '[' ? ']' : '[');
                                                 continue;
                                         }
                                         break;
@@ -1210,11 +1279,6 @@ static void parse_prompt(const char *prmt_ptr)
 }
 #endif
 
-#define setTermSettings(fd, argp) tcsetattr(fd, TCSANOW, argp)
-#define getTermSettings(fd, argp) tcgetattr(fd, argp);
-
-static sighandler_t previous_SIGWINCH_handler;
-
 static void cmdedit_setwidth(unsigned w, int redraw_flg)
 {
         cmdedit_termw = w;
@@ -1261,7 +1325,9 @@ static void win_changed(int nsig)
  */
 int read_line_input(const char *prompt, char *command, int maxsize, line_input_t *st)
 {
-        int lastWasTab = FALSE;
+#if ENABLE_FEATURE_TAB_COMPLETION
+        smallint lastWasTab = FALSE;
+#endif
         unsigned int ic;
         unsigned char c;
         smallint break_out = 0;
@@ -1269,14 +1335,22 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
         smallint vi_cmdmode = 0;
         smalluint prevc;
 #endif
+        struct termios initial_settings;
+        struct termios new_settings;
 
-        getTermSettings(0, (void *) &initial_settings);
-        /* Happens when e.g. stty -echo was run before */
-        if (!(initial_settings.c_lflag & ECHO)) {
-                parse_prompt(prompt);
+        INIT_S();
+
+        if (tcgetattr(STDIN_FILENO, &initial_settings) < 0
+         || !(initial_settings.c_lflag & ECHO)
+        ) {
+                /* Happens when e.g. stty -echo was run before */
+                int len;
+                parse_and_put_prompt(prompt);
                 fflush(stdout);
                 fgets(command, maxsize, stdin);
-                return strlen(command);
+                len = strlen(command);
+                DEINIT_S();
+                return len;
         }
 
 // FIXME: audit & improve this
@@ -1296,7 +1370,7 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
         command_ps = command;
         command[0] = '\0';
 
-        memcpy(&new_settings, &initial_settings, sizeof(new_settings));
+        new_settings = initial_settings;
         new_settings.c_lflag &= ~ICANON;        /* unbuffered input */
         /* Turn off echoing and CTRL-C, so we can trap it */
         new_settings.c_lflag &= ~(ECHO | ECHONL | ISIG);
@@ -1308,7 +1382,7 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
 #define _POSIX_VDISABLE '\0'
 #endif
         new_settings.c_cc[VINTR] = _POSIX_VDISABLE;
-        setTermSettings(0, (void *) &new_settings);
+        tcsetattr(STDIN_FILENO, TCSANOW, &new_settings);
 
         /* Now initialize things */
         previous_SIGWINCH_handler = signal(SIGWINCH, win_changed);
@@ -1319,11 +1393,6 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
 
                 entry = getpwuid(geteuid());
                 if (entry) {
-                        /* If we enter read_line_input for the Nth time,
-                         * they may be already allocated! Need to free. */
-                        free(user_buf);
-                        if (home_pwd_buf != null_str)
-                                free(home_pwd_buf);
                         user_buf = xstrdup(entry->pw_name);
                         home_pwd_buf = xstrdup(entry->pw_dir);
                         /* They are not freed on exit (too small to bother) */
@@ -1331,12 +1400,12 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
         }
 #endif
         /* Print out the command prompt */
-        parse_prompt(prompt);
+        parse_and_put_prompt(prompt);
 
         while (1) {
                 fflush(stdout);
 
-                if (safe_read(0, &c, 1) < 1) {
+                if (safe_read(STDIN_FILENO, &c, 1) < 1) {
                         /* if we can't read input then exit */
                         goto prepare_to_die;
                 }
@@ -1411,9 +1480,11 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
                         input_backspace();
                         break;
 
+#if ENABLE_FEATURE_TAB_COMPLETION
                 case '\t':
                         input_tab(&lastWasTab);
                         break;
+#endif
 
 #if ENABLE_FEATURE_EDITING_FANCY_KEYS
                 case CTRL('K'):
@@ -1526,7 +1597,7 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
                         int nc, sc;
                         sc = cursor;
                         prevc = ic;
-                        if (safe_read(0, &c, 1) < 1)
+                        if (safe_read(STDIN_FILENO, &c, 1) < 1)
                                 goto prepare_to_die;
                         if (c == (prevc & 0xff)) {
                                 /* "cc", "dd" */
@@ -1587,7 +1658,7 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
                         put();
                         break;
                 case 'r'|vbit:
-                        if (safe_read(0, &c, 1) < 1)
+                        if (safe_read(STDIN_FILENO, &c, 1) < 1)
                                 goto prepare_to_die;
                         if (c == 0)
                                 beep();
@@ -1610,19 +1681,19 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
                         }
 #endif
                         /* escape sequence follows */
-                        if (safe_read(0, &c, 1) < 1)
+                        if (safe_read(STDIN_FILENO, &c, 1) < 1)
                                 goto prepare_to_die;
                         /* different vt100 emulations */
                         if (c == '[' || c == 'O') {
                 vi_case('['|vbit:)
                 vi_case('O'|vbit:)
-                                if (safe_read(0, &c, 1) < 1)
+                                if (safe_read(STDIN_FILENO, &c, 1) < 1)
                                         goto prepare_to_die;
                         }
                         if (c >= '1' && c <= '9') {
                                 unsigned char dummy;
 
-                                if (safe_read(0, &dummy, 1) < 1)
+                                if (safe_read(STDIN_FILENO, &dummy, 1) < 1)
                                         goto prepare_to_die;
                                 if (dummy != '~')
                                         c = '\0';
@@ -1687,7 +1758,7 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
 #if ENABLE_FEATURE_NONPRINTABLE_INVERSE_PUT
                         /* Control-V -- Add non-printable symbol */
                         if (c == CTRL('V')) {
-                                if (safe_read(0, &c, 1) < 1)
+                                if (safe_read(STDIN_FILENO, &c, 1) < 1)
                                         goto prepare_to_die;
                                 if (c == 0) {
                                         beep();
@@ -1727,8 +1798,10 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
                 if (break_out)                  /* Enter is the command terminator, no more input. */
                         break;
 
+#if ENABLE_FEATURE_TAB_COMPLETION
                 if (c != '\t')
                         lastWasTab = FALSE;
+#endif
         }
 
         if (command_len > 0)
@@ -1739,18 +1812,18 @@ int read_line_input(const char *prompt, char *command, int maxsize, line_input_t
                 command[command_len] = '\0';
         }
 
-#if ENABLE_FEATURE_CLEAN_UP && ENABLE_FEATURE_TAB_COMPLETION
+#if ENABLE_FEATURE_TAB_COMPLETION
         free_tab_completion_data();
 #endif
 
-#if ENABLE_FEATURE_EDITING_FANCY_PROMPT
-        free((char*)cmdedit_prompt);
-#endif
         /* restore initial_settings */
-        setTermSettings(STDIN_FILENO, (void *) &initial_settings);
+        tcsetattr(STDIN_FILENO, TCSANOW, &initial_settings);
         /* restore SIGWINCH handler */
         signal(SIGWINCH, previous_SIGWINCH_handler);
         fflush(stdout);
+
+        DEINIT_S();
+
         return command_len;
 }