moved biggest stack buffers to malloc space, or made their size configurable

(8k of shell line edit buffer is an overkill)

# make ARCH=i386 bloatcheck
function                                             old     new   delta
read_line_input                                     3933    3967     +34
ifaddrlist                                           348     345      -3
do_loadfont                                          208     191     -17
edit_file                                            840     819     -21
.rodata                                           129112  129080     -32
uncompress                                          1305    1268     -37
loadfont_main                                        566     495     -71
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/6 up/down: 34/-181)          Total: -147 bytes

2 files changed, 34 insertions, 23 deletions

diff --git a/libbb/Config.in b/libbb/Config.in
index 112a3d658..a1ff7c056 100644
--- a/libbb/Config.in
+++ b/libbb/Config.in
@@ -30,7 +30,17 @@ config FEATURE_EDITING
         bool "Command line editing"
         default n
         help
-          Enable command editing (mainly for shell).
+          Enable line editing (mainly for shell command line).
+
+config FEATURE_EDITING_MAX_LEN
+        int "Maximum length of input"
+        range 128 8192
+        default 1024
+        depends on FEATURE_EDITING
+        help
+          Line editing code uses on-stack buffers for storage.
+          You may want to decrease this parameter if your target machine
+          benefits from smaller stack usage.
 
 config FEATURE_EDITING_FANCY_KEYS
         bool "Additional editing keys"
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index b950d7f26..1f2e6a54e 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -28,7 +28,6 @@
    - not true viewing if length prompt less terminal width
  */
 
-//#include <sys/ioctl.h>
 #include "libbb.h"
 
 
@@ -59,6 +58,7 @@
 #define ENABLE_FEATURE_GETUSERNAME_AND_HOMEDIR \
 (ENABLE_FEATURE_USERNAME_COMPLETION || ENABLE_FEATURE_EDITING_FANCY_PROMPT)
 
+enum { MAX_LINELEN = CONFIG_FEATURE_EDITING_MAX_LEN };
 
 static line_input_t *state;
 
@@ -327,8 +327,8 @@ static void username_tab_completion(char *ud, char *with_shash_flg)
                                 home = entry->pw_dir;
                 }
                 if (home) {
-                        if ((userlen + strlen(home) + 1) < BUFSIZ) {
-                                char temp2[BUFSIZ];     /* argument size */
+                        if ((userlen + strlen(home) + 1) < MAX_LINELEN) {
+                                char temp2[MAX_LINELEN];     /* argument size */
 
                                 /* /home/user/... */
                                 sprintf(temp2, "%s%s", home, ud);
@@ -410,7 +410,7 @@ static void exe_n_cwd_tab_completion(char *command, int type)
 {
         DIR *dir;
         struct dirent *next;
-        char dirbuf[BUFSIZ];
+        char dirbuf[MAX_LINELEN];
         struct stat st;
         char *path1[1];
         char **paths = path1;
@@ -496,16 +496,16 @@ static void exe_n_cwd_tab_completion(char *command, int type)
 #define QUOT (UCHAR_MAX+1)
 
 #define collapse_pos(is, in) { \
-        memmove(int_buf+(is), int_buf+(in), (BUFSIZ+1-(is)-(in))*sizeof(int)); \
-        memmove(pos_buf+(is), pos_buf+(in), (BUFSIZ+1-(is)-(in))*sizeof(int)); }
+        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)); }
 
 static int find_match(char *matchBuf, int *len_with_quotes)
 {
         int i, j;
         int command_mode;
         int c, c2;
-        int int_buf[BUFSIZ + 1];
-        int pos_buf[BUFSIZ + 1];
+        int int_buf[MAX_LINELEN + 1];
+        int pos_buf[MAX_LINELEN + 1];
 
         /* set to integer dimension characters and own positions */
         for (i = 0;; i++) {
@@ -731,7 +731,7 @@ static void input_tab(int *lastWasTab)
         if (!*lastWasTab) {
                 char *tmp, *tmp1;
                 int len_found;
-                char matchBuf[BUFSIZ];
+                char matchBuf[MAX_LINELEN];
                 int find_type;
                 int recalc_pos;
 
@@ -781,6 +781,7 @@ 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++)
@@ -807,7 +808,7 @@ static void input_tab(int *lastWasTab)
                 }
                 len_found = strlen(tmp);
                 /* have space to placed match? */
-                if ((len_found - strlen(matchBuf) + command_len) < BUFSIZ) {
+                if ((len_found - strlen(matchBuf) + command_len) < MAX_LINELEN) {
                         /* before word for match   */
                         command_ps[cursor - recalc_pos] = 0;
                         /* save   tail line        */
@@ -888,14 +889,14 @@ static void load_history(const char *fromfile)
         fp = fopen(fromfile, "r");
         if (fp) {
                 for (hi = 0; hi < MAX_HISTORY;) {
-                        char * hl = xmalloc_getline(fp);
+                        char *hl = xmalloc_getline(fp);
                         int l;
 
                         if (!hl)
                                 break;
                         l = strlen(hl);
-                        if (l >= BUFSIZ)
-                                hl[BUFSIZ-1] = 0;
+                        if (l >= MAX_LINELEN)
+                                hl[MAX_LINELEN-1] = '\0';
                         if (l == 0 || hl[0] == ' ') {
                                 free(hl);
                                 continue;
@@ -1264,8 +1265,8 @@ int read_line_input(const char* prompt, char* command, int maxsize, line_input_t
 #endif
 
 // FIXME: audit & improve this
-        if (maxsize > BUFSIZ)
-                maxsize = BUFSIZ;
+        if (maxsize > MAX_LINELEN)
+                maxsize = MAX_LINELEN;
 
         /* With null flags, no other fields are ever used */
         state = st ? st : (line_input_t*) &const_int_0;
@@ -1646,14 +1647,14 @@ int read_line_input(const char* prompt, char* command, int maxsize, line_input_t
                                 /* Delete */
                                 input_delete(0);
                                 break;
-                        case '1':
-                        case 'H':
-                                /* <Home> */
+                        case '1': // vt100? linux vt? or what?
+                        case '7': // vt100? linux vt? or what?
+                        case 'H': /* xterm's <Home> */
                                 input_backward(cursor);
                                 break;
-                        case '4':
-                        case 'F':
-                                /* <End> */
+                        case '4': // vt100? linux vt? or what?
+                        case '8': // vt100? linux vt? or what?
+                        case 'F': /* xterm's <End> */
                                 input_end();
                                 break;
                         default:
@@ -1766,7 +1767,7 @@ const char *applet_name = "debug stuff usage";
 
 int main(int argc, char **argv)
 {
-        char buff[BUFSIZ];
+        char buff[MAX_LINELEN];
         char *prompt =
 #if ENABLE_FEATURE_EDITING_FANCY_PROMPT
                 "\\[\\033[32;1m\\]\\u@\\[\\x1b[33;1m\\]\\h:"