lineedit: remove pos_buf[] array (up to 16k!); fix compat bugs

pos_buf is a strange hack, easy to do without it.
This also allows lines >32k long to be handled.
Also simplified match prefix generations and made behavior more like bash.

function                                             old     new   delta
remove_chunk                                           -      43     +43
collapse_pos                                          79       -     -79
build_match_prefix                                   804     579    -225
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 0/1 up/down: 43/-304)          Total: -261 bytes

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

1 files changed, 49 insertions, 83 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index e40917f62..fff5c1a89 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -99,7 +99,6 @@ static bool BB_ispunct(CHAR_T c) { return ((unsigned)c < 256 && ispunct(c)); }
 
 
 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
@@ -156,7 +155,6 @@ struct lineedit_statics {
 #if ENABLE_FEATURE_TAB_COMPLETION
         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
 };
 
@@ -824,15 +822,16 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
  */
 #define QUOT (UCHAR_MAX+1)
 #define int_buf (S.find_match__int_buf)
-#define pos_buf (S.find_match__pos_buf)
 #define dbg_bmp 0
-static void collapse_pos(int beg, int end)
+static void remove_chunk(int beg, int end)
 {
         /* beg must be <= end */
         if (beg == end)
                 return;
-        memmove(int_buf+beg, int_buf+end, (MAX_LINELEN+1-end) * sizeof(int_buf[0]));
-        memmove(pos_buf+beg, pos_buf+end, (MAX_LINELEN+1-end) * sizeof(pos_buf[0]));
+
+        while ((int_buf[beg] = int_buf[end]) != 0)
+                beg++, end++;
+
         if (dbg_bmp) {
                 int i;
                 for (i = 0; int_buf[i]; i++)
@@ -846,42 +845,39 @@ static NOINLINE int build_match_prefix(char *matchBuf)
         int command_mode;
 /*      Were local, but it used too much stack */
 /*      int16_t int_buf[MAX_LINELEN + 1]; */
-/*      int16_t pos_buf[MAX_LINELEN + 1]; */
 
         if (dbg_bmp) printf("\n%s\n", matchBuf);
 
-        for (i = 0;; i++) {
-                int_buf[i] = (unsigned char)matchBuf[i];
-                if (int_buf[i] == 0) {
-                        pos_buf[i] = -1; /* end-of-line indicator */
-                        break;
-                }
-                pos_buf[i] = i;
-        }
+        i = 0;
+        while ((int_buf[i] = (unsigned char)matchBuf[i]) != '\0')
+                i++;
 
         /* Mark every \c as "quoted c" */
         for (i = j = 0; matchBuf[i]; i++, j++) {
                 if (matchBuf[i] == '\\') {
-                        collapse_pos(j, j + 1);
+                        remove_chunk(j, j + 1);
                         int_buf[j] |= QUOT;
                         i++;
                 }
         }
-        /* Quote-mark "chars" and 'chars' */
+        /* Quote-mark "chars" and 'chars', drop delimiters */
         {
                 int in_quote = 0;
-                for (i = 0; int_buf[i]; i++) {
+                i = 0;
+                while (int_buf[i]) {
                         int cur = int_buf[i];
+                        if (!cur)
+                                break;
                         if (cur == '\'' || cur == '"') {
-                                if (!in_quote)
-                                        in_quote = cur;
-                                else if (cur == in_quote)
-                                        in_quote = 0;
-                                else
-                                        int_buf[i] |= QUOT;
-                        } else if (in_quote && cur != '$') {
-                                int_buf[i] |= QUOT;
+                                if (!in_quote || (cur == in_quote)) {
+                                        in_quote ^= cur;
+                                        remove_chunk(i, i + 1);
+                                        continue;
+                                }
                         }
+                        if (in_quote)
+                                int_buf[i] = cur | QUOT;
+                        i++;
                 }
         }
 
@@ -898,53 +894,39 @@ static NOINLINE int build_match_prefix(char *matchBuf)
                         } else if (cur == '|' && prev == '>') {
                                 continue;
                         }
-                        collapse_pos(0, i + 1 + (cur == int_buf[i + 1]));
+                        remove_chunk(0, i + 1 + (cur == int_buf[i + 1]));
                         i = -1;  /* back to square 1 */
                 }
         }
         /* Remove all `cmd` */
-//BUG: `cmd` should count as a word: `cmd` c<tab> should search for files c*, not commands c*
         for (i = 0; int_buf[i]; i++) {
                 if (int_buf[i] == '`') {
                         for (j = i + 1; int_buf[j]; j++) {
                                 if (int_buf[j] == '`') {
-                                        collapse_pos(i, j + 1);
+                                        /* `cmd` should count as a word:
+                                         * `cmd` c<tab> should search for files c*,
+                                         * not commands c*. Therefore we don't drop
+                                         * `cmd` entirely, we replace it with single `.
+                                         */
+                                        remove_chunk(i, j);
                                         goto next;
                                 }
                         }
                         /* No closing ` - command mode, remove all up to ` */
-                        collapse_pos(0, i + 1);
+                        remove_chunk(0, i + 1);
                         break;
- next:
-                        i--;  /* hack increment */
+ next: ;
                 }
         }
 
-        /* Remove (command...(command...)...) and {command...{command...}...} */
-        {
-                int paren_lvl = 0;
-                int curly_lvl = 0;
-                for (i = 0; int_buf[i]; i++) {
-                        if (int_buf[i] == '(' || int_buf[i] == '{') {
-                                if (int_buf[i] == '(')
-                                        paren_lvl++;
-                                else
-                                        curly_lvl++;
-                                collapse_pos(0, i + 1);
-                                i = -1;  /* hack increment */
-                        }
-                }
-                for (i = 0; pos_buf[i] >= 0 && (paren_lvl > 0 || curly_lvl > 0); i++) {
-                        if ((int_buf[i] == ')' && paren_lvl > 0)
-                         || (int_buf[i] == '}' && curly_lvl > 0)
-                        ) {
-                                if (int_buf[i] == ')')
-                                        paren_lvl--;
-                                else
-                                        curly_lvl--;
-                                collapse_pos(0, i + 1);
-                                i = -1;  /* hack increment */
-                        }
+        /* Remove "cmd (" and "cmd {"
+         * Example: "if { c<tab>"
+         * In this example, c should be matched as command pfx.
+         */
+        for (i = 0; int_buf[i]; i++) {
+                if (int_buf[i] == '(' || int_buf[i] == '{') {
+                        remove_chunk(0, i + 1);
+                        i = -1;  /* hack increment */
                 }
         }
 
@@ -952,7 +934,7 @@ static NOINLINE int build_match_prefix(char *matchBuf)
         for (i = 0; int_buf[i]; i++)
                 if (int_buf[i] != ' ')
                         break;
-        collapse_pos(0, i);
+        remove_chunk(0, i);
 
         /* Determine completion mode */
         command_mode = FIND_EXE_ONLY;
@@ -960,9 +942,9 @@ static NOINLINE int build_match_prefix(char *matchBuf)
                 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'
-//BUG: must check "cd ", not "cd"
+                         && (char)int_buf[0] == 'c'
+                         && (char)int_buf[1] == 'd'
+                         && i == 2 /* -> int_buf[2] == ' ' */
                         ) {
                                 command_mode = FIND_DIR_ONLY;
                         } else {
@@ -979,36 +961,20 @@ static NOINLINE int build_match_prefix(char *matchBuf)
         for (--i; i >= 0; i--) {
                 int cur = int_buf[i];
                 if (cur == ' ' || cur == '<' || cur == '>' || cur == '|' || cur == '&') {
-                        collapse_pos(0, i + 1);
+                        remove_chunk(0, i + 1);
                         break;
                 }
         }
-        /* Skip all leading unquoted ' or " */
-//BUG: bash doesn't do this
-        for (i = 0; int_buf[i] == '\'' || int_buf[i] == '"'; i++)
-                continue;
-        /* Skip quoted or unquoted // or /~ */
-//BUG: bash doesn't do this
-        while ((char)int_buf[i] == '/'
-         && ((char)int_buf[i+1] == '/' || (char)int_buf[i+1] == '~')
-        ) {
-                i++;
-        }
 
-        /* set only match and destroy quotes */
-        {
-                int pos = 0;
-                for (j = 0; pos_buf[i] >= 0; i++) {
-                        matchBuf[j++] = matchBuf[pos_buf[i]];
-                        pos = pos_buf[i] + 1;
-                }
-                matchBuf[j] = '\0';
-        }
+        /* Store only match prefix */
+        i = 0;
+        while ((matchBuf[i] = int_buf[i]) != '\0')
+                i++;
+        if (dbg_bmp) printf("final matchBuf:'%s'\n", matchBuf);
 
         return command_mode;
 }
 #undef int_buf
-#undef pos_buf
 
 /*
  * Display by column (original idea from ls applet,