lineedit: clean up tab completion code (variable reuse, comments)

Noted bugs in behavior.
Added debugging machinery.
Decoupled variables reused for unrelated purposes: apparently,
when not forced to use liveness analysis, gcc fares better.

function                                             old     new   delta
complete_cmd_dir_file                                699     705      +6
collapse_pos                                          75      79      +4
build_match_prefix                                   892     838     -54
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 10/-54)            Total: -44 bytes

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

1 files changed, 85 insertions, 69 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 7bb709f9d..dd9d85b28 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -716,6 +716,7 @@ static NOINLINE void complete_cmd_dir_file(char *command, int type)
         char **paths = path1;
         int npaths;
         int i;
+        unsigned pf_len;
         char *pfind;
         char *dirbuf = NULL;
 
@@ -738,6 +739,7 @@ static NOINLINE void complete_cmd_dir_file(char *command, int type)
 #endif
                 path1[0] = dirbuf;
         }
+        pf_len = strlen(pfind);
 
         for (i = 0; i < npaths; i++) {
                 DIR *dir;
@@ -756,7 +758,7 @@ static NOINLINE void complete_cmd_dir_file(char *command, int type)
                         if (!pfind[0] && DOT_OR_DOTDOT(name_found))
                                 continue;
                         /* match? */
-                        if (strncmp(name_found, pfind, strlen(pfind)) != 0)
+                        if (strncmp(name_found, pfind, pf_len) != 0)
                                 continue; /* no */
 
                         found = concat_path_file(paths[i], name_found);
@@ -812,21 +814,31 @@ static NOINLINE void complete_cmd_dir_file(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)
 {
         /* 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]));
+        if (dbg_bmp) {
+                int i;
+                for (i = 0; int_buf[i]; i++)
+                        bb_putchar((unsigned char)int_buf[i]);
+                bb_putchar('\n');
+        }
 }
 static NOINLINE int build_match_prefix(char *matchBuf, int *len_with_quotes)
 {
         int i, j;
         int command_mode;
-        int c, c2;
 /*      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) {
@@ -845,20 +857,21 @@ static NOINLINE int build_match_prefix(char *matchBuf, int *len_with_quotes)
                 }
         }
         /* Quote-mark "chars" and 'chars' */
-        c2 = 0;
-        for (i = 0; int_buf[i]; i++) {
-                c = int_buf[i];
-                if (c == '\'' || c == '"') {
-                        if (c2 == 0)
-                                c2 = c;
-                        else {
-                                if (c == c2)
-                                        c2 = 0;
+        {
+                int in_quote = 0;
+                for (i = 0; int_buf[i]; i++) {
+                        int cur = int_buf[i];
+                        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 != '$') {
+                                int_buf[i] |= QUOT;
                         }
-                } else if (c2 != 0 && c != '$')
-                        int_buf[i] |= QUOT;
+                }
         }
 
         /* Remove everything up to command delimiters:
@@ -866,64 +879,61 @@ static NOINLINE int build_match_prefix(char *matchBuf, int *len_with_quotes)
          * but careful with '>&' '<&' '>|'
          */
         for (i = 0; int_buf[i]; i++) {
-                int n;
-                c = int_buf[i];
-                c2 = int_buf[i + 1];
-                j = i ? int_buf[i - 1] : -1;
-                n = 0;
-                if (c == ';' || c == '&' || c == '|') {
-                        n = 1 + (c == c2);
-                        if (c == '&') {
-                                if (j == '>' || j == '<')
-                                        n = 0;
-                        } else if (c == '|' && j == '>')
-                                n = 0;
-                }
-                if (n) {
-                        collapse_pos(0, i + n);
-                        i = -1;  /* hack increment */
+                int cur = int_buf[i];
+                if (cur == ';' || cur == '&' || cur == '|') {
+                        int prev = i ? int_buf[i - 1] : 0;
+                        if (cur == '&' && (prev == '>' || prev == '<')) {
+                                continue;
+                        } else if (cur == '|' && prev == '>') {
+                                continue;
+                        }
+                        collapse_pos(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);
-                                        j = 0;
-                                        break;
+                                        goto next;
                                 }
                         }
-                        if (j) {
-                                /* No closing ` - command mode, remove all up to ` */
-                                collapse_pos(0, i + 1);
-                                break;
-                        }
+                        /* No closing ` - command mode, remove all up to ` */
+                        collapse_pos(0, i + 1);
+                        break;
+ next:
                         i--;  /* hack increment */
                 }
         }
 
         /* Remove (command...(command...)...) and {command...{command...}...} */
-        c = 0;  /* "recursive" level */
-        c2 = 0;
-        for (i = 0; int_buf[i]; i++) {
-                if (int_buf[i] == '(' || int_buf[i] == '{') {
-                        if (int_buf[i] == '(')
-                                c++;
-                        else
-                                c2++;
-                        collapse_pos(0, i + 1);
-                        i = -1;  /* hack increment */
+        {
+                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 && (c > 0 || c2 > 0); i++) {
-                if ((int_buf[i] == ')' && c > 0) || (int_buf[i] == '}' && c2 > 0)) {
-                        if (int_buf[i] == ')')
-                                c--;
-                        else
-                                c2--;
-                        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 */
+                        }
                 }
         }
 
@@ -931,8 +941,7 @@ static NOINLINE int build_match_prefix(char *matchBuf, int *len_with_quotes)
         for (i = 0; int_buf[i]; i++)
                 if (int_buf[i] != ' ')
                         break;
-        if (i)
-                collapse_pos(0, i);
+        collapse_pos(0, i);
 
         /* Determine completion mode */
         command_mode = FIND_EXE_ONLY;
@@ -942,6 +951,7 @@ static NOINLINE int build_match_prefix(char *matchBuf, int *len_with_quotes)
                          && command_mode == FIND_EXE_ONLY
                          && matchBuf[pos_buf[0]] == 'c'
                          && matchBuf[pos_buf[1]] == 'd'
+//BUG: must check "cd ", not "cd"
                         ) {
                                 command_mode = FIND_DIR_ONLY;
                         } else {
@@ -950,36 +960,42 @@ static NOINLINE int build_match_prefix(char *matchBuf, int *len_with_quotes)
                         }
                 }
         }
+        if (dbg_bmp) printf("command_mode(0:exe/1:dir/2:file):%d\n", command_mode);
 
         /* Remove everything except last word */
         for (i = 0; int_buf[i]; i++) /* quasi-strlen(int_buf) */
                 continue;
         for (--i; i >= 0; i--) {
-                c = int_buf[i];
-                if (c == ' ' || c == '<' || c == '>' || c == '|' || c == '&') {
+                int cur = int_buf[i];
+                if (cur == ' ' || cur == '<' || cur == '>' || cur == '|' || cur == '&') {
                         collapse_pos(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;
-        /* collapse quote or unquote // or /~ */
-        while ((int_buf[i] & ~QUOT) == '/'
-         && ((int_buf[i+1] & ~QUOT) == '/' || (int_buf[i+1] & ~QUOT) == '~')
+        /* 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 */
-        j = 0;
-        for (c = 0; pos_buf[i] >= 0; i++) {
-                matchBuf[c++] = matchBuf[pos_buf[i]];
-                j = pos_buf[i] + 1;
+        {
+                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';
+                /* old length matchBuf with quotes symbols */
+                *len_with_quotes = pos ? pos - pos_buf[0] : 0;
+                if (dbg_bmp) printf("len_with_quotes:%d\n", *len_with_quotes);
         }
-        matchBuf[c] = '\0';
-        /* old length matchBuf with quotes symbols */
-        *len_with_quotes = j ? j - pos_buf[0] : 0;
 
         return command_mode;
 }