lineedit: return prefix len from tab completion helpers

This kills horrific logic which deletes and re-adds prefix (!)

function                                             old     new   delta
complete_cmd_dir_file                                705     731     +26
complete_username                                    121     124      +3
input_tab                                           1041    1016     -25
build_match_prefix                                   838     804     -34
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/2 up/down: 29/-59)            Total: -30 bytes

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

1 files changed, 50 insertions, 36 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index dd9d85b28..e40917f62 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -638,14 +638,16 @@ static char *username_path_completion(char *ud)
         return tilde_name;
 }
 
-/* ~use<tab> - find all users with this prefix */
-static NOINLINE void complete_username(const char *ud)
+/* ~use<tab> - find all users with this prefix.
+ * Return the length of the prefix used for matching.
+ */
+static NOINLINE unsigned complete_username(const char *ud)
 {
         /* Using _r function to avoid pulling in static buffers */
         char line_buff[256];
         struct passwd pwd;
         struct passwd *result;
-        int userlen;
+        unsigned userlen;
 
         ud++; /* skip ~ */
         userlen = strlen(ud);
@@ -658,6 +660,8 @@ static NOINLINE void complete_username(const char *ud)
                 }
         }
         endpwent();
+
+        return 1 + userlen;
 }
 #endif  /* FEATURE_USERNAME_COMPLETION */
 
@@ -710,14 +714,17 @@ static int path_parse(char ***p)
         return npth;
 }
 
-static NOINLINE void complete_cmd_dir_file(char *command, int type)
+/* Complete command, directory or file name.
+ * Return the length of the prefix used for matching.
+ */
+static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
 {
         char *path1[1];
         char **paths = path1;
         int npaths;
         int i;
         unsigned pf_len;
-        char *pfind;
+        const char *pfind;
         char *dirbuf = NULL;
 
         npaths = 1;
@@ -797,8 +804,12 @@ static NOINLINE void complete_cmd_dir_file(char *command, int type)
         if (paths != path1) {
                 free(paths[0]); /* allocated memory is only in first member */
                 free(paths);
+        } else if (dirbuf) {
+                pf_len += strlen(dirbuf);
+                free(dirbuf);
         }
-        free(dirbuf);
+
+        return pf_len;
 }
 
 /* build_match_prefix:
@@ -829,7 +840,7 @@ static void collapse_pos(int beg, int end)
                 bb_putchar('\n');
         }
 }
-static NOINLINE int build_match_prefix(char *matchBuf, int *len_with_quotes)
+static NOINLINE int build_match_prefix(char *matchBuf)
 {
         int i, j;
         int command_mode;
@@ -992,9 +1003,6 @@ static NOINLINE int build_match_prefix(char *matchBuf, int *len_with_quotes)
                         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);
         }
 
         return command_mode;
@@ -1067,12 +1075,13 @@ static NOINLINE void input_tab(smallint *lastWasTab)
                 return;
 
         if (!*lastWasTab) {
-                char *tmp, *tmp1;
+                char *tmp;
                 size_t len_found;
 /*              char matchBuf[MAX_LINELEN]; */
 #define matchBuf (S.input_tab__matchBuf)
+                /* Length of string used for matching */
+                unsigned match_pfx_len = match_pfx_len;
                 int find_type;
-                int recalc_pos;
 #if ENABLE_UNICODE_SUPPORT
                 /* cursor pos in command converted to multibyte form */
                 int cursor_mb;
@@ -1095,7 +1104,7 @@ static NOINLINE void input_tab(smallint *lastWasTab)
 #endif
                 tmp = matchBuf;
 
-                find_type = build_match_prefix(matchBuf, &recalc_pos);
+                find_type = build_match_prefix(matchBuf);
 
                 /* Free up any memory already allocated */
                 free_tab_completion_data();
@@ -1105,11 +1114,11 @@ static NOINLINE void input_tab(smallint *lastWasTab)
                  * then try completing this word as a username. */
                 if (state->flags & USERNAME_COMPLETION)
                         if (matchBuf[0] == '~' && strchr(matchBuf, '/') == NULL)
-                                complete_username(matchBuf);
+                                match_pfx_len = complete_username(matchBuf);
 #endif
                 /* Try to match a command in $PATH, or a directory, or a file */
                 if (!matches)
-                        complete_cmd_dir_file(matchBuf, find_type);
+                        match_pfx_len = complete_cmd_dir_file(matchBuf, find_type);
                 /* Remove duplicates */
                 if (matches) {
                         unsigned i;
@@ -1130,23 +1139,26 @@ static NOINLINE void input_tab(smallint *lastWasTab)
                 }
                 /* Did we find exactly one match? */
                 if (num_matches != 1) { /* no */
+                        char *tmp1;
                         beep();
                         if (!matches)
                                 return; /* no matches at all */
                         /* Find common prefix */
                         tmp1 = xstrdup(matches[0]);
                         for (tmp = tmp1; *tmp; tmp++) {
-                                for (len_found = 1; len_found < num_matches; len_found++) {
-                                        if (matches[len_found][tmp - tmp1] != *tmp) {
-                                                *tmp = '\0';
-                                                break;
+                                unsigned n;
+                                for (n = 1; n < num_matches; n++) {
+                                        if (matches[n][tmp - tmp1] != *tmp) {
+                                                goto stop;
                                         }
                                 }
                         }
-                        if (*tmp1 == '\0') { /* have unique prefix? */
+ stop:
+                        if (tmp1 == tmp) { /* have unique prefix? */
                                 free(tmp1); /* no */
                                 return;
                         }
+                        *tmp = '\0';
                         tmp = add_quote_for_spec_chars(tmp1);
                         free(tmp1);
                         len_found = strlen(tmp);
@@ -1163,41 +1175,43 @@ static NOINLINE void input_tab(smallint *lastWasTab)
                 }
 
 #if !ENABLE_UNICODE_SUPPORT
-                /* have space to place the match? */
+                /* Have space to place the match? */
                 /* The result consists of three parts with these lengths: */
-                /* (cursor - recalc_pos) + len_found + (command_len - cursor) */
+                /* cursor + (len_found - match_pfx_len) + (command_len - cursor) */
                 /* it simplifies into: */
-                if ((int)(len_found + command_len - recalc_pos) < S.maxsize) {
+                if ((int)(len_found - match_pfx_len + command_len) < S.maxsize) {
+                        int pos;
                         /* save tail */
-                        strcpy(matchBuf, command_ps + cursor);
+                        strcpy(matchBuf, &command_ps[cursor]);
                         /* add match and tail */
-                        sprintf(&command_ps[cursor - recalc_pos], "%s%s", tmp, matchBuf);
+                        sprintf(&command_ps[cursor], "%s%s", tmp + match_pfx_len, matchBuf);
                         command_len = strlen(command_ps);
                         /* new pos */
-                        recalc_pos = cursor - recalc_pos + len_found;
+                        pos = cursor + len_found - match_pfx_len;
                         /* write out the matched command */
-                        redraw(cmdedit_y, command_len - recalc_pos);
+                        redraw(cmdedit_y, command_len - pos);
                 }
 #else
                 {
                         char command[MAX_LINELEN];
                         int len = save_string(command, sizeof(command));
-                        /* have space to place the match? */
-                        /* (cursor_mb - recalc_pos) + len_found + (len - cursor_mb) */
-                        if ((int)(len_found + len - recalc_pos) < MAX_LINELEN) {
+                        /* Have space to place the match? */
+                        /* cursor_mb + (len_found - match_pfx_len) + (len - cursor_mb) */
+                        if ((int)(len_found - match_pfx_len + len) < MAX_LINELEN) {
+                                int pos;
                                 /* save tail */
-                                strcpy(matchBuf, command + cursor_mb);
+                                strcpy(matchBuf, &command[cursor_mb]);
                                 /* where do we want to have cursor after all? */
-                                strcpy(&command[cursor_mb - recalc_pos], tmp);
+                                strcpy(&command[cursor_mb], tmp + match_pfx_len);
                                 len = load_string(command, S.maxsize);
                                 /* add match and tail */
-                                sprintf(&command[cursor_mb - recalc_pos], "%s%s", tmp, matchBuf);
+                                sprintf(&command[cursor_mb], "%s%s", tmp + match_pfx_len, matchBuf);
                                 command_len = load_string(command, S.maxsize);
                                 /* write out the matched command */
                                 /* paranoia: load_string can return 0 on conv error,
-                                 * prevent passing len = (0 - 12) to redraw */
-                                len = command_len - len;
-                                redraw(cmdedit_y, len >= 0 ? len : 0);
+                                 * prevent passing pos = (0 - 12) to redraw */
+                                pos = command_len - len;
+                                redraw(cmdedit_y, pos >= 0 ? pos : 0);
                         }
                 }
 #endif