lineedit: fix completion with Unicode chars

function                                             old     new   delta
read_line_input                                     4966    5002     +36
bb_wcstombs                                          170     159     -11
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 36/-11)             Total: 25 bytes

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

2 files changed, 14 insertions, 4 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index de7042491..381203a22 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -1061,9 +1061,16 @@ static void input_tab(smallint *lastWasTab)
 
                 /* Make a local copy of the string --
                  * up to the position of the cursor */
+#if !ENABLE_UNICODE_SUPPORT
                 save_string(matchBuf, cursor + 1);
-#if ENABLE_UNICODE_SUPPORT
-                cursor_mb = strlen(matchBuf);
+#else
+                {
+                        CHAR_T wc = command_ps[cursor];
+                        command_ps[cursor] = 0;
+                        save_string(matchBuf, MAX_LINELEN);
+                        command_ps[cursor] = wc;
+                        cursor_mb = strlen(matchBuf);
+                }
 #endif
                 tmp = matchBuf;
 
@@ -1167,7 +1174,10 @@ static void input_tab(smallint *lastWasTab)
                                 sprintf(&command[cursor_mb - recalc_pos], "%s%s", tmp, matchBuf);
                                 command_len = load_string(command, S.maxsize);
                                 /* write out the matched command */
-                                redraw(cmdedit_y, command_len - len);
+                                /* 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);
                         }
                 }
 #endif
diff --git a/libbb/unicode.c b/libbb/unicode.c
index c4b5f86ee..70c6abe00 100644
--- a/libbb/unicode.c
+++ b/libbb/unicode.c
@@ -131,7 +131,7 @@ size_t FAST_FUNC wcstombs(char *dest, const wchar_t *src, size_t n)
                 size_t len = wcrtomb_internal(tbuf, wc);
 
                 if (len > n)
-                        len = n;
+                        break;
                 memcpy(dest, tbuf, len);
                 if (wc == L'\0')
                         return org_n - n;