lineedit: allocate matchBuf only temporarily: saves MAX_LINELEN bytes
authorDenys Vlasenko <dvlasenk@redhat.com>
Fri, 3 Sep 2010 12:09:24 +0000 (14:09 +0200)
committerDenys Vlasenko <dvlasenk@redhat.com>
Fri, 3 Sep 2010 12:09:24 +0000 (14:09 +0200)
function                                             old     new   delta
input_tab                                           1027    1041     +14
build_match_prefix                                   590     562     -28
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 14/-28)            Total: -14 bytes

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
libbb/lineedit.c

index ff5d284..a917c5f 100644 (file)
@@ -150,11 +150,6 @@ struct lineedit_statics {
 #if ENABLE_FEATURE_EDITING_ASK_TERMINAL
        smallint sent_ESC_br6n;
 #endif
-
-       /* Formerly these were big buffers on stack: */
-#if ENABLE_FEATURE_TAB_COMPLETION
-       char input_tab__matchBuf[MAX_LINELEN];
-#endif
 };
 
 /* See lineedit_ptr_hack.c */
@@ -810,17 +805,17 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
 }
 
 /* build_match_prefix:
- * On entry, matchBuf contains everything up to cursor at the moment <tab>
+ * On entry, match_buf contains everything up to cursor at the moment <tab>
  * was pressed. This function looks at it, figures out what part of it
  * constitutes the command/file/directory prefix to use for completion,
- * and rewrites matchBuf to contain only that part.
+ * and rewrites match_buf to contain only that part.
  */
+#define dbg_bmp 0
 /* Helpers: */
 /* QUOT is used on elements of int_buf[], which are bytes,
  * not Unicode chars. Therefore it works correctly even in Unicode mode.
  */
 #define QUOT (UCHAR_MAX+1)
-#define dbg_bmp 0
 static void remove_chunk(int16_t *int_buf, int beg, int end)
 {
        /* beg must be <= end */
@@ -837,25 +832,29 @@ static void remove_chunk(int16_t *int_buf, int beg, int end)
                bb_putchar('\n');
        }
 }
-static NOINLINE int build_match_prefix(char *matchBuf)
+/* Caller ensures that match_buf points to a malloced buffer
+ * big enough to hold strlen(match_buf)*2 + 2
+ */
+static NOINLINE int build_match_prefix(char *match_buf)
 {
        int i, j;
        int command_mode;
-       int16_t *int_buf;
+       int16_t *int_buf = (int16_t*)match_buf;
 
-       if (dbg_bmp) printf("\n%s\n", matchBuf);
+       if (dbg_bmp) printf("\n%s\n", match_buf);
 
-       int_buf = xmalloc(sizeof(int_buf[0]) * (strlen(matchBuf) + 1));
-       i = 0;
-       while ((int_buf[i] = (unsigned char)matchBuf[i]) != '\0')
-               i++;
+       /* Copy in reverse order, since they overlap */
+       i = strlen(match_buf);
+       do {
+               int_buf[i] = (unsigned char)match_buf[i];
+               i--;
+       } while (i >= 0);
 
        /* Mark every \c as "quoted c" */
-       for (i = j = 0; matchBuf[i]; i++, j++) {
-               if (matchBuf[i] == '\\') {
-                       remove_chunk(int_buf, j, j + 1);
-                       int_buf[j] |= QUOT;
-                       i++;
+       for (i = 0; int_buf[i]; i++) {
+               if (int_buf[i] == '\\') {
+                       remove_chunk(int_buf, i, i + 1);
+                       int_buf[i] |= QUOT;
                }
        }
        /* Quote-mark "chars" and 'chars', drop delimiters */
@@ -964,13 +963,12 @@ static NOINLINE int build_match_prefix(char *matchBuf)
                }
        }
 
-       /* Store only match prefix */
+       /* Convert back to string of _chars_ */
        i = 0;
-       while ((matchBuf[i] = int_buf[i]) != '\0')
+       while ((match_buf[i] = int_buf[i]) != '\0')
                i++;
-       free(int_buf);
 
-       if (dbg_bmp) printf("final matchBuf:'%s'\n", matchBuf);
+       if (dbg_bmp) printf("final match_buf:'%s'\n", match_buf);
 
        return command_mode;
 }
@@ -1037,9 +1035,8 @@ static char *add_quote_for_spec_chars(char *found)
 static NOINLINE void input_tab(smallint *lastWasTab)
 {
        char *chosen_match;
+       char *match_buf;
        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;
@@ -1065,21 +1062,26 @@ static NOINLINE void input_tab(smallint *lastWasTab)
        }
 
        *lastWasTab = 1;
+       chosen_match = NULL;
 
-       /* Make a local copy of the string --
-        * up to the position of the cursor */
+       /* Make a local copy of the string up to the position of the cursor.
+        * build_match_prefix will expand it into int16_t's, need to allocate
+        * twice as much as the string_len+1.
+        * (we then also (ab)use this extra space later - see (**))
+        */
+       match_buf = xmalloc(MAX_LINELEN * sizeof(int16_t));
 #if !ENABLE_UNICODE_SUPPORT
-       save_string(matchBuf, cursor + 1);
+       save_string(match_buf, cursor + 1); /* +1 for NUL */
 #else
        {
                CHAR_T wc = command_ps[cursor];
                command_ps[cursor] = BB_NUL;
-               save_string(matchBuf, MAX_LINELEN);
+               save_string(match_buf, MAX_LINELEN);
                command_ps[cursor] = wc;
-               cursor_mb = strlen(matchBuf);
+               cursor_mb = strlen(match_buf);
        }
 #endif
-       find_type = build_match_prefix(matchBuf);
+       find_type = build_match_prefix(match_buf);
 
        /* Free up any memory already allocated */
        free_tab_completion_data();
@@ -1088,12 +1090,12 @@ static NOINLINE void input_tab(smallint *lastWasTab)
        /* If the word starts with `~' and there is no slash in the word,
         * then try completing this word as a username. */
        if (state->flags & USERNAME_COMPLETION)
-               if (matchBuf[0] == '~' && strchr(matchBuf, '/') == NULL)
-                       match_pfx_len = complete_username(matchBuf);
+               if (match_buf[0] == '~' && strchr(match_buf, '/') == NULL)
+                       match_pfx_len = complete_username(match_buf);
 #endif
        /* Try to match a command in $PATH, or a directory, or a file */
        if (!matches)
-               match_pfx_len = complete_cmd_dir_file(matchBuf, find_type);
+               match_pfx_len = complete_cmd_dir_file(match_buf, find_type);
        /* Remove duplicates */
        if (matches) {
                unsigned i;
@@ -1117,7 +1119,7 @@ static NOINLINE void input_tab(smallint *lastWasTab)
                char *cp;
                beep();
                if (!matches)
-                       return; /* no matches at all */
+                       goto ret; /* no matches at all */
                /* Find common prefix */
                chosen_match = xstrdup(matches[0]);
                for (cp = chosen_match; *cp; cp++) {
@@ -1130,8 +1132,7 @@ static NOINLINE void input_tab(smallint *lastWasTab)
                }
  stop:
                if (cp == chosen_match) { /* have unique prefix? */
-                       free(chosen_match); /* no */
-                       return;
+                       goto ret; /* no */
                }
                *cp = '\0';
                cp = add_quote_for_spec_chars(chosen_match);
@@ -1158,9 +1159,9 @@ static NOINLINE void input_tab(smallint *lastWasTab)
        if ((int)(len_found - match_pfx_len + command_len) < S.maxsize) {
                int pos;
                /* save tail */
-               strcpy(matchBuf, &command_ps[cursor]);
+               strcpy(match_buf, &command_ps[cursor]);
                /* add match and tail */
-               sprintf(&command_ps[cursor], "%s%s", chosen_match + match_pfx_len, matchBuf);
+               sprintf(&command_ps[cursor], "%s%s", chosen_match + match_pfx_len, match_buf);
                command_len = strlen(command_ps);
                /* new pos */
                pos = cursor + len_found - match_pfx_len;
@@ -1169,19 +1170,20 @@ static NOINLINE void input_tab(smallint *lastWasTab)
        }
 #else
        {
-               char command[MAX_LINELEN];
-               int len = save_string(command, sizeof(command));
+               /* Use 2nd half of match_buf as scratch space - see (**) */
+               char *command = match_buf + MAX_LINELEN;
+               int len = save_string(command, 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(match_buf, &command[cursor_mb]);
                        /* where do we want to have cursor after all? */
                        strcpy(&command[cursor_mb], chosen_match + match_pfx_len);
                        len = load_string(command, S.maxsize);
                        /* add match and tail */
-                       sprintf(&command[cursor_mb], "%s%s", chosen_match + match_pfx_len, matchBuf);
+                       sprintf(&command[cursor_mb], "%s%s", chosen_match + match_pfx_len, match_buf);
                        command_len = load_string(command, S.maxsize);
                        /* write out the matched command */
                        /* paranoia: load_string can return 0 on conv error,
@@ -1191,8 +1193,9 @@ static NOINLINE void input_tab(smallint *lastWasTab)
                }
        }
 #endif
+ ret:
        free(chosen_match);
-#undef matchBuf
+       free(match_buf);
 }
 
 #endif  /* FEATURE_TAB_COMPLETION */