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0fd5dbba8

Avi Halachmi
Avi Halachmi
2017-10-12
SUCCESS Duration: 144s

Subject

lineedit: improve multiline PS1 - redraw using last PS1 line. Closes 10381

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

libbb/lineedit.c +64 -24
libbb/lineedit.c+64 -24
@@ -37,11 +37,6 @@
*
* Unicode in PS1 is not fully supported: prompt length calulation is wrong,
* resulting in line wrap problems with long (multi-line) input.
- *
- * Multi-line PS1 (e.g. PS1="\n[\w]\n$ ") has problems with history
- * browsing: up/down arrows result in scrolling.
- * It stems from simplistic "cmdedit_y = cmdedit_prmt_len / cmdedit_termw"
- * calculation of how many lines the prompt takes.
*/
#include "busybox.h"
#include "NUM_APPLETS.h"
@@ -133,7 +128,7 @@ struct lineedit_statics {
unsigned cmdedit_x; /* real x (col) terminal position */
unsigned cmdedit_y; /* pseudoreal y (row) terminal position */
- unsigned cmdedit_prmt_len; /* length of prompt (without colors etc) */
+ unsigned cmdedit_prmt_len; /* on-screen length of last/sole prompt line */
unsigned cursor;
int command_len; /* must be signed */
@@ -143,6 +138,7 @@ struct lineedit_statics {
CHAR_T *command_ps;
const char *cmdedit_prompt;
+ const char *prompt_last_line; /* last/sole prompt line */
#if ENABLE_USERNAME_OR_HOMEDIR
char *user_buf;
@@ -185,6 +181,7 @@ extern struct lineedit_statics *const lineedit_ptr_to_statics;
#define command_len (S.command_len )
#define command_ps (S.command_ps )
#define cmdedit_prompt (S.cmdedit_prompt )
+#define prompt_last_line (S.prompt_last_line)
#define user_buf (S.user_buf )
#define home_pwd_buf (S.home_pwd_buf )
#define matches (S.matches )
@@ -437,14 +434,20 @@ static void beep(void)
bb_putchar('\007');
}
-static void put_prompt(void)
+/* Full or last/sole prompt line, reset edit cursor, calculate terminal cursor.
+ * cmdedit_y is always calculated for the last/sole prompt line.
+ */
+static void put_prompt_custom(bool is_full)
{
- fputs(cmdedit_prompt, stdout);
+ fputs((is_full ? cmdedit_prompt : prompt_last_line), stdout);
cursor = 0;
cmdedit_y = cmdedit_prmt_len / cmdedit_termw; /* new quasireal y */
cmdedit_x = cmdedit_prmt_len % cmdedit_termw;
}
+#define put_prompt_last_line() put_prompt_custom(0)
+#define put_prompt() put_prompt_custom(1)
+
/* Move back one character */
/* (optimized for slow terminals) */
static void input_backward(unsigned num)
@@ -509,7 +512,7 @@ static void input_backward(unsigned num)
printf("\r" ESC"[%uA", cmdedit_y);
cmdedit_y = 0;
sv_cursor = cursor;
- put_prompt(); /* sets cursor to 0 */
+ put_prompt_last_line(); /* sets cursor to 0 */
while (cursor < sv_cursor)
put_cur_glyph_and_inc_cursor();
} else {
@@ -530,18 +533,27 @@ static void input_backward(unsigned num)
}
}
-/* draw prompt, editor line, and clear tail */
-static void redraw(int y, int back_cursor)
+/* See redraw and draw_full below */
+static void draw_custom(int y, int back_cursor, bool is_full)
{
if (y > 0) /* up y lines */
printf(ESC"[%uA", y);
bb_putchar('\r');
- put_prompt();
+ put_prompt_custom(is_full);
put_till_end_and_adv_cursor();
printf(SEQ_CLEAR_TILL_END_OF_SCREEN);
input_backward(back_cursor);
}
+/* Move y lines up, draw last/sole prompt line, editor line[s], and clear tail.
+ * goal: redraw the prompt+input+cursor in-place, overwriting the previous */
+#define redraw(y, back_cursor) draw_custom((y), (back_cursor), 0)
+
+/* Like above, but without moving up, and while using all the prompt lines.
+ * goal: draw a full prompt+input+cursor unrelated to a previous position.
+ * note: cmdedit_y always ends up relating to the last/sole prompt line */
+#define draw_full(back_cursor) draw_custom(0, (back_cursor), 1)
+
/* Delete the char in front of the cursor, optionally saving it
* for later putback */
#if !ENABLE_FEATURE_EDITING_VI
@@ -1106,7 +1118,7 @@ static NOINLINE void input_tab(smallint *lastWasTab)
int sav_cursor = cursor;
goto_new_line();
showfiles();
- redraw(0, command_len - sav_cursor);
+ draw_full(command_len - sav_cursor);
}
return;
}
@@ -1782,14 +1794,37 @@ static void ask_terminal(void)
#define ask_terminal() ((void)0)
#endif
+/* Note about multi-line PS1 (e.g. "\n\w \u@\h\n> ") and prompt redrawing:
+ *
+ * If the prompt has any newlines, after we print it once we use only its last
+ * line to redraw in-place, which makes it simpler to calculate how many lines
+ * we should move the cursor up to align the redraw (cmdedit_y). The earlier
+ * prompt lines just stay on screen and we redraw below them.
+ *
+ * Use cases for all prompt lines beyond the initial draw:
+ * - After clear-screen (^L) or after displaying tab-completion choices, we
+ * print the full prompt, as it isn't redrawn in-place.
+ * - During terminal resize we could try to redraw all lines, but we don't,
+ * because it requires delicate alignment, it's good enough with only the
+ * last line, and doing it wrong is arguably worse than not doing it at all.
+ *
+ * Terminology wise, if it doesn't mention "full", then it means the last/sole
+ * prompt line. We use the prompt (last/sole line) while redrawing in-place,
+ * and the full where we need a fresh one unrelated to an earlier position.
+ *
+ * If PS1 is not multiline, the last/sole line and the full are the same string.
+ */
+
/* Called just once at read_line_input() init time */
#if !ENABLE_FEATURE_EDITING_FANCY_PROMPT
static void parse_and_put_prompt(const char *prmt_ptr)
{
const char *p;
- cmdedit_prompt = prmt_ptr;
+ cmdedit_prompt = prompt_last_line = prmt_ptr;
p = strrchr(prmt_ptr, '\n');
- cmdedit_prmt_len = unicode_strwidth(p ? p+1 : prmt_ptr);
+ if (p)
+ prompt_last_line = p + 1;
+ cmdedit_prmt_len = unicode_strwidth(prompt_last_line);
put_prompt();
}
#else
@@ -1973,7 +2008,11 @@ static void parse_and_put_prompt(const char *prmt_ptr)
if (cwd_buf != (char *)bb_msg_unknown)
free(cwd_buf);
# endif
- cmdedit_prompt = prmt_mem_ptr;
+ /* see comment (above this function) about multiline prompt redrawing */
+ cmdedit_prompt = prompt_last_line = prmt_mem_ptr;
+ prmt_ptr = strrchr(cmdedit_prompt, '\n');
+ if (prmt_ptr)
+ prompt_last_line = prmt_ptr + 1;
put_prompt();
}
#endif
@@ -2145,7 +2184,7 @@ static int32_t reverse_i_search(int timeout)
match_buf[0] = '\0';
/* Save and replace the prompt */
- saved_prompt = cmdedit_prompt;
+ saved_prompt = prompt_last_line;
saved_prmt_len = cmdedit_prmt_len;
goto set_prompt;
@@ -2218,10 +2257,10 @@ static int32_t reverse_i_search(int timeout)
cursor = match - matched_history_line;
//FIXME: cursor position for Unicode case
- free((char*)cmdedit_prompt);
+ free((char*)prompt_last_line);
set_prompt:
- cmdedit_prompt = xasprintf("(reverse-i-search)'%s': ", match_buf);
- cmdedit_prmt_len = unicode_strwidth(cmdedit_prompt);
+ prompt_last_line = xasprintf("(reverse-i-search)'%s': ", match_buf);
+ cmdedit_prmt_len = unicode_strwidth(prompt_last_line);
goto do_redraw;
}
}
@@ -2241,8 +2280,8 @@ static int32_t reverse_i_search(int timeout)
if (matched_history_line)
command_len = load_string(matched_history_line);
- free((char*)cmdedit_prompt);
- cmdedit_prompt = saved_prompt;
+ free((char*)prompt_last_line);
+ prompt_last_line = saved_prompt;
cmdedit_prmt_len = saved_prmt_len;
redraw(cmdedit_y, command_len - cursor);
@@ -2451,8 +2490,9 @@ int FAST_FUNC read_line_input(line_input_t *st, const char *prompt, char *comman
case CTRL('L'):
vi_case(CTRL('L')|VI_CMDMODE_BIT:)
/* Control-l -- clear screen */
- printf(ESC"[H"); /* cursor to top,left */
- redraw(0, command_len - cursor);
+ /* cursor to top,left; clear to the end of screen */
+ printf(ESC"[H" ESC"[J");
+ draw_full(command_len - cursor);
break;
#if MAX_HISTORY > 0
case CTRL('N'):