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-rw-r--r--kernel/debug/kdb/kdb_io.c99
1 files changed, 56 insertions, 43 deletions
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 9443bc63c5..2aeaf9765b 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -184,6 +184,33 @@ char kdb_getchar(void)
unreachable();
}
+/**
+ * kdb_position_cursor() - Place cursor in the correct horizontal position
+ * @prompt: Nil-terminated string containing the prompt string
+ * @buffer: Nil-terminated string containing the entire command line
+ * @cp: Cursor position, pointer the character in buffer where the cursor
+ * should be positioned.
+ *
+ * The cursor is positioned by sending a carriage-return and then printing
+ * the content of the line until we reach the correct cursor position.
+ *
+ * There is some additional fine detail here.
+ *
+ * Firstly, even though kdb_printf() will correctly format zero-width fields
+ * we want the second call to kdb_printf() to be conditional. That keeps things
+ * a little cleaner when LOGGING=1.
+ *
+ * Secondly, we can't combine everything into one call to kdb_printf() since
+ * that renders into a fixed length buffer and the combined print could result
+ * in unwanted truncation.
+ */
+static void kdb_position_cursor(char *prompt, char *buffer, char *cp)
+{
+ kdb_printf("\r%s", kdb_prompt_str);
+ if (cp > buffer)
+ kdb_printf("%.*s", (int)(cp - buffer), buffer);
+}
+
/*
* kdb_read
*
@@ -212,7 +239,6 @@ static char *kdb_read(char *buffer, size_t bufsize)
* and null byte */
char *lastchar;
char *p_tmp;
- char tmp;
static char tmpbuffer[CMD_BUFLEN];
int len = strlen(buffer);
int len_tmp;
@@ -249,12 +275,8 @@ poll_again:
}
*(--lastchar) = '\0';
--cp;
- kdb_printf("\b%s \r", cp);
- tmp = *cp;
- *cp = '\0';
- kdb_printf(kdb_prompt_str);
- kdb_printf("%s", buffer);
- *cp = tmp;
+ kdb_printf("\b%s ", cp);
+ kdb_position_cursor(kdb_prompt_str, buffer, cp);
}
break;
case 10: /* linefeed */
@@ -272,19 +294,14 @@ poll_again:
memcpy(tmpbuffer, cp+1, lastchar - cp - 1);
memcpy(cp, tmpbuffer, lastchar - cp - 1);
*(--lastchar) = '\0';
- kdb_printf("%s \r", cp);
- tmp = *cp;
- *cp = '\0';
- kdb_printf(kdb_prompt_str);
- kdb_printf("%s", buffer);
- *cp = tmp;
+ kdb_printf("%s ", cp);
+ kdb_position_cursor(kdb_prompt_str, buffer, cp);
}
break;
case 1: /* Home */
if (cp > buffer) {
- kdb_printf("\r");
- kdb_printf(kdb_prompt_str);
cp = buffer;
+ kdb_position_cursor(kdb_prompt_str, buffer, cp);
}
break;
case 5: /* End */
@@ -300,11 +317,10 @@ poll_again:
}
break;
case 14: /* Down */
- memset(tmpbuffer, ' ',
- strlen(kdb_prompt_str) + (lastchar-buffer));
- *(tmpbuffer+strlen(kdb_prompt_str) +
- (lastchar-buffer)) = '\0';
- kdb_printf("\r%s\r", tmpbuffer);
+ case 16: /* Up */
+ kdb_printf("\r%*c\r",
+ (int)(strlen(kdb_prompt_str) + (lastchar - buffer)),
+ ' ');
*lastchar = (char)key;
*(lastchar+1) = '\0';
return lastchar;
@@ -314,15 +330,6 @@ poll_again:
++cp;
}
break;
- case 16: /* Up */
- memset(tmpbuffer, ' ',
- strlen(kdb_prompt_str) + (lastchar-buffer));
- *(tmpbuffer+strlen(kdb_prompt_str) +
- (lastchar-buffer)) = '\0';
- kdb_printf("\r%s\r", tmpbuffer);
- *lastchar = (char)key;
- *(lastchar+1) = '\0';
- return lastchar;
case 9: /* Tab */
if (tab < 2)
++tab;
@@ -366,15 +373,25 @@ poll_again:
kdb_printf("\n");
kdb_printf(kdb_prompt_str);
kdb_printf("%s", buffer);
+ if (cp != lastchar)
+ kdb_position_cursor(kdb_prompt_str, buffer, cp);
} else if (tab != 2 && count > 0) {
- len_tmp = strlen(p_tmp);
- strncpy(p_tmp+len_tmp, cp, lastchar-cp+1);
- len_tmp = strlen(p_tmp);
- strncpy(cp, p_tmp+len, len_tmp-len + 1);
- len = len_tmp - len;
- kdb_printf("%s", cp);
- cp += len;
- lastchar += len;
+ /* How many new characters do we want from tmpbuffer? */
+ len_tmp = strlen(p_tmp) - len;
+ if (lastchar + len_tmp >= bufend)
+ len_tmp = bufend - lastchar;
+
+ if (len_tmp) {
+ /* + 1 ensures the '\0' is memmove'd */
+ memmove(cp+len_tmp, cp, (lastchar-cp) + 1);
+ memcpy(cp, p_tmp+len, len_tmp);
+ kdb_printf("%s", cp);
+ cp += len_tmp;
+ lastchar += len_tmp;
+ if (cp != lastchar)
+ kdb_position_cursor(kdb_prompt_str,
+ buffer, cp);
+ }
}
kdb_nextline = 1; /* reset output line number */
break;
@@ -385,13 +402,9 @@ poll_again:
memcpy(cp+1, tmpbuffer, lastchar - cp);
*++lastchar = '\0';
*cp = key;
- kdb_printf("%s\r", cp);
+ kdb_printf("%s", cp);
++cp;
- tmp = *cp;
- *cp = '\0';
- kdb_printf(kdb_prompt_str);
- kdb_printf("%s", buffer);
- *cp = tmp;
+ kdb_position_cursor(kdb_prompt_str, buffer, cp);
} else {
*++lastchar = '\0';
*cp++ = key;