Merging upstream version 6.9.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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;