Print control codes only in graphic mode

Non handled codes must be ignored, except in graphic mode. Also STR
sequences have higher priority than control codes, so they must be handled
before of them.
---
 st.c |  160 ++++++++++++++++++++++++++++++++++++------------------------------
 1 file changed, 87 insertions(+), 73 deletions(-)

st.c

@@ -1784,56 +1784,80 @@ tputtab(bool forward) {
 void
 tputc(char *c, int len) {
 	uchar ascii = *c;
+	bool control = ascii < '\x20' || ascii == 0177;
 
 	if(iofd != -1)
 		write(iofd, c, len);
-
-	switch(ascii) {
-	case '\t':	/* HT */
-		tputtab(1);
-		return;
-	case '\b':	/* BS */
-		tmoveto(term.c.x-1, term.c.y);
-		return;
-	case '\r':	/* CR */
-		tmoveto(0, term.c.y);
-		return;
-	case '\f':	/* LF */
-	case '\v':	/* VT */
-	case '\n':	/* LF */
-		/* go to first col if the mode is set */
-		tnewline(IS_SET(MODE_CRLF));
-		return;
-	case '\a':	/* BEL */
-		if(term.esc & ESC_STR)
+	/*
+	 * STR sequences must be checked before of anything
+	 * because it can use some control codes as part of the sequence
+	 */
+	if(term.esc & ESC_STR) {
+		switch(ascii) {
+		case '\033':
+			term.esc = ESC_START | ESC_STR_END;
 			break;
-		if(!(xw.state & WIN_FOCUSED))
-			xseturgency(1);
-		return;
-	case '\033':	/* ESC */
-		csireset();
-		term.esc = ESC_START;
-		return;
-	case '\016':	/* SO */
-		term.c.attr.mode |= ATTR_GFX;
-		break;
-	case '\017':	/* SI */
-		term.c.attr.mode &= ~ATTR_GFX;
-		return;
-	case '\032':	/* SUB */
-	case '\030':	/* CAN */
-		csireset();
+		case '\a': /* backwards compatibility to xterm */
+			term.esc = 0;
+			strhandle();
+			break;
+		default:
+			strescseq.buf[strescseq.len++] = ascii;
+			if(strescseq.len+1 >= STR_BUF_SIZ) {
+				term.esc = 0;
+				strhandle();
+			}
+		}
 		return;
-	default:
-	/* case '\005':	ENQ (IGNORED) */
-	/* case '\000':	NUL (IGNORED) */
-	/* case '\021':	XON (IGNORED) */
-	/* case '\023':	XOFF (IGNORED) */
-	/* case 0177:	DEL (IGNORED) */
-		break;
 	}
-
-	if(term.esc & ESC_START) {
+	/*
+	 * Actions of control codes must be performed as soon they arrive
+	 * because they can be embedded inside a control sequence, and
+	 * they must not cause conflicts with sequences.
+	 */
+	if(control) {
+		switch(ascii) {
+		case '\t':	/* HT */
+			tputtab(1);
+			return;
+		case '\b':	/* BS */
+			tmoveto(term.c.x-1, term.c.y);
+			return;
+		case '\r':	/* CR */
+			tmoveto(0, term.c.y);
+			return;
+		case '\f':	/* LF */
+		case '\v':	/* VT */
+		case '\n':	/* LF */
+			/* go to first col if the mode is set */
+			tnewline(IS_SET(MODE_CRLF));
+			return;
+		case '\a':	/* BEL */
+			if(!(xw.state & WIN_FOCUSED))
+				xseturgency(1);
+			return;
+		case '\033':	/* ESC */
+			csireset();
+			term.esc = ESC_START;
+			return;
+		case '\016':	/* SO */
+			term.c.attr.mode |= ATTR_GFX;
+			return;
+		case '\017':	/* SI */
+			term.c.attr.mode &= ~ATTR_GFX;
+			return;
+		case '\032':	/* SUB */
+		case '\030':	/* CAN */
+			csireset();
+			return;
+		 case '\005':	/* ENQ (IGNORED) */
+		 case '\000':	/* NUL (IGNORED) */
+		 case '\021':	/* XON (IGNORED) */
+		 case '\023':	/* XOFF (IGNORED) */
+		 case 0177:	/* DEL (IGNORED) */
+			return;
+		}
+	} else if(term.esc & ESC_START) {
 		if(term.esc & ESC_CSI) {
 			csiescseq.buf[csiescseq.len++] = ascii;
 			if(BETWEEN(ascii, 0x40, 0x7E)
@@ -1841,22 +1865,6 @@ tputc(char *c, int len) {
 				term.esc = 0;
 				csiparse(), csihandle();
 			}
-		} else if(term.esc & ESC_STR) {
-			switch(ascii) {
-			case '\033':
-				term.esc = ESC_START | ESC_STR_END;
-				break;
-			case '\a': /* backwards compatibility to xterm */
-				term.esc = 0;
-				strhandle();
-				break;
-			default:
-				strescseq.buf[strescseq.len++] = ascii;
-				if(strescseq.len+1 >= STR_BUF_SIZ) {
-					term.esc = 0;
-					strhandle();
-				}
-			}
 		} else if(term.esc & ESC_STR_END) {
 			term.esc = 0;
 			if(ascii == '\\')
@@ -1955,20 +1963,26 @@ tputc(char *c, int len) {
 				term.esc = 0;
 			}
 		}
-	} else {
-		if(sel.bx != -1 && BETWEEN(term.c.y, sel.by, sel.ey))
-			sel.bx = -1;
-		if(ascii >= '\020' || term.c.attr.mode & ATTR_GFX) {
-			if(IS_SET(MODE_WRAP) && term.c.state & CURSOR_WRAPNEXT)
-				tnewline(1); /* always go to first col */
-			tsetchar(c);
-			if(term.c.x+1 < term.col) {
-				tmoveto(term.c.x+1, term.c.y);
-			} else {
-				term.c.state |= CURSOR_WRAPNEXT;
-			}
-		}
+		/*
+		 * All characters which forms part of a sequence are not
+		 * printed
+		 */
+		return;
 	}
+	/*
+	 * Display control codes only if we are in graphic mode
+	 */
+	if(control && !(term.c.attr.mode & ATTR_GFX))
+		return;
+	if(sel.bx != -1 && BETWEEN(term.c.y, sel.by, sel.ey))
+		sel.bx = -1;
+	if(IS_SET(MODE_WRAP) && term.c.state & CURSOR_WRAPNEXT)
+		tnewline(1); /* always go to first col */
+	tsetchar(c);
+	if(term.c.x+1 < term.col)
+		tmoveto(term.c.x+1, term.c.y);
+	else
+		term.c.state |= CURSOR_WRAPNEXT;
 }
 
 int