gets_s() updated to handle backspace and control-C

README.md

@@ -316,6 +316,8 @@ In the relevant: example, test or any other directory created at the same level.
 
   - Updated `tests/scanf` to include test of `fscanf()`
 
+- `gets_s()` updated to handle backspace, cursor left and control-C during input
+
 ### To-Do / Known Issues:
 
 - Testing / validation

lib/libc/gets_s.c.src

@@ -3,98 +3,162 @@
 	section	.text,"ax",@progbits
 	public	_gets_s
 _gets_s:
-	ld	hl, -6
+	ld	hl, -9
 	call	__frameset
-	ld	de, (ix + 6)
-	ld	iy, (ix + 9)
+	ld	iy, (ix + 6)
+	ld	de, (ix + 9)
 	ld	bc, 0
-	or	a, a
-	sbc	hl, hl
-	ld	(ix - 3), hl
-	push	de
-	pop	hl
+	lea	hl, iy
 	add	hl, bc
 	or	a, a
 	sbc	hl, bc
 	jr	nz, BB0_2
-	lea	hl, iy
+	ex	de, hl
 	add	hl, bc
 	or	a, a
 	sbc	hl, bc
-	jp	z, BB0_13
+	jp	z, BB0_24
 BB0_2:
 	ld	a, (_stdin)
 	cp	a, -128
-	jr	nz, BB0_8
-	ld	(ix - 6), de
+	jp	nz, BB0_17
+	or	a, a
+	sbc	hl, hl
+	ex	de, hl
+	ld	(ix - 6), iy
 BB0_4:
+	ld	(ix - 3), de
 	call	_getchar
 	push	hl
 	pop	de
+	ld	bc, 3
+	or	a, a
+	sbc	hl, bc
+	jp	z, BB0_20
+	push	de
+	pop	hl
+	ld	bc, 8
+	or	a, a
+	sbc	hl, bc
+	ld	iy, (ix - 6)
+	jr	z, BB0_8
+	push	de
+	pop	hl
 	ld	bc, 10
 	or	a, a
 	sbc	hl, bc
-	jr	z, BB0_11
-	ld	iy, (ix - 3)
-	lea	hl, iy
+	jp	z, BB0_21
+	push	de
+	pop	hl
+	ld	bc, 127
+	or	a, a
+	sbc	hl, bc
+	jr	nz, BB0_14
+BB0_8:
+	ld	bc, (ix - 3)
+	push	bc
+	pop	hl
+	add	hl, bc
+	or	a, a
+	sbc	hl, bc
+	ld	hl, 0
+	jr	z, BB0_10
+	push	bc
+	pop	hl
+	dec	hl
+BB0_10:
+	ld	(ix - 9), hl
+	push	bc
+	pop	hl
+	add	hl, bc
+	or	a, a
+	sbc	hl, bc
+	ld	bc, -1
+	jr	nz, BB0_12
+	ld	bc, 0
+BB0_12:
+	add	iy, bc
+	ld	(ix - 6), iy
+	ex	de, hl
+	ld	de, 8
+	or	a, a
+	sbc	hl, de
+	ld	hl, (ix - 9)
+	ex	de, hl
+	jr	nz, BB0_4
+	ld	hl, 32
+	push	hl
+	call	_putchar
+	pop	hl
+	ld	hl, 127
+	push	hl
+	call	_putchar
+	pop	hl
+	ld	de, (ix - 9)
+	jp	BB0_4
+BB0_14:
+	ld	hl, (ix - 3)
 	ld	bc, (ix + 9)
 	or	a, a
 	sbc	hl, bc
-	jr	nc, BB0_7
+	jr	nc, BB0_16
 	ld	a, e
-	ld	hl, (ix - 6)
-	ld	(hl), a
-	inc	hl
-	ld	(ix - 6), hl
-BB0_7:
+	ld	(iy), a
 	inc	iy
-	ld	(ix - 3), iy
-	jr	BB0_4
-BB0_8:
+	ld	(ix - 6), iy
+BB0_16:
+	ld	de, (ix - 3)
+	inc	de
+	jp	BB0_4
+BB0_17:
 	ld	hl, _stdin
 	push	hl
 	ld	hl, (ix + 9)
 	push	hl
-	push	de
+	push	iy
 	call	_fgets
-	ld	bc, 0
 	pop	de
 	pop	de
 	pop	de
 	add	hl, bc
 	or	a, a
 	sbc	hl, bc
-	jr	z, BB0_13
+	ld	bc, 0
+	jr	z, BB0_24
 	ld	hl, (ix + 6)
 	push	hl
 	call	_strlen
-	ld	bc, (ix + 6)
 	push	hl
 	pop	de
 	pop	hl
-	push	bc
+	ld	hl, (ix + 6)
+	push	hl
 	pop	iy
 	add	iy, de
 	ld	a, (iy - 1)
 	cp	a, 10
-	jr	nz, BB0_13
+	jr	nz, BB0_23
 	dec	iy
-	ld	(ix - 6), iy
-	jr	BB0_12
-BB0_11:
+	jr	BB0_22
+BB0_20:
+	ld	hl, 1
+	push	hl
+	call	_exit
+	pop	hl
+BB0_21:
 	ld	hl, (ix - 3)
 	ld	de, (ix + 9)
 	or	a, a
 	sbc	hl, de
-	ld	bc, 0
-	jr	nc, BB0_13
-BB0_12:
-	ld	hl, (ix - 6)
-	ld	(hl), 0
 	ld	hl, (ix + 6)
+	ld	bc, 0
+	jr	nc, BB0_24
+BB0_22:
+	ld	(iy), 0
+BB0_23:
 	push	hl
 	pop	bc
-BB0_13:
+BB0_24:
 	push	bc
 	pop	hl
 	ld	sp, ix
@@ -107,6 +171,8 @@ BB0_13:
 	extern	__Unwind_SjLj_Register
 	extern	__Unwind_SjLj_Unregister
 	extern	__frameset
+	extern	_exit
 	extern	_fgets
+	extern	_putchar
 	extern	_strlen
 	extern	_getchar

src/libc/gets_s.c

@@ -28,18 +28,26 @@ Parameters
 Return value
 
 str on success, a null pointer on failure.
+
+Updates:
+26/07/2023 - added handling for backspace, cursor left and control-C
+
 */
 
 #include <stdio.h>
 #include <string.h>
+#include <stdlib.h>
+
+#define BS_KEY '\x7f'
+
 
 char *gets_s( char *__restrict str, rsize_t n )
 {
-	rsize_t cnt = 0;							// counter for number of characters read
-	int c;										// the current input character
-	char *s = str; 								// location to store next character
+	rsize_t cnt = 0;								// counter for number of characters read
+	int c;											// the current input character
+	char *s = str; 									// location to store next character
 
-	if ( !(str || n) ) return( NULL );  		// check error conditions
+	if ( !(str || n) ) return( NULL );  			// check error conditions
 //	if ( n > RSIZE_MAX ) return( NULL );
 
 	if ( stdin->fhandle != FH_STDIN ) {
@@ -50,14 +58,20 @@ char *gets_s( char *__restrict str, rsize_t n )
 	}
 
 	c = getchar();
-	while ( c != '\n' )						// Keep collecting input until end of line
+	while ( c != '\n' )								// Keep collecting input until end of line
 	{
-		if ( cnt < n ) *s++ = c;			// Store characters if not reached end of buffer
-		cnt++;
+	    if ( c == '\x03' ) exit( EXIT_FAILURE );    // Exit if control C is pressed
+	    if ( c == BS_KEY || c == '\b' ) {
+	    	if ( cnt > 0 ) { cnt--; s--; }
+	    	if ( c == '\b' ) { putchar(' '); putchar(BS_KEY); }
+	    } else {
+			if ( cnt < n ) *s++ = c;				// Store characters if not reached end of buffer
+			cnt++;
+		}
 		c = getchar();
 	}
-	if ( cnt >= n ) return( NULL );			// Return error if no. of characters received > max -1
-	*s = '\0';								// terminate the string
+	if ( cnt >= n ) return( NULL );					// Return error if no. of characters received > max -1
+	*s = '\0';										// terminate the string
 
 	return( str );
 }