Implement conio cgets

include/conio.h

@@ -110,6 +110,24 @@ char cgetc (void);
 ** 1 (see below), a blinking cursor is displayed while waiting.
 */
 
+char *cgets (char *buffer);
+/* Get a string of characters directly from the console. The standard interface
+** is quirky:
+**
+**   - set buffer[0] to the size of the buffer - 2, must be > 0
+**   - call cgets
+**   - buffer[1] will have the number of characters read
+**   - the actual string starts at buffer + 2
+**   - trailing CRLF are removed
+**   - terminating \0 is appended
+**   - therefore the maximum number of characters which can be read is the size
+**     of the buffer - 3!
+**
+**   param: buffer - where to save the input
+**  return: buffer + 2 (i.e. start of the string) if successful, NULL otherwise
+**  author: Russell-S-Harper
+*/
+
 int cscanf (const char* format, ...);
 /* Like scanf(), but uses direct keyboard input */
 

libsrc/conio/cgets.c

@@ -0,0 +1,117 @@
+/*  Created: 2025-06-15 Russell-S-Harper
+** Modified: <iso-date> <author>
+**    Notes: <e.g. revisions made to support target, edge cases, bugs, etc.>
+**
+** char *cgets(char *buffer);
+*/
+
+#include <stddef.h>
+#include <string.h>
+#include <conio.h>
+
+#ifndef CRLF
+#define CRLF    "\r\n"
+#endif  /* CRLF */
+
+enum {CGETS_SIZE, CGETS_READ, CGETS_DATA, CGETS_HDR_LEN = CGETS_DATA};
+
+static char *cgetsx (char *buffer, int size);
+
+char *cgets (char *buffer)
+/* Get a string of characters directly from the console. The standard interface
+** is quirky:
+**
+**   - set buffer[0] to the size of the buffer - 2, must be > 0
+**   - call cgets
+**   - buffer[1] will have the number of characters read
+**   - the actual string starts at buffer + 2
+**   - trailing CRLF are removed
+**   - terminating \0 is appended
+**   - therefore the maximum number of characters which can be read is the size
+**     of the buffer - 3!
+**
+**   param: buffer - where to save the input
+**  return: buffer + 2 (or start of the string) if successful, NULL otherwise
+**     see: cgetsx for equivalent functionality but with a saner interface!
+*/
+{
+    /* Default to NULL */
+    char *result = NULL;
+
+    if (buffer && buffer[CGETS_SIZE]) {
+        /* Initialize just in case the caller didn't! */
+        buffer[CGETS_READ] = 0;
+        buffer[CGETS_DATA] = '\0';
+
+        /* Call cgetsx to do the real work */
+        result = cgetsx (buffer + CGETS_HDR_LEN, (unsigned char)buffer[CGETS_SIZE]);
+
+        /* Trim trailing CRLF and set how many characters were read */
+        if (result) {
+            result[strcspn (result, CRLF)] = '\0';
+            buffer[CGETS_READ] = (unsigned char)strlen (result);
+        }
+    }
+
+    /* Done */
+    return result;
+}
+
+static char *cgetsx (char *buffer, int size)
+/* Like fgets but specifically for the console. Stops when CR/LF or size - 1
+** characters are read. Will append a terminating \0, so at most size - 1
+** characters can be read. Note that this function could be made public and
+** have features like cursor vs no-cursor, and/or echo vs echo-pwd vs no-echo
+** added to extend the functionality.
+**
+**   param: buffer - where to save the input
+**   param: size - the size of buffer
+**  return: buffer if successful, NULL otherwise
+*/
+{
+    int i = 0;
+    unsigned char w, x, y;
+    char c;
+
+    if (buffer && size > 1) {
+        /* Just need the width */
+        screensize (&w, &y);
+        /* Actually just the last column! */
+        --w;
+        cursor (1);
+        for (i = 0, --size; i < size; ) {
+            c = cgetc ();
+            /* Handle backspace */
+            if (c == '\b') {
+                if (i > 0) {
+                    /* Remove the character */
+                    buffer[--i] = '\0';
+                    /* Logic to account for line wrapping */
+                    y = wherey ();
+                    x = wherex ();
+                    y = x? y: y - 1;
+                    x = x? x - 1: w;
+                    /* Clear the character and the cursor */
+                    gotoxy (x, y);
+                    cputs ("  ");
+                    gotoxy (x, y);
+                }
+            /* Handle CRLF */
+            } else if (strchr (CRLF, c)) {
+                /* Clear the cursor and advance to the next line */
+                cputs (" " CRLF);
+                buffer[i] = c;
+                buffer[++i] = '\0';
+                break;
+            /* Handle regular characters */
+            } else {
+                cputc (c);
+                buffer[i] = c;
+                buffer[++i] = '\0';
+            }
+        }
+        cursor (0);
+    }
+
+    return (i > 0)? buffer: NULL;
+}