input_line.c

Go to the documentation of this file.

/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2025 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */


case OP_INPUT_LINE: {
 /* operand bit flags:
 * bit0 (1): has prompt (string or any value convertible to string) — top of stack holds prompt when set
 * bit1 (2): hidden input (do not echo typed characters)
 */
 int has_prompt = (inst.operand & 1) ? 1 : 0;
 int hidden = (inst.operand & 2) ? 1 : 0;
 if (has_prompt) {
 /* pop prompt value and print without newline */
 Value pv = pop_value(vm);
 char *pstr = value_to_string_alloc(&pv);
 if (pstr) {
 fputs(pstr, stdout);
 fflush(stdout);
 free(pstr);
 }
 free_value(pv);
 }

 /* For hidden input, temporarily disable terminal echo if possible */
 int echo_disabled = 0;
#ifdef _WIN32
 if (hidden) {
 HANDLE hStdin = GetStdHandle(STD_INPUT_HANDLE);
 if (hStdin != INVALID_HANDLE_VALUE) {
 DWORD mode;
 if (GetConsoleMode(hStdin, &mode)) {
 DWORD newMode = mode & ~(ENABLE_ECHO_INPUT);
 if (SetConsoleMode(hStdin, newMode)) {
 echo_disabled = 1;
 }
 }
 }
 }
#else
 if (hidden) {
 /* POSIX termios */
 struct termios oldt;
 if (tcgetattr(STDIN_FILENO, &oldt) == 0) {
 struct termios newt = oldt;
 newt.c_lflag &= ~(ECHO);
 if (tcsetattr(STDIN_FILENO, TCSANOW, &newt) == 0) {
 echo_disabled = 1;
 }
 }
 }
#endif

 /* read a line from stdin, dynamically grow buffer */
 size_t cap = 128;
 size_t len = 0;
 char *buf = (char *)malloc(cap);
 if (!buf) {
 fprintf(stderr, "Runtime error: out of memory reading input");
 push_value(vm, make_string(""));
 /* On early exit, try to restore echo if we turned it off */
 goto restore_echo_and_break;
 }

 int ch;
 while ((ch = fgetc(stdin)) != EOF) {
 if (ch == '\r') {
 /* Handle CRLF by consuming optional following '\n' */
 int next = fgetc(stdin);
 if (next != EOF && next != '\n') {
 ungetc(next, stdin);
 }
 break;
 }
 if (ch == '\n') {
 break;
 }
 if (len + 1 >= cap) {
 cap *= 2;
 char *nb = (char *)realloc(buf, cap);
 if (!nb) {
 free(buf);
 fprintf(stderr, "Runtime error: out of memory reading input");
 push_value(vm, make_string(""));
 goto push_done;
 }
 buf = nb;
 }
 buf[len++] = (char)ch;
 }

 /* null-terminate */
 if (len + 1 >= cap) {
 char *nb = (char *)realloc(buf, len + 1);
 if (!nb) {
 free(buf);
 fprintf(stderr, "Runtime error: out of memory finalizing input");
 push_value(vm, make_string(""));
 goto push_done;
 }
 buf = nb;
 }
 buf[len] = '\0';

 /* push as Fun string */
 push_value(vm, make_string(buf));
 free(buf);

push_done:
 /* If we disabled echo, restore terminal settings and print a newline for UX */
#ifdef _WIN32
 if (echo_disabled) {
 HANDLE hStdin = GetStdHandle(STD_INPUT_HANDLE);
 if (hStdin != INVALID_HANDLE_VALUE) {
 DWORD mode;
 if (GetConsoleMode(hStdin, &mode)) {
 /* Re-enable ECHO flag */
 mode |= ENABLE_ECHO_INPUT;
 SetConsoleMode(hStdin, mode);
 }
 }
 if (has_prompt) {
 fputc('\n', stdout);
 fflush(stdout);
 }
 }
#else
 if (echo_disabled) {
 struct termios t;
 if (tcgetattr(STDIN_FILENO, &t) == 0) {
 t.c_lflag |= ECHO;
 tcsetattr(STDIN_FILENO, TCSANOW, &t);
 }
 if (has_prompt) {
 fputc('\n', stdout);
 fflush(stdout);
 }
 }
#endif
restore_echo_and_break:
 break;
}