input_line.c File Reference

Implements the OP_INPUT_LINE opcode for interactive console input. More...

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Functions
	if (has_prompt)
	if (hidden)
	if (!buf)
	while ((ch=fgetc(stdin)) !=EOF)
	if (len+1 >=cap)
	push_value (vm, make_string(buf))
	free (buf)
	if (tcgetattr(STDIN_FILENO, &t)==0)

Variables
case	OP_INPUT_LINE
int	hidden = (inst.operand & 2) ? 1 : 0
int	echo_disabled = 0
size_t	cap = 128
size_t	len = 0
char *	buf = (char *)malloc(cap)
int	ch
push_done	__pad0__
restore_echo_and_break	__pad1__

Detailed Description

Implements the OP_INPUT_LINE opcode for interactive console input.

This snippet handles the OP_INPUT_LINE instruction in the VM dispatch. It can optionally print a prompt (taken from the stack) and can read input in a hidden mode (terminal echo disabled) suitable for passwords.

Operand bits (inst.operand):

• bit0 (1): Has prompt. When set, the top of the stack is popped and converted to string, printed without a trailing newline.
• bit1 (2): Hidden input. When set, terminal echo is temporarily disabled while reading the line (best-effort, platform dependent).

Stack effects:

• If bit0 is set: pop(prompt)
• Always: push(result_string)

Behavior:

• Converts an optional prompt Value to string using value_to_string_alloc, prints it to stdout without a newline, and flushes the stream.
• If hidden is requested, disables terminal echo (POSIX termios or Win32 console modes) before reading.
• Reads a single line from stdin, accepting both "\n" and "\r\n" endings.
• Restores terminal echo if it was disabled and, when a prompt was printed, emits a newline for a better UX.
• Pushes the captured line as a Fun string (never NULL; empty string on failure or EOF).

Errors and corner cases:

• Memory allocation failures are reported to stderr; an empty string is pushed in such cases to keep execution flowing.
• If echo toggling fails, input still proceeds with echo enabled.
• EOF before any character yields an empty string.

Example: // Bytecode: [optional PUSH prompt], OP_INPUT_LINE(operand) // operand bit0=1 (has prompt), bit1=2 (hidden) can be combined // Stack before (bit0=1): ["Enter password: "] // Stack after: ["user-typed-line"]

Definition in file input_line.c.

Function Documentation

free()

free

(

buf

)

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if() [1/5]

if

(

!

buf

)

Definition at line 104 of file input_line.c.

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if() [2/5]

if

(

has_prompt

)

Definition at line 59 of file input_line.c.

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if() [3/5]

if

(

hidden

)

Definition at line 87 of file input_line.c.

if() [4/5]

if

(

len+1 >=

cap

)

Definition at line 139 of file input_line.c.

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if() [5/5]

if

(

tcgetattr(STDIN_FILENO, &t)

= = 0

)

Definition at line 176 of file input_line.c.

push_value()

push_value	(	vm	,
		make_string(buf)	)

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while()

while

(

(ch=fgetc(stdin)) !

= EOF

)

Definition at line 112 of file input_line.c.

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Variable Documentation

__pad0__

push_done __pad0__

Definition at line 155 of file input_line.c.

__pad1__

restore_echo_and_break __pad1__

Definition at line 186 of file input_line.c.

buf

buf[len] = (char *)malloc(cap)

Definition at line 103 of file input_line.c.

cap

size_t cap = 128

Definition at line 101 of file input_line.c.

ch

int ch

Definition at line 111 of file input_line.c.

echo_disabled

int echo_disabled = 0

Definition at line 72 of file input_line.c.

hidden

int hidden = (inst.operand & 2) ? 1 : 0

Definition at line 58 of file input_line.c.

len

size_t len = 0

Definition at line 102 of file input_line.c.

OP_INPUT_LINE

case OP_INPUT_LINE

Definition at line 52 of file input_line.c.