Add bounds checking for arduino_pins array access in digital_pin_gpios path

[Copilot]

Addresses feedback from PR #4 regarding missing bounds validation when accessing arduino_pins[gpin] in the digital_pin_gpios configuration path. Without bounds checking, invalid pin numbers cause out-of-bounds memory access across multiple call sites (digitalWrite/Read, interrupts, tone, etc.).

Changes

• local_gpio_port(): Return nullptr when gpin >= ARRAY_SIZE(arduino_pins)
• local_gpio_pin(): Return pin_size_t(-1) when gpin >= ARRAY_SIZE(arduino_pins)
• global_gpio_pin_configure(): Early return -1 before array access when pinNumber >= ARRAY_SIZE(arduino_pins)

The non-digital_pin_gpios path already had implicit bounds checking through local_gpio_port_r() recursion. find_gpio_port_callback() null checking was added in commit c38fdbb.

// Before
constexpr inline const struct device *local_gpio_port(pin_size_t gpin) {
#if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), digital_pin_gpios)
  return arduino_pins[gpin].port;  // Direct access, no bounds check
#else
  return local_gpio_port_r(gpin, gpio_ports, 0, gpio_ngpios, ARRAY_SIZE(gpio_ports));
#endif
}

// After  
constexpr inline const struct device *local_gpio_port(pin_size_t gpin) {
#if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), digital_pin_gpios)
  return (gpin < ARRAY_SIZE(arduino_pins)) ? arduino_pins[gpin].port : nullptr;
#else
  return local_gpio_port_r(gpin, gpio_ports, 0, gpio_ngpios, ARRAY_SIZE(gpio_ports));
#endif
}

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[Copilot]

Pull request overview

Adds bounds validation for digital_pin_gpios-backed pin mapping to prevent out-of-bounds access of arduino_pins[] in the Zephyr Arduino core.

Changes:

• Add bounds checks to local_gpio_port() / local_gpio_pin() for digital_pin_gpios builds.
• Add early return in global_gpio_pin_configure() to avoid out-of-range arduino_pins[] indexing.
• Ignore CodeQL-generated build/source-root artifacts in .gitignore.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 2 comments.

File	Description
cores/arduino/zephyrCommon.cpp	Adds bounds checks for arduino_pins[] access in the digital_pin_gpios path.
.gitignore	Ignores CodeQL artifact directories/files.

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[Copilot]

In the digital_pin_gpios path, global_gpio_pin_configure() returns -1 for an invalid pinNumber. Elsewhere in this file invalid arguments typically return -EINVAL/-ENOTSUP (e.g. analogRead()), and Zephyr GPIO APIs return negative errno codes. Consider returning -EINVAL here as well to keep error semantics consistent (even if most callers currently ignore the return value).

[Copilot]

local_gpio_port() now returns nullptr and local_gpio_pin() can return pin_size_t(-1) for out-of-range pins, but at least one call site (e.g. attachInterrupt()) assumes a valid port/pin: it asserts pcb != nullptr even when port is nullptr, and then does BIT(local_gpio_pin(pinNumber)) which becomes a shift by -1. Please add consistent guards in callers (or in a shared helper) to early-return when local_gpio_port() is null and/or local_gpio_pin() is -1 before any indexing/bit-shifts/dereferences.