From 279c233cb1f32ed42419ed6a9c2e14c1c1bc80e7 Mon Sep 17 00:00:00 2001
From: Micha White <botahamec@outlook.com>
Date: Wed, 8 Nov 2023 14:09:17 -0500
Subject: Create a script system

---
 scripts/src/libs/system.rs | 154 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)
 create mode 100644 scripts/src/libs/system.rs

(limited to 'scripts/src/libs/system.rs')

diff --git a/scripts/src/libs/system.rs b/scripts/src/libs/system.rs
new file mode 100644
index 0000000..e2d0ddb
--- /dev/null
+++ b/scripts/src/libs/system.rs
@@ -0,0 +1,154 @@
+use std::mem::align_of;
+use std::{borrow::Cow, process::Command};
+
+use chrono::Offset;
+use wasmtime::{Caller, Memory};
+
+use crate::{ScriptManager, WasmScriptState};
+
+use super::LIBRARY_NAME;
+
+pub fn _get_memory<'a>(caller: &'a mut Caller<WasmScriptState>) -> (Memory, &'a mut [u8]) {
+	let memory = caller.get_export("memory").unwrap().into_memory().unwrap();
+	let mem_ptr = memory.data_mut(caller);
+	(memory, mem_ptr)
+}
+
+fn _get_string<'a>(
+	caller: &'a mut Caller<WasmScriptState>,
+	offset: u32,
+	length: u32,
+) -> Option<Cow<'a, str>> {
+	let (_, mem_ptr) = _get_memory(caller);
+	if (offset as usize + length as usize) > mem_ptr.len() {
+		return None;
+	}
+
+	Some(String::from_utf8_lossy(
+		&mem_ptr[offset as usize..length as usize],
+	))
+}
+
+fn _log(caller: &mut Caller<WasmScriptState>, level: log::Level, message: u32, length: u32) -> u32 {
+	let Some(message) = _get_string(caller, message, length) else {
+		return 4;
+	};
+	log::log!(level, "{}", message);
+	0
+}
+
+pub fn _alloc<'a>(
+	mut caller: &'a mut Caller<WasmScriptState>,
+	size: u32,
+	align: u32,
+) -> Option<(u32, &'a mut [u8])> {
+	// find bumper location in memory
+	let bump_offset = caller.data().bump_pointer;
+	let (memory, memory_ptr) = _get_memory(caller);
+	let bump_ptr = &memory_ptr[bump_offset as usize..];
+
+	// calculate pointer to the new allocation
+	let offset = bump_ptr.as_ptr().align_offset(align as usize);
+	let new_offset = bump_offset + offset as u32;
+
+	// update bump pointer
+	let bump_offset = &mut caller.data_mut().bump_pointer;
+	*bump_offset = new_offset + size;
+
+	// grow memory if necessary
+	let bump_offset = *bump_offset;
+	if memory.data_size(&caller) < bump_offset as usize {
+		let delta = (size + offset as u32) / (64 * 1024) + 1;
+		if memory.grow(&mut caller, delta as u64).is_err() {
+			return None;
+		}
+	}
+
+	let new_ptr = &mut _get_memory(caller).1[new_offset as usize..size as usize];
+	Some((new_offset, new_ptr))
+}
+
+fn allocate(mut caller: Caller<WasmScriptState>, size: u32, align: u32) -> u32 {
+	match _alloc(&mut caller, size, align) {
+		Some((ptr, _)) => ptr,
+		None => 0,
+	}
+}
+
+fn free_sized(mut caller: Caller<'_, WasmScriptState>, ptr: u32, size: u32) -> u32 {
+	let bump_offset = &mut caller.data_mut().bump_pointer;
+	if ptr + size == *bump_offset {
+		*bump_offset = ptr;
+	}
+
+	0
+}
+
+fn free_aligned_sized(
+	caller: Caller<'_, WasmScriptState>,
+	ptr: u32,
+	_alignment: u32,
+	size: u32,
+) -> u32 {
+	free_sized(caller, ptr, size)
+}
+
+fn env_var(mut caller: Caller<'_, WasmScriptState>, name: u32, length: u32) -> u32 {
+	let Some(name) = _get_string(&mut caller, name, length) else {
+		return 4;
+	};
+	let Ok(value) = std::env::var(name.to_string()) else {
+		return 1;
+	};
+
+	let Some((offset, ptr)) = _alloc(&mut caller, value.len() as u32, align_of::<u8>() as u32)
+	else {
+		return 0;
+	};
+	ptr.clone_from_slice(value.as_bytes());
+
+	offset
+}
+
+fn random_number() -> u64 {
+	rand::random()
+}
+
+fn current_time_utc() -> (i64, u32) {
+	let duration = chrono::Utc::now() - chrono::DateTime::<chrono::Utc>::MIN_UTC;
+	(
+		duration.num_seconds(),
+		duration.to_std().unwrap().subsec_nanos(),
+	)
+}
+
+fn local_offset() -> i32 {
+	chrono::Local::now().offset().fix().local_minus_utc()
+}
+
+fn log(mut caller: Caller<'_, WasmScriptState>, message: u32, length: u32) {
+	_log(&mut caller, log::Level::Info, message, length);
+}
+
+fn log_warn(mut caller: Caller<'_, WasmScriptState>, message: u32, length: u32) {
+	_log(&mut caller, log::Level::Warn, message, length);
+}
+
+fn log_error(mut caller: Caller<'_, WasmScriptState>, message: u32, length: u32) {
+	_log(&mut caller, log::Level::Error, message, length);
+}
+
+pub fn library(manager: &mut ScriptManager) -> Option<()> {
+	manager.add_library_function(LIBRARY_NAME, "aligned_alloc", allocate)?;
+	manager.add_library_function(LIBRARY_NAME, "free_sized", free_sized)?;
+	manager.add_library_function(LIBRARY_NAME, "free_aligned_sized", free_aligned_sized)?;
+	manager.add_library_function(LIBRARY_NAME, "env_var", env_var)?;
+	manager.add_library_function(LIBRARY_NAME, "random_number", random_number)?;
+	manager.add_library_function(LIBRARY_NAME, "current_time_utc", current_time_utc)?;
+	manager.add_library_function(LIBRARY_NAME, "local_offset", local_offset)?;
+	manager.add_library_function(LIBRARY_NAME, "log", log)?;
+	manager.add_library_function(LIBRARY_NAME, "log_warn", log_warn)?;
+	manager.add_library_function(LIBRARY_NAME, "log_error", log_error)?;
+
+	Some(())
+}
-- 
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