1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161

use alloc::{format, vec::Vec};
use parity_wasm::elements;

/// Export all declared mutable globals as `prefix_index`.
///
/// This will export all internal mutable globals under the name of
/// concat(`prefix`, `"_"`, `i`) where i is the index inside the range of
/// [0..total number of internal mutable globals].
pub fn export_mutable_globals(module: &mut elements::Module, prefix: &str) {
	let exports = global_section(module)
		.map(|section| {
			section
				.entries()
				.iter()
				.enumerate()
				.filter_map(
					|(index, global)| {
						if global.global_type().is_mutable() {
							Some(index)
						} else {
							None
						}
					},
				)
				.collect::<Vec<_>>()
		})
		.unwrap_or_default();

	if module.export_section().is_none() {
		module
			.sections_mut()
			.push(elements::Section::Export(elements::ExportSection::default()));
	}

	for (symbol_index, export) in exports.into_iter().enumerate() {
		let new_entry = elements::ExportEntry::new(
			format!("{}_{}", prefix, symbol_index),
			elements::Internal::Global(
				(module.import_count(elements::ImportCountType::Global) + export) as _,
			),
		);
		export_section(module)
			.expect("added above if does not exists")
			.entries_mut()
			.push(new_entry);
	}
}

fn export_section(module: &mut elements::Module) -> Option<&mut elements::ExportSection> {
	for section in module.sections_mut() {
		if let elements::Section::Export(sect) = section {
			return Some(sect)
		}
	}
	None
}

fn global_section(module: &mut elements::Module) -> Option<&mut elements::GlobalSection> {
	for section in module.sections_mut() {
		if let elements::Section::Global(sect) = section {
			return Some(sect)
		}
	}
	None
}

#[cfg(test)]
mod tests {

	use super::export_mutable_globals;
	use parity_wasm::elements;

	fn parse_wat(source: &str) -> elements::Module {
		let module_bytes = wat::parse_str(source).unwrap();
		wasmparser::validate(&module_bytes).unwrap();
		elements::deserialize_buffer(module_bytes.as_ref()).expect("failed to parse module")
	}

	macro_rules! test_export_global {
		(name = $name:ident; input = $input:expr; expected = $expected:expr) => {
			#[test]
			fn $name() {
				let mut input_module = parse_wat($input);
				let expected_module = parse_wat($expected);

				export_mutable_globals(&mut input_module, "exported_internal_global");

				let actual_bytes = elements::serialize(input_module)
					.expect("injected module must have a function body");

				let expected_bytes = elements::serialize(expected_module)
					.expect("injected module must have a function body");

				let actual_wat = wasmprinter::print_bytes(actual_bytes).unwrap();
				let expected_wat = wasmprinter::print_bytes(expected_bytes).unwrap();

				if actual_wat != expected_wat {
					for diff in diff::lines(&expected_wat, &actual_wat) {
						match diff {
							diff::Result::Left(l) => println!("-{}", l),
							diff::Result::Both(l, _) => println!(" {}", l),
							diff::Result::Right(r) => println!("+{}", r),
						}
					}
					panic!()
				}
			}
		};
	}

	test_export_global! {
		name = simple;
		input = r#"
		(module
			(global (;0;) (mut i32) (i32.const 1))
			(global (;1;) (mut i32) (i32.const 0)))
		"#;
		expected = r#"
		(module
			(global (;0;) (mut i32) (i32.const 1))
			(global (;1;) (mut i32) (i32.const 0))
			(export "exported_internal_global_0" (global 0))
			(export "exported_internal_global_1" (global 1)))
		"#
	}

	test_export_global! {
		name = with_import;
		input = r#"
		(module
			(import "env" "global" (global $global i64))
			(global (;0;) (mut i32) (i32.const 1))
			(global (;1;) (mut i32) (i32.const 0)))
		"#;
		expected = r#"
		(module
			(import "env" "global" (global $global i64))
			(global (;0;) (mut i32) (i32.const 1))
			(global (;1;) (mut i32) (i32.const 0))
			(export "exported_internal_global_0" (global 1))
			(export "exported_internal_global_1" (global 2)))
		"#
	}

	test_export_global! {
		name = with_import_and_some_are_immutable;
		input = r#"
		(module
			(import "env" "global" (global $global i64))
			(global (;0;) i32 (i32.const 1))
			(global (;1;) (mut i32) (i32.const 0)))
		"#;
		expected = r#"
		(module
			(import "env" "global" (global $global i64))
			(global (;0;) i32 (i32.const 1))
			(global (;1;) (mut i32) (i32.const 0))
			(export "exported_internal_global_0" (global 2)))
		"#
	}
}