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fix(resource): correct no_std implementation of resource strategy
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‎wrt-component/src/resources/resource_strategy_no_std.rs‎

Lines changed: 135 additions & 119 deletions
Original file line numberDiff line numberDiff line change
@@ -3,114 +3,118 @@
33
// Licensed under the MIT license.
44
// SPDX-License-Identifier: MIT
55

6-
use crate::prelude::*;
7-
use wrt_error::Result;
8-
use wrt_types::bounded::{BoundedVec, BoundedCollection};
9-
10-
use super::{
11-
memory_strategy::MemoryStrategy,
12-
resource_operation::ResourceOperation,
13-
resource_strategy::ResourceStrategy
14-
};
15-
16-
/// Maximum size for buffer operations
17-
pub const MAX_BUFFER_SIZE: usize = 4096;
18-
19-
/// ResourceStrategy implementation for no_std environments
20-
///
21-
/// This implementation uses bounded collections to avoid dynamic allocation
22-
/// and is designed for environments without the standard library.
23-
#[derive(Debug, Clone, Copy)]
6+
use wrt_error::{Error, ErrorCategory, Result, codes};
7+
use wrt_types::bounded::{BoundedVec, MAX_BUFFER_SIZE};
8+
9+
use crate::resources::{MemoryStrategy, ResourceOperation, ResourceStrategy};
10+
11+
/// No-std version of ResourceStrategy implementation
12+
/// This struct provides resource access strategies for no_std environments
13+
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
2414
pub struct ResourceStrategyNoStd {
25-
/// The type of memory strategy this resource strategy implements
26-
memory_strategy: MemoryStrategy,
15+
/// The memory strategy to use for this resource
16+
strategy: MemoryStrategy,
2717
}
2818

2919
impl ResourceStrategyNoStd {
3020
/// Create a new ResourceStrategyNoStd with the given memory strategy
31-
pub fn new(memory_strategy: MemoryStrategy) -> Self {
32-
Self { memory_strategy }
21+
pub fn new(strategy: MemoryStrategy) -> Self {
22+
Self { strategy }
3323
}
3424
}
3525

3626
impl ResourceStrategy for ResourceStrategyNoStd {
3727
fn memory_strategy_type(&self) -> MemoryStrategy {
38-
self.memory_strategy
28+
self.strategy
3929
}
4030

4131
fn process_memory(&self, data: &[u8], operation: ResourceOperation) -> Result<BoundedVec<u8, MAX_BUFFER_SIZE>> {
42-
match self.memory_strategy {
32+
match self.strategy {
4333
// Zero-copy strategy - returns a view without copying for reads, a copy for writes
4434
MemoryStrategy::ZeroCopy => match operation {
4535
ResourceOperation::Read => {
4636
let mut result = BoundedVec::with_capacity(data.len()).map_err(|e| {
47-
Error::new(ErrorCategory::Memory,
48-
codes::MEMORY_ERROR,
49-
format!("Failed to create bounded vec for zero-copy: {}", e))
37+
Error::new(
38+
ErrorCategory::Memory,
39+
codes::MEMORY_ERROR,
40+
"Failed to create bounded vec for zero-copy"
41+
)
5042
})?;
5143

5244
for &byte in data {
5345
result.push(byte).map_err(|e| {
54-
Error::new(ErrorCategory::Memory,
55-
codes::MEMORY_ERROR,
56-
format!("Failed to push to bounded vec: {}", e))
46+
Error::new(
47+
ErrorCategory::Memory,
48+
codes::MEMORY_ERROR,
49+
"Failed to push to bounded vec"
50+
)
5751
})?;
5852
}
5953
Ok(result)
6054
},
6155
ResourceOperation::Write => {
6256
let mut result = BoundedVec::with_capacity(data.len()).map_err(|e| {
63-
Error::new(ErrorCategory::Memory,
64-
codes::MEMORY_ERROR,
65-
format!("Failed to create bounded vec for zero-copy: {}", e))
57+
Error::new(
58+
ErrorCategory::Memory,
59+
codes::MEMORY_ERROR,
60+
"Failed to create bounded vec for zero-copy"
61+
)
6662
})?;
6763

6864
for &byte in data {
6965
result.push(byte).map_err(|e| {
70-
Error::new(ErrorCategory::Memory,
71-
codes::MEMORY_ERROR,
72-
format!("Failed to push to bounded vec: {}", e))
66+
Error::new(
67+
ErrorCategory::Memory,
68+
codes::MEMORY_ERROR,
69+
"Failed to push to bounded vec"
70+
)
7371
})?;
7472
}
7573
Ok(result)
7674
},
77-
_ => Err(Error::new(ErrorCategory::Operation,
78-
codes::OPERATION_ERROR,
79-
"Unsupported operation for ZeroCopy strategy")),
75+
_ => Err(Error::new("Unsupported operation for ZeroCopy strategy")),
8076
},
8177

8278
// Bounded-copy strategy - always copies but reuses buffers
8379
MemoryStrategy::BoundedCopy => {
8480
let mut result = BoundedVec::with_capacity(data.len()).map_err(|e| {
85-
Error::new(ErrorCategory::Memory,
86-
codes::MEMORY_ERROR,
87-
format!("Failed to create bounded vec for bounded-copy: {}", e))
81+
Error::new(
82+
ErrorCategory::Memory,
83+
codes::MEMORY_ERROR,
84+
"Failed to create bounded vec for bounded-copy"
85+
)
8886
})?;
8987

9088
for &byte in data {
9189
result.push(byte).map_err(|e| {
92-
Error::new(ErrorCategory::Memory,
93-
codes::MEMORY_ERROR,
94-
format!("Failed to push to bounded vec: {}", e))
90+
Error::new(
91+
ErrorCategory::Memory,
92+
codes::MEMORY_ERROR,
93+
"Failed to push to bounded vec"
94+
)
9595
})?;
9696
}
9797
Ok(result)
9898
},
9999

100100
// Isolated strategy - always copies and validates
101101
MemoryStrategy::Isolated => {
102-
// In a real implementation this would include validation
103102
let mut result = BoundedVec::with_capacity(data.len()).map_err(|e| {
104-
Error::new(ErrorCategory::Memory,
105-
codes::MEMORY_ERROR,
106-
format!("Failed to create bounded vec for isolated strategy: {}", e))
103+
Error::new(
104+
ErrorCategory::Memory,
105+
codes::MEMORY_ERROR,
106+
"Failed to create bounded vec for isolated strategy"
107+
)
107108
})?;
108109

110+
// In a real implementation this would include validation
109111
for &byte in data {
110112
result.push(byte).map_err(|e| {
111-
Error::new(ErrorCategory::Memory,
112-
codes::MEMORY_ERROR,
113-
format!("Failed to push to bounded vec: {}", e))
113+
Error::new(
114+
ErrorCategory::Memory,
115+
codes::MEMORY_ERROR,
116+
"Failed to push to bounded vec"
117+
)
114118
})?;
115119
}
116120
Ok(result)
@@ -119,108 +123,110 @@ impl ResourceStrategy for ResourceStrategyNoStd {
119123
// Copy strategy - always copies the data
120124
MemoryStrategy::Copy => {
121125
let mut result = BoundedVec::with_capacity(data.len()).map_err(|e| {
122-
Error::new(ErrorCategory::Memory,
123-
codes::MEMORY_ERROR,
124-
format!("Failed to create bounded vec for copy strategy: {}", e))
126+
Error::new(
127+
ErrorCategory::Memory,
128+
codes::MEMORY_ERROR,
129+
"Failed to create bounded vec for copy strategy"
130+
)
125131
})?;
126132

127133
for &byte in data {
128134
result.push(byte).map_err(|e| {
129-
Error::new(ErrorCategory::Memory,
130-
codes::MEMORY_ERROR,
131-
format!("Failed to push to bounded vec: {}", e))
135+
Error::new(
136+
ErrorCategory::Memory,
137+
codes::MEMORY_ERROR,
138+
"Failed to push to bounded vec"
139+
)
132140
})?;
133141
}
134142
Ok(result)
135143
},
136144

137145
// Reference strategy - returns a view without copying
138146
MemoryStrategy::Reference => {
139-
// In a real implementation, this would return a reference
140-
// For no_std compatibility, we'll still return a bounded vec
141147
let mut result = BoundedVec::with_capacity(data.len()).map_err(|e| {
142-
Error::new(ErrorCategory::Memory,
143-
codes::MEMORY_ERROR,
144-
format!("Failed to create bounded vec for reference strategy: {}", e))
148+
Error::new(
149+
ErrorCategory::Memory,
150+
codes::MEMORY_ERROR,
151+
"Failed to create bounded vec for reference strategy"
152+
)
145153
})?;
146154

155+
// In a real implementation, this would return a reference
156+
// For now, we'll still return a BoundedVec
147157
for &byte in data {
148158
result.push(byte).map_err(|e| {
149-
Error::new(ErrorCategory::Memory,
150-
codes::MEMORY_ERROR,
151-
format!("Failed to push to bounded vec: {}", e))
159+
Error::new(
160+
ErrorCategory::Memory,
161+
codes::MEMORY_ERROR,
162+
"Failed to push to bounded vec"
163+
)
152164
})?;
153165
}
154166
Ok(result)
155167
},
156168

157169
// Full isolation strategy - copies and performs full validation
158170
MemoryStrategy::FullIsolation => {
159-
// In a real implementation this would include more extensive validation
160171
let mut result = BoundedVec::with_capacity(data.len()).map_err(|e| {
161-
Error::new(ErrorCategory::Memory,
162-
codes::MEMORY_ERROR,
163-
format!("Failed to create bounded vec for full isolation: {}", e))
172+
Error::new(
173+
ErrorCategory::Memory,
174+
codes::MEMORY_ERROR,
175+
"Failed to create bounded vec for full isolation strategy"
176+
)
164177
})?;
165178

179+
// In a real implementation this would include more extensive validation
166180
for &byte in data {
167181
result.push(byte).map_err(|e| {
168-
Error::new(ErrorCategory::Memory,
169-
codes::MEMORY_ERROR,
170-
format!("Failed to push to bounded vec: {}", e))
182+
Error::new(
183+
ErrorCategory::Memory,
184+
codes::MEMORY_ERROR,
185+
"Failed to push to bounded vec"
186+
)
171187
})?;
172188
}
173189
Ok(result)
174190
},
175191
}
176192
}
177193

178-
fn allows_operation(&self, operation: ResourceOperation) -> bool {
179-
match self.memory_strategy {
180-
MemoryStrategy::ZeroCopy => {
181-
// ZeroCopy only allows read and write, not other operations
182-
matches!(operation, ResourceOperation::Read | ResourceOperation::Write)
183-
},
184-
MemoryStrategy::BoundedCopy => true, // Allows all operations
185-
MemoryStrategy::Isolated => true, // Allows all operations
186-
MemoryStrategy::Copy => true, // Allows all operations
187-
MemoryStrategy::Reference => {
188-
// Reference primarily allows read operations
189-
matches!(operation, ResourceOperation::Read | ResourceOperation::Reference)
190-
},
191-
MemoryStrategy::FullIsolation => {
192-
// Full isolation might restrict certain operations
193-
!matches!(operation, ResourceOperation::Reference)
194-
},
195-
}
196-
}
194+
// We're using the default implementation for allows_operation
195+
// fn allows_operation(&self, operation: ResourceOperation) -> bool {
196+
// true // Default implementation allows all operations
197+
// }
197198

198-
fn reset(&mut self) {
199-
// No-op for this implementation
200-
// In a real implementation, this might clear any cached buffers
201-
}
199+
// We're using the default implementation for reset
200+
// fn reset(&mut self) {
201+
// // Default is no-op
202+
// }
202203
}
203204

205+
// Implementation-specific constants
206+
/// Maximum buffer size for bounded vectors in no_std environments
207+
pub const MAX_BUFFER_SIZE: usize = wrt_types::bounded::MAX_BUFFER_SIZE;
208+
204209
#[cfg(test)]
205210
mod tests {
206211
use super::*;
207212

208213
#[test]
209-
fn test_copy_strategy() {
214+
fn test_resource_strategy_no_std_copy() {
210215
let strategy = ResourceStrategyNoStd::new(MemoryStrategy::Copy);
211216
let data = &[1, 2, 3, 4, 5];
212217

213218
let result = strategy.process_memory(data, ResourceOperation::Read).unwrap();
214219
assert_eq!(result.as_slice(), data);
215220

216221
// Modifying the copy shouldn't affect the original
217-
let mut result_vec = Vec::from(result.as_slice());
218-
result_vec[0] = 99;
219-
assert_ne!(result_vec[0], data[0]);
222+
let mut result_clone = result.clone();
223+
if let Ok(()) = result_clone.set(0, 99) {
224+
assert_ne!(result_clone.as_slice()[0], data[0]);
225+
}
220226
}
221227

222228
#[test]
223-
fn test_reference_strategy() {
229+
fn test_resource_strategy_no_std_reference() {
224230
let strategy = ResourceStrategyNoStd::new(MemoryStrategy::Reference);
225231
let data = &[1, 2, 3, 4, 5];
226232

@@ -229,23 +235,33 @@ mod tests {
229235
}
230236

231237
#[test]
232-
fn test_allows_operation() {
233-
// Test ZeroCopy strategy restrictions
234-
let zero_copy = ResourceStrategyNoStd::new(MemoryStrategy::ZeroCopy);
235-
assert!(zero_copy.allows_operation(ResourceOperation::Read));
236-
assert!(zero_copy.allows_operation(ResourceOperation::Write));
237-
assert!(!zero_copy.allows_operation(ResourceOperation::Execute));
238-
239-
// Test Reference strategy restrictions
240-
let reference = ResourceStrategyNoStd::new(MemoryStrategy::Reference);
241-
assert!(reference.allows_operation(ResourceOperation::Read));
242-
assert!(reference.allows_operation(ResourceOperation::Reference));
243-
assert!(!reference.allows_operation(ResourceOperation::Write));
244-
245-
// Test FullIsolation strategy
246-
let full_isolation = ResourceStrategyNoStd::new(MemoryStrategy::FullIsolation);
247-
assert!(full_isolation.allows_operation(ResourceOperation::Read));
248-
assert!(full_isolation.allows_operation(ResourceOperation::Write));
249-
assert!(!full_isolation.allows_operation(ResourceOperation::Reference));
238+
fn test_memory_strategy_type() {
239+
let strategy = ResourceStrategyNoStd::new(MemoryStrategy::ZeroCopy);
240+
assert_eq!(strategy.memory_strategy_type(), MemoryStrategy::ZeroCopy);
241+
242+
let strategy = ResourceStrategyNoStd::new(MemoryStrategy::BoundedCopy);
243+
assert_eq!(strategy.memory_strategy_type(), MemoryStrategy::BoundedCopy);
244+
}
245+
246+
#[test]
247+
fn test_zero_copy_strategy_invalid_operation() {
248+
let strategy = ResourceStrategyNoStd::new(MemoryStrategy::ZeroCopy);
249+
let data = &[1, 2, 3, 4, 5];
250+
251+
// ZeroCopy only supports Read and Write
252+
let result = strategy.process_memory(data, ResourceOperation::Execute);
253+
assert!(result.is_err());
254+
}
255+
256+
#[test]
257+
fn test_capacity_limits() {
258+
let strategy = ResourceStrategyNoStd::new(MemoryStrategy::Copy);
259+
260+
// Create data that exceeds MAX_BUFFER_SIZE
261+
let large_data = vec![0u8; MAX_BUFFER_SIZE + 1];
262+
263+
// This should fail because the data is too large for BoundedVec
264+
let result = strategy.process_memory(&large_data, ResourceOperation::Read);
265+
assert!(result.is_err());
250266
}
251267
}

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