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smartcontract: move CreateCallAndUnwrapIteratorScript there

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RPC client shouldn't build scripts and this function can be useful as a
reusable building block.
This commit is contained in:
Roman Khimov 2022-07-25 15:46:20 +03:00
parent 68b5260fb5
commit 1b6f4051d8
2 changed files with 79 additions and 65 deletions
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66
pkg/rpcclient/helper.go
View file

@ -6,17 +6,12 @@ import (
"fmt"
"github.com/nspcc-dev/neo-go/pkg/config"
"github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames"
"github.com/nspcc-dev/neo-go/pkg/core/transaction"
"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
"github.com/nspcc-dev/neo-go/pkg/rpcclient/nns"
"github.com/nspcc-dev/neo-go/pkg/smartcontract"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)
@ -121,72 +116,13 @@ func (c *Client) InvokeAndPackIteratorResults(contract util.Uint160, operation s
if len(maxIteratorResultItems) != 0 {
max = maxIteratorResultItems[0]
}
bytes, err := createIteratorUnwrapperScript(contract, operation, params, max)
bytes, err := smartcontract.CreateCallAndUnwrapIteratorScript(contract, operation, params, max)
if err != nil {
return nil, fmt.Errorf("failed to create iterator unwrapper script: %w", err)
}
return c.InvokeScript(bytes, signers)
}
func createIteratorUnwrapperScript(contract util.Uint160, operation string, params []smartcontract.Parameter, maxIteratorResultItems int) ([]byte, error) {
script := io.NewBufBinWriter()
emit.Int(script.BinWriter, int64(maxIteratorResultItems))
// Pack arguments for System.Contract.Call.
arr, err := smartcontract.ExpandParameterToEmitable(smartcontract.Parameter{
Type: smartcontract.ArrayType,
Value: params,
})
if err != nil {
return nil, fmt.Errorf("failed to expand parameters array to emitable: %w", err)
}
emit.Array(script.BinWriter, arr.([]interface{})...)
emit.AppCallNoArgs(script.BinWriter, contract, operation, callflag.All) // The System.Contract.Call itself, it will push Iterator on estack.
emit.Opcodes(script.BinWriter, opcode.NEWARRAY0) // Push new empty array to estack. This array will store iterator's elements.
// Start the iterator traversal cycle.
iteratorTraverseCycleStartOffset := script.Len()
emit.Opcodes(script.BinWriter, opcode.OVER) // Load iterator from 1-st cell of estack.
emit.Syscall(script.BinWriter, interopnames.SystemIteratorNext) // Call System.Iterator.Next, it will pop the iterator from estack and push `true` or `false` to estack.
jmpIfNotOffset := script.Len()
emit.Instruction(script.BinWriter, opcode.JMPIFNOT, // Pop boolean value (from the previous step) from estack, if `false`, then iterator has no more items => jump to the end of program.
[]byte{
0x00, // jump to loadResultOffset, but we'll fill this byte after script creation.
})
emit.Opcodes(script.BinWriter, opcode.DUP, // Duplicate the resulting array from 0-th cell of estack and push it to estack.
opcode.PUSH2, opcode.PICK) // Pick iterator from the 2-nd cell of estack.
emit.Syscall(script.BinWriter, interopnames.SystemIteratorValue) // Call System.Iterator.Value, it will pop the iterator from estack and push its current value to estack.
emit.Opcodes(script.BinWriter, opcode.APPEND) // Pop iterator value and the resulting array from estack. Append value to the resulting array. Array is a reference type, thus, value stored at the 1-th cell of local slot will also be updated.
emit.Opcodes(script.BinWriter, opcode.DUP, // Duplicate the resulting array from 0-th cell of estack and push it to estack.
opcode.SIZE, // Pop array from estack and push its size to estack.
opcode.PUSH3, opcode.PICK, // Pick maxIteratorResultItems from the 3-d cell of estack.
opcode.GE) // Compare len(arr) and maxIteratorResultItems
jmpIfMaxReachedOffset := script.Len()
emit.Instruction(script.BinWriter, opcode.JMPIF, // Pop boolean value (from the previous step) from estack, if `false`, then max array elements is reached => jump to the end of program.
[]byte{
0x00, // jump to loadResultOffset, but we'll fill this byte after script creation.
})
jmpOffset := script.Len()
emit.Instruction(script.BinWriter, opcode.JMP, // Jump to the start of iterator traverse cycle.
[]byte{
uint8(iteratorTraverseCycleStartOffset - jmpOffset), // jump to iteratorTraverseCycleStartOffset; offset is relative to JMP position.
})
// End of the program: push the result on stack and return.
loadResultOffset := script.Len()
emit.Opcodes(script.BinWriter, opcode.NIP, // Remove iterator from the 1-st cell of estack
opcode.NIP) // Remove maxIteratorResultItems from the 1-st cell of estack, so that only resulting array is left on estack.
if err := script.Err; err != nil {
return nil, fmt.Errorf("failed to build iterator unwrapper script: %w", err)
}
// Fill in JMPIFNOT instruction parameter.
bytes := script.Bytes()
bytes[jmpIfNotOffset+1] = uint8(loadResultOffset - jmpIfNotOffset) // +1 is for JMPIFNOT itself; offset is relative to JMPIFNOT position.
// Fill in jmpIfMaxReachedOffset instruction parameter.
bytes[jmpIfMaxReachedOffset+1] = uint8(loadResultOffset - jmpIfMaxReachedOffset) // +1 is for JMPIF itself; offset is relative to JMPIF position.
return bytes, nil
}
// topIterableFromStack returns the list of elements of `resultItemType` type from the top element
// of the provided stack. The top element is expected to be an Array, otherwise an error is returned.
func topIterableFromStack(st []stackitem.Item, resultItemType interface{}) ([]interface{}, error) {

78
pkg/smartcontract/entry.go Normal file
View file

@ -0,0 +1,78 @@
package smartcontract
import (
"fmt"
"github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
)
// CreateCallAndUnwrapIteratorScript creates a script that calls 'operation' method
// of the 'contract' with the specified arguments. This method is expected to return
// an iterator that then is traversed (using iterator.Next) with values (iterator.Value)
// extracted and added into array. At most maxIteratorResultItems number of items is
// processed this way (and this number can't exceed VM limits), the result of the
// script is an array containing extracted value elements. This script can be useful
// for interactions with RPC server that have iterator sessions disabled.
func CreateCallAndUnwrapIteratorScript(contract util.Uint160, operation string, params []Parameter, maxIteratorResultItems int) ([]byte, error) {
script := io.NewBufBinWriter()
emit.Int(script.BinWriter, int64(maxIteratorResultItems))
// Pack arguments for System.Contract.Call.
arr, err := ExpandParameterToEmitable(Parameter{
Type: ArrayType,
Value: params,
})
if err != nil {
return nil, fmt.Errorf("expanding params to emitable: %w", err)
}
emit.Array(script.BinWriter, arr.([]interface{})...)
emit.AppCallNoArgs(script.BinWriter, contract, operation, callflag.All) // The System.Contract.Call itself, it will push Iterator on estack.
emit.Opcodes(script.BinWriter, opcode.NEWARRAY0) // Push new empty array to estack. This array will store iterator's elements.
// Start the iterator traversal cycle.
iteratorTraverseCycleStartOffset := script.Len()
emit.Opcodes(script.BinWriter, opcode.OVER) // Load iterator from 1-st cell of estack.
emit.Syscall(script.BinWriter, interopnames.SystemIteratorNext) // Call System.Iterator.Next, it will pop the iterator from estack and push `true` or `false` to estack.
jmpIfNotOffset := script.Len()
emit.Instruction(script.BinWriter, opcode.JMPIFNOT, // Pop boolean value (from the previous step) from estack, if `false`, then iterator has no more items => jump to the end of program.
[]byte{
0x00, // jump to loadResultOffset, but we'll fill this byte after script creation.
})
emit.Opcodes(script.BinWriter, opcode.DUP, // Duplicate the resulting array from 0-th cell of estack and push it to estack.
opcode.PUSH2, opcode.PICK) // Pick iterator from the 2-nd cell of estack.
emit.Syscall(script.BinWriter, interopnames.SystemIteratorValue) // Call System.Iterator.Value, it will pop the iterator from estack and push its current value to estack.
emit.Opcodes(script.BinWriter, opcode.APPEND) // Pop iterator value and the resulting array from estack. Append value to the resulting array. Array is a reference type, thus, value stored at the 1-th cell of local slot will also be updated.
emit.Opcodes(script.BinWriter, opcode.DUP, // Duplicate the resulting array from 0-th cell of estack and push it to estack.
opcode.SIZE, // Pop array from estack and push its size to estack.
opcode.PUSH3, opcode.PICK, // Pick maxIteratorResultItems from the 3-d cell of estack.
opcode.GE) // Compare len(arr) and maxIteratorResultItems
jmpIfMaxReachedOffset := script.Len()
emit.Instruction(script.BinWriter, opcode.JMPIF, // Pop boolean value (from the previous step) from estack, if `false`, then max array elements is reached => jump to the end of program.
[]byte{
0x00, // jump to loadResultOffset, but we'll fill this byte after script creation.
})
jmpOffset := script.Len()
emit.Instruction(script.BinWriter, opcode.JMP, // Jump to the start of iterator traverse cycle.
[]byte{
uint8(iteratorTraverseCycleStartOffset - jmpOffset), // jump to iteratorTraverseCycleStartOffset; offset is relative to JMP position.
})
// End of the program: push the result on stack and return.
loadResultOffset := script.Len()
emit.Opcodes(script.BinWriter, opcode.NIP, // Remove iterator from the 1-st cell of estack
opcode.NIP) // Remove maxIteratorResultItems from the 1-st cell of estack, so that only resulting array is left on estack.
if err := script.Err; err != nil {
return nil, fmt.Errorf("emitting iterator unwrapper script: %w", err)
}
// Fill in JMPIFNOT instruction parameter.
bytes := script.Bytes()
bytes[jmpIfNotOffset+1] = uint8(loadResultOffset - jmpIfNotOffset) // +1 is for JMPIFNOT itself; offset is relative to JMPIFNOT position.
// Fill in jmpIfMaxReachedOffset instruction parameter.
bytes[jmpIfMaxReachedOffset+1] = uint8(loadResultOffset - jmpIfMaxReachedOffset) // +1 is for JMPIF itself; offset is relative to JMPIF position.
return bytes, nil
}