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Add return code to get_block_hash_fn #73

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merged 3 commits into from
Sep 3, 2018
Merged

Add return code to get_block_hash_fn #73

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d9f7ff2
Add return code to get_block_hash_fn
axic Aug 20, 2018
d0bc507
go: Add error output to Host.GetBlockHash()
chfast Sep 3, 2018
ced1c26
examples: Better get_block_hash example
chfast Sep 3, 2018
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4 changes: 2 additions & 2 deletions bindings/go/evmc/host.c
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Original file line number Diff line number Diff line change
Expand Up @@ -97,8 +97,8 @@ static inline void go_exported_functions_type_checks()
tx_context = getTxContext(context);

evmc_get_block_hash_fn get_block_hash_fn = NULL;
get_block_hash_fn(uint256be, context, number);
getBlockHash(uint256be, context, number);
status = get_block_hash_fn(uint256be, context, number);
status = getBlockHash(uint256be, context, number);

evmc_emit_log_fn emit_log_fn = NULL;
emit_log_fn(context, address, data, size, uint256be, size);
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12 changes: 9 additions & 3 deletions bindings/go/evmc/host.go
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Expand Up @@ -79,7 +79,7 @@ type HostContext interface {
Selfdestruct(addr common.Address, beneficiary common.Address)
GetTxContext() (gasPrice common.Hash, origin common.Address, coinbase common.Address, number int64, timestamp int64,
gasLimit int64, difficulty common.Hash)
GetBlockHash(number int64) common.Hash
GetBlockHash(number int64) (common.Hash, error)
EmitLog(addr common.Address, topics []common.Hash, data []byte)
Call(kind CallKind,
destination common.Address, sender common.Address, value *big.Int, input []byte, gas int64, depth int,
Expand Down Expand Up @@ -182,11 +182,17 @@ func getTxContext(pCtx unsafe.Pointer) C.struct_evmc_tx_context {
}

//export getBlockHash
func getBlockHash(pResult *C.struct_evmc_uint256be, pCtx unsafe.Pointer, number int64) {
func getBlockHash(pResult *C.struct_evmc_uint256be, pCtx unsafe.Pointer, number int64) C.int {
idx := int((*C.struct_extended_context)(pCtx).index)
ctx := getHostContext(idx)

*pResult = evmcUint256be(ctx.GetBlockHash(number))
blockhash, err := ctx.GetBlockHash(number)
if err != nil {
return C.int(0)
}

*pResult = evmcUint256be(blockhash)
return C.int(1)
}

//export emitLog
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26 changes: 18 additions & 8 deletions examples/example_host.cpp
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Expand Up @@ -9,6 +9,13 @@

#include <evmc/helpers.h>

struct example_host_context : evmc_context
{
example_host_context();

evmc_tx_context tx_context = {};
};

static evmc_uint256be balance(evmc_context* context, const evmc_address* address)
{
(void)context;
Expand Down Expand Up @@ -107,11 +114,17 @@ static evmc_tx_context get_tx_context(evmc_context* context)
return result;
}

static void get_block_hash(evmc_uint256be* result, evmc_context* context, int64_t number)
static int get_block_hash(evmc_uint256be* result, evmc_context* context, int64_t number)
{
(void)result;
(void)context;
(void)number;
example_host_context* host = static_cast<example_host_context*>(context);
int64_t current_block_number = host->tx_context.block_number;

if (number >= current_block_number || number < current_block_number - 256)
return 0;

evmc_uint256be example_block_hash{};
*result = example_block_hash;
return 1;
}

static void emit_log(evmc_context* context,
Expand All @@ -134,10 +147,7 @@ static const evmc_host_interface interface = {
copy_code, selfdestruct, call, get_tx_context, get_block_hash, emit_log,
};

struct example_host_context : evmc_context
{
example_host_context() : evmc_context{&interface} {}
};
example_host_context::example_host_context() : evmc_context{&interface} {}

extern "C" {

Expand Down
18 changes: 10 additions & 8 deletions include/evmc/evmc.h
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Expand Up @@ -153,17 +153,19 @@ typedef struct evmc_tx_context (*evmc_get_tx_context_fn)(struct evmc_context* co
/**
* Get block hash callback function.
*
* This callback function is used by an EVM to query the block hash of
* a given block.
* This callback function is used by an VM to query the block hash of
* a given block. If the requested block is not found, then an appropriate
* result code is returned.
*
* @param[out] result The returned block hash value.
* @param[out] result The returned block hash value. Only written to
* if the return value is 1 (information is avialable).
* @param context The pointer to the Host execution context.
* @param number The block number. Must be a value between
* (and including) 0 and 255.
* @param number The block number.
* @return 1 if the information is available, 0 otherwise.
*/
typedef void (*evmc_get_block_hash_fn)(struct evmc_uint256be* result,
struct evmc_context* context,
int64_t number);
typedef int (*evmc_get_block_hash_fn)(struct evmc_uint256be* result,
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Should it return evmc_status_code (https://github.com/ethereum/evmc/blob/master/include/evmc/evmc.h#L191)?

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I don't think so, but we could consider having another enum for more regular cases.

Success/failure/invalid args.

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@chfast do we want an enum instead?

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I don't know yet. I have the review all similar cases and create the superset of possible error codes. If we end up with up to 4 items we can use it in all cases.

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We can merge it with int, but you have to improve documentation of @result and @param number.

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Should we wait for #116 first?

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The #116 is ready, just needs review.

struct evmc_context* context,
int64_t number);

/**
* The execution status code.
Expand Down