break
The command break works similarly to a GDB breakpoint.
A breakpoint in ethdbg can be simple or conditional.
💥 Simple Breakpoint
A simple breakpoint can be placed on a specific value of the <PC> or at a specific <OPCODE>
Syntax:
break <PC>break <OPCODE>
| ❗️ Note |
|---|
| Make sure the chosen OPCODE is available in the EVM version currently executing the transaction. |
💥 Conditional Breakpoint
The expressiveness of a conditional breakpoint is currently still limited, but they already support some interesting combination of events.
A conditional breakpoint is set by specifying a tuple of the form <what><when><value>.
Multiple <what><when><value> tuples create more complex stop conditions that must all be satisfied for the breakpoint to trigger (AND).
Syntax: break <what><when><value>,<what><when><value>,...
Currently we support the following <what> and <when>:
| What | Description |
|---|---|
pc |
Value of the program counter to break at |
op |
OPCODE at which to stop |
addr |
Contract address currently executing code |
saddr |
Contract address which currently backs the storage |
value |
stop when a particular amount of ETH is sent as part of a CALL |
gas_remaining |
stop when a specific value of gas is remaining |
| ❗️ Note |
|---|
Note how addr and saddr represent different addresses. addr is the code address, i.e., the address of the smart contract currently executing. On the other hand, saddr is the storage address, i.e., the address of the contract whose storage will be modified when storage operations occur. For more information on the distinction, see the difference between the CALL and DELEGATECALL instructions. |
| When | Description |
|---|---|
[= or ==] |
Equality |
!= |
NOT equality |
[> or >=] |
Greater than/Greater or Equal then |
[< or <=] |
Lower than/Lower or Equal then |
For instance, one can set a breakpoint which only triggers when the OPCODE is an SSTORE that operates on the storage of a specific contract address by doing:
