feat(cheatcodes): tryFfi (rebased) (#5660)

* chore: add tryffi cheatcode to abi

* feat: impl

* chore: tests

Author: Evalir

crates/abi/abi/HEVM.sol

@@ -3,9 +3,11 @@ struct Rpc { string name; string url; }
 struct DirEntry { string errorMessage; string path; uint64 depth; bool isDir; bool isSymlink; }
 struct FsMetadata { bool isDir; bool isSymlink; uint256 length; bool readOnly; uint256 modified; uint256 accessed; uint256 created; }
 struct Wallet { address addr; uint256 publicKeyX; uint256 publicKeyY; uint256 privateKey; }
+struct FfiResult { int32 exit_code; bytes stdout; bytes stderr; }
 
 allowCheatcodes(address)
 
+tryFfi(string[])(FfiResult)
 ffi(string[])(bytes)
 
 breakpoint(string)

crates/abi/src/bindings/hevm.rs

@@ -11,6 +11,50 @@ use serde::Deserialize;
 use serde_json::Value;
 use std::{collections::BTreeMap, env, path::Path, process::Command};
 
+/// Invokes a `Command` with the given args and returns the exit code, stdout, and stderr.
+///
+/// If stdout or stderr are valid hex, it returns the hex decoded value.
+fn try_ffi(state: &Cheatcodes, args: &[String]) -> Result {
+    if args.is_empty() || args[0].is_empty() {
+        bail!("Can't execute empty command");
+    }
+    let name = &args[0];
+    let mut cmd = Command::new(name);
+    if args.len() > 1 {
+        cmd.args(&args[1..]);
+    }
+
+    trace!(?args, "invoking try_ffi");
+
+    let output = cmd
+        .current_dir(&state.config.root)
+        .output()
+        .map_err(|err| fmt_err!("Failed to execute command: {err}"))?;
+
+    let exit_code = output.status.code().unwrap_or(1);
+
+    let trimmed_stdout = String::from_utf8(output.stdout)?;
+    let trimmed_stdout = trimmed_stdout.trim();
+
+    // The stdout might be encoded on valid hex, or it might just be a string,
+    // so we need to determine which it is to avoid improperly encoding later.
+    let encoded_stdout: Token =
+        if let Ok(hex) = hex::decode(trimmed_stdout.strip_prefix("0x").unwrap_or(trimmed_stdout)) {
+            Token::Bytes(hex)
+        } else {
+            Token::Bytes(trimmed_stdout.into())
+        };
+
+    let res = abi::encode(&[Token::Tuple(vec![
+        Token::Int(exit_code.into()),
+        encoded_stdout,
+        // We can grab the stderr output as-is.
+        Token::Bytes(output.stderr),
+    ])]);
+
+    Ok(res.into())
+}
+
 /// Invokes a `Command` with the given args and returns the abi encoded response
 ///
 /// If the output of the command is valid hex, it returns the hex decoded value
@@ -461,6 +505,13 @@ pub fn apply(state: &mut Cheatcodes, call: &HEVMCalls) -> Option<Result> {
                 Err(fmt_err!("FFI disabled: run again with `--ffi` if you want to allow tests to call external scripts."))
             }
         }
+        HEVMCalls::TryFfi(inner) => {
+            if state.config.ffi {
+                try_ffi(state, &inner.0)
+            } else {
+                Err(fmt_err!("FFI disabled: run again with `--ffi` if you want to allow tests to call external scripts."))
+            }
+        }
         HEVMCalls::GetCode(inner) => get_code(state, &inner.0),
         HEVMCalls::GetDeployedCode(inner) => get_deployed_code(state, &inner.0),
         HEVMCalls::SetEnv(inner) => set_env(&inner.0, &inner.1),

crates/evm/src/executor/inspector/cheatcodes/ext.rs

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: Unlicense
+pragma solidity >=0.8.18;
+
+import "ds-test/test.sol";
+import "./Vm.sol";
+
+contract TryFfiTest is DSTest {
+    Vm constant vm = Vm(HEVM_ADDRESS);
+
+    function testTryFfi() public {
+        string[] memory inputs = new string[](3);
+        inputs[0] = "bash";
+        inputs[1] = "-c";
+        inputs[2] =
+            "echo -n 0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000966666920776f726b730000000000000000000000000000000000000000000000";
+
+        Vm.FfiResult memory f = vm.tryFfi(inputs);
+        (string memory output) = abi.decode(f.stdout, (string));
+        assertEq(output, "ffi works", "ffi failed");
+        assertEq(f.exit_code, 0, "ffi failed");
+    }
+
+    function testTryFfiFail() public {
+        string[] memory inputs = new string[](3);
+        inputs[0] = "bash";
+        inputs[1] = "-c";
+        inputs[2] = "quikmafs";
+
+        Vm.FfiResult memory f = vm.tryFfi(inputs);
+        assert(f.exit_code != 0);
+        assertEq(string(f.stderr), string("bash: quikmafs: command not found\n"));
+    }
+}

testdata/cheats/TryFfi.sol

@@ -52,6 +52,12 @@ interface Vm {
         uint256 privateKey;
     }
 
+    struct FfiResult {
+        int32 exit_code;
+        bytes stdout;
+        bytes stderr;
+    }
+
     // Set block.timestamp (newTimestamp)
     function warp(uint256) external;
 
@@ -116,6 +122,9 @@ interface Vm {
     // Performs a foreign function call via terminal, (stringInputs) => (result)
     function ffi(string[] calldata) external returns (bytes memory);
 
+    // Performs a foreign function call via terminal and returns the exit code, stdout, and stderr
+    function tryFfi(string[] calldata) external returns (FfiResult memory);
+
     // Set environment variables, (name, value)
     function setEnv(string calldata, string calldata) external;