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do_.rs
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do_.rs
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use std::thread;
use nu_engine::{eval_block_with_early_return, redirect_env, CallExt};
use nu_protocol::ast::Call;
use nu_protocol::engine::{Closure, Command, EngineState, Stack};
use nu_protocol::{
Category, Example, IntoSpanned, ListStream, PipelineData, RawStream, ShellError, Signature,
SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct Do;
impl Command for Do {
fn name(&self) -> &str {
"do"
}
fn usage(&self) -> &str {
"Run a closure, providing it with the pipeline input."
}
fn signature(&self) -> Signature {
Signature::build("do")
.required(
"closure",
SyntaxShape::OneOf(vec![SyntaxShape::Closure(None), SyntaxShape::Any]),
"The closure to run.",
)
.input_output_types(vec![(Type::Any, Type::Any)])
.switch(
"ignore-errors",
"ignore errors as the closure runs",
Some('i'),
)
.switch(
"ignore-shell-errors",
"ignore shell errors as the closure runs",
Some('s'),
)
.switch(
"ignore-program-errors",
"ignore external program errors as the closure runs",
Some('p'),
)
.switch(
"capture-errors",
"catch errors as the closure runs, and return them",
Some('c'),
)
.switch(
"env",
"keep the environment defined inside the command",
None,
)
.rest(
"rest",
SyntaxShape::Any,
"The parameter(s) for the closure.",
)
.category(Category::Core)
}
fn run(
&self,
engine_state: &EngineState,
caller_stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let block: Closure = call.req(engine_state, caller_stack, 0)?;
let rest: Vec<Value> = call.rest(engine_state, caller_stack, 1)?;
let ignore_all_errors = call.has_flag(engine_state, caller_stack, "ignore-errors")?;
let ignore_shell_errors = ignore_all_errors
|| call.has_flag(engine_state, caller_stack, "ignore-shell-errors")?;
let ignore_program_errors = ignore_all_errors
|| call.has_flag(engine_state, caller_stack, "ignore-program-errors")?;
let capture_errors = call.has_flag(engine_state, caller_stack, "capture-errors")?;
let has_env = call.has_flag(engine_state, caller_stack, "env")?;
let mut callee_stack = caller_stack.captures_to_stack(block.captures);
let block = engine_state.get_block(block.block_id);
let params: Vec<_> = block
.signature
.required_positional
.iter()
.chain(block.signature.optional_positional.iter())
.collect();
for param in params.iter().zip(&rest) {
if let Some(var_id) = param.0.var_id {
callee_stack.add_var(var_id, param.1.clone())
}
}
if let Some(param) = &block.signature.rest_positional {
if rest.len() > params.len() {
let mut rest_items = vec![];
for r in rest.into_iter().skip(params.len()) {
rest_items.push(r);
}
let span = if let Some(rest_item) = rest_items.first() {
rest_item.span()
} else {
call.head
};
callee_stack.add_var(
param
.var_id
.expect("Internal error: rest positional parameter lacks var_id"),
Value::list(rest_items, span),
)
}
}
let result = eval_block_with_early_return(
engine_state,
&mut callee_stack,
block,
input,
call.redirect_stdout,
call.redirect_stdout,
);
if has_env {
// Merge the block's environment to the current stack
redirect_env(engine_state, caller_stack, &callee_stack);
}
match result {
Ok(PipelineData::ExternalStream {
stdout,
stderr,
exit_code,
span,
metadata,
trim_end_newline,
}) if capture_errors => {
// Use a thread to receive stdout message.
// Or we may get a deadlock if child process sends out too much bytes to stderr.
//
// For example: in normal linux system, stderr pipe's limit is 65535 bytes.
// if child process sends out 65536 bytes, the process will be hanged because no consumer
// consumes the first 65535 bytes
// So we need a thread to receive stdout message, then the current thread can continue to consume
// stderr messages.
let stdout_handler = stdout
.map(|stdout_stream| {
thread::Builder::new()
.name("stderr redirector".to_string())
.spawn(move || {
let ctrlc = stdout_stream.ctrlc.clone();
let span = stdout_stream.span;
RawStream::new(
Box::new(std::iter::once(
stdout_stream.into_bytes().map(|s| s.item),
)),
ctrlc,
span,
None,
)
})
.map_err(|e| e.into_spanned(call.head))
})
.transpose()?;
// Intercept stderr so we can return it in the error if the exit code is non-zero.
// The threading issues mentioned above dictate why we also need to intercept stdout.
let mut stderr_ctrlc = None;
let stderr_msg = match stderr {
None => "".to_string(),
Some(stderr_stream) => {
stderr_ctrlc = stderr_stream.ctrlc.clone();
stderr_stream.into_string().map(|s| s.item)?
}
};
let stdout = if let Some(handle) = stdout_handler {
match handle.join() {
Err(err) => {
return Err(ShellError::ExternalCommand {
label: "Fail to receive external commands stdout message"
.to_string(),
help: format!("{err:?}"),
span,
});
}
Ok(res) => Some(res),
}
} else {
None
};
let mut exit_code_ctrlc = None;
let exit_code: Vec<Value> = match exit_code {
None => vec![],
Some(exit_code_stream) => {
exit_code_ctrlc = exit_code_stream.ctrlc.clone();
exit_code_stream.into_iter().collect()
}
};
if let Some(Value::Int { val: code, .. }) = exit_code.last() {
if *code != 0 {
return Err(ShellError::ExternalCommand {
label: "External command failed".to_string(),
help: stderr_msg,
span,
});
}
}
Ok(PipelineData::ExternalStream {
stdout,
stderr: Some(RawStream::new(
Box::new(std::iter::once(Ok(stderr_msg.into_bytes()))),
stderr_ctrlc,
span,
None,
)),
exit_code: Some(ListStream::from_stream(
exit_code.into_iter(),
exit_code_ctrlc,
)),
span,
metadata,
trim_end_newline,
})
}
Ok(PipelineData::ExternalStream {
stdout,
stderr,
exit_code: _,
span,
metadata,
trim_end_newline,
}) if ignore_program_errors && !call.redirect_stdout => {
Ok(PipelineData::ExternalStream {
stdout,
stderr,
exit_code: None,
span,
metadata,
trim_end_newline,
})
}
Ok(PipelineData::Value(Value::Error { .. }, ..)) | Err(_) if ignore_shell_errors => {
Ok(PipelineData::empty())
}
Ok(PipelineData::ListStream(ls, metadata)) if ignore_shell_errors => {
// check if there is a `Value::Error` in given list stream first.
let mut values = vec![];
let ctrlc = ls.ctrlc.clone();
for v in ls {
if let Value::Error { .. } = v {
values.push(Value::nothing(call.head));
} else {
values.push(v)
}
}
Ok(PipelineData::ListStream(
ListStream::from_stream(values.into_iter(), ctrlc),
metadata,
))
}
r => r,
}
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Run the closure",
example: r#"do { echo hello }"#,
result: Some(Value::test_string("hello")),
},
Example {
description: "Run a stored first-class closure",
example: r#"let text = "I am enclosed"; let hello = {|| echo $text}; do $hello"#,
result: Some(Value::test_string("I am enclosed")),
},
Example {
description: "Run the closure and ignore both shell and external program errors",
example: r#"do --ignore-errors { thisisnotarealcommand }"#,
result: None,
},
Example {
description: "Run the closure and ignore shell errors",
example: r#"do --ignore-shell-errors { thisisnotarealcommand }"#,
result: None,
},
Example {
description: "Run the closure and ignore external program errors",
example: r#"do --ignore-program-errors { nu --commands 'exit 1' }; echo "I'll still run""#,
result: None,
},
Example {
description: "Abort the pipeline if a program returns a non-zero exit code",
example: r#"do --capture-errors { nu --commands 'exit 1' } | myscarycommand"#,
result: None,
},
Example {
description: "Run the closure, with a positional parameter",
example: r#"do {|x| 100 + $x } 77"#,
result: Some(Value::test_int(177)),
},
Example {
description: "Run the closure, with input",
example: r#"77 | do {|x| 100 + $in }"#,
result: None, // TODO: returns 177
},
Example {
description: "Run the closure and keep changes to the environment",
example: r#"do --env { $env.foo = 'bar' }; $env.foo"#,
result: Some(Value::test_string("bar")),
},
]
}
}
mod test {
#[test]
fn test_examples() {
use super::Do;
use crate::test_examples;
test_examples(Do {})
}
}