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Add error type wrapping all possible errors #122

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Add error type wrapping all possible errors #122

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955a92c
Create error type using thiserror crate
DevinR528 Oct 11, 2020
a21f4fa
Use new error type everywhere applicable
DevinR528 Oct 11, 2020
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1 change: 1 addition & 0 deletions Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ gimli = "0.22.0"
capstone = "0.7.0"
addr2line = "0.13.0"
syntect = {version = "4.4.0", optional = true}
thiserror = "1.0.21"

# Dependencies specific to macOS & Linux
[target.'cfg(unix)'.dependencies]
Expand Down
4 changes: 2 additions & 2 deletions examples/gui.rs
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Expand Up @@ -20,7 +20,7 @@ mod example {
};
use headcrab::{
symbol::DisassemblySource, symbol::RelocatedDwarf, target::LinuxTarget, target::UnixTarget,
CrabResult,
CrabError, CrabResult,
};
use imgui::{im_str, ClipboardBackend, Condition, FontSource, ImStr, ImString};
use imgui_glium_renderer::Renderer;
Expand Down Expand Up @@ -135,7 +135,7 @@ mod example {
if let Some(remote) = &self.remote {
Ok(remote)
} else {
Err("No running process".to_string().into())
Err(CrabError::HeadCrab("No running process".to_string()))
}
}

Expand Down
45 changes: 28 additions & 17 deletions examples/repl.rs
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Expand Up @@ -16,7 +16,7 @@ mod example {
use headcrab::{
symbol::{DisassemblySource, RelocatedDwarf, Snippet},
target::{AttachOptions, LinuxTarget, UnixTarget},
CrabResult,
CrabError, CrabResult,
};

#[cfg(target_os = "linux")]
Expand Down Expand Up @@ -147,15 +147,15 @@ mod example {
if let Some(remote) = &self.remote {
Ok(remote)
} else {
Err("No running process".to_string().into())
Err(CrabError::HeadCrab("No running process".to_string()))
}
}

fn mut_remote(&mut self) -> CrabResult<&mut LinuxTarget> {
if let Some(remote) = &mut self.remote {
Ok(remote)
} else {
Err("No running process".to_string().into())
Err(CrabError::HeadCrab("No running process".to_string()))
}
}

Expand Down Expand Up @@ -308,7 +308,8 @@ mod example {
return Ok(());
}

let command = ReplCommand::from_str(command)?;
let command =
ReplCommand::from_str(command).map_err(|e| CrabError::HeadCrab(e.to_string()))?;
match command {
ReplCommand::Help(()) => {
ReplCommand::print_help(std::io::stdout(), color).unwrap();
Expand Down Expand Up @@ -349,11 +350,18 @@ mod example {
return print_source_for_top_of_stack_symbol(context, 3);
}
ReplCommand::Registers(sub_cmd) => match &*sub_cmd {
"" => Err(format!(
"Expected subcommand found nothing. Try `regs read`"
))?,
"" => {
return Err(CrabError::HeadCrab(
"Expected subcommand found nothing. Try `regs read`".into(),
));
}
"read" => println!("{:?}", context.remote()?.read_regs()?),
_ => Err(format!("Unknown `regs` subcommand `{}`", sub_cmd))?,
_ => {
return Err(CrabError::HeadCrab(format!(
"Unknown `regs` subcommand `{}`",
sub_cmd
)));
}
},
ReplCommand::Backtrace(sub_cmd) => {
return show_backtrace(context, &sub_cmd);
Expand Down Expand Up @@ -394,26 +402,28 @@ mod example {
if let Ok(addr) = {
usize::from_str_radix(&location, 10)
.map(|addr| addr as usize)
.map_err(|e| Box::new(e))
.map_err(CrabError::ParseInt)
.or_else(|_e| {
if location.starts_with("0x") {
let raw_num = location.trim_start_matches("0x");
usize::from_str_radix(raw_num, 16)
.map(|addr| addr as usize)
.map_err(|_e| Box::new(format!("Invalid address format.")))
.map_err(|_e| CrabError::HeadCrab("Invalid address format.".into()))
} else {
context
.debuginfo()
.get_symbol_address(&location)
.ok_or(Box::new(format!("No such symbol {}", location)))
.ok_or_else(|| {
CrabError::HeadCrab(format!("No such symbol {}", location))
})
}
})
} {
context.mut_remote()?.set_breakpoint(addr)?;
} else {
Err(format!(
"Breakpoints must be set on a symbol or at a given address. For example `b main` or `b 0x0000555555559394` or even `b 93824992252820`"
))?
return Err(CrabError::HeadCrab(
"Breakpoints must be set on a symbol or at a given address. For example `b main` or `b 0x0000555555559394` or even `b 93824992252820`".into()
));
}
Ok(())
}
Expand Down Expand Up @@ -508,9 +518,10 @@ mod example {
println!(" {} {}", name, location);
}

let (_dwarf, unit, dw_die_offset) = frame
.function_debuginfo()
.ok_or_else(|| "No dwarf debuginfo for function".to_owned())?;
let (_dwarf, unit, dw_die_offset) =
frame.function_debuginfo().ok_or_else(|| {
CrabError::HeadCrab("No dwarf debuginfo for function".to_owned())
})?;

let mut eval_ctx = X86_64EvalContext {
frame_base: None,
Expand Down
41 changes: 41 additions & 0 deletions src/error.rs
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@@ -0,0 +1,41 @@
use thiserror::Error;

#[derive(Error, Debug)]
pub enum CrabError {
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I think there should be a separate error type for target and one for symbol.

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@DevinR528 DevinR528 Oct 11, 2020 •
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Does there still need to be a top-level wrapper for pub type CrabResult<T> = Result<T, ErrorType>;? Something like

pub enum CrabError {
    Target(crate::target::TargetError),
    Symbol(crate::symbol::SymbolError),
}

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Or should each mod (target and symbol) have their own Result type?

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@bjorn3 bjorn3 Oct 12, 2020 •
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Does there still need to be a top-level wrapper for pub type CrabResult = Result<T, ErrorType>;? Something like

That could be useful.

Or should each mod (target and symbol) have their own Result type?

Yes please.

#[error("Error occurred in headcrab: {0}")]
HeadCrab(String),

#[error("{0}")]
Dwarf(String),

#[error("Hardware breakpoint error: {0}")]
HardwareBP(#[from] crate::target::HardwareBreakpointError),

#[error("Error occurred with breakpoint: {0}")]
Breakpoint(#[from] crate::target::BreakpointError),

#[error("Error occurred during gmili parsing: {0}")]
Symbol(#[from] gimli::Error),

#[error("Error occurred while reading object file: {0}")]
Object(#[from] object::read::Error),

#[error("Error occurred while monitoring process: {0}")]
NixPtrace(#[from] nix::Error),

#[error("Error occurred while reading /proc: {0}")]
// NOTE: If a `ProcError::InternalError` is found this is a bug in the `procfs` crate.
ProcFs(#[from] procfs::ProcError),

#[error("{0}")]
StdIo(#[from] std::io::Error),

#[error("{0}")]
ParseInt(#[from] std::num::ParseIntError),

#[error("{0}")]
Utf8Error(#[from] std::str::Utf8Error),

#[error("{0}")]
FfiNull(#[from] std::ffi::NulError),
}
5 changes: 4 additions & 1 deletion src/lib.rs
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@@ -1,10 +1,13 @@
//! Headcrab, a modern Rust debugging library.

pub type CrabResult<T> = Result<T, Box<dyn std::error::Error + Send + Sync + Sync>>;
pub type CrabResult<T> = Result<T, error::CrabError>;

pub mod error;
/// Functions to work with target processes: reading & writing memory, process control functions, etc.
pub mod target;

/// Symbolication layer.
#[cfg(unix)]
pub mod symbol;

pub use error::CrabError;
28 changes: 18 additions & 10 deletions src/symbol/dwarf_utils.rs
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@@ -1,7 +1,7 @@
use gimli::{DebuggingInformationEntry, Dwarf, Unit, UnitOffset, ValueType};

use super::Reader;
use crate::CrabResult;
use crate::{CrabError, CrabResult};

macro_rules! dwarf_attr {
(str($dwarf:ident,$unit:ident) $entry:ident.$name:ident || $missing:ident) => {
Expand All @@ -18,12 +18,11 @@ macro_rules! dwarf_attr {
dwarf_attr_exists_action_action!($missing, unit_ref)
}
val => {
return Err(format!(
return Err(crate::error::CrabError::Dwarf(format!(
"`{:?}` is not a valid value for a {} attribute",
val,
gimli::$name,
)
.into())
)))
}
}
} else {
Expand All @@ -35,7 +34,10 @@ macro_rules! dwarf_attr {
dwarf_attr_exists_action_action!(
$missing,
attr.udata_value()
.ok_or(concat!("invalid value for", stringify!($name)))?
.ok_or(crate::error::CrabError::Dwarf(format!(
"invalid value for {}",
stringify!($name)
)))?
)
} else {
dwarf_attr_missing_action!($missing, $name)
Expand All @@ -48,9 +50,11 @@ macro_rules! dwarf_attr {
dwarf_attr_exists_action_action!($missing, encoding)
}
encoding => {
return Err(
format!("invalid value for {}: {:?}", gimli::$name, encoding).into(),
)
return Err(crate::error::CrabError::Dwarf(format!(
"invalid value for {}: {:?}",
gimli::$name,
encoding
)))
}
}
} else {
Expand Down Expand Up @@ -83,7 +87,10 @@ macro_rules! dwarf_attr_missing_action {
continue;
};
(error, $name:ident) => {
return Err(concat!("missing ", stringify!($name), " attribute").into());
return Err(crate::error::CrabError::Dwarf(format!(
"missing {} attribute",
stringify!($name),
)));
};
(None, $name:ident) => {
None
Expand Down Expand Up @@ -181,7 +188,8 @@ fn value_type_from_base_type(
Ok(ValueType::Generic)
} else {
let base_type_die = unit.entry(base_type)?;
Ok(ValueType::from_entry(&base_type_die)?.ok_or_else(|| "not a base type".to_owned())?)
Ok(ValueType::from_entry(&base_type_die)?
.ok_or_else(|| CrabError::Dwarf("not a base type".to_owned()))?)
}
}

Expand Down
35 changes: 23 additions & 12 deletions src/symbol/frame.rs
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Expand Up @@ -3,6 +3,7 @@ use std::fmt;

use super::dwarf_utils::SearchAction;
use super::*;
use crate::{CrabError, CrabResult};

pub struct Frame<'a> {
dwarf: &'a gimli::Dwarf<Reader<'a>>,
Expand Down Expand Up @@ -68,7 +69,7 @@ impl<'a> Frame<'a> {
) -> CrabResult<()> {
let (dwarf, unit, dw_die_offset) = self
.function_debuginfo()
.ok_or_else(|| "No dwarf debuginfo for function".to_owned())?;
.ok_or_else(|| CrabError::Dwarf("No dwarf debuginfo for function".to_owned()))?;

dwarf_utils::search_tree(unit, Some(dw_die_offset), |entry, _indent| {
if entry.offset() == dw_die_offset {
Expand All @@ -95,7 +96,7 @@ impl<'a> Frame<'a> {
) -> CrabResult<()> {
let (dwarf, unit, dw_die_offset) = self
.function_debuginfo()
.ok_or_else(|| "No dwarf debuginfo for function".to_owned())?;
.ok_or_else(|| CrabError::Dwarf("No dwarf debuginfo for function".to_owned()))?;
dwarf_utils::search_tree(unit, Some(dw_die_offset), |entry, _indent| {
if entry.tag() == gimli::DW_TAG_inlined_subroutine && entry.offset() != dw_die_offset {
return Ok(SearchAction::SkipChildren); // Already visited by addr2line frame iter
Expand Down Expand Up @@ -162,21 +163,27 @@ impl<'ctx> LocalValue<'ctx> {
match encoding {
gimli::DW_ATE_unsigned | gimli::DW_ATE_signed => {
let size = u8::try_from(size).map_err(|_| {
format!("`{}` is too big for DW_ATE_unsigned or DW_ATE_signed", size,)
CrabError::Dwarf(format!(
"`{}` is too big for DW_ATE_unsigned or DW_ATE_signed",
size
))
})?;
let data = match self {
LocalValue::Pieces(pieces) => {
if pieces.len() != 1 {
return Err("too many pieces for an integer value".into());
return Err(CrabError::Dwarf(
"too many pieces for an integer value".into(),
));
}

if pieces[0].size_in_bits.is_none()
|| pieces[0].size_in_bits.unwrap() == u64::from(size) * 8
{
} else {
return Err(
format!("wrong size for piece {:?}", pieces[0]).into()
);
return Err(CrabError::Dwarf(format!(
"wrong size for piece {:?}",
pieces[0]
)));
}
// FIXME handle this
assert!(
Expand All @@ -187,7 +194,9 @@ impl<'ctx> LocalValue<'ctx> {

let value = match &pieces[0].location {
gimli::Location::Empty => {
return Err("found empty piece for an integer value".into())
return Err(CrabError::Dwarf(
"found empty piece for an integer value".into(),
))
}
gimli::Location::Register { register } => {
eval_ctx.register(
Expand All @@ -207,9 +216,9 @@ impl<'ctx> LocalValue<'ctx> {
value: _,
byte_offset: _,
} => {
return Err(
"found implicit pointer for an integer value".into()
)
return Err(CrabError::Dwarf(
"found implicit pointer for an integer value".into(),
))
}
};
match value {
Expand All @@ -223,7 +232,9 @@ impl<'ctx> LocalValue<'ctx> {
gimli::Value::I64(data) => data as u64,
gimli::Value::U64(data) => data,
gimli::Value::F32(_) | gimli::Value::F64(_) => {
return Err("found float piece for an integer value".into())
return Err(CrabError::Dwarf(
"found float piece for an integer value".into(),
))
}
}
}
Expand Down
5 changes: 3 additions & 2 deletions src/symbol/relocate.rs
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@@ -1,4 +1,5 @@
use super::*;
use crate::CrabError;

pub struct RelocatedDwarf(Vec<RelocatedDwarfEntry>);

Expand Down Expand Up @@ -56,11 +57,11 @@ impl RelocatedDwarfEntry {
})
})
.ok_or_else(|| {
format!(
CrabError::HeadCrab(format!(
"Couldn't find segment for `{}`+0x{:x}",
file.display(),
offset
)
))
})?;
Ok(RelocatedDwarfEntry {
address_range: address,
Expand Down
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