From e125c072fa67d332690049f998ecdfe6eee5ec29 Mon Sep 17 00:00:00 2001
From: ridethepig <protonghost@163.com>
Date: Sun, 5 Mar 2023 15:51:20 +0000
Subject: [PATCH] milestone 3

---
 proj-1/deet/src/debugger.rs         | 21 ++++++++++++++++-
 proj-1/deet/src/debugger_command.rs |  6 ++++-
 proj-1/deet/src/inferior.rs         | 35 ++++++++++++++++++++++++++---
 proj-1/deet/src/main.rs             |  2 ++
 4 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/proj-1/deet/src/debugger.rs b/proj-1/deet/src/debugger.rs
index 9622477..055f8b8 100644
--- a/proj-1/deet/src/debugger.rs
+++ b/proj-1/deet/src/debugger.rs
@@ -2,18 +2,30 @@ use crate::debugger_command::DebuggerCommand;
 use crate::inferior::{Inferior, Status};
 use rustyline::error::ReadlineError;
 use rustyline::Editor;
+use crate::dwarf_data::{DwarfData, Error as DwarfError};
 
 pub struct Debugger {
     target: String,
     history_path: String,
     readline: Editor<()>,
     inferior: Option<Inferior>,
+    debug_data: DwarfData,
 }
 
 impl Debugger {
     /// Initializes the debugger.
     pub fn new(target: &str) -> Debugger {
-        // TODO (milestone 3): initialize the DwarfData
+        let debug_data = match DwarfData::from_file(target) {
+            Ok(val) => val,
+            Err(DwarfError::ErrorOpeningFile) => {
+                println!("Could not open file {}", target);
+                std::process::exit(1);
+            }
+            Err(DwarfError::DwarfFormatError(err)) => {
+                println!("Could not debugging symbols from {}: {:?}", target, err);
+                std::process::exit(1);
+            }
+        };
 
         let history_path = format!("{}/.deet_history", std::env::var("HOME").unwrap());
         let mut readline = Editor::<()>::new();
@@ -25,6 +37,7 @@ impl Debugger {
             history_path,
             readline,
             inferior: None,
+            debug_data,
         }
     }
 
@@ -98,6 +111,12 @@ impl Debugger {
                         eprintln!("Error running(continue) subprocess");
                     }
                 }
+                DebuggerCommand::Backtrace => {
+                    let res = self.inferior.as_ref().unwrap().print_backtrace(&self.debug_data);
+                    if let Err(res) = res {
+                        eprintln!("Error backtracing: {}", res);
+                    }
+                }
             }
         }
     }
diff --git a/proj-1/deet/src/debugger_command.rs b/proj-1/deet/src/debugger_command.rs
index 01a7494..3c32d92 100644
--- a/proj-1/deet/src/debugger_command.rs
+++ b/proj-1/deet/src/debugger_command.rs
@@ -2,6 +2,7 @@ pub enum DebuggerCommand {
     Quit,
     Run(Vec<String>),
     Continue,
+    Backtrace,
 }
 
 impl DebuggerCommand {
@@ -13,9 +14,12 @@ impl DebuggerCommand {
                 Some(DebuggerCommand::Run(
                     args.iter().map(|s| s.to_string()).collect(),
                 ))
-            }
+            },
             "c" | "cont" | "continue" => {
                 Some(DebuggerCommand::Continue)
+            },
+            "bt" | "back" | "backtrace" => {
+                Some(DebuggerCommand::Backtrace)
             }
             // Default case:
             _ => None,
diff --git a/proj-1/deet/src/inferior.rs b/proj-1/deet/src/inferior.rs
index 3bceee4..c242d33 100644
--- a/proj-1/deet/src/inferior.rs
+++ b/proj-1/deet/src/inferior.rs
@@ -3,9 +3,12 @@ use nix::sys::signal;
 use nix::sys::signal::Signal;
 use nix::sys::wait::{waitpid, WaitPidFlag, WaitStatus};
 use nix::unistd::Pid;
+use std::convert::TryInto;
 use std::os::unix::process::CommandExt;
 use std::process::Child;
 use std::process::Command;
+
+use crate::dwarf_data::DwarfData;
 #[derive(Debug)]
 pub enum Status {
     /// Indicates inferior stopped. Contains the signal that stopped the process, as well as the
@@ -52,8 +55,7 @@ impl Inferior {
                 eprintln!("child stopped by {}, expected SIGTRAP", signal);
                 return None;
             }
-        }
-        else {
+        } else {
             eprintln!("child at status ?, expected to stop");
             return None;
         }
@@ -61,7 +63,7 @@ impl Inferior {
         //     "Inferior::new not implemented! target={}, args={:?}",
         //     target, args
         // );
-        Some(Inferior {child})
+        Some(Inferior { child })
     }
 
     /// Returns the pid of this inferior.
@@ -93,4 +95,31 @@ impl Inferior {
         self.child.kill().expect("Failed to kill subprocess");
         self.wait(None)
     }
+
+    pub fn print_backtrace(&self, debug_data: &DwarfData) -> Result<(), nix::Error> {
+        let regs = ptrace::getregs(self.pid())?;
+
+        let mut pc = regs.rip as usize;
+        let mut bp = regs.rbp as usize;
+        loop {
+            let func_name = debug_data
+                .get_function_from_addr(pc)
+                .unwrap_or(String::from("Unknown"));
+            let file_line = debug_data
+                .get_line_from_addr(pc)
+                .unwrap_or(crate::dwarf_data::Line {
+                    file: String::from("Unknown"),
+                    number: 0,
+                    address: 0,
+                });
+            // println!("[%rip={:#x}] {} ({})", pc, func_name, file_line);
+            println!("{} ({})", func_name, file_line);
+            if func_name == "main" {
+                break;
+            }
+            pc = ptrace::read(self.pid(), (bp + 8) as ptrace::AddressType)? as usize;
+            bp = ptrace::read(self.pid(), bp as ptrace::AddressType)? as usize;
+        }
+        Ok(())
+    }
 }
diff --git a/proj-1/deet/src/main.rs b/proj-1/deet/src/main.rs
index a944ed0..31405e9 100644
--- a/proj-1/deet/src/main.rs
+++ b/proj-1/deet/src/main.rs
@@ -1,6 +1,8 @@
 mod debugger;
 mod debugger_command;
 mod inferior;
+mod dwarf_data;
+mod gimli_wrapper;
 
 use crate::debugger::Debugger;
 use nix::sys::signal::{signal, SigHandler, Signal};