modernize error handling (#88)

Problem

Currently, we do error handling with the `failure` crate which
requires that users are aware of `failure` and use it in their
library or application.

Solution

Switch error handling to use the `thiserror` crate which allows us
to derive `std::error::Error` for our error type.

Result

This library's public API now uses `std::error::Error` in the
`Result`s. This allows better composition within higher level
libraries and applications.

Author: brayniac

Cargo.toml

@@ -14,9 +14,9 @@ edition = '2018'
 [dependencies]
 bcc-sys = "0.13.0"
 byteorder = "1.3.4"
-failure = "0.1.7"
 libc = "0.2.68"
 regex = "1.3.5"
+thiserror = "1.0.19"
 
 [dev-dependencies]
 clap = "2.33.0"

examples/biosnoop.rs

@@ -1,7 +1,7 @@
 use bcc::core::BPF;
 use bcc::perf::init_perf_map;
+use bcc::BccError;
 use clap::{App, Arg};
-use failure::Error;
 
 use core::sync::atomic::{AtomicBool, Ordering};
 use std::ptr;
@@ -24,7 +24,7 @@ struct data_t {
     name: [u8; 16],
 }
 
-fn do_main(runnable: Arc<AtomicBool>) -> Result<(), Error> {
+fn do_main(runnable: Arc<AtomicBool>) -> Result<(), BccError> {
     let matches = App::new("biosnoop")
         .about("Trace block I/O")
         .arg(
@@ -134,7 +134,6 @@ fn main() {
 
     if let Err(x) = do_main(runnable) {
         eprintln!("Error: {}", x);
-        eprintln!("{}", x.backtrace());
         std::process::exit(1);
     }
 }

examples/opensnoop.rs

@@ -1,12 +1,7 @@
-extern crate bcc;
-extern crate byteorder;
-extern crate failure;
-extern crate libc;
-
 use bcc::core::BPF;
 use bcc::perf::init_perf_map;
+use bcc::BccError;
 use clap::{App, Arg};
-use failure::Error;
 
 use core::sync::atomic::{AtomicBool, Ordering};
 use std::ptr;
@@ -34,7 +29,7 @@ struct data_t {
     fname: [u8; 255], // NAME_MAX
 }
 
-fn do_main(runnable: Arc<AtomicBool>) -> Result<(), Error> {
+fn do_main(runnable: Arc<AtomicBool>) -> Result<(), BccError> {
     let matches = App::new("opensnoop")
         .about("Prints out filename + PID every time a file is opened")
         .arg(
@@ -112,7 +107,6 @@ fn main() {
     match do_main(runnable) {
         Err(x) => {
             eprintln!("Error: {}", x);
-            eprintln!("{}", x.backtrace());
             std::process::exit(1);
         }
         _ => {}

examples/runqlat.rs

@@ -1,6 +1,6 @@
 use bcc::core::BPF;
+use bcc::BccError;
 use clap::{App, Arg};
-use failure::Error;
 
 use core::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
@@ -23,7 +23,7 @@ fn attach_events(bpf: &mut BPF) {
         .unwrap();
 }
 
-#[cfg(any(not(feature = "v0_4_0"), not(feature = "v0_5_0"),))]
+#[cfg(not(any(feature = "v0_4_0", feature = "v0_5_0")))]
 fn attach_events(bpf: &mut BPF) {
     if bpf.support_raw_tracepoint() {
         let raw_tp_sched_wakeup = bpf.load_raw_tracepoint("raw_tp__sched_wakeup").unwrap();
@@ -50,7 +50,7 @@ fn attach_events(bpf: &mut BPF) {
     }
 }
 
-fn do_main(runnable: Arc<AtomicBool>) -> Result<(), Error> {
+fn do_main(runnable: Arc<AtomicBool>) -> Result<(), BccError> {
     let matches = App::new("runqlat")
         .about("Reports distribution of scheduler latency")
         .arg(
@@ -131,7 +131,6 @@ fn main() {
     match do_main(runnable) {
         Err(x) => {
             eprintln!("Error: {}", x);
-            eprintln!("{}", x.backtrace());
             std::process::exit(1);
         }
         _ => {}

examples/softirqs.rs

@@ -1,6 +1,7 @@
 use bcc::core::BPF;
+use bcc::BccError;
 use clap::{App, Arg};
-use failure::Error;
+use std::error::Error;
 
 use core::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
@@ -73,7 +74,7 @@ impl fmt::Display for SoftIRQ {
     }
 }
 
-fn do_main(runnable: Arc<AtomicBool>) -> Result<(), Error> {
+fn do_main(runnable: Arc<AtomicBool>) -> Result<(), BccError> {
     let matches = App::new("softirqs")
         .about("Reports time spent in IRQ Handlers")
         .arg(
@@ -169,7 +170,6 @@ fn main() {
     match do_main(runnable) {
         Err(x) => {
             eprintln!("Error: {}", x);
-            eprintln!("{}", x.backtrace());
             std::process::exit(1);
         }
         _ => {}

examples/strlen.rs

@@ -1,17 +1,16 @@
 extern crate bcc;
 extern crate byteorder;
-extern crate failure;
 extern crate libc;
 
 use bcc::core::BPF;
+use bcc::BccError;
 use byteorder::{NativeEndian, ReadBytesExt};
-use failure::Error;
 
 use core::sync::atomic::{AtomicBool, Ordering};
 use std::io::Cursor;
 use std::sync::Arc;
 
-fn do_main(runnable: Arc<AtomicBool>) -> Result<(), Error> {
+fn do_main(runnable: Arc<AtomicBool>) -> Result<(), BccError> {
     let code = "
 #include <uapi/linux/ptrace.h>
 
@@ -75,7 +74,6 @@ fn main() {
     match do_main(runnable) {
         Err(x) => {
             eprintln!("Error: {}", x);
-            eprintln!("{}", x.backtrace());
             std::process::exit(1);
         }
         _ => {}

examples/tcpretrans.rs

@@ -1,8 +1,7 @@
 use bcc::core::BPF;
-extern crate chrono;
+use bcc::BccError;
 use chrono::Utc;
 use clap::{App, Arg};
-use failure::Error;
 
 use core::sync::atomic::{AtomicBool, Ordering};
 use std::net::Ipv4Addr;
@@ -38,7 +37,7 @@ struct ipv6_data_t {
     type_: u64,
 }
 
-fn do_main(runnable: Arc<AtomicBool>) -> Result<(), Error> {
+fn do_main(runnable: Arc<AtomicBool>) -> Result<(), BccError> {
     let matches = App::new("biosnoop")
         .arg(
             Arg::with_name("duration")
@@ -81,7 +80,7 @@ fn do_main(runnable: Arc<AtomicBool>) -> Result<(), Error> {
     Ok(())
 }
 
-fn print_ipv4_event() -> Box<FnMut(&[u8]) + Send> {
+fn print_ipv4_event() -> Box<dyn FnMut(&[u8]) + Send> {
     Box::new(|x| {
         let event = parse_ipv4_struct(x);
         println!(
@@ -97,7 +96,7 @@ fn print_ipv4_event() -> Box<FnMut(&[u8]) + Send> {
     })
 }
 
-fn print_ipv6_event() -> Box<FnMut(&[u8]) + Send> {
+fn print_ipv6_event() -> Box<dyn FnMut(&[u8]) + Send> {
     Box::new(|x| {
         let event = parse_ipv6_struct(x);
         println!(
@@ -131,7 +130,6 @@ fn main() {
 
     if let Err(x) = do_main(runnable) {
         eprintln!("Error: {}", x);
-        eprintln!("{}", x.backtrace());
         std::process::exit(1);
     }
 }

src/core/kprobe/v0_4_0.rs

@@ -1,10 +1,10 @@
 use bcc_sys::bccapi::bpf_probe_attach_type_BPF_PROBE_ENTRY as BPF_PROBE_ENTRY;
 use bcc_sys::bccapi::bpf_probe_attach_type_BPF_PROBE_RETURN as BPF_PROBE_RETURN;
 use bcc_sys::bccapi::*;
-use failure::*;
 
 use crate::core::make_alphanumeric;
 use crate::types::MutPointer;
+use crate::BccError;
 
 use regex::Regex;
 
@@ -23,11 +23,9 @@ pub struct Kprobe {
 }
 
 impl Kprobe {
-    fn new(name: &str, attach_type: u32, function: &str, code: File) -> Result<Self, Error> {
-        let cname =
-            CString::new(name).map_err(|_| format_err!("Nul byte in Kprobe name: {}", name))?;
-        let cfunction = CString::new(function)
-            .map_err(|_| format_err!("Nul byte in Kprobe function: {}", function))?;
+    fn new(name: &str, attach_type: u32, function: &str, code: File) -> Result<Self, BccError> {
+        let cname = CString::new(name)?;
+        let cfunction = CString::new(function)?;
         let (pid, cpu, group_fd) = (-1, 0, -1);
         let ptr = unsafe {
             bpf_attach_kprobe(
@@ -43,7 +41,15 @@ impl Kprobe {
             )
         };
         if ptr.is_null() {
-            Err(format_err!("Failed to attach Kprobe: {}", name))
+            match attach_type {
+                BPF_PROBE_ENTRY => Err(BccError::AttachKprobe {
+                    name: name.to_string(),
+                }),
+                BPF_PROBE_RETURN => Err(BccError::AttachKretprobe {
+                    name: name.to_string(),
+                }),
+                _ => unreachable!(),
+            }
         } else {
             Ok(Self {
                 p: ptr,
@@ -53,19 +59,17 @@ impl Kprobe {
         }
     }
 
-    pub fn attach_kprobe(function: &str, code: File) -> Result<Self, Error> {
+    pub fn attach_kprobe(function: &str, code: File) -> Result<Self, BccError> {
         let name = format!("p_{}", &make_alphanumeric(function));
         Kprobe::new(&name, BPF_PROBE_ENTRY, function, code)
-            .map_err(|_| format_err!("Failed to attach Kprobe: {}", name))
     }
 
-    pub fn attach_kretprobe(function: &str, code: File) -> Result<Self, Error> {
+    pub fn attach_kretprobe(function: &str, code: File) -> Result<Self, BccError> {
         let name = format!("r_{}", &make_alphanumeric(function));
         Kprobe::new(&name, BPF_PROBE_RETURN, function, code)
-            .map_err(|_| format_err!("Failed to attach Kretprobe: {}", name))
     }
 
-    pub fn get_kprobe_functions(event_re: &str) -> Result<Vec<String>, Error> {
+    pub fn get_kprobe_functions(event_re: &str) -> Result<Vec<String>, BccError> {
         let mut fns: Vec<String> = vec![];
 
         enum Section {
@@ -117,19 +121,18 @@ impl Kprobe {
                 Section::End => (),
             }
             // All functions defined as NOKPROBE_SYMBOL() start with the
-            // prefix _kbl_addr_*, blacklisting them by looking at the name
+            // prefix _kbl_addr_*, excluding them by looking at the name
             // allows to catch also those symbols that are defined in kernel
             // modules.
             if fname.starts_with("_kbl_addr_") {
                 continue;
             }
-            // Explicitly blacklist perf-related functions, they are all
-            // non-attachable.
-            else if fname.starts_with("__perf") || fname.starts_with("perf_") {
+            // Exclude perf-related functions, they are all non-attachable.
+            if fname.starts_with("__perf") || fname.starts_with("perf_") {
                 continue;
             }
             // Exclude all gcc 8's extra .cold functions
-            else if re.is_match(fname) {
+            if re.is_match(fname) {
                 continue;
             }
             if (t == "t" || t == "w") && fname.contains(event_re) {

src/core/kprobe/v0_6_0.rs

@@ -1,9 +1,9 @@
 use bcc_sys::bccapi::bpf_probe_attach_type_BPF_PROBE_ENTRY as BPF_PROBE_ENTRY;
 use bcc_sys::bccapi::bpf_probe_attach_type_BPF_PROBE_RETURN as BPF_PROBE_RETURN;
 use bcc_sys::bccapi::*;
-use failure::*;
 
 use crate::core::make_alphanumeric;
+use crate::BccError;
 
 use regex::Regex;
 
@@ -21,11 +21,9 @@ pub struct Kprobe {
 }
 
 impl Kprobe {
-    fn new(name: &str, attach_type: u32, function: &str, code: File) -> Result<Self, Error> {
-        let cname =
-            CString::new(name).map_err(|_| format_err!("Nul byte in Kprobe name: {}", name))?;
-        let cfunction = CString::new(function)
-            .map_err(|_| format_err!("Nul byte in Kprobe function: {}", function))?;
+    fn new(name: &str, attach_type: u32, function: &str, code: File) -> Result<Self, BccError> {
+        let cname = CString::new(name)?;
+        let cfunction = CString::new(function)?;
         let ptr = unsafe {
             bpf_attach_kprobe(
                 code.as_raw_fd(),
@@ -36,7 +34,15 @@ impl Kprobe {
             )
         };
         if ptr < 0 {
-            Err(format_err!("Failed to attach Kprobe: {}", name))
+            match attach_type {
+                BPF_PROBE_ENTRY => Err(BccError::AttachKprobe {
+                    name: name.to_string(),
+                }),
+                BPF_PROBE_RETURN => Err(BccError::AttachKretprobe {
+                    name: name.to_string(),
+                }),
+                _ => unreachable!(),
+            }
         } else {
             Ok(Self {
                 p: ptr,
@@ -46,19 +52,17 @@ impl Kprobe {
         }
     }
 
-    pub fn attach_kprobe(function: &str, code: File) -> Result<Self, Error> {
+    pub fn attach_kprobe(function: &str, code: File) -> Result<Self, BccError> {
         let name = format!("p_{}", &make_alphanumeric(function));
         Kprobe::new(&name, BPF_PROBE_ENTRY, function, code)
-            .map_err(|_| format_err!("Failed to attach Kprobe: {}", name))
     }
 
-    pub fn attach_kretprobe(function: &str, code: File) -> Result<Self, Error> {
+    pub fn attach_kretprobe(function: &str, code: File) -> Result<Self, BccError> {
         let name = format!("r_{}", &make_alphanumeric(function));
         Kprobe::new(&name, BPF_PROBE_RETURN, function, code)
-            .map_err(|_| format_err!("Failed to attach Kretprobe: {}", name))
     }
 
-    pub fn get_kprobe_functions(event_re: &str) -> Result<Vec<String>, Error> {
+    pub fn get_kprobe_functions(event_re: &str) -> Result<Vec<String>, BccError> {
         let mut fns: Vec<String> = vec![];
 
         enum Section {
@@ -110,19 +114,18 @@ impl Kprobe {
                 Section::End => (),
             }
             // All functions defined as NOKPROBE_SYMBOL() start with the
-            // prefix _kbl_addr_*, blacklisting them by looking at the name
+            // prefix _kbl_addr_*, excluding them by looking at the name
             // allows to catch also those symbols that are defined in kernel
             // modules.
             if fname.starts_with("_kbl_addr_") {
                 continue;
             }
-            // Explicitly blacklist perf-related functions, they are all
-            // non-attachable.
-            else if fname.starts_with("__perf") || fname.starts_with("perf_") {
+            // Exclude perf-related functions, they are all non-attachable.
+            if fname.starts_with("__perf") || fname.starts_with("perf_") {
                 continue;
             }
             // Exclude all gcc 8's extra .cold functions
-            else if re.is_match(fname) {
+            if re.is_match(fname) {
                 continue;
             }
             if (t == "t" || t == "w") && fname.contains(event_re) {