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// // imag - the personal information management suite for the commandline // Copyright (C) 2015, 2016 Matthias Beyer <mail@beyermatthias.de> and contributors // // This library is free software; you can redistribute it and/or // modify it under the terms of the GNU Lesser General Public // License as published by the Free Software Foundation; version // 2.1 of the License. // // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU // Lesser General Public License for more details. // // You should have received a copy of the GNU Lesser General Public // License along with this library; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA // use std::error::Error; use std::io::Write; use std::io::stderr; use ansi_term::Colour::Red; /// Print an Error type and its cause recursively /// /// The error is printed with "Error NNNN :" as prefix, where "NNNN" is a number which increases /// which each recursion into the errors cause. The error description is used to visualize what /// failed and if there is a cause "-- caused by:" is appended, and the cause is printed on the next /// line. /// /// Example output: /// /// ```ignore /// Error 1 : Some error -- caused by: /// Error 2 : Some other error -- caused by: /// Error 3 : Yet another Error -- caused by: /// ... /// /// Error <NNNN> : <Error description> /// ``` pub fn trace_error(e: &Error) { print_trace_maxdepth(count_error_causes(e), e, ::std::u64::MAX); write!(stderr(), "\n").ok(); } /// Convenience function: calls `trace_error()` with `e` and afterwards `std::process::exit()` /// with `code` pub fn trace_error_exit(e: &Error, code: i32) -> ! { use std::process::exit; debug!("Tracing error..."); trace_error(e); debug!("Calling exit()"); exit(code); } /// Print an Error type and its cause recursively, but only `max` levels /// /// Output is the same as for `trace_error()`, though there are only `max` levels printed. pub fn trace_error_maxdepth(e: &Error, max: u64) { let n = count_error_causes(e); let msg = Red.blink().paint(format!("{}/{} Levels of errors will be printed\n", (if max > n { n } else { max }), n)); write!(stderr(), "{}", msg).ok(); print_trace_maxdepth(n, e, max); write!(stderr(), "").ok(); } /// Print an Error type and its cause recursively with the debug!() macro /// /// Output is the same as for `trace_error()`. pub fn trace_error_dbg(e: &Error) { print_trace_dbg(0, e); } /// Helper function for `trace_error()` and `trace_error_maxdepth()`. /// /// Returns the cause of the last processed error in the recursion, so `None` if all errors where /// processed. fn print_trace_maxdepth(idx: u64, e: &Error, max: u64) -> Option<&Error> { if e.cause().is_some() && idx > 0 { e.cause().map(|cause| { match print_trace_maxdepth(idx - 1, cause, max) { None => write!(stderr(), "\n").ok(), Some(_) => write!(stderr(), " -- caused:\n").ok(), }; }); } else { write!(stderr(), "\n").ok(); } write!(stderr(), "{}: {}", Red.paint(format!("ERROR[{:>4}]", idx)), e.description()).ok(); e.cause() } /// Count errors in `Error::cause()` recursively fn count_error_causes(e: &Error) -> u64 { 1 + e.cause().map(|c| count_error_causes(c)).unwrap_or(0) } fn print_trace_dbg(idx: u64, e: &Error) { debug!("{}: {}", Red.blink().paint(format!("ERROR[{:>4}]", idx)), e.description()); if e.cause().is_some() { e.cause().map(|c| print_trace_dbg(idx + 1, c)); } } /// Helper functions for `Result<T, E>` types to reduce overhead in the following situations: /// /// ```ignore /// function().map_err(|e| { trace_error(&e); e }) /// ``` /// /// and variants pub trait MapErrTrace { fn map_err_trace(self) -> Self; fn map_err_dbg_trace(self) -> Self; fn map_err_trace_exit(self, code: i32) -> Self; fn map_err_trace_maxdepth(self, max: u64) -> Self; } impl<U, E: Error> MapErrTrace for Result<U, E> { /// Simply call `trace_error()` on the Err (if there is one) and return the error. /// /// This does nothing besides the side effect of printing the error trace fn map_err_trace(self) -> Self { self.map_err(|e| { trace_error(&e); e }) } /// Simply call `trace_error_dbg()` on the Err (if there is one) and return the error. /// /// This does nothing besides the side effect of printing the error trace fn map_err_dbg_trace(self) -> Self { self.map_err(|e| { trace_error_dbg(&e); e }) } /// Simply call `trace_error_exit(code)` on the Err (if there is one). /// /// This does not return if there is an Err(e). fn map_err_trace_exit(self, code: i32) -> Self { self.map_err(|e| { trace_error_exit(&e, code) }) } /// Simply call `trace_error_maxdepth(max)` on the Err (if there is one) and return the error. /// /// This does nothing besides the side effect of printing the error trace to a certain depth fn map_err_trace_maxdepth(self, max: u64) -> Self { self.map_err(|e| { trace_error_maxdepth(&e, max); e }) } }