Simplify Redox backtrace/ to not include non-Redox implementations

6 files changed, 3 insertions, 207 deletions

diff --git a/src/libstd/sys/redox/backtrace/mod.rs b/src/libstd/sys/redox/backtrace/mod.rs
index 2171494c499..40b957d847b 100644
--- a/src/libstd/sys/redox/backtrace/mod.rs
+++ b/src/libstd/sys/redox/backtrace/mod.rs
@@ -8,80 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-/// Backtrace support built on libgcc with some extra OS-specific support
-///
-/// Some methods of getting a backtrace:
-///
-/// * The backtrace() functions on unix. It turns out this doesn't work very
-///   well for green threads on macOS, and the address to symbol portion of it
-///   suffers problems that are described below.
-///
-/// * Using libunwind. This is more difficult than it sounds because libunwind
-///   isn't installed everywhere by default. It's also a bit of a hefty library,
-///   so possibly not the best option. When testing, libunwind was excellent at
-///   getting both accurate backtraces and accurate symbols across platforms.
-///   This route was not chosen in favor of the next option, however.
-///
-/// * We're already using libgcc_s for exceptions in rust (triggering thread
-///   unwinding and running destructors on the stack), and it turns out that it
-///   conveniently comes with a function that also gives us a backtrace. All of
-///   these functions look like _Unwind_*, but it's not quite the full
-///   repertoire of the libunwind API. Due to it already being in use, this was
-///   the chosen route of getting a backtrace.
-///
-/// After choosing libgcc_s for backtraces, the sad part is that it will only
-/// give us a stack trace of instruction pointers. Thankfully these instruction
-/// pointers are accurate (they work for green and native threads), but it's
-/// then up to us again to figure out how to translate these addresses to
-/// symbols. As with before, we have a few options. Before, that, a little bit
-/// of an interlude about symbols. This is my very limited knowledge about
-/// symbol tables, and this information is likely slightly wrong, but the
-/// general idea should be correct.
-///
-/// When talking about symbols, it's helpful to know a few things about where
-/// symbols are located. Some symbols are located in the dynamic symbol table
-/// of the executable which in theory means that they're available for dynamic
-/// linking and lookup. Other symbols end up only in the local symbol table of
-/// the file. This loosely corresponds to pub and priv functions in Rust.
-///
-/// Armed with this knowledge, we know that our solution for address to symbol
-/// translation will need to consult both the local and dynamic symbol tables.
-/// With that in mind, here's our options of translating an address to
-/// a symbol.
-///
-/// * Use dladdr(). The original backtrace()-based idea actually uses dladdr()
-///   behind the scenes to translate, and this is why backtrace() was not used.
-///   Conveniently, this method works fantastically on macOS. It appears dladdr()
-///   uses magic to consult the local symbol table, or we're putting everything
-///   in the dynamic symbol table anyway. Regardless, for macOS, this is the
-///   method used for translation. It's provided by the system and easy to do.o
-///
-///   Sadly, all other systems have a dladdr() implementation that does not
-///   consult the local symbol table. This means that most functions are blank
-///   because they don't have symbols. This means that we need another solution.
-///
-/// * Use unw_get_proc_name(). This is part of the libunwind api (not the
-///   libgcc_s version of the libunwind api), but involves taking a dependency
-///   to libunwind. We may pursue this route in the future if we bundle
-///   libunwind, but libunwind was unwieldy enough that it was not chosen at
-///   this time to provide this functionality.
-///
-/// * Shell out to a utility like `readelf`. Crazy though it may sound, it's a
-///   semi-reasonable solution. The stdlib already knows how to spawn processes,
-///   so in theory it could invoke readelf, parse the output, and consult the
-///   local/dynamic symbol tables from there. This ended up not getting chosen
-///   due to the craziness of the idea plus the advent of the next option.
-///
-/// * Use `libbacktrace`. It turns out that this is a small library bundled in
-///   the gcc repository which provides backtrace and symbol translation
-///   functionality. All we really need from it is the backtrace functionality,
-///   and we only really need this on everything that's not macOS, so this is the
-///   chosen route for now.
-///
-/// In summary, the current situation uses libgcc_s to get a trace of stack
-/// pointers, and we use dladdr() or libbacktrace to translate these addresses
-/// to symbols. This is a bit of a hokey implementation as-is, but it works for
-/// all unix platforms we support right now, so it at least gets the job done.
+/// See sys/unix/backtrace/mod.rs for an explanation of the method used here.
 
 pub use self::tracing::unwind_backtrace;
 pub use self::printing::{foreach_symbol_fileline, resolve_symname};
@@ -91,7 +18,6 @@ mod tracing;
 // symbol resolvers:
 mod printing;
 
-#[cfg(not(any(target_os = "macos", target_os = "ios", target_os = "emscripten")))]
 pub mod gnu {
     use io;
     use fs;
diff --git a/src/libstd/sys/redox/backtrace/tracing/mod.rs b/src/libstd/sys/redox/backtrace/printing.rs
index c9c8e260d2f..3e937dbe623 100644
--- a/src/libstd/sys/redox/backtrace/tracing/mod.rs
+++ b/src/libstd/sys/redox/backtrace/printing.rs
@@ -1,4 +1,4 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -8,11 +8,4 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-pub use self::imp::*;
-
-#[cfg(not(all(target_os = "ios", target_arch = "arm")))]
-#[path = "gcc_s.rs"]
-mod imp;
-#[cfg(all(target_os = "ios", target_arch = "arm"))]
-#[path = "backtrace_fn.rs"]
-mod imp;
+pub use sys_common::gnu::libbacktrace::{foreach_symbol_fileline, resolve_symname};
diff --git a/src/libstd/sys/redox/backtrace/printing/dladdr.rs b/src/libstd/sys/redox/backtrace/printing/dladdr.rs
deleted file mode 100644
index 05a071a7978..00000000000
--- a/src/libstd/sys/redox/backtrace/printing/dladdr.rs
+++ /dev/null
@@ -1,53 +0,0 @@
-// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-use io;
-use intrinsics;
-use ffi::CStr;
-use libc;
-use sys::backtrace::BacktraceContext;
-use sys_common::backtrace::Frame;
-
-pub fn resolve_symname<F>(frame: Frame,
-                          callback: F,
-                          _: &BacktraceContext) -> io::Result<()>
-    where F: FnOnce(Option<&str>) -> io::Result<()>
-{
-    unsafe {
-        let mut info: Dl_info = intrinsics::init();
-        let symname = if dladdr(frame.exact_position, &mut info) == 0 {
-            None
-        } else {
-            CStr::from_ptr(info.dli_sname).to_str().ok()
-        };
-        callback(symname)
-    }
-}
-
-pub fn foreach_symbol_fileline<F>(_symbol_addr: Frame,
-                                  _f: F,
-                                  _: &BacktraceContext) -> io::Result<bool>
-    where F: FnMut(&[u8], libc::c_int) -> io::Result<()>
-{
-    Ok(false)
-}
-
-#[repr(C)]
-struct Dl_info {
-    dli_fname: *const libc::c_char,
-    dli_fbase: *mut libc::c_void,
-    dli_sname: *const libc::c_char,
-    dli_saddr: *mut libc::c_void,
-}
-
-extern {
-    fn dladdr(addr: *const libc::c_void,
-              info: *mut Dl_info) -> libc::c_int;
-}
diff --git a/src/libstd/sys/redox/backtrace/printing/mod.rs b/src/libstd/sys/redox/backtrace/printing/mod.rs
deleted file mode 100644
index 1ae82e01100..00000000000
--- a/src/libstd/sys/redox/backtrace/printing/mod.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-pub use self::imp::{foreach_symbol_fileline, resolve_symname};
-
-#[cfg(any(target_os = "macos", target_os = "ios",
-          target_os = "emscripten"))]
-#[path = "dladdr.rs"]
-mod imp;
-
-#[cfg(not(any(target_os = "macos", target_os = "ios",
-              target_os = "emscripten")))]
-mod imp {
-    pub use sys_common::gnu::libbacktrace::{foreach_symbol_fileline, resolve_symname};
-}
diff --git a/src/libstd/sys/redox/backtrace/tracing/gcc_s.rs b/src/libstd/sys/redox/backtrace/tracing.rs
index cfeabaddda9..cfeabaddda9 100644
--- a/src/libstd/sys/redox/backtrace/tracing/gcc_s.rs
+++ b/src/libstd/sys/redox/backtrace/tracing.rs
diff --git a/src/libstd/sys/redox/backtrace/tracing/backtrace_fn.rs b/src/libstd/sys/redox/backtrace/tracing/backtrace_fn.rs
deleted file mode 100644
index ecd32aa9462..00000000000
--- a/src/libstd/sys/redox/backtrace/tracing/backtrace_fn.rs
+++ /dev/null
@@ -1,48 +0,0 @@
-// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-/// As always - iOS on arm uses SjLj exceptions and
-/// _Unwind_Backtrace is even not available there. Still,
-/// backtraces could be extracted using a backtrace function,
-/// which thanks god is public
-///
-/// As mentioned in a huge comment block in `super::super`, backtrace
-/// doesn't play well with green threads, so while it is extremely nice and
-/// simple to use it should be used only on iOS devices as the only viable
-/// option.
-
-use io;
-use libc;
-use sys::backtrace::BacktraceContext;
-use sys_common::backtrace::Frame;
-
-#[inline(never)] // if we know this is a function call, we can skip it when
-                 // tracing
-pub fn unwind_backtrace(frames: &mut [Frame])
-    -> io::Result<(usize, BacktraceContext)>
-{
-    const FRAME_LEN: usize = 100;
-    assert!(FRAME_LEN >= frames.len());
-    let mut raw_frames = [::ptr::null_mut(); FRAME_LEN];
-    let nb_frames = unsafe {
-        backtrace(raw_frames.as_mut_ptr(), raw_frames.len() as libc::c_int)
-    } as usize;
-    for (from, to) in raw_frames.iter().zip(frames.iter_mut()).take(nb_frames) {
-        *to = Frame {
-            exact_position: *from,
-            symbol_addr: *from,
-        };
-    }
-    Ok((nb_frames as usize, BacktraceContext))
-}
-
-extern {
-    fn backtrace(buf: *mut *mut libc::c_void, sz: libc::c_int) -> libc::c_int;
-}