on 32-bit platform (e.g. PI) including sys/param.h causes 'shift left with overflow error'.

[noyez]

Input C/C++ Header

#include <sys/param.h>

Bindgen Invocation

        let bindings = bindgen::Builder::default()
            .no_unstable_rust()
            .header("use_sys_param.h")
            .generate()
            .expect("Unable to generate bindings");

Actual Results

pi@pirepeater:~/source/bindgen-test$ RUST_BACKTRACE=1 RUST_LOG=bindgen cargo build
   Compiling bindgen-test v0.1.0 (file:///home/pi/source/bindgen-test)
error: failed to run custom build command for `bindgen-test v0.1.0 (file:///home/pi/source/bindgen-test)`
process didn't exit successfully: `/home/pi/source/bindgen-test/target/debug/build/bindgen-test-d1b6d9223679bb31/build-script-build` (exit code: 101)
--- stderr
thread 'main' panicked at 'attempt to shift left with overflow', /home/pi/.cargo/registry/src/github.com-1ecc6299db9ec823/bindgen-0.25.3/src/ir/comp.rs:297
stack backtrace:
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
             at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at /checkout/src/libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at /checkout/src/libstd/sys_common/backtrace.rs:60
             at /checkout/src/libstd/panicking.rs:355
   3: std::panicking::default_hook
             at /checkout/src/libstd/panicking.rs:371
   4: std::panicking::rust_panic_with_hook
             at /checkout/src/libstd/panicking.rs:549
   5: std::panicking::begin_panic
             at /checkout/src/libstd/panicking.rs:511
   6: std::panicking::begin_panic_fmt
             at /checkout/src/libstd/panicking.rs:495
   7: rust_begin_unwind
             at /checkout/src/libstd/panicking.rs:471
   8: core::panicking::panic_fmt
             at /checkout/src/libcore/panicking.rs:69
   9: core::panicking::panic
             at /checkout/src/libcore/panicking.rs:49
  10: bindgen::ir::comp::Bitfield::mask
             at /home/pi/.cargo/registry/src/github.com-1ecc6299db9ec823/bindgen-0.25.3/src/ir/comp.rs:297
  11: <bindgen::ir::comp::Bitfield as bindgen::codegen::FieldCodegen<'a>>::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:3017
  12: <bindgen::ir::comp::BitfieldUnit as bindgen::codegen::FieldCodegen<'a>>::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:2933
  13: <bindgen::ir::comp::Field as bindgen::codegen::FieldCodegen<'a>>::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:2095
  14: <bindgen::ir::comp::CompInfo as bindgen::codegen::CodeGenerator>::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:3525
  15: <bindgen::ir::ty::Type as bindgen::codegen::CodeGenerator>::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:1675
  16: <bindgen::ir::item::Item as bindgen::codegen::CodeGenerator>::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:1465
  17: <bindgen::ir::module::Module as bindgen::codegen::CodeGenerator>::codegen::{{closure}}
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:1486
  18: <bindgen::ir::module::Module as bindgen::codegen::CodeGenerator>::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:1510
  19: <bindgen::ir::item::Item as bindgen::codegen::CodeGenerator>::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:1451
  20: bindgen::codegen::codegen::{{closure}}
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:5925
  21: bindgen::ir::context::BindgenContext::gen
             at /home/pi/.cargo/registry/src/github.com-1ecc6299db9ec823/bindgen-0.25.3/src/ir/context.rs:662
  22: bindgen::codegen::codegen
             at ./target/debug/build/bindgen-bb02d811d9c942d5/out/codegen.rs:5903
  23: bindgen::Bindings::generate
             at /home/pi/.cargo/registry/src/github.com-1ecc6299db9ec823/bindgen-0.25.3/src/lib.rs:1075
  24: bindgen::Builder::generate
             at /home/pi/.cargo/registry/src/github.com-1ecc6299db9ec823/bindgen-0.25.3/src/lib.rs:778
  25: build_script_build::main
             at ./build.rs:33
  26: __rust_maybe_catch_panic
             at /checkout/src/libpanic_unwind/lib.rs:98
  27: std::rt::lang_start
             at /checkout/src/libstd/panicking.rs:433
             at /checkout/src/libstd/panic.rs:361
             at /checkout/src/libstd/rt.rs:57
  28: main
  29: __libc_start_main

Expected Results

On my 32-bit arm platforms (namely a Raspberry PI, and Beaglebone), I Expect it not to crash when running build program. I found this when working w/ a c-library, and narrowed it down the sys/param.h

There is no crash on 64-bit platforms.

RUST_LOG=bindgen Output

there was no useful output. I pasted everything in the Actual Results section.

[emilio]

Can you see, of the files that get recursively included, which one contains structs with bitfields?

That is computing a bitfield, that presumably is too wide for us to represent as a simple bitmask op in 32 bits?

Perhaps switching the bitfield mask to u64 would be the most reasonable thing to do.

Thanks for the report!

[noyez]

Sorry -- i probably should have tried to narrow it down a bit further before submitting. I finally found the offending struct from /usr/include/arm-linux-gnueabihf/sys/ucontext.h on my PI. The problem appears to be unsigned int types that are given 32 bits of a bit field.

Below is a code snippet that will trigger this error in bindgen.

// from: /usr/include/arm-linux-gnueabihf/sys/ucontext.h
//
struct _libc_fpstate
{
  struct
  {
    unsigned int sign1:1;
    unsigned int unused:15;
    unsigned int sign2:1;
    unsigned int exponent:14;
    unsigned int j:1;
    unsigned int mantissa1:31;
    unsigned int mantissa0:32;  /* casues overflow error */
  } fpregs[8];
  unsigned int fpsr:32;         /* casues overflow error */
  unsigned int fpcr:32;         /* casues overflow error */
  unsigned char ftype[8];
  unsigned int init_flag;
};

[emilio]

Well, that makes sense, thanks a lot for finding that out!

[emilio]

More minimized, and also reproducible in 64-bit:

#define POINTER_WIDTH (sizeof(void*) * 8)

struct Foo {
  unsigned long m_bitfield: POINTER_WIDTH;
};

[emilio]

Fix at #742. Need to think about what the correct fix is for larger than-word-size bitfields. C++ truncates, but that shouldn't block that fix.