android JNINativeMethod wrong size

[Dushistov]

Input C/C++ Header

typedef struct {
    const char* name;
    const char* signature;
    void*       fnPtr;
} JNINativeMethod;

Bindgen Invocation

fn gen_binding<P1, P2>(
    target: &str,
    include_dirs: &[P1],
    c_headers: &[P2],
    output_rust: &Path,
) -> Result<(), String>
where
    P1: AsRef<Path> + fmt::Debug,
    P2: AsRef<Path> + fmt::Debug,
{
    assert!(!c_headers.is_empty());
    let c_file_path = &c_headers[0];

    let mut bindings: bindgen::Builder =
        bindgen::builder().header(c_file_path.as_ref().to_str().unwrap());
    bindings = include_dirs.iter().fold(bindings, |acc, x| {
        acc.clang_arg("-I".to_string() + x.as_ref().to_str().unwrap())
    });
    println!("Generate binding for {:?}", c_headers);
    bindings = bindings
        .rust_target(RustTarget::Stable_1_19)
        //long double not supported yet, see https://github.com/servo/rust-bindgen/issues/550
        .hide_type("max_align_t");
    bindings = if target.contains("windows") {
        //see https://github.com/servo/rust-bindgen/issues/578
        bindings.trust_clang_mangling(false)
    } else {
        bindings
    };
    bindings = c_headers[1..].iter().fold(
        Ok(bindings),
        |acc: Result<bindgen::Builder, String>, header| {
            let c_file_path = header;
            let c_file_str = c_file_path
                .as_ref()
                .to_str()
                .ok_or_else(|| {
                    format!("Invalid unicode in path to {:?}", c_file_path.as_ref())
                })?;
            Ok(acc.unwrap().clang_arg("-include").clang_arg(c_file_str))
        },
    )?;

    let generated_bindings = bindings
        .generate()
        .map_err(|_| "Failed to generate bindings".to_string())?;
    generated_bindings
        .write_to_file(output_rust)
        .map_err(|err| err.to_string())?;

    Ok(())
}

Actual Results

Expected Results

I compile on linux/amd64 for arm-linux-androideabi.
If I run generated by bindgen unit tests I got:

---- android_c_headers::bindgen_test_layout_JNINativeMethod stdout ----
        thread 'android_c_headers::bindgen_test_layout_JNINativeMethod' panicked at 'assertion failed: `(left == right)`
  left: `12`,
 right: `24`: Size of: JNINativeMethod', /home/evgeniy/projects/rust-infra/swig/target/arm-linux-androideabi/debug/build/android-528bccd24539c265/out/android_c_headers.rs:275:4

Test that failed:

#[repr(C)]
#[derive(Debug, Copy)]
pub struct JNINativeMethod {
    pub name: *const ::std::os::raw::c_char,
    pub signature: *const ::std::os::raw::c_char,
    pub fnPtr: *mut ::std::os::raw::c_void,
}
#[test]
fn bindgen_test_layout_JNINativeMethod() {
    assert_eq!(::std::mem::size_of::<JNINativeMethod>() , 24usize , concat ! (
               "Size of: " , stringify ! ( JNINativeMethod ) ));
    assert_eq! (::std::mem::align_of::<JNINativeMethod>() , 8usize , concat !
                ( "Alignment of " , stringify ! ( JNINativeMethod ) ));
    assert_eq! (unsafe {
                & ( * ( 0 as * const JNINativeMethod ) ) . name as * const _
                as usize } , 0usize , concat ! (
                "Alignment of field: " , stringify ! ( JNINativeMethod ) ,
                "::" , stringify ! ( name ) ));
    assert_eq! (unsafe {
                & ( * ( 0 as * const JNINativeMethod ) ) . signature as *
                const _ as usize } , 8usize , concat ! (
                "Alignment of field: " , stringify ! ( JNINativeMethod ) ,
                "::" , stringify ! ( signature ) ));
    assert_eq! (unsafe {
                & ( * ( 0 as * const JNINativeMethod ) ) . fnPtr as * const _
                as usize } , 16usize , concat ! (
                "Alignment of field: " , stringify ! ( JNINativeMethod ) ,
                "::" , stringify ! ( fnPtr ) ));
}

[emilio]

Looks a lot like you're generating methods for a 64-bit target and compiling with a 32-bit target.

[emilio]

Have you tried passing the target down to libclang using clang_arg? I don't recall if I did it so it was autodetected or not.

[Dushistov]

@emilio

Have you tried passing the target down to libclang using clang_arg?

I tried this:

    //build.rs
    let target = env::var("TARGET").unwrap();
    let generated_bindings = bindings
        .clang_arg(format!("-target {}", target))
        .generate()
        .map_err(|_| "Failed to generate bindings".to_string())?;

got this:

Generate binding for ["/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../sysroot/usr/include/android/bitmap.h", "/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../sysroot/usr/include/jni.h"]
error: unknown argument: '-target arm-linux-androideabi', err: true

--- stderr
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: "Failed to generate bindings"', /checkout/src/libcore/result.rs:860:4

-target option I took from here: https://clang.llvm.org/docs/CrossCompilation.html

[Dushistov]

@emilio

I was able to fix issue with target like this:

        .clang_arg(format!("--target={}", target))

but for some reason with --target=arm-linux-androideabi bindgen emit two __va_list:

pub type __va_list = __builtin_va_list;

pub struct __va_list {
    pub __ap: *mut ::std::os::raw::c_void,
}

and resulted code not compiled,

as you see I do not use emit_builtins or similar, so
looks like --target changes something.

Android jni.h has only

#include <sys/cdefs.h>
#include <stdarg.h>

at start of jni.h

So here is two issues:

1. bindgen not use TARGET supplied by cargo to build.rs,
   may be any option to bindgen::Builder like .use_cargo_env_cfg(mut self)?

2. if use --target then some defines or includes changed, and bindgen take to __va_list from somewhere, instead of one.

[Dushistov]

The difference between --target=arm-linux-androideabi except right sizeof values in unit tests is this:

//no --target=
pub type __builtin_va_list = [__va_list_tag; 1usize];
#[repr(C)]
#[derive(Debug, Copy)]
pub struct __va_list_tag {
    pub gp_offset: ::std::os::raw::c_uint,
    pub fp_offset: ::std::os::raw::c_uint,
    pub overflow_arg_area: *mut ::std::os::raw::c_void,
    pub reg_save_area: *mut ::std::os::raw::c_void,
}

//with --target=
pub type __builtin_va_list = __va_list;
#[repr(C)]
#[derive(Debug, Copy)]
pub struct __va_list {
    pub __ap: *mut ::std::os::raw::c_void,
}

[Dushistov]

Here difference difference of bindgen --dump-preprocessed-input with and without --target=:

--- __bindgen.i	2017-09-03 14:14:27.780836405 +0300
+++ __bindgen-bad.i	2017-09-03 14:14:08.600835491 +0300
@@ -1,7 +1,7 @@
 # 1 "__bindgen.c"
 # 1 "<built-in>" 1
 # 1 "<built-in>" 3
-# 322 "<built-in>" 3
+# 320 "<built-in>" 3
 # 1 "<command line>" 1
 # 1 "<built-in>" 2
 # 1 "./bitmap.h" 1
@@ -484,7 +484,7 @@
 /* Define this type if we are doing the whole job,
    or if we want this type in particular.  */
 # 147 "/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../lib/gcc/arm-linux-androideabi/4.9.x/include/stddef.h"
-typedef long int ptrdiff_t;
+typedef int ptrdiff_t;
 # 157 "/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../lib/gcc/arm-linux-androideabi/4.9.x/include/stddef.h"
 /* If this symbol has done its job, get rid of it.  */
 
@@ -496,7 +496,7 @@
 /* Define this type if we are doing the whole job,
    or if we want this type in particular.  */
 # 212 "/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../lib/gcc/arm-linux-androideabi/4.9.x/include/stddef.h"
-typedef long unsigned int size_t;
+typedef unsigned int size_t;
 # 238 "/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../lib/gcc/arm-linux-androideabi/4.9.x/include/stddef.h"
 /* Wide character type.
    Locale-writers should change this as necessary to
@@ -521,7 +521,7 @@
    since it no longer defines _BSD_RUNE_T_ yet still desires to export
    rune_t in some cases... */
 # 324 "/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../lib/gcc/arm-linux-androideabi/4.9.x/include/stddef.h"
-typedef int wchar_t;
+typedef unsigned int wchar_t;
 # 358 "/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../lib/gcc/arm-linux-androideabi/4.9.x/include/stddef.h"
 /*  In 4.3bsd-net2, leave these undefined to indicate that size_t, etc.
     are already defined.  */
@@ -784,8 +784,11 @@
  */
 
 
-typedef long intptr_t;
-typedef unsigned long uintptr_t;
+
+
+
+typedef int intptr_t;
+typedef unsigned int uintptr_t;
 # 216 "/home/evgeniy/toolchains/android-16-arm-linux-androideabi-4.9/bin/../sysroot/usr/include/stdint.h"
 /*
  *  intmax_t & uintmax_t

[Dushistov]

Reduced tes case:

$ cat bitmap.h

//from include/machine/_types.h from sys/_types.h from stdint.h
typedef __builtin_va_list       __va_list;

$ bindgen --version
bindgen 0.30.0
$ bindgen --no-layout-tests bitmap.h 
/* automatically generated by rust-bindgen */

pub type __va_list = __builtin_va_list;
pub type __builtin_va_list = [__va_list_tag; 1usize];
#[repr(C)]
#[derive(Debug, Copy)]
pub struct __va_list_tag {
    pub gp_offset: ::std::os::raw::c_uint,
    pub fp_offset: ::std::os::raw::c_uint,
    pub overflow_arg_area: *mut ::std::os::raw::c_void,
    pub reg_save_area: *mut ::std::os::raw::c_void,
}
impl Clone for __va_list_tag {
    fn clone(&self) -> Self { *self }
}

$ bindgen --no-layout-tests bitmap.h -- --target=arm-linux-androideabi
/* automatically generated by rust-bindgen */

pub type __va_list = __builtin_va_list;
pub type __builtin_va_list = __va_list;
#[repr(C)]
#[derive(Debug, Copy)]
pub struct __va_list {
    pub __ap: *mut ::std::os::raw::c_void,
}
impl Clone for __va_list {
    fn clone(&self) -> Self { *self }
}

[Dushistov]

I suppose __va_list issue is separate issues, not related that bindgen in build.rs not analyze TARGET environment variable, so I move it to #946

[pepyakin]

Just wanted to note, that I experienced same problem with the Emscripten (see #947 (comment))

This worked for me as well:

// build.rs
let target = env::var("TARGET").unwrap();
let generated_bindings = bindings
        .clang_arg(format!("--target={}", target))
        .generate()