rust/src/rt/rust_test_helpers.c
Brian Campbell ee79bfa18a Abort on stack overflow instead of re-raising SIGSEGV
We use guard pages that cause the process to abort to protect against
undefined behavior in the event of stack overflow.  We have a handler
that catches segfaults, prints out an error message if the segfault was
due to a stack overflow, then unregisters itself and returns to allow
the signal to be re-raised and kill the process.

This caused some confusion, as it was unexpected that safe code would be
able to cause a segfault, while it's easy to overflow the stack in safe
code.  To avoid this confusion, when we detect a segfault in the guard
page, abort instead of the previous behavior of re-raising the SIGSEGV.

To test this, we need to adapt the tests for segfault to actually check
the exit status.  Doing so revealed that the existing test for segfault
behavior was actually invalid; LLVM optimizes the explicit null pointer
reference down to an illegal instruction, so the program aborts with
SIGILL instead of SIGSEGV and the test didn't actually trigger the
signal handler at all.  Use a C helper function to get a null pointer
that LLVM can't optimize away, so we get our segfault instead.

This is a [breaking-change] if anyone is relying on the exact signal
raised to kill a process on stack overflow.

Closes #31273
2016-02-05 20:41:18 -05:00

245 lines
4.3 KiB
C

// Copyright 2013 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.
// Helper functions used only in tests
#include <stdint.h>
#include <assert.h>
#include <stdarg.h>
// These functions are used in the unit tests for C ABI calls.
uint32_t
rust_dbg_extern_identity_u32(uint32_t u) {
return u;
}
uint64_t
rust_dbg_extern_identity_u64(uint64_t u) {
return u;
}
double
rust_dbg_extern_identity_double(double u) {
return u;
}
char
rust_dbg_extern_identity_u8(char u) {
return u;
}
typedef void *(*dbg_callback)(void*);
void *
rust_dbg_call(dbg_callback cb, void *data) {
return cb(data);
}
void rust_dbg_do_nothing() { }
struct TwoU8s {
uint8_t one;
uint8_t two;
};
struct TwoU8s
rust_dbg_extern_return_TwoU8s() {
struct TwoU8s s;
s.one = 10;
s.two = 20;
return s;
}
struct TwoU8s
rust_dbg_extern_identity_TwoU8s(struct TwoU8s u) {
return u;
}
struct TwoU16s {
uint16_t one;
uint16_t two;
};
struct TwoU16s
rust_dbg_extern_return_TwoU16s() {
struct TwoU16s s;
s.one = 10;
s.two = 20;
return s;
}
struct TwoU16s
rust_dbg_extern_identity_TwoU16s(struct TwoU16s u) {
return u;
}
struct TwoU32s {
uint32_t one;
uint32_t two;
};
struct TwoU32s
rust_dbg_extern_return_TwoU32s() {
struct TwoU32s s;
s.one = 10;
s.two = 20;
return s;
}
struct TwoU32s
rust_dbg_extern_identity_TwoU32s(struct TwoU32s u) {
return u;
}
struct TwoU64s {
uint64_t one;
uint64_t two;
};
struct TwoU64s
rust_dbg_extern_return_TwoU64s() {
struct TwoU64s s;
s.one = 10;
s.two = 20;
return s;
}
struct TwoU64s
rust_dbg_extern_identity_TwoU64s(struct TwoU64s u) {
return u;
}
struct TwoDoubles {
double one;
double two;
};
struct TwoDoubles
rust_dbg_extern_identity_TwoDoubles(struct TwoDoubles u) {
return u;
}
struct ManyInts {
int8_t arg1;
int16_t arg2;
int32_t arg3;
int16_t arg4;
int8_t arg5;
struct TwoU8s arg6;
};
// MSVC doesn't allow empty structs or unions
#ifndef _MSC_VER
struct Empty {
};
void
rust_dbg_extern_empty_struct(struct ManyInts v1, struct Empty e, struct ManyInts v2) {
assert(v1.arg1 == v2.arg1 + 1);
assert(v1.arg2 == v2.arg2 + 1);
assert(v1.arg3 == v2.arg3 + 1);
assert(v1.arg4 == v2.arg4 + 1);
assert(v1.arg5 == v2.arg5 + 1);
assert(v1.arg6.one == v2.arg6.one + 1);
assert(v1.arg6.two == v2.arg6.two + 1);
}
#endif
intptr_t
rust_get_test_int() {
return 1;
}
char *
rust_get_null_ptr() {
return 0;
}
/* Debug helpers strictly to verify ABI conformance.
*
* FIXME (#2665): move these into a testcase when the testsuite
* understands how to have explicit C files included.
*/
struct quad {
uint64_t a;
uint64_t b;
uint64_t c;
uint64_t d;
};
struct floats {
double a;
uint8_t b;
double c;
};
struct quad
rust_dbg_abi_1(struct quad q) {
struct quad qq = { q.c + 1,
q.d - 1,
q.a + 1,
q.b - 1 };
return qq;
}
struct floats
rust_dbg_abi_2(struct floats f) {
struct floats ff = { f.c + 1.0,
0xff,
f.a - 1.0 };
return ff;
}
int
rust_dbg_static_mut = 3;
void
rust_dbg_static_mut_check_four() {
assert(rust_dbg_static_mut == 4);
}
struct S {
uint64_t x;
uint64_t y;
uint64_t z;
};
uint64_t get_x(struct S s) {
return s.x;
}
uint64_t get_y(struct S s) {
return s.y;
}
uint64_t get_z(struct S s) {
return s.z;
}
uint64_t get_c_many_params(void *a, void *b, void *c, void *d, struct quad f) {
return f.c;
}
// Calculates the average of `(x + y) / n` where x: i64, y: f64. There must be exactly n pairs
// passed as variadic arguments.
double rust_interesting_average(uint64_t n, ...) {
va_list pairs;
double sum = 0.0;
int i;
va_start(pairs, n);
for(i = 0; i < n; i += 1) {
sum += (double)va_arg(pairs, int64_t);
sum += va_arg(pairs, double);
}
va_end(pairs);
return sum / n;
}