Re: getcontext() -> Bus error?
Re: getcontext() -> Bus error?
- Subject: Re: getcontext() -> Bus error?
- From: Edd Dawson <email@hidden>
- Date: Mon, 11 Feb 2008 01:53:13 +0000
Kevin Van Vechten wrote:
On Feb 3, 2008, at 4:43 PM, Edd Dawson wrote:
That seems to have stopped the bus error -- thanks! -- but now I'm
getting what I believe is fishy behaviour from swapcontext(). The
following program prints "about to swapcontext()..." indefinitely.
The 4096-byte stack storage provided is too small for Darwin. The stack
size should be at least MINSIGSTKSZ (include signal.h to get this
constant).
Thanks again, Kevin. That worked great!
I hope this is my final question on the matter. The following code is failing on
Leopard. The assert() in main() is triggered. The vector's size appears to be 3?!
#define _XOPEN_SOURCE
#include <ucontext.h>
#include <signal.h>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <vector>
struct context
{
context(ucontext_t ctx, void (*func)()) :
ctx_(ctx), func_(func), stack_(MINSIGSTKSZ)
{
ctx_.uc_stack.ss_sp = &stack_.front();
ctx_.uc_stack.ss_size = stack_.size();
ctx_.uc_link = 0;
makecontext(&ctx_, func_, 0);
}
context(ucontext_t ctx) :
ctx_(ctx), func_(0), stack_()
{
}
static void change(context &from, context &to)
{
swapcontext(&from.ctx_, &to.ctx_);
}
ucontext_t ctx_;
void (*func_)();
std::vector<char> stack_;
};
std::vector<context *> all;
void die(const char *msg)
{
perror(msg);
exit(666);
}
void hello()
{
puts("hello");
assert(all.size() == 2);
context::change(*all[1], *all[0]);
}
int main()
{
ucontext_t ctx;
if (getcontext(&ctx) == -1) die("getcontext failed");
all.push_back(new context(ctx));
if (getcontext(&ctx) == -1) die("getcontext failed");
all.push_back(new context(ctx, &hello));
assert(all.size() == 2);
context::change(*all[0], *all[1]);
return 0;
}
I'm compiling with:
g++ getcontext3.cpp -o getcontext3 -W -Wall -ansi -pedantic
Thanks again for all your help so far!
Kind regards,
Edd
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