dwarf-assembly/stack_walker_libunwind/stack_walker.cpp

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#include "../stack_walker/stack_walker.hpp"
#include <libunwind.h>
#include <vector>
#include <cassert>
struct UnwPtrs {
unw_context_t* ctx;
unw_cursor_t* cursor;
};
static std::vector<UnwPtrs> to_delete;
bool stack_walker_init() {
return true;
}
void stack_walker_close() {
for(auto& del: to_delete) {
delete del.ctx;
delete del.cursor;
}
}
static unw_cursor_t* get_cursor(const unwind_context_t& context) {
// This is subtly dirty.
// unwind_context_t::rip is uint64_t, thus suitable for a pointer.
return (unw_cursor_t*) context.rip;
}
static void set_cursor(unwind_context_t& context, unw_cursor_t* unw_cursor) {
// This is subtly dirty.
// unwind_context_t::rip is uint64_t, thus suitable for a pointer.
context.rip = (uintptr_t) unw_cursor;
}
unwind_context_t get_context() {
int rc;
unw_context_t* unw_context = new unw_context_t;
rc = unw_getcontext(unw_context);
if(rc < 0)
assert(0);
unw_cursor_t* cursor = new unw_cursor_t;
rc = unw_init_local(cursor, unw_context);
if(rc < 0)
assert(0);
rc = unw_step(cursor);
if(rc < 0)
assert(0);
unwind_context_t out;
set_cursor(out, cursor);
to_delete.push_back(UnwPtrs({unw_context, cursor}));
return out;
}
bool unwind_context(unwind_context_t& ctx) {
int rc = unw_step(get_cursor(ctx));
return rc > 0;
}
void walk_stack(const std::function<void(const unwind_context_t&)>& mapped) {
unwind_context_t context = get_context();
do {
mapped(context);
} while(unwind_context(context));
}
uintptr_t get_register(const unwind_context_t& ctx, StackWalkerRegisters reg) {
unw_cursor_t* cursor = get_cursor(ctx);
unw_regnum_t regnum = 0;
switch(reg) {
case SW_REG_RIP:
regnum = UNW_X86_64_RIP;
break;
case SW_REG_RSP:
regnum = UNW_X86_64_RSP;
break;
case SW_REG_RBP:
regnum = UNW_X86_64_RBP;
break;
}
uintptr_t out;
int rc = unw_get_reg(cursor, regnum, &out);
if(rc < 0)
assert(false);
return out;
}