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#ifndef _SIGNAL_H
#define _SIGNAL_H
#include <stdc_common.h>
typedef long sig_atomic_t; // there are no "asynchronous interrupts"
#define SIG_DFL ((void *)0)
#define SIG_IGN _sig_ign
#define SIG_ERR ((void *)-1)
typedef void (*_Sighandler)(int);
struct sigaction {
void (*handler)(int);
unsigned long flags;
void (*restorer)(void);
unsigned long mask;
};
unsigned char _signal_restorer[] = {
0x48,0xb8,15,0,0,0,0,0,0,0, // mov rax, 15 (sigreturn)
0x0f,0x05 // syscall
};
#define _SIGNAL_HANDLERS 0xfff000
#define _LE64(x) (x)&0xff, ((x)>> 8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, (x)>>56
// we need to do this weird indirection because linux has a different
// calling convention from us.
unsigned char _signal_handler[] = {
// signal # passed in rdi
0x48,0x89,0xf8, // mov rax, rdi (signal #)
0x50, // push rax
0x50, // push rax (allocate space for return value)
0x48,0xb8,_LE64(_SIGNAL_HANDLERS), // mov rax, _SIGNAL_HANDLERS
0x48,0x89,0xc3, // mov rbx, rax
0x48,0x89,0xf8, // mov rax, rdi (signal #)
0x48,0xc1,0xe0,0x03, // shl rax, 3
0x48,0x01,0xd8, // add rax, rbx
0x48,0x89,0xc3, // mov rbx, rax
0x48,0x8b,0x03, // mov rax, [rbx]
0xff,0xd0, // call rax
0x48,0x81,0xc4,16,0,0,0, // add rsp, 16
0xc3 // ret
};
#define _SA_RESTORER 0x04000000
int __sigaction(int signum, const struct sigaction *act, struct sigaction *oldact) {
return __syscall(13, signum, act, oldact, 8, 0, 0);
}
void _sig_ign(int signal) {
return;
}
static unsigned long _sig_mask = 0;
_Sighandler signal(int sig, _Sighandler func) {
void **handlers = _SIGNAL_HANDLERS;
_Sighandler ret = handlers[sig];
if (func == SIG_IGN) {
func = _sig_ign;
}
handlers[sig] = func;
if (func == SIG_DFL) {
_sig_mask &= ~(1ul << (sig-1));
} else {
_sig_mask |= 1ul << (sig-1);
}
struct sigaction act = {0};
act.handler = func == SIG_DFL ? SIG_DFL : (void*)_signal_handler;
act.mask = _sig_mask;
act.flags = _SA_RESTORER;
act.restorer = _signal_restorer;
__sigaction(sig, &act, NULL);
return ret;
}
int raise(int signal) {
return kill(getpid(), signal);
}
#endif // _SIGNAL_H
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